6:31 pm0
Lens Movements
There is quite a bit of confusion—at least in the terminology—regarding the lens adjustments made possible by perspective control lenses (also called "tilt/shift" lenses). The best, thoroughest, clearest explanation I've come across for this part of the photography technique comes from chapter 10, "View-Camera Adjustments", in Ansel Adams' famous "The Camera" book. I recommend you look it up for a more extensive explanation complete with illustrations and examples.
What gives these lenses their potential is that they have a larger image circle than regular lenses. Instead of simply being large enough to cover the sensor, their image circle extends far beyond and can therefore be moved around without introducing vignetting (not to be confused with illumination fall-off).
Geometric Distortion
The first set of adjustments are made to control convergence.
For example, this is what happens when the top part of a building appears smaller than the bottom part, because of a viewpoint that forces the camera to be tilted back. You cannot adjust the perspective with lens movements (only physically moving to a different position can change the relative distance the camera stands from the bottom and the top part of the building), but you can do something about the converging lines.
The basic idea is to position the camera so that the sensor plane is parallel to the surface you want to keep straight and simply slide the lens in order to place the part of the image circle that contains the subject where you want it. The amount of correction is therefore limited by how large the image circle is.
The sliding of the lens can be made in any direction allowed by the lens, to correct for lines converging in various directions (convergence doesn't necessarily only happen when looking up!) You can also create high-quality panoramic images by sliding the lens between exposures (never actually panning the camera), to produce (almost) seamless stitches.
If the lens is slid upwards, the movement is called a "rise". A downwards slide is called a "fall". Sideways, it is called a "shift" (left or right).
Focus Plane
The second set of adjustments are made to control the focus plane.
With regular lenses, the sensor plane and the lens plane are parallel, resulting in a parallel focus plane (depth of field extends front to back, parallel to the sensor). By changing the angle of the lens, the Scheimpflug principle explains that the plane of focus will end up at an angle as well, with the depth of field extending like a cone around that plane (see article for a complete explanation).
You don't need to bother with all that math. In simple terms, what it means is that because you can change the angle of the plane of focus, you can exert more control over which part of the image will be sharp. You could, for example, achieve a sharp image from right in front of the lens to the infinity, without requiring an overly small aperture that would be at worse impossible with regular lenses, at best detrimental to image quality because of diffraction.
By exploiting this optical phenomenon in the "wrong" direction, you can create a very slim section of sharpness in the image (almost perpendicular to the sensor plane), with the rest falling sideways out of focus — the trick behind the "fake miniature" effect.
When the lens is angled up or down, the movement is called a "tilt". When the lens is angled left or right, the movement is called a "swing".
Because the lens can be rotated, a combination of rise/fall/shift/tilt/swing can be achieved (depending on the capabilities of the lens — recent designs allow the slide movements to be rotated independently from the tilt/swing movements).
2:25 am0
Gel That Flash
When you want to harmonize the color of your flash with the ambient light, you first have to know which color the ambient light is, obviously. You might try to go at it by eye, or even by tradition, but you might not get the result you expected (for example, fluorescent light used to be very green, but this is not necessarily a reliable presumption anymore, since they now come in many colors, with arbitrary names like "cool white").
Since we don't walk around with colorimeters or computers to analyze our images (and because we just don't have the time to fool around anyway), there is an easy trick to reliably figure out which color the ambient light actually is. Your camera has an RGB histogram — all you need to do is to fill the frame with a neutral reference and you'll know!
Remember that since you only want to read the ambient light for this test, you need to turn off your flash. Also, it is important to use the "daylight" (neutral) white balance to do this test, otherwise you will not get a true assessment of the color (you will get something that was corrected in one way or another). The neutral reference could be a grey card (ideally), but it could also just be a white wall or piece of paper — as long as it fills the frame and is "close enough" to neutral you'll be alright, since you won't be able to surgically match your flash to that color anyway (there's only so much you can do with a couple of gels!)
I tested this in my living room, where the lamps use "compact fluorescent" bulbs — those are hard to guess. When the image appears on your LCD, display the RGB histogram, and you will see the color dominance right there:
In this case, we can see that there is far more red and green than blue. We can also see that although this is fluorescent, this is definitely not just green. Remember that with light, red+green=yellow! So in this case we have some kind of orange, because the red component is a bit stronger than the green.
Now all you have to do is pick gels that will add the same cast to your flash. If I had to act quickly, I would pick a strong orange and I know that I would get a pretty decent result. With just this one quick test, I am certain not to make a huge mistake and use a color that is way off.
To illustrate the effect the different gels produce on your flash, you can do a similar test: shoot a neutral reference, in "daylight" white balance, but this time with only the flash exposure (use a fast shutter speed and low ISO to remove any ambient light).
Using a strong green gel, we get this result:
Definitely not! Notice how the histogram doesn't look at all like the one I had with the ambient light only. Let's try a strong orange gel:
Well, this is much better. I could certainly shoot knowing that the color of the ambient light and the color of my flash are "close enough". If you want to match the ambient light even more closely, it's possible — at some point you'll get something like this:
A-ha! Well this is very, very close. But I had to use three different gels (from what I had in my kit), so this is getting a bit crazy. Also remember that each gel you add in front of your flash cuts some light — the more gels you use, the less powerful your flash becomes.
In practice, you might only have 2 or 3 degrees of orange and green in a basic kit. That's fine — most discrepancies can be removed with just these, even if they are not "perfect". The more you do this, the more you will be able to pick the appropriate gel (or combination of gels), since you will know what histogram they produce.
6:55 pm0
Mixing Flash with Ambient
Setting the shutter speed in the light meter
When using a Sekonic L-358 light meter to read a flash exposure (the same applies to other models, I am simply not familiar with them), one of the nice features it has is its ability to indicate which percentage of the total exposure came from the flash — the rest of the exposure being from the ambient light available in the location where the metering was done.
Here is a figure taken from the L-358's user manual:
Metering flash exposure
As you can see in this example, 70% — "Percentage of flash in total exposure" — means that the flash was responsible for 70% of the total light, while 30% came from the ambient light available. The total amount of light ended up requiring an aperture of f/5.6 and 3/10th (let's call this f/6.3).
If 30% of the total light gathered by the light meter during a reading comes from the ambient light, if you change the shutter speed (without changing the flash power), you should expect that percentage to change: the longer you expose, the more the ambient light will have an impact on the total light, since you will gather more of it (while still gathering the same amount of flash). On the other hand, if you expose for a very brief moment, you will gather very little of the ambient light (while still gathering the same amount of flash), so the ambient light won't have much of an impact in the total light.
You might very well end up in a situation where the flash is only responsible for a small fraction of the total light (say, 10%) or, at the other extreme, end up in a situation where the ambient light has no influence on the exposure (which would give a 100% flash exposure). For example, when working in a studio environment, we usually don't mind leaving the modeling lights on when shooting, because we know that the light they produce is insignificant in the total exposure compared to the flash power (we get a 100% flash exposure all the time regardless).
Now, coming back to a location shoot where we mix some ambient light with flash, we should often expect situations where the percentage of the flash in the total exposure will not be 100%. In the situation of the figure above, where 70% of the total light came from the flash, suppose we were to expose for 1/30 instead of 1/125 — that is two stops more ambient, giving us a brighter background. In this case, the flash would now only account for ~40% of the total exposure. What's more, since we're adding ambient light to the previous exposure (flash remained the same), we now have more light overall, so we must use a smaller aperture — we go from f/6.3 to ~f/9.
This makes the shutter speed a crucial parameter to provide to the light meter, otherwise the obtained value will be wrong.
The only situation in which we could ignore the shutter speed would be in a pitch-black room where the only light is the flash — in this case, the ambient light (or lack thereof) would have no impact in the reading whatsoever.
Changing our perception of flash color gels
If you're mixing flash with ambient light, you know that you can (must?) correct the color of the flash so that its light color is well harmonized with the ambient light color, lest you get a quirky result.
But you can also use color gels not necessarily because you want to make the two light sources the same, but because you want to add an effect, such as warming up the subject so that it contrasts more with a colder background, for example.
In the image below, both the foreground and the background lights are of the same neutral color:
Foreground and background light have same color
Using a CTO gel (orange) on the flash aimed at the subject, you can warm up the subject, which will further isolate it from the background (which will now be of a relatively colder color than subject, even if it is the same as in the first shot):
Foreground light is warmer than background light (note: a strong color was used to make the illustration obvious)
Indeed, while the background remained the same, it can be said that the subject is warmer.
You will notice that I also (conveniently) included a gray card in the frame. If we take the picture above (the same exact file), but that we color correct using the gray card, here's what we get:
Image above, but white balance corrected with the gray card
You will notice that the subject is now perfectly neutral — exactly back to what we had in the first frame — but that the background turned blue (colder)! In this case, can it be said that the subject is warmer than in the first shot? Absolutely not — in fact, they are exactly the same, after correction, even if a "warming" gel was used.
If you're going to include a gray card (or GretagMacbeth chart) in your frame, you might want to do it while you're not using a gel on the subject, otherwise, balancing the color with a neutral reference will remove any color you might have thrown on the subject and, rather, affect the background. If you're going to include a gray card in your frame while you are using a gel, the way you should look at it is that you are in fact changing the color of the background in the opposite direction than that of the color gel (e.g.: if you're using a warming color on the subject, you're actually not changing the subject, but rendering the background colder!)
The fact that we are using a "warming" gel has no bearing on the final look of the image, because it depends on the white balance selected. A "warming" gel might therefore be more meaningfully seen as a "gel that makes the background colder"! That is why, when you work indoors under tungsten lights, you use a warming gel: not to warm up the subject (you still want it neutral), but rather to make the background colder.
8:11 am0
On White Balance
So you want to get accurate white balance. There are many ways to get there, if you know why you are doing it and what you want to achieve.
If you're shooting raw, you're probably aware that you don't technically need to worry about it at capture time, because it's not set in stone — whatever setting you use won't definitely affect your final image; you'll easily be able to change it in your raw processor. (Of course if you're shooting JPEG, then you'll definitely want to nail it as close as possible to your objective to minimize the amount of manipulation required. But you're not shooting JPEG anyway, are you?)
So you're shooting raw. Why even bother performing your white balance at capture time, then?
- One reason might be to get a better approximate histogram, so that you can better judge your exposure. Indeed, you might think that one of the channels is clipping when, in fact, it's the color cast that was throwing off the histogram. But then again, if you're evaluating the exposure another way (say, with a light meter), then this won't matter to you.
- Another reason might be to get a better approximate image preview, so that you can better judge the colors. Of course, you can't really rely on the image preview on that little LCD for accurate color evaluation, but surely, if the color balance is completely off, it might be quite misleading. But then again, you might only use the image on the LCD to judge the composition, pose and other aspects of the image, keeping in mind that color will be dealt with afterwards, so this, too, might not matter to you.
- Yet another reason might be so that when the unprocessed images pop up on your computer screen, the client watching you work will have a better idea of what the images will look like right away. Indeed, the client might not respond well if there is an annoying color cast in the images, even if you know you'll fix it later. But if you're not shooting tethered with a client watching over your shoulder, this might not matter to you either. (Note that some raw processors, such as Capture One, can be configured to automatically apply a certain white balance to all imported images, so that the images are immediately corrected, regardless of how they were shot, which is another reason why performing in-camera white balance might be irrelevant to you.)
Only you can know how important it is for images to be properly balanced at capture time, but if you want to do it, there are many ways to go about it.
- One way is to use the Auto White Balance feature of your camera. Sometimes, in rapidly/wildly changing light situations, this setting might be more efficient at getting a decent approximate white balance than having to fiddle repeatedly with your camera's parameters. If you're not working in such a difficult situation and the color of the light is not changing — say, you're working in a studio — then this setting might, on the contrary, produce unpredictable results.
- To get consistent results, another way is to use one of the white balance presets your camera offers — things like "sunny", "cloudy", "tungsten", "fluorescent", etc. This usually won't give you an exact result, but you'll likely get reasonably close to your target for your histogram and image preview to be very usable.
- If this is not good enough, a more sophisticated way to set the white balance would be to manually enter a kelvin temperature (which, unfortunately, only affects the blue-yellow axis, not the green-magenta color), or further tweak the result with the "white balance shift" tool. (Have fun. Who wants to spend time doing that?)
- Finally, the most accurate in-camera result you can achieve would be to use the "Custom White Balance" feature.
Bear in mind that whatever approach you choose, none — not even the custom one — will give you a surgically exact result. The only way to get a better result would be to include a neutral reference in a photo under each light situation, and later use that reference to synchronize the white balance for all the images shot under this type of lighting.
For the most accurate readings, you might include a tool like a WhiBal gray card, which is good to take care of the white balance, or go one step further with an X-Rite ColorChecker Passport, which includes a good ol' Gretag MacBeth color chart as well as the software required to generate camera calibration profiles for Lightroom — serious business!
If you don't want to spend the money (or carry these around, or shoot those test shots), for fairly good results, many common objects will be good enough to get you close to your target and allow you to work without having to worry too much about color. This might be a piece of white paper, tissue, gray hair, etc. It would be pretty hard to judge if these references are absolutely neutral (unlikely), so you understand that those are not perfect solutions. (For example, stuff usually increasingly turns yellow as it gets older.)
But keep in mind that few situations require critically accurate color — you be the judge. (Sometimes, even a perfect white balance won't be enough and colors will have to be manually tweaked in Photoshop with a virtual reference anyway (such as a Pantone swatch), and yet even then, color accuracy will likely take another hit when the image gets to the printer, so this discussion is at least partly moot.)
Now, in those situations where extreme color accuracy will not be an issue, you will have to determine if accurately reproducing the scene is what's important to you. Often, perfect color balance will not yield the image that will look better to your eye — you might very well decide that warming, cooling or otherwise coloring your image will produce something that is more pleasing, whatever light was there the moment you took the picture. You might even decide to convert your images to monochrome, and maybe even to tone them. Yet another reason why you might not need to worry too much about technical accuracy, but more about achieving an image that speaks to you.
For those reasons, on a more practical/pragmatic note, unless critical color accuracy is expected, I will usually save time and use one of the camera presets to get reasonably close results in-camera (so that I can still get useful information out of my histogram and image preview), include a WhiBal in the first shot if there are no other useful neutral references around, and tweak the results in post anyway. If I know in advance that I will deliberately change the look of an image, I might use a different preset (such as using a "cloudy" setting on a sunny day to make the image warmer); this will give me a better instant feedback, even if it won't have any definitive effect on the image until I make the final decision/adjustment in post.
If you still want to perform a custom white balance to get as close as you can in-camera, note that Canon and Nikon employ dramatically different procedures to achieve this (I am not familiar with the way other brands work):
- With a Canon camera, the procedure requires a ridiculous number of steps (which explains why I usually don't bother). You first have to shoot a picture of a neutral reference, filling the center part of the frame with it. You then have to go to the "Custom WB" menu option. You then have to point the camera to the picture of the neutral reference you want to use for the calibration (usually the one you just shot), and then confirm your choice. You then have, each time, to dismiss a non-removable reminder that tells you to change your white balance setting to "Custom". You then have to go ahead and change the white balance setting to "Custom". (Still there?) If this wasn't enough, you'll also be left with an otherwise useless frame, on your memory card, that was shot just for this, which you might want to delete. (Or you'll keep it and use it to perfect the correction in post...)
- With a Nikon camera, the procedure is decisively more efficient (take a hint, Canon). Set the camera to the "Pre" (preset) white balance setting. Hold the white balance button for two seconds until "PRE" starts blinking. Shoot your neutral reference.
If the procedure fails because the camera doesn't want to take the shot, this is because you're in a "one-shot/AF-A" autofocus mode that won't allow you to shoot until focus is obtained. Contrary to what you might have been told, performing a custom white balance does not require the camera to be set to manual focus, but since the neutral reference is usually a plain card, the AF system simply won't be able to achieve focus, which is the reason it will appear not to work. Just focus on something else or set the lens to manual focus — it doesn't really matter, as long as the center part of the frame contains the neutral reference. (If you're shooting in a continuous AF mode, this won't be an issue.)
If the procedure fails with the camera telling you it couldn't perform the calibration, that's because the exposure was completely off: the camera cannot read the color information out of a clipped highlight. Make the exposure average, or use a semi-automatic mode just for that shot (such as aperture-priority).
Make sure you actually do your reading based on the actual light conditions you'll be shooting in... This is especially relevant when you're working with flash — you don't want to perform your studio calibration based on the ambient light, or your location calibration on incorrectly gelled/randomly bounced mixed-light and get results that don't make sense.
7:04 pm0
Notes on TTL Flash
Since there seems to be a lot of misunderstanding concerning the use of Speedlites (portable electronic flashes), I feel the need to bring some precisions. (Note that although a lot of functionalities, parameters and behaviors are similar from one brand to another, since I am more familiar with Canon equipment, there are times when it will be preferable that you look for additional information.)
What is TTL flash metering?
At first there was manual flash exposure, which meant that the photographer had to know the guide number of his unit and calculate effective distances against apertures and ISO numbers using the inverse-square law bla bla bla... For example, a flash unit with an (imperial) guide number of 100 would correctly expose a subject 25 feet away with an aperture of f/4 (because 100 = 25 x 4). And, oh, that's for ISO 100, and no, you can't see if what you just did was correct, because you're shooting film. Now calculate equivalences along the way, as you're shooting your event. Lots of maths, trial and error (but mostly error). Thank goodness, this era is long gone.
Then there was automatic flash exposure, which was calculated by the flash unit itself using a little photo cell. The flash would emit light and judge if enough had been emitted by the general amount of light reflected back. Needless to say, this was not very precise and could only hope to work when the flash was used on the camera's hot shoe. (Later versions offered a way to separate the photo cell from the flash unit so the flash could indeed be used off-camera, but this only solved part of the problem.)
Then, at last, came TTL flash metering. (TTL metering had appeared long before for ambient light metering, but was now also available for flash exposure.) Instead of letting the flash unit calculate if the proper amount of light had been emitted, it left that job to the camera, using exactly what it had seen "Through The Lens". The thing to remember, though, is that the core addition to TTL flash is not so much the fact that the camera and flash unit now talk to each other using more pins on the shoe (which it obviously has to, to achieve the result), but the fact that the metering is done by the camera, through its lens! The more the camera and flash can talk the better to automate the process and achieve more accurate results, but that doesn't change the core fact of who's doing the metering.
What's the focal length got to do with the flash?
The flash doesn't have to know what focal length is used to work properly, but by concentrating its beam on an area that is not wider than the area covered by the focal length, it can preserve its power that would otherwise be wasted to light areas not even seen by the camera. By doing so, it can actually improve its effective reach and illuminate more distanced subjects. This used to be performed manually with Fresnel adapters installed on the end of flash units, but is now fully automated — insofar as the unit is able to. (As a matter of fact, if you're using very long lenses (in wildlife photography, for example), you might be interested by accessories such as the Better Beamer.)
The image area, when using a longer focal length, is increasingly smaller than the area covered by a flash that doesn't concentrate its beam
The flash's zoom allows it to concentrate its beam to the meaningful area, improving its reach/conserving its power
That's all there is to it! The fact that each flash unit can cover different "zoom" ranges doesn't mean it stops working properly if the lens is set to a longer focal length, it only means it won't be able to concentrate further its beam, therefore not improving its effective range further. There is nothing you can do about it (apart from hooking an accessory to the end of the flash).
Why does the flash ignore the lens' focal length when aiming its beam anywhere but forward?
Well, this should be rather obvious: if you're not beaming in front of you with the flash, then whatever focal length you are using is meaningless for the flash, since its beam is no longer aimed in the same direction.
When you aim the beam to the ceiling, for example, what you're hoping to do is to bounce the light so that the (main) source of light now becomes the ceiling — at this point, changing the flash's zoom would mean beaming a wider or narrower spot on the ceiling, which has absolutely nothing to do with the lens' focal length. Setting the orientation angle of the flash head likely has a much more significant impact on the reach/effect of the bounced light than how wide the beam is on the ceiling, depending on how far it is, etc. Since the camera has no way of knowing how far the ceiling is (or if it is flat, etc.), there is no way it can decide how wide the beam should be. Therefore, it defaults to an average value — not the longest, because a small beam on the ceiling would mean harsher light, which is exactly what we are usually trying to avoid.
You can always change the flash's zoom value manually, if you so wish, but there is no question that linking the focal length to the flash's zoom when beaming anywhere but in front doesn't make any sense.
Additionally, with Canon Speedlites (I cannot comment on other brands, which I don't know as well), when using the included diffuser (the one that retracts inside the flash head), the flash's zoom automatically goes to its widest value — because the point of this diffuser is to achieve an extra-wide angle of 14mm (14mm being the widest lens available in the Canon lineup). This also means that the flash won't be as powerful, since it is spreading its beam much more.
Is the flash metering related to the focus point?
Since I am more familiar with Canon equipment, I cannot confirm for every other brand (check your equipment's documentation), but I would think that the behavior is very similar. With Canon cameras, ever since E-TTL II came along (that's a long time ago, circa 2004), flash metering is no longer linked to the autofocus point selected. This means that you can use the "focus-recompose-shoot" technique freely without worrying that the flash metering will be thrown off.
The metering will also use information from the focus distance (when available — this is a per-lens capability) to calculate its power. This means that if the focus distance is on a subject, it will likely expose the subject properly and pretty much ignore the background (which means potentially leaving it dark). If the focus distance is on a background, it will likely expose the background properly and pretty much ignore the subject (which means potentially overexposing it). Exactly what we would expect, considering that the in-focus area is likely the most important part to light properly.
What is the FEL button doing?
First, we have to understand that regardless of our usage of the Flash Exposure Lock (FEL) function, there is always a pre-flash when using TTL metering. Since the pre-flash occurs right before the actual exposure begins, it is hardly noticeable. (When using rear-curtain synchronization, the two separate flashes will be very obvious, because they will occur before the exposure and right before the end of the exposure, respectively, giving you plenty of time to see the two bursts.)
So the goal of the FEL is not to generate a pre-flash (that, we always get). The point is to lock the flash metering — exactly the way the auto-exposure lock (AEL) works with ambient light, but with flash. Why would you do that? Well, if you don't want the flash to be metered based on the final scene (because there might be something you anticipate will throw off the metering, such as a bright white background or, conversely, lots of black tuxedos in the frame), you can trigger the calculation on a different scene or on a specific area of the scene (by zooming in on a subject's face, or by using a different metering zone pattern, for example) and then recomposing-shooting, which will use the flash metering that was calculated before.
If you're systematically using the FEL before each time you shoot, ad nauseum, without significantly changing the frame, you are wasting your time (and battery power). I hardly ever use that function, but it can be useful in difficult situations — just as much as AEL is with ambient light (which I never use). Instead, I tend to prefer using exposure compensation, which I find more predictable.
Note that here, Canons and Nikons work rather differently. Canon's FEL locks the flash metering only as long as you hold the shutter release half-way (otherwise it forgets the flash metering after about 16 seconds, or very quickly after a shot). A little star (*) appears in the viewfinder as long as the FEL is active, and a new FEL will have to be be performed each following time you need it. Nikon's FEL (at least, the way I was told it worked) locks the flash metering for as long as you don't press the FEL button again — the flash exposure will be the same for all the following frames until you unlock it.
What about exposure compensation?
Like I was saying, I tend to prefer exposure compensation over FEL, because I can better judge how to tweak the exposure than by trying to aim at something that I think would be closer to what I want (good luck!)
There are two ways you can apply flash exposure compensation (FEC). You can either apply FEC on the camera, or on the flash unit itself. With Canon (again, I cannot confirm for other brands), if you apply a FEC on the flash unit, it overrides whatever setting was in the camera. I personally prefer applying FEC with the camera, because I can reach the button right next to the shutter release without even having to move my eye away from the viewfinder, and I see what I'm doing from the display at the bottom of the viewfinder.
To wrap up...
One thing is for sure, working with flash requires practice, because it is much less predictable (especially when bouncing off various surfaces). It gets particularly tricky when mixing flash with ambient light, because now you have two independent exposures to oversee, plus color balancing with gels, etc.
Get to work!
2:52 pm0
Camera Raw Workflow Options
You know that "link" at the bottom of Camera Raw?
Camera Raw Workflow Options "link"
It allows you to change a couple of important Camera Raw options. These settings are not image-specific, meaning that they are not saved in the metadata of a file (be it in the XMP or embedded in a DNG) and therefore cannot be synchronized between images. These settings are global and if you never change them, they will never change from image to image.
With that said, let's look at these options in more detail:
Camera Raw Workflow Options Window
First of all, we have to understand that a raw file is not yet processed, it is not yet a matrix of "pixels", therefore it doesn't yet have a color depth or color space — it is only the end result of the processing that is made to fit inside those constraints.
In order for Camera Raw to present to you a preview of the file as it will look like once processed and to present to you an histogram that is representative of that preview, it has to know to which color space and bit depth you will export the file. (If you've been working with Adobe Lightroom, you know that there is no such option window — that is because Lightroom works natively in ProPhoto RGB at 16 bits/channel and only (optionally) converts to more restrictive constraints when images are exported or sent to an external editor.)
In Camera Raw, you will notice right away that if you choose a smaller color space in the workflow options (say, sRGB), the image preview and histogram will automatically reflect that change: highlights and shadows will be clipped far sooner, as a result of values being constrained to a narrower gamut. Therefore, you should set these options before you start processing your raw file, otherwise you will be mistaken in setting your white point, saturation and other significant values.
Speaking of color spaces...
Different people have different opinions on the matter of color space, but I prefer to work just like Lightroom, in ProPhoto RGB at 16 bits/channel, and only squish image data at the very end of the workflow (usually when exporting images for the web). If you've been reading reviews of the latest inkjet printers, you will know that Adobe RGB is not big enough any longer. Here is an excerpt from a review of the Epson Stylus Pro 7900/9900 printers:
This new ink set is called Ultrachrome HDR and for the first time in an Epson Pro series printer Green and Orange inks are utilized. This actually allows these printers to exceed Adobe RGB in certain parts of the spectrum, by a not inconsiderable margin.
What this tells us is that we don't know what new technology will pop up around the next corner, therefore we should keep as much information in our original files as possible — it doesn't hurt since we're keeping the files in 16 bits/channel.
Speaking of bit depth...
Indeed, there is no question that you should work in 16 bits/channel. 8 bits/channel is generally okay for a final image, but not for one that is still subject to manipulation (since, as we know, manipulation implies loss of information). If you start with 8 bits/channel and manipulate, you will end up with less than 8 bits/channel, and this will likely show up as posterization (especially in smooth gradients) — you know you're in this situation when your histogram has gaps.
That being said, Color Space and Bit Depth are really the only two workflow options you should consider while working in Camera Raw, as they are the only ones that will have an immediate effect — all the others will only have meaning once you export the image out of Camera Raw.
The only time you would play with the other settings (Size, Resolution and Sharpening) is if you were going to use Camera Raw itself to export finished products. I personally prefer to let Photoshop handle that, so I actually never touch these settings (except the first time I open up Camera Raw after installing the Adobe Suite, of course), leaving them as they appear in the screenshot above, for optimal quality.
The problem is that if you change these settings, the next time you open up Camera Raw, you will have to reset them back to the original values — something you are likely to forget, which would mess up your files (more on that later). This constant hassle to reset the settings back and forth depending on the usage of the file (immediate export vs. further work in Photoshop) is enough to make me want to batch process my exports through Photoshop and always leave these options alone to the optimal quality.
To complete our exploration of the options...
As I was saying, unless you're going to, say, export JPEGs for the web directly from Camera Raw, you should leave the Size option to the 1:1 value (no upresing nor downresing). Resizing is better left to the specialists — the algorithm applied here is not as optimal, nor as parametrable as the one you can use in Photoshop. Every resizing calls for interpolation, which means loss of detail, so you should only go through one resizing procedure, if needed, at the very end of the workflow, before you export.
Resolution, as it's been said before, doesn't mean anything until you start talking about printing. Whatever value you put here is meaningless as long as the file is not actualized. Stick to 72 if the file is going on the web (merely because that is the established standard), but otherwise, this number has no effect on the image whatsoever.
Output Sharpening, too, should definitely only be used if you're going to export files directly from Camera Raw. This, too, is a step that should be done at the very end, and is specific to where the file will be going. You don't apply the same sharpening on files viewed on screen vs. files printed on glossy paper vs. files printed on matte paper vs. etc., so you shouldn't apply it at this point if the file will be going to Photoshop for further processing.
To wrap up
Frankly, unless you're going to use Camera Raw to export images directly, to get optimal results, save time and avoid mistakes, I strongly recommend you use the settings shown in the screenshot above and never bother touching them again.
But it gets better...
Wouldn't it be nice if you could just change your mind later, once you're in Photoshop and it's too late because you've left Camera Raw? Wouldn't it be great if every setting in Camera Raw could still be changed later, once you're in Photoshop (and I really mean every setting, not just the workflow options)?
Well, they can, and it's amazingly simple to do! Instead of using the "Open Image" button (which rasterizes the raw file for good), simply hold the "shift" key to turn the button in an "Open Object" button. Ta-dah! You're now working with a "Smart Object": the raw file is now embedded inside your Photoshop layer and can always be edited back in Camera Raw when needed.
Raw file appears as a Smart Object
To bring the raw file back in Camera Raw, simply double-click on its thumbnail, and voila!
Note that this embedded raw file is not linked in any way to the original raw file that was opened as a Smart Object — you could always move the initial raw file or delete it altogether and it would not affect your image in Photoshop. Note as well that any Camera Raw parameters you change when editing your Smart Object will not be applied to the original raw file neither. It really is a copy of the raw file that was embedded inside the Smart Object, not just a link that was established.
7:18 pm0
Expose to the Right (and then some)
Following up on the previous post, where I was making the point that fully embracing the new photographic technologies meant more than shooting raw, I would like to point out to a recent post by Michael Reichmann. His text, from just a couple of weeks ago, was an open letter to Leica, explaining his ideas on how to improve their cameras.
The most interesting part of the letter, for me, wasn't so much Leica-related, but the part where he clearly stated how camera makers (and camera users, by extension) should fully come to terms with the actual behavior of the current technology:
All major digital camera makers seem to be stuck in the film era when it comes to exposure metering and setting. Part of the problem is that consumers want the image on the rear LCD or in the viewfinder to "look right", but looking right and being optimum from a raw image quality perspective are not the same thing. [...] In other words – let's leave the film exposure paradigm behind. Digital exposure is different than film exposure, and basing 21st Century cameras on 19th Century exposure rules has to end.
Well that's all good — we're all familiar with the "expose to the right" approach to optimizing exposure, and that understanding leads us to deliberately use generous exposures in the field, when gathering ambient light.
But what about when we're working in a controlled environment, when using strobes in a studio for example? There, it's as if we suddenly forget the "expose to the right" mantra and rather rely on our flash meters to calculate the exposure. If we want to push the reasoning all the way, shouldn't we reconsider our approach?
Let's consider this very simple experiment. Single Speedlight in a Lastolite EzyBox to camera left, ISO100 at f/5.6. This is what we get (as expected): a "correct" exposure.
Flash Meter at f/5.6, ISO100
I took an item on my desk that contained bright white, so that we can really see what's going on:
Tissue Box at f/5.6, ISO100
Whites are white — no doubt about it. Now let's double the flash power (f/8), but leave the aperture at f/5.6. This is what we get, straight out of the camera:
Tissue Box, 1-Stop Over-Exposure
Overexposed! But of course, this is exactly what we would expect — exposing to the right is supposed to optimize the file, not get the best result straight out of the camera (or on the LCD display, or on the histogram). As a matter of fact, this is what the two histograms look like, without any adjustment:
Histogram Comparison
According to this histogram, we were too enthusiastic and went too far to the right — we know that we shouldn't clip the highlights, because then we can't bring them back at all. To adjust the exposure so that we get (visually) the same result as the first file, I simply pull back the "Exposure" slider in Camera Raw — I'm not even messing around with the "Recovery" hack, there is no need, there is plenty of information in the highlights. Ta-dah! This is the result I get:
Tissue Box, Exposure Adjusted in Camera Raw
Well well. Nothing is clipped now, I get information everywhere from that same file, which was over-exposed by a full stop.
The question is, did this really have any effect on the quality of the image? Well yes it did indeed. Remember that this image was shot at ISO100, so the noise was already pretty low. But by taking a region from the blurred background and bringing up the exposure to get a middle gray (which, obviously, enhances the noise further) and removing any kind of noise reduction there was, we get this result:
Noise Comparison (200%)
I will grant you that, in practice, this would not be much to write home about. But certainly, even in an ideal situation, there is a difference — deeper shadows, in particular, would benefit even more from this 1-stop gain.
Now this is where it gets interesting. Because we know that the "expose to the right" approach has a more obvious impact on the quality of a file in the shadows, and especially when we're dealing with high ISOs, there is another situation where we should definitely apply it.
When we're working in a mixed "flash+ambient light" exposure! In these situations, we normally have large parts of the image in darker tones, and we're usually working with rather high ISOs to get acceptable shutter speeds. The typical exposure is usually somewhere around the -2 stops for the ambient, over which we add the flash. Well, I'll let you work out how you incorporate the lesson from situation to situation, but in the end it should probably look more like -1 stop for the ambient, +1 stop for the flash!
1:24 am1
Camera Raw is not Just an Import Plug-in (Anymore)
Back in 2002, when Adobe Photoshop 7 came out, it featured a new plug-in called Camera Raw 1.0, to provide support for reading raw files. At the time, the functionalities offered by Camera Raw were very limited, and it was used basically as a mere import plug-in for raw files. Camera Raw started to be a more serious tool at around version 3 (with CS2), and by version 4 (with CS3) it had matured into a pretty powerful raw processor.
If you've been shooting for a long time and actually went through the transition from film to digital (I have not), you've had to relearn your post-processing workflow many times over to adapt to the rapidly changing technology. You've likely started to work with digital long before digital cameras (and raw files) even existed, and your basic workflow meant scanning negatives/slides into high resolution TIFF files and going straight to Photoshop to do all the processing. When serious digital cameras came out and you started using them, you've been told that raw files contained much more information than JPEGs (or even TIFFs, for some cameras used to optionally shoot straight to TIFF), so you've gladly begun shooting raw.
Now even you are advocating shooting raw to preserve all the information the camera can capture — which is good — but you may still see the raw processing step as a mere intermediary to Photoshop, where all the serious stuff goes down. You'll say things like "Well, you see, here you have all these sliders that you can play around with to change your exposure, white balance, curves and all — kind of a simplified version of the basic functionalities you get in Photoshop... But, you know, we are all eager to bring that file into Photoshop, a much more powerful tool anyway, so we'll go right ahead and press 'Open'." You'll then lecture on using the Threshold adjustment layer to find your black and white points, using Color Samplers to locate them, and use a Levels or Curves adjustment layer to set the clipping with the black and white eyedroppers — you won't fail to mention that one should probably aim for 10 black and 245 white at most, because printers cannot manage further extremes; you'll add a Color Correction adjustment layer to fix the color cast; etc.
Now that's what is known as old think.
Don't get me wrong; I'm not saying this won't allow you to achieve satisfactory results — go right ahead and use whatever you are more comfortable with. Daniel Malka said it best when he said: "If it looks good, it's good, right?" If you've been looking at Joey L's early work, for example, and have been blown away by the results he achieved, you wouldn't really care to know that his Photoshop techniques were, at the time, profoundly lacking (as even he acknowledges).
But still, if that is the way you see your typical workflow, you are missing out on what raw files have to offer; you haven't fully embraced the digital workflow to the fullest; you have kind of a half-assed approach to image processing that is tainted by your past experience; you aren't extracting all the detail you can out of your files. Even a 16-bit, ProPhoto RGB TIFF file only has a fraction of what the raw file has to offer, for the simple reason that as soon as you leave the raw file, you are working with a baked file: everything you'll do to the image from this point will be destructive, and you'll never be able to extract all the detail that was available in the source file. That's because a raw file has not been demosaiced, it's still in a linear gamma, and all the settings you play with are only parametric: they are not affecting "pixels" yet.
For optimal results, ideally, you should be doing as much of the work as possible on the raw file (be it using Camera Raw, Lightroom or any other raw processor) and only open the image in Photoshop once you've exhausted all the possibilities, for more complex local/pixel-level editing (when needed). Camera Raw and other raw processors now even provide some level of parametric local adjustments (especially since Camera Raw 5, Lightroom 2, etc.), so there is no excuse. The white and black points (referred to as "Exposure" and "Blacks" in Camera Raw/Lightroom) are particularly important, because you cannot recover blown highlights once the image has been baked, no matter the bit depth and color space...
But don't take my word for it. For an excellent primer on the raw processing workflow, you should definitely read the first three chapters of the Real World Camera Raw books by Bruce Fraser and Jeff Schewe — even if you're not working specifically with Camera Raw. (Note that Lighroom uses exactly the same processing engine as Camera Raw.) Or you can always watch one of the comprehensive video tutorials with Jeff Schewe and Michael Reichmann back at the Luminous Landscape.
1:28 amOff
Exporting JPEGs for the Web from Lightroom
There seems to be quite a bit of confusion regarding the exportation of JPEG files from Lightroom. The "Export" window itself is rather straightforward, but you still have to know which setting is more appropriate for your needs. In particular, three settings may need further explanation.
Screen Sharpening
In a complete image processing workflow, there are commonly three different kinds of sharpening applied at different stages and for very different purposes.
It is important to understand that most of the sharpening is necessary even if one does not want to apply it "for effect", because of various limitations along the workflow. It should be noted that a basic sharpening workflow is not aimed at correcting soft images (caused by focusing error or motion blur), but at maintaining optimal detail in files that already contain as much as they can.
- Capture Sharpening (or Input Sharpening) is applied first and is necessary to restore loss of detail inherent in digital capture. That is particularly obvious when anti-aliasing filters are placed in front of image sensors to reduce moiré, as is very often the case (except on most digital backs, the Leica M9, and others). That is why the default behavior in Lightroom/Camera Raw and other raw processors is to systematically apply at least a basic amount of capture sharpening, which must then be refined manually (depending on various factors such as frequency). Note that this is true only when shooting raw files—shooting JPEGs means that the camera has already applied sharpening, so additional work on the file must be done carefully.
- Creative Sharpening is usually applied locally on specific regions of an image that require it most (such as the eyes and mouth when working on a portrait). This is the only kind of sharpening that is applied "for effect", where the photographer decides whether he wants his image to look natural or more crunchy.
- Output Sharpening is applied at the very end and is totally dependent upon the destination of the image. Luckily for us (and thanks to the work of Bruce Fraser and the guys at PixelGenius), Lightroom makes it incredibly easy to properly perform this task, which used to require a lot of trial and error. The thing is that if the image is going to an inkjet printer on glossy paper, the sharpening applied is not the same as the one applied for matte paper, and is not the same depending on the resolution of the print, and is very different from the one applied for viewing an image on screen. On one hand, inkjet printers inherently introduce a certain loss of detail because of the nature of the technology itself, so some additional sharpening must be applied—sharpening that would definitely look ugly if the image were to be viewed on screen. On the other hand, images need to be resized to be of an appropriate size for viewing on screen, and resizing an image calls for interpolation algorithms, which also means a loss of per pixel detail. This is why Screen Sharpening is required, not "for effect", but to maintain optimal detail when the image is to be viewed on screen.
Applying a "Standard" amount of screen sharpening to JPEG files exported for viewing on a web page is a very good idea—not to make the images look crunchy, but to retain an optimal level of perceptible detail.
Note that whether you intend to export images for the web or to print them, output sharpening is not something Photoshop will do automatically or even offer. When you want to do it yourself in Photoshop, the burden is on you to apply the optimal sharpening for a given destination—good luck! Do yourself a favor and just don't do it that way... Either print/export from Lightroom, or use PixelGenius' PhotoKit Sharpener and skip output sharpening altogether in Lightroom.
Resolution
When exporting images for viewing on screen, the resolution of the file has absolutely no meaning, so whatever value you put in that field has no importance and, contrary to what you might have been told, will have no effect on the exported file—files won't have more or less detail, and file size will not be affected at all. The important factor when exporting files for the web is the size (in pixels), not the "resolution".
Traditionally, images consumed on a computer screen have been set at 72 ppi (so you might as well put that), but that really depends on the resolution of each monitor—something you have no control over when you publish images on the web.
Color Space
If a file is going on a web page, because we cannot know if the browser used to view the image will support color management, we should aim for the common denominator (it won't support it) and choose the sRGB color space (the default presumption when color management is not supported).
The gamut of the sRGB color space is smaller than the gamut of the AdobeRGB (1998) color space, which itself is smaller than the gamut of the ProPhoto RGB color space—that much is true. But "color spaces" must not be confused with "color models".
The fact that most commercial printers offer very limited gamuts has nothing to do with the fact that they work in CMYK (a color model, not a color space). One simply has to have a look at Bill Atkinson's book to realize that commercial printers are technically able to achieve excellent gamuts and color fidelity when they put in the required effort.
In other words, the CMYK color model itself does not define the gamut, so it would simply make no sense to state that "CMYK has a smaller gamut than color space X".
4:56 pm2
Tethered Power Consumption
Does using your camera tethered use more battery power?
Well, in a way, I would be forced to answer: yes, it does—at least, that's what I have observed with my Canon cameras (I can't comment for other brands). It's not so much that the cameras consume more battery power, it's that once the camera is plugged in and recognized by the EOS Utility (in the case of my Canon cameras), it will never go to sleep!
You know how after a while (say, a minute), the cameras will go in "stand by" mode (you can tell, because its top display turns off), consuming very, very little power? (So little, in fact, that I sometimes don't even bother turning them off.) Well, they never do that when they are hooked to the computer, to maintain the communication alive.
You'll notice that if you hook your camera to your computer and never fire a single frame, a couple of hours later the battery will be dead anyway! If you're going to shoot for a full day tethered, I recommend you bring a second battery with you—or, at least, recharge your battery during lunch time...