X-E2 DR400 limits test

Started Mar 18, 2014 | Discussions thread
OP Ysarex Senior Member • Posts: 1,767
Re: X-E2 DR400 limits test

nixda wrote:

Ysarex wrote:

nixda wrote:

Ysarex wrote:

nixda wrote:

Ysarex wrote:

km25 wrote:

Shoot Raw+JPEG.

Capturing a raw file when the DR function is active seems to be a wasted effort. I did capture a raw file for the image posted and even with a +1.3 exp. comp. the raw file is badly underexposed -- I'd say frankly worthless. I was surprised to see that.

The JPEG is derived from the raw data. It is as underexposed as is the raw version. But what you see is the effect of the DR setting. With DR 400, the exposure is reduced by 2 stops. Software that recognizes the DR setting will automatically boost the brightness. Software that does not recognize the DR setting and does not boost the brightness will give you an initial image that looks underexposed (because it is). If you increase the brightness manually yourself, the image will look fine again.

That makes sense. The reason for the forced ISO 800 is to begin with a 2 stop exposure reduction right up front (make sure the highlights don't clip). This strikes me as a seriously dumb kludge and a really bad way to try and get a decent result. High contrast light is tricky and hard to meter -- that's why I ran a bracket set. I'd much rather work to get a best exposure than start off with a given 2 stop deficit.

Um, adjusting the exposure so that nothing important is being clipped is proper technique. The DR modes just help those out who don't want to adjust the exposure themselves and/or do raw processing. It's not dumb at all; in fact, it's a quite decent approach. It won't work for all situations, and it has its drawbacks, but it is a quick and easy way for JPEG shooters to have some insurance.

Isn't "quick and easy" just a nice way of saying dumb kludge?

AF must then be a dumb kluge to you as well. And elevators. And cars.

I agree that clipped highlights are to be avoided, however so is underexposure. We all know that digital sensors give us the cleanest data from the high end of the exposure scale.

I did save a raw file for the above photo. The EXRII processor's DR function render's the JPEG highlights from that file as well exposed. In an exposure from the bracket set with an additional +.3 exposure the JPEG highlights begin to clip. So the exposure I posted above represents the DR function's limit. AND YET a look at the raw file's histogram for the above photo reveals bad underexposure. Nearly two stops of the sensor's prime capacity are wasted. I've only got one word for that -- that's dumb.

No, your interpretation of all that is 'dumb', to use your own word

What you are looking at is the JPEG engine's behavior. If the raw data aren't clipped, then they aren't clipped. What the JPEG engine does with it, or how you instruct the JPEG engine to use the raw data, is entirely different. If the raw data aren't clipped, but the JPEG is, then this would be user error.

Admittedly I didn't do my homework before testing the DR function and I didn't think hard about what it was doing. I would have assumed that the goal would be to get maximum sensor exposure (without highlight clipping) and then lift the shadows and apply a tone curve to tame the contrast. Apparently that's not what it does.

I look at that raw file histogram and I can't see anything other than a mistake.

The mistake was yours. You simply didn't set the exposure correctly. The camera is not necessarily going to do that for you, even if you choose all-AUTO. The DR expansion modes are not some magical ETTR. In fact, far from it. ETTR makes sense only at base ISO. DR expansion, by definition, raises the ISO. Trying to do ETTR with raised ISO is a waste of time, IMO, and so is using a DR expansion mode expecting that it would do ETTR for you.

I admit I didn't investigate how the DR function actually works before hand. I did say that I ran a bracket set for the exposure so that I could select the best exposure later. I did that. Any more exposure beyond the exposure in the posted photo and the JPEG processor clipped the highlights. I've already noted that. If as you say I didn't set the exposure correctly then you're suggesting that I should have either exposed less or exposed and clipped the highlights. Which would have been correct?

You might have had better luck with your example scene if you had metered all across the scene and determined the brightest spot you wanted to retain in your image and used the corresponding metering values for your exposure. Some sort of average metering won't be able to determine that. And neither will it know which highlights exactly you want to retain.

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