Over exposed or Under exposed?

[Gingerbaker]

I think people who insist on always exposing to the right are forgetting the fundamentals; ultimately it depends on what you're capturing. If it's a purely reflective scene - say a model's face - in a studio - why on earth would you want to expose, say, a midtone skin as a highlight? It's NOT a highlight - and will NEVER be a highlight - and noise isn't going to be detectable if the exposure is correct.

So why force the values into an area that isn't correct - to theoretically minimise something that wasn't a problem in the first place - only to have to shift the tones back down in post processing, trying to deal with the issues that this can cause in the process. It's crazy.

On the other hand - as I mentioned above - if it's a scene where there's a very high dynamic range to start with then - yes, one needs to use an much of the cameras DR ability. Horses for courses.

Well, I suppose I should have ben more clear, but I thought it was assumed we were talking about a full-spectrum image. Nobody I know would advise pushing every exposure all the way to the right, so I think you have created a bit of strawman, whilst we were speaking at cross purposes to a large degree.

However, deliberate underexposure does not make sense to me either. The idea that one can reliably underexpose by 5 stops is wildly optimistic and not good strategy. And I'll bet it is not your suggestion that people do that as a rule. I really think that our difference of opinion is not that large of a disagreement when getting down to brass tacks.

I can tell you, this, however, my Canon 5D will not produce great results at 5 stops underexposure, although I have seen an amazing result (here?) with the new Pentax dslr acomplishing such a feat on a picture of a dog in a backyard. As ISO goes up, the headroom for getting a good result pumping up an underexposure gets smaller and smaller for my 5D. Proper exposure, as I think you have said, is key at higher ISO's.

Now, I shoot always in RAW, and Colin, I think you sometimes stay in jpg. I know that I can reliably recover up to two stops of highlights in ACR which means that a bit of highlight warning on my LCD is no problem whatsoever. I guess one can recover about 1/2 to maybe one stop of highlights when shooting in jpg by using the shadow and highlights tool, so the margin for error becomes more worrisome for jpg.

But deliberate underexposure? For heaven's sake, why?

[_GUI_]

But deliberate underexposure? For heaven's sake, why?

It all depends on the situation and shooting conditions. Some deliberate underexposure (doesn't need to be as many as 6 stops) could make sense. Think that your scene is low or medium dynamic range, and that you don't have time to carefully choose exposure. Why not underexpose by about 2 stops to make sure you will never ruin the highlights? clipped highlights are irrecoverable and affect strongly to the perception of the image.

The Canon 5D (if you are talking about the classic 5D) is old fashioned technology today. I did a simulation of Canon 5D vs Pentax K5 in dynamic range, comparing the 6 stops underexposed shot in the K5 with a 6 stops underexposed shot on the 5D. The result was that the K5 outperformed the 5D:




With the same RAW file from the K5, I did now a comparision in low light conditions. I compared the 6 stops underexposed ISO80 RAW from the K5 with a 2 stops underexposed ISO1600 RAW from the 5D. Now both cameras performed similar:




This means the K5 has a much higher DR than the 5D at low ISO, but similar DR in low light conditions which force us to use high ISO (the ISO80 shot on the K5 is valid for the low light comparision since this sensor doesn't benefit of pushing ISO to get better exposure as already commented in this thread).

Regards

[Gingerbaker]

Wow, gui, that's an amzing result for a 6 stop underexposure. Yes, I'm jealous!

I think I remember where I saw the 5-stop under photo of the dog - it was at The Online Photographer, maybe a month ago. The detail and color rendition were not absolutely perfect, but nevertheless jaw-dropping.

Enjoy your camera!

[_GUI_]

Enjoy your camera!

Well, I don't have a Pentax K5. In fact my cameras are a Canon 350D, 5D (classic) and Olympus E-P1. But yes, I try to find time to enjoy them

[Colin Southern]

Well, I suppose I should have ben more clear, but I thought it was assumed we were talking about a full-spectrum image.

Hmmm - not sure where that assumption came from.

However, deliberate underexposure does not make sense to me either.

It's never ideal, but can be a useful technique to increase shutter speed, or occasionally for other reasons.

The idea that one can reliably underexpose by 5 stops is wildly optimistic and not good strategy.

I wasn't suggesting that it was a good strategy - I was merely demonstrating the safety margin contained in a normal RAW exposure. However, there may well be situations where it's desireable to dig an additional 5 stops of shadow.

Original ...



4 stops of recovered shadow detail ...

I can tell you, this, however, my Canon 5D will not produce great results at 5 stops underexposure, although I have seen an amazing result (here?) with the new Pentax dslr acomplishing such a feat on a picture of a dog in a backyard. As ISO goes up, the headroom for getting a good result pumping up an underexposure gets smaller and smaller for my 5D. Proper exposure, as I think you have said, is key at higher ISO's.

Proper exposure is one of the keys to EVERY good photo, regardless of ISO.

Now, I shoot always in RAW, and Colin, I think you sometimes stay in jpg.

No, I'm pretty much a 100% RAW shooter.

[meltimtiman]

Thanks a million for the replies, everybody. Been trying them out on some blown out shots when I used my flash off-cam and I think I was able to salvage most of them by using your inputs. It was easier since I shoot 100% RAW.

Thanks again.

Mel