Is it better to under expose than over expose?

ash59uk

ash59uk

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Chris
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If you are in a shoot it or lose it situation for example photographing a fast low flying aircraft is it better to risk under exposure rather than over exposure if you haven`t the time to make sure you have set the camera correctly, then adjusting the image exposure on pc?
Or can the software deal with either equally well?
 
Better to get it right but yes better to under expose as highlights can never be recovered.

That said it depends on how much you over expose / under expose. It's not an easy one to answer.

A stop maybe 2 of over exposure can generally be recovered pretty well. If the image is dark, when you recover under exposure you will add a lot of noise to the image.

Pluses and minuses to both
 
The fundamental difference between shooting on film and digital is how they deal with overexposure. Film gracefully soften glows in a nice way, Digits just clip - nastily.


If you are worried about the risk of either under or over-exposing, you should shoot RAW, as this will give you more lattidude in recovering information at a later stage, as you can make more choices at the developing stage. But its only a small help, maybe a stop at best depending on your sensor etc etc


Software deals with Noise increasingly well (as do more recent sensors) - its remarkable what I can pull out of pitch darkness with the combination of the Kx (or K5, D7000, D3S, etc), raw, and Lightroom 3 - however Clipping is just Clipping. Once you've hit that maximum ceiling, you're stuffed, there's nowhere to go!
 
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ash59uk said:
If you are in a shoot it or lose it situation for example photographing a fast low flying aircraft is it better to risk under exposure rather than over exposure if you haven`t the time to make sure you have set the camera correctly, then adjusting the image exposure on pc?
Or can the software deal with either equally well?
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In part it will depend on whether you shoot in raw or jpg. If you overexpose any parts of the image with jpg they are gone forever, with raw, as mentioned, you can recover a couple of stops in post.

But it also depends on your subject, chances are in the example you gave, the sky will be the brightest part of the image and will be the first thing to go. So if you weren't so bothered about that you would probably get a better image of the plane if the sky was blown a bit.

The reason some people do what is termed expose to the right (ETTR), which means slightly overexposing and pulling down exposure in post, is because of the way digital works. Each camera has a certain dynamic range, the range of brightness to darkest tone it can capture in a single exposure. With raw the information captured is not divided in a linear fashion, there are more bits of information packed together in the highlight end than in the shadow end. By ETTR you tend to get more detail in the mid to upper range and less noise in the shadows.

Sorry that's a terrible explanation and you might already know all this so I apologise in advance. And I would say the best thing to do is practice with the camera until you can predict how it will react and you can make any needed adjustments on the fly without even looking away from the viewfimder.

And if all else fails bracket the **** out of it ;)
 
Shoot raw, ETTR, don't be afraid to see a hint of clipping in unimportant highlight areas. That will maximise dynamic range and minimise noise. Example of the magic of raw adjustment to an ETTR image....

20110405_221311_000.jpg


At low ISO values, if you do underexpose then you can brighten the image without too much problem, but you may introduce noise into the shadow areas. At higher ISOs you really want to avoid underexposing at all.
 
tdodd said:
Shoot raw, ETTR, don't be afraid to see a hint of clipping in unimportant highlight areas. That will maximise dynamic range and minimise noise. Example of the magic of raw adjustment to an ETTR image....

At low ISO values, if you do underexpose then you can brighten the image without too much problem, but you may introduce noise into the shadow areas. At higher ISOs you really want to avoid underexposing at all.
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Now that's a much neater answer, sorry I was trying to give technical details without getting too technical :p
 
Always try and get it right in camera, or as close as you can. I found looking through lightroom that the images that were out were nearly always under exposed rather than over. Always less than one F stop. It seems something that I naturally did, probably thanks to my lecturers at uni.
Most modern cameras seem to be much more forgiving with noise in the darker areas. My old d70s was terrible but my d300 is worlds apart!
 
markosparko1994 said:
yes, it is but often when its brightened it just looks like an over contrasted image
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That depends on he software you use and what technique you adopt to adjust the image. If you use Lightroom or ACR and increase the exposure alone for an underexposed image then your blacks and shadows stay rooted in the depths of darkness. You will need to look at adjusting the black level and maybe adding some fill light, or brightness, to also adjust the shadows and mid tones.

Example....

Adjusting exposure alone :
20110406_064359_000.jpg


Adjusting exposure, fill, blacks, brightness and contrast :
20110406_065116_000.jpg



But look at the noise. This was at 800 ISO.
20110406_065338_000.jpg



I can get cleaner results from the same camera at 3200 ISO by exposing correctly to begin with. :
20110406_065639_000.jpg
 
I would like to thank you all for your comments and advice but sadly my camera doesn`t do raw.
I bought a highly recommended bridge camera the fuji s5700 cheaply on ebay to see if I would regain my interest in photography.Well I have.
I am now saving my pennies, I have my eye on a pentax K100D super as my old me super has been excellent and is still in full working order, I also have a couple of MF lenses a 28mm and a 200mm telephoto (nothing special) but with the kit lens they would keep me going for a while until i can upgrade the lenses.

I normally walk around in Av with an F8 aperture and iso 200 so that I can take a quick shot and hopefully not be too far off the mark, as I said in my op if something comes out of the blue and is travelling fast you may not have time to adjust the camera, it might be quicker with a dslr as I believe they have wheels front and back for making adjustments quickly.
 
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If you can't shoot to raw then you need to be very careful not to overexpose too far. If you clip important highlights in JPEG you cannot get them back. Nonetheless it is best to try to avoid underexposing if you can.

I don't shoot JPEG at all, except when using my compact, which is almost never, but I think the best thing to do for JPEGs is to get the image as close to perfect as you can within the camera. The less fiddling about you have to do later on - especially with white balance and exposure - the better. Use your histogram to judge exposure accuracy and, if you have some sort of highlight warning indicator then be sure to use it to help detect and correct nasty surprises.
 
tdodd said:
If you can't shoot to raw then you need to be very careful not to overexpose too far. If you clip important highlights in JPEG you cannot get them back. Nonetheless it is best to try to avoid underexposing if you can.

I don't shoot JPEG at all, except when using my compact, which is almost never, but I think the best thing to do for JPEGs is to get the image as close to perfect as you can within the camera. The less fiddling about you have to do later on - especially with white balance and exposure - the better. Use your histogram to judge exposure accuracy and, if you have some sort of highlight warning indicator then be sure to use it to help detect and correct nasty surprises.
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I do try to use the histogram but it is all new to me I practice by taking one in auto then go into av and take several more of the same scene using the histogram to adjust each one to different settings to see which is best.
The more I get into digital the more I think my 35mm knowledge is not only very rusty but outdated too.
 
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ash59uk said:
I do try to use the histogram but it is all new to me I practice by taking one in auto then go into av and take several more of the same scene using the histogram to adjust each one to different settings to see which is best.
The more I get into digital the more I think my 35mm knowledge is not only very rusty but outdated too.
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Digital is very different from shooting film. I think highlight warning is one of the most useful things a digital camera can have for getting good exposures. It shows you which part of an image is overexposed which is just what you want with digital. I wouldn't even consider buying a camera these days that didn't have this feature, although I think all the current models do.
 
Please correct me if I'm wrong, but I thought the human eye was more sensitive to dark situations than light, therefore 'overexposing' images helps use more 'bits' for those important dark areas..?
 
I prefer to underexpose a little if possible, Generally try and use grads though to keep the shadows as shot and only have to pull up the highlights afterwards.
 
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cocjh1 said:
Please correct me if I'm wrong, but I thought the human eye was more sensitive to dark situations than light, therefore 'overexposing' images helps use more 'bits' for those important dark areas..?
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no no no, don't go there, don't make try to make any correlation between the human eye/brain and a camera, especially not a digital one. Really, don't. They are so different in the way they work and behave its not even worth considering, you'll only make things worse... :nono:
 
Go Back to Basics. If shooting the likes of Aircraft they will invariably be set against a bright sky. Camera on auto says "Ouch very bright, shut down fno or speed up shutter" result silhouette.

Aircraft are camouflaged to evade other fighter pilots shooting them down, they are mostly grey. Take a substitute reading from the ground, Grass is good, and use that setting to get a great average. Try it, its surprisingly accurate, did me OK for 22 yrs as a RAF PhotoG
 
garryg163 said:
Go Back to Basics. If shooting the likes of Aircraft they will invariably be set against a bright sky. Camera on auto says "Ouch very bright, shut down fno or speed up shutter" result silhouette.

Aircraft are camouflaged to evade other fighter pilots shooting them down, they are mostly grey. Take a substitute reading from the ground, Grass is good, and use that setting to get a great average. Try it, its surprisingly accurate, did me OK for 22 yrs as a RAF PhotoG
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Good idea - and strange as it may seem when I was a pro tog (many years ago) I used to use the back of my hand!

I had already checked it out (my hand) and adjusted the ASA ratings of my films to get a good exposure overall!

After all you can forget a grey card but never your hand!

.
 
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