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underexposure for colors- bad idea?
Hi everyone..

Reading Bryan Peterson's 'Understanding Exposure' the other day, he mentioned that for slide film, underexposure by up to a stop renders rich tones and colors to photographs, and he had photos to illustrate his point..

My question is- would this technique work in digital? I have tried underexposing a few shots and have got washed out colors that have been hard to fix, but maybe I'm doing something wrong..

While I do understand that this is against ETTR recommendation as the underexposed parts in an image have progressive less data- but, I occasionally get the urge to get better colors in-camera and minimize post processing on my foolish top ( erm, laptop )..

Thanks in advance for looking/ posting,AP.

Person : personality :: camera : camerality..

Comments (11)

In the old days we underexposed in bright sunlight to gain saturation. With digital, you just choose greater saturation in your menus or during post processing...

Comment #1

The guideline is "Epose for Shadow" though this was for film. In the book you mention, underexposing by 1 stop sounds peculiar, since slide film USED to be far less forgiving than nagative film and 1 stop used to be as much as you dared go.Now all of this is very, very general, so wait for the experts to chime in........

Comment #2

Also some camera's in bright sunlight over exposure when in auto mode..

For anyone wanting to test this just take 5 to 10 shots on a nice sunny summer day..

To start with take a shot and see what the f stop, shutter speed, and ISO of the picture is..

Some cameras have a + - when it comes to exposure and on others you can change the f stop and or the shutter speed. So start under and go to what would default then go over and see how they come out..

If you don't know how then break out the manual and start reading. It is well worth leaning how to get most of what ever camera you own..

Good luck...

Comment #3

AnuragP wrote:.

While I do understand that this is against ETTR recommendation as theunderexposed parts in an image have progressive less data- but, Ioccasionally get the urge to get better colors in-camera and minimizepost processing on my foolish top ( erm, laptop )..

If you ask the question, you don't understand ETTR. The whole point of ETTR is to get files that respond best to things like saturation increase (and many other things as well) in post processing..

Digital is not film. There is much to learn about how to get what you want from a digital file, and much of it is contrary to the approaches used with film. Much of it too is directly related to the fact that, unless you are willing to accept from your camera what the engineers told it to do, you need to do some digital darkroom work..

Film darkroom work was just as important, it's just that you always hired someone to do it for you..

Nothing is enough for the man to whom nothing is enough...

Comment #4

... your comments are well made, and much appreciated..

As GuideNet pointed out, the problem is in translating the recommendation for film to digital. I realize the difference of digital vis-a-vis print film, but having never used slide film, assumed it's characteristics to be more similar to digital. That is why I am interested in finding out whether underexposure could work for digital..

Please see my response to Aletheia where I have described Peterson's observation, and my motivation in more detail..

Thanks,AP...

Comment #5

Thanks, Aletheia for taking the time to comment on my question..

If you ask the question, you don't understand ETTR. The whole pointof ETTR is to get files that respond best to things like saturationincrease (and many other things as well) in post processing..

I concede that I might not grasp the idea behind ETTR properly..

In short, here's what I understand, please rectify where necessary- the digital sensor captures the most data in the 'rightmost' stop, halving the amount progressively in each lower stop. This means that the shadow areas have much less data in them..

So, ETTR proposes that we expose for the highlights so that the shadows have more information to work with..

The motivation, as I can see, is that 1) in the underexposed/ shadow parts of the image, noise dominates, due to lack of data captured 2) if we try to 'gain up', ie, overexpose these parts, then the noise is further amplified. So, exposure correction for the shadows/ underexposed parts is harder. This should be alleviated with ETTR..

What I do not understand is how ETTR would help saturation increase ( unless you are specifically talking of underexposed parts) in RAW- if I'm exposing to the right, I'm already rolling in a surfeit of photons at the bucket sites. If anything, there's a risk of blowing out a color channel. I'd appreciate if you would clarify this..

Digital is not film. There is much to learn about how to get whatyou want from a digital file, and much of it is contrary to theapproaches used with film..

That's my feeble attempt here . Let me quote what Peterson said-.

"When you underexpose slide film a bit, the colors are usually more vivid and contrast increases... In general, color slide film allows for both a one-stop-underexposure and one-stop-overexposure margin of error.".

My motivation- not to increase the overall saturation, but the contrast (see quote above), so as to help in subject isolation. Peterson, at another place gives an illustration of a scene with white flower (seeds) in late afternoon sun, with a barn wall in the background in shadows. In normal exposure, the flowers and the barn are clearly visible. In the one-stop underexposed shot, Peterson makes the barn wall render as 'very dark shapes' and the white flowers/ seeds become rich golden. He does not say if he uses slide film..

So, he successfully isolated the subject, increased contrast and got great colors. Not understanding much about film, would this approach not work with digital? If not, then an explanation would be greatly appreciated, as also a strategy to achieve this result in post processing..

Many thanks,AP.

Person : personality :: camera : camerality..

Comment #6

When you underexpose film you are dealing with a chemical reaction that creates colors in a very complex way such that the "density" of those colors appears to increase with slight underexposure..

Digital is very different. What you need in digital photography is good information from which you can create, in fact, almost any effect you want. For most people, what they want is a "good picture" of what they saw when they tripped the shutter..

What many photographers are after is good information that will allow them to get the image they have in their minds onto the computer screen. That is very different from film. You need a file from your camera that has as much information as you can get. From that information you can process it in a way that creates digital image qualities like saturation or contrast or luminosity without distorting the numbers so much that they produce "artifacts" and image flaws like posterization..

Now, if you are shooting Jpegs, just dial up lots of saturation and contrast in the parameters of the camera and let the meter do it's job. The camera will process the numbers for you and you will have a more saturated picture. If you underexpose it, the camera programming has less to work with and will do a much less effective job of interpreting the picture. It will be noisier too..

If you shoot it Raw, you can take that information to a Raw processing program and make your own decisions about how much saturation, contrast, etc. you like in that image. If you have underexposed the picture, the Raw processor will have less information to work with and your options will be fewer. All sorts of problems get created when you try to massage colors from too little information..

In fact, one of the advantages of Raw is that you can make a lot of changes to the image while there are still 16 bits to work with for each color, rather than the 8 bits that are available in Jpegs. The extra bits are information that can be useful for preventing problems with large "adjustments" of an image..

It's all about having lots of good quality bits to work with because any processing you do to an image damages, changes, or even destroys some of the information you got when you made the shot. You need all you can get at the start..

If you shoot Jpeg, you want an exposure lets the camera make the image look like the original scene. If you shoot Raw, you can do the same thing, or you can even "expose to the right" a little (without ever blowing the highlights past that 255) and then pull it back in post processing. That will allow some of that good highlight information to slide down into the shadows and increase detail and reduce noise..

So, don't underexpose digital. It doesn't help anything. Expose it correctly, or even a little to the right of the histogram if you are shooting Raw and working the images yourself. If you don't have enough saturation or contrast, adjust something to get it, but never underexpose.

Here's a good start on the theory..

Http://www.luminous-landscape.com/tutorials/expose-right.shtml.

Nothing is enough for the man to whom nothing is enough...

Comment #7

Velvia was and is famous for saturation if you under expose it, but usually it was a modest 1/3 stop down. I notice on my new Xsi I have the choice of 1/3'rd stops or half stops. Half stops were commonly used for film and 1/3rd stops for slides, as slides like digital had a smaller dynamic range. Film negative exposures could be tossed about more aggressively, to speak metaphorically..

As others have pointed out, even in a basic program like Picasa2 (distributed for free by Goggle), you have so much more control over the image as compared to the photographers of years gone by. What is now being said is that if you go to white balance and set it for a "cloudy" day, even though it is relatively sunny out, the program will "warm" up the photo..

I think you might find this write up in Wikipedia interesting:.

Http://en.wikipedia.org/wiki/VelviaRationally I have no hope, irrationally I believe in miracles.Joni Mitchell..

Comment #8

When you underexpose with digital, all you do is get more noise in your photo. Exposing to the right is a guide to help you get the most out of your digital (RAW) files and minimize noise..

Read this article on Luminous Landscape, it might help....

Http://www.luminous-landscape.com/tutorials/expose-right.shtml.

The greatest of mankind's criminals are those who delude themselves into thinking they have done 'the right thing.'- Rayna Butler..

Comment #9

Thank you, again, Aletheia, for a much detailed & helpful reply.The advice on 16-bit processing and exposure method for jpeg vs rawwas insightful, and so was the hyperlink..

So, don't underexpose digital. It doesn't help anything. Expose itcorrectly, or even a little to the right of the histogram if you areshooting Raw and working the images yourself. If you don't haveenough saturation or contrast, adjust something to get it, but neverunderexpose.

Guess that sums it up nicely for digital. I will have to be careful whilereading photography books focused ( unintended ) on film from now on..

-AP..

Comment #10

GodSpeaks wrote:.

When you underexpose with digital, all you do is get more noise inyour photo. Exposing to the right is a guide to help you get themost out of your digital (RAW) files and minimize noise..

Read this article on Luminous Landscape, it might help....

Http://www.luminous-landscape.com/tutorials/expose-right.shtml.

The greatest of mankind's criminals are those who delude themselvesinto thinking they have done 'the right thing.'- Rayna Butler.

With the D2x there is a tendancy to blow out the red channel. Shooting Cardinals becomes a nightmare... .

But I can lower the saturation settings in Camera raw by a Very small amount, and restore the channel and the detail in the feathers. On the other hand, deliberatlly underexposing destroys the entire image..

Dave..

Comment #11

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This question was taken from a support group/message board and re-posted here so others can learn from it.

 

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