Does digital have same contrast ratio as film?

[jean_henderson]

<p>For a couple of years back in the day I worked the zone system in B&W. I know that B&W has a deeper ratio than color in film. Do these ratios hold true for digital work? I no longer have the standard charts to check this out for myself so hope that someone can enlighten me. Thank you.</p>

[lad_lueck]

<p>Digital captures linearly. Film has toe and shoulder.<br>

In digital, you capture as exposed as possible, without clipping the highlights, and in post you apply the tone curve that gives you the feel you want...</p>

[jean_henderson]

<p>Thank you, Lad. I think I've got it. You expose for a range that includes highlights because you can't unblow them, but you can lighten up the shadows in post if they are underexposed. Is that right?</p>

[eric_boutilier_brown1]

<p>You are correct - in simple terms - Expose for the highlights, process for the shadows.</p>

[jean_henderson]

<p>Thanks!</p>

[ben_goren]

<p>Jean,</p>

 

<p>A couple words of caution.</p>

 

<p>While blown highlights are simply gone, and while you can recover something from the

shadows…in most cameras, there’s a lot of ugly noise lurking in the shadows, at least

if you try to boost them too much.</p>

 

<p>Digital also has the potential to blow only one or two of the three channel, which can be even

harder to deal with than blowing all three channels. Red flowers in sunlight are notorious for

exposing (excuse me) this problem.</p>

 

<p>My advice is to aim for traditional, “proper,” exposure whenever the

scene’s contrast will permit. When not, make a judgement call as to which of the highlights

you’re willing to lose and which shadows you don’t object to blocking, and set an

exposure that does so. If you must have both, that’s the time to bracket multiple exposures

and merge them into one (either with HDR software or by my preferred method of masking the best

parts of the different exposures). I find that, however, Adobe Camera Raw has some tools that lets one pull a <em>lot</em> more contrast out of a single exposure than you would believe, making HDR much less necessary than in the past.</p>

 

<p>Another interesting technique is to take multiple identical exposures and then merge them. This

reduces noise, and can also be used to eliminate moving objects (people, cars, <i>etc.</i>) from a

scene; if you want to see what Times Square looks like when it’s empty, this is the way to

do it. In Photoshop CS4, this is done by creating a stack and then setting the mode to “median.”</p>

 

<p>If you’re shooting a particularly low-contrast scene, consider trying to “overexpose” by at least a stop or two (being sure to not put the highlights in danger). The end result after adjusting the exposure in post-processing is to lower your ISO even further. Then again, modern cameras are essentially noiseless below ISO 400, so it may be a lot of work for not much gain.</p>

 

<p>You may be interested in what’s called “UNIWB.” The problem is that no

camera on the market displays a histogram that matches the data in the RAW file, which makes

judging when you’ve actually blown highlights somewhat difficult. Single-channel blowouts

are especially hard to judge. The idea behind UNIWB is to create a white balance such that the

histogram more accurately reflects the RAW file, usually, by setting it to one where all three

channels have equal luminance. The technique has merit but also drawbacks; I was excited when I

learned about it, but I’m not having as much luck applying it as I had hoped for. If you want

to give it a try, Google is your friend.</p>

 

<p>In all instances, though, the <em>correct</em> exposure is (of course) the one that lets you best create the image you have visualized. With modern digital cameras, that often winds up being pretty darned close to the same exposure you’d want with film, and with caveats similar to what you’d keep in mind for shooting slides.</p>

 

<p>A final word: an excellent experiment is to shoot images of a gray card with the bug at each of the stops of the meter, as well as a stop or two beyond the top and bottom. When you examine the results, you’ll get an excellent feel for where each “zone” fits. For the underexposed shots, try boosting the exposure to see what kind of noise you can expect; for the overexposed, get a feel for where clipping starts to happen. Do the same in the field: knowingly over- and under-expose a few frames, just so you can see how your camera behaves in such circumstances and what you can and can’t do to recover from it.</p>

 

<p>Cheers,</p>

 

<p>b&</p>

[jean_henderson]

<p>Wow, Ben! What a thorough response! Thank you so much as it was just what I was looking for. However, for the time being, I can only shoot JPEG, so I will put into practice as much as I can and, perhaps, learn the exposure basics of digital even better until I can do even more with RAW when I get the K20d. I have always sought to get a proper exposure and compose within the frame, but I am learning that PP in digital is an essential aspect of the process of even when shooting for minimal PP. Thank you again.</p>

[Tim_Lookingbill]

<p>To get some good jpegs I'ld suggest you shoot a test scene containing a lot of color and tonal range like a group of colorful flowers containing a wide variety of hues lit by direct sunlight with the sun positioned about 45 degrees off horizon. Set your camera's color space to AdobeRGB. Make adjustments to the saturation and contrast settings and have the histogram graph turned on to see on the camera's LCD and check the results on your computer and readjust if need be. This is sort of calibrating your incamera settings where the changing parameters will be the exposure according to each scene.</p>

<p>I've done this with my Pentax K100D DSLR where its default settings creates overly contrasty and saturated jpegs. I switched to Natural image mode and reduced the contrast all the way down and put saturation in the middle. The images in my gallery were shot this way with minimal editing, usually to open up shadow detail.</p>

<p>When you switch to Raw these settings won't make any difference unless you use the camera's supplied Raw converter. Third party converters don't have access to this data, however, Adobe Camera Raw now has settings that mimic certain brands of camera's jpeg preset output and uses the name of the camera's preset within a drop down menu selection.</p>

[steve_wagner1]

<p>By contrast ratio do you mean exposure latitude?</p>