Digital and exposure

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Digital and exposure

Postby asaroha on Tue Aug 01, 2006 1:05 am

I've been wondering, is there any reason not to set exposure compensation to underexpose on my d50 ? in other word, why should one not underexpose when you're shooting with a DSLR ?

Unlike film you can adjust level, adjust exposure compensation when converting RAW etc. So is there any reason to worry about getting the exposure spot on the first time and risking lost of detail in highlight areas? Sorry if this sounds newbieish :?
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Postby gstark on Tue Aug 01, 2006 1:34 am

You don't quite have the control that you're suggesting.

Think about this for a moment : were that to be the case, then - and I'm taking it to the ultimate level - exposure settings would no longer be required. You would just make your image, and adjust the exposure in PP.

The reality is that exposure is not a finite setting: there are always variables that will suggest that, forany one scene, there moght be any of a half dozen different, but correctr, exposure settings, depending upon the photographer and his needs and desires at the time, And no, I'm not talking about the one EV with a half dozen equivalent variants - I'm saying a half dozen different EVs.

So, within thyat range, I think that you still meed to ensure that the basics are correctly addressed, and that means correct exposure to ensure the result that you desire. Consider EV adjustments done in PP to be a last resort offerring.
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Postby asaroha on Tue Aug 01, 2006 2:20 am

Are you saying that the term "correct exposure" itself is subjective ? That is a good point, but assuming you don't go to the extreme and make it so dark that you lost shadow details, would it not be safer to errr on the safe side and set say -05 ev permanently on the camera ?
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Postby beetleboy on Tue Aug 01, 2006 3:16 am

You'll quickly find that deliberately underexposing and then "rescuing" an image in post is just like increasing your ISO. You'll start to encourage grain /noise (and not very pretty stuff either!) and other ugly artifacts will raise their ugly heads!

As you mentioned, you don't want to lose shadow detail either...underexposure (especially consistently) is a good way to do just that! The tail end of the histogram loves to clip, just tempt it!!

There is, however, always a place for creative interpretation and if underexposure gets you there and it works for you; you've achieved what you set out to achieve!

Geez I go on and on when insomnia kicks in!
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Postby gstark on Tue Aug 01, 2006 7:26 am

beetleboy wrote:Geez I go on and on when insomnia kicks in!


Liam,

I hope you're not looking for an argument. :)

asaroha wrote:Are you saying that the term "correct exposure" itself is subjective ?


Yes. It is always dependant upon a large number of variables, which includes not just the scene that you're shooting, but also the effect that you are wishing to achieve. If , for instance, you're shooting for a high key effect, do you care all that much about shadow details?
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Postby Jeff on Tue Aug 01, 2006 8:32 am

Continuing on with exposure settings is the highlight screen on the D70 a reliable guide to exposure?
If you expose for the highlights you end up with a very much under exposed shot. I'm justing to play with the manual settings instead of just using A or S modes, and would like to know what you guys think and how many of you use manual settings?

Jeff
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Postby gstark on Tue Aug 01, 2006 8:38 am

Jeff,

Not if you're just chimping the image.

If, however, you use the histogram ... that's as good as it gets. Learn to read the histogram, and you'll be there.
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Postby Jeff on Tue Aug 01, 2006 8:48 am

Thanks Gary,but what is chimping the image.

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Postby johnd on Tue Aug 01, 2006 1:56 pm

Jeff wrote:Thanks Gary,but what is chimping the image.

Jeff

Chimping = Taking a quick look and decide to keep or re-shoot.

As Gary has said, the histogram is your friend. If you deliberately push it to the right or left you will sacrifice either shadow detail or highlight detail.

From my pserspective, I don't like seeing the "noise" of red/green underexposed shadows that you can get if you underexpose the shot. My preference is blown highlights rather then noise in the shadows. Mind you, you can use levels or raw converter to turn the red-green noise into pure black (which IMHO looks better).

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Postby Aussie Dave on Tue Aug 01, 2006 3:15 pm

asaroha wrote:Are you saying that the term "correct exposure" itself is subjective ?


All exposure settings are subjective, IMO. It all comes down to what you are exposing for...the highlights, the mid-tones or the shadows, or somewhere in between ??

What may look over or under exposed to me may be exactly what you were trying to capture. After all, isn't it all an artform :roll:

Jeff - I always shoot in manual mode and vary my aperture, shutter speeds or both to expose the shot how I want it to. The only difference I can see between using M over S or A mode is that I like to be in control of everything (and I hate using EV comp :lol: ).
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Postby Jeff on Tue Aug 01, 2006 4:06 pm

Thanks johnd and Aussie Dave for your comments.
Aussie Dave when you use manual do you select the aperture first then adjust the shutter speed according to the analog exposure display.This what I have been doing and trying to have the reading slightly to the right of centre. This is probably a dumb question but it is good to get some feedback.

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Postby losfp on Tue Aug 01, 2006 4:21 pm

When I am using manual settings, I find that I tend to use a system that is very much like a virtual A priority or S priority. ie: There is always one setting where I know what I want. So most of the time, I might manually set my aperture to f/8, and then adjust ss to suit. OR I might know I want a fast SS, so I might stick it on 1/1000, and adjust aperture to suit.
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Postby Aussie Dave on Thu Aug 03, 2006 5:56 pm

Jeff wrote:Thanks johnd and Aussie Dave for your comments.
Aussie Dave when you use manual do you select the aperture first then adjust the shutter speed according to the analog exposure display.This what I have been doing and trying to have the reading slightly to the right of centre. This is probably a dumb question but it is good to get some feedback.

Jeff


It really all depends on what I'm shooting. If I'm shooting something with motion in it, I am somewhat restricted in what shutter speeds I select (nothing too slow), but then if there's not much light available, then the aperture (and sometimes ISO) needs to be compromised and changed accordingly to give the exposure I'm shooting for.

Vice Versa if I'm going for a nice portrait and I want to try and shoot with a specific f-stop.....then the shutter speed is what I compromise and play with.

Does this make sense ??
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Postby PiroStitch on Thu Aug 03, 2006 6:03 pm

Agreed exposure is totally a subjective thing.

Have a look at the image I posted here.

If I had tried to make it so that no highlights were blown at all, I wouldn't have been able to capture the model's face.

Jeff, I only shoot in manual mode. I know some people swear by shutter priority or aperture priority as modern technology means that the camera's electronics is better at determining the exposure, blah blah blah. I don't still don't trust it :)
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Postby michael_ on Sun Aug 06, 2006 2:20 pm

beetleboy wrote:You'll quickly find that deliberately underexposing and then "rescuing" an image in post is just like increasing your ISO. You'll start to encourage grain /noise (and not very pretty stuff either!) and other ugly artifacts will raise their ugly heads!

As you mentioned, you don't want to lose shadow detail either...underexposure (especially consistently) is a good way to do just that! The tail end of the histogram loves to clip, just tempt it!!

There is, however, always a place for creative interpretation and if underexposure gets you there and it works for you; you've achieved what you set out to achieve!

Geez I go on and on when insomnia kicks in!


very important points in here and i only just realised the increase in noise when trying to brighten the scene abit as i had underexposed the image in one of my recent caps, i thought it may just have been my eyes but now i know its not the case.

Learn something new everyday.
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Postby wendellt on Sun Aug 06, 2006 2:31 pm

sometimes overexposign is good
especially for portraits with backgrounds that compliment the subject matte
rever se ythose highly nostalgic images of girls runnign in fields backlit by the sun image totally blown but it looks good remoinds you of heaven or some divine thing

i persoanlly like artistic use of blown highlights

of course for technical subjects where over exposed bits a re just too obvious and dont look artisitc thats whern you have to be more concerned about exposure
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