k20d Expanded Dynamic Range opinions

[flyer]

When you take pictures with EDR "off" and "on" and look at the histogram, you can clearly see the histogram has been moved to the left giving more "room" for highlights. So, to me EDR seems to help preserving highlights.

[augustmoon]

Originally Posted by flyer

When you take pictures with EDR "off" and "on" and look at the histogram, you can clearly see the histogram has been moved to the left giving more "room" for highlights. So, to me EDR seems to help preserving highlights.

Which doesn't help with the shadow detail, as once it is all sorted out, you wind up with a lot more noise in the shadows, than if you exposed the best you could, maybe letting one or two channels clip in the highlights and recovering them later, while protecting the noise and total levels available. In RAW, moving the histogram to the left is the opposite to proper exposure to getting the most detail, and less noise and less banding, more room for adjustments, and better sharpening results. But if you are shooting jpeg only and don't want to have to deal with any of this post processing, then maybe it helps some images.

[flyer]

Pentax stated that EDR was at the expense of noise. But, it is still worth having "just in case". I didn't need it so far, but you never know...

[augustmoon]

I agree, it's a tool to use if it is needed. (I know I made it sound like it should never be used in my pervious post) if you have a scene you can't get a shot of without complete clipping, then it's probably best to use it and get the shot and clean the noise up later. I just wasn't recommending using it being used as a normal shooting mode...

[coloseu]

My former Fuji S5 Pro, the DR "champion", would have DR till 400% and that would mean a gain of 2 stops when compared to the normal 7 stops DR on normal camera. So the Fuji would allow 9 stops diference or if you prefer a 2 stop gain over normal circumstances. The K20D is suposed to gain a 1 full stop, so allowing 8 stops of DR over the usual 7. My believe from my very early tests is that, when comparing to Fuji that 200% is more 100% in the Fuji equivalent chart. So only half a stop. I was soooo impressed with the results from the S5Pro that I just can´t see those diferences in the Pentax, not even by half (what it is supposed to be). But the Fuji had another sensor and the DR outcame from the unique interpolation system. I believe that is the key to the unique DR of the S5Pro, while the DR in Pentax is more of a gimnick when compared to Fuji, it still works - just not as much as one would hope.
So if you want the best for DR go for the S5Pro, if not be happy to gain half a stop.

[WMBP]

I don't think anybody has offered an answer to the question I asked earlier: does this feature in the K20D do anything that I can't do myself, by exposing to the left in order to avoid clipping, and then bringing the exposure back up on the computer?

Will

[PentaxPoke]

Originally Posted by WMBP

I don't think anybody has offered an answer to the question I asked earlier: does this feature in the K20D do anything that I can't do myself, by exposing to the left in order to avoid clipping, and then bringing the exposure back up on the computer?

Will

Will, I would say no. I think you are right that you could do the exact same thing yourself in PP. The ironic thing is that we should be exposing right not left for noise! I guess to be fair, they do warn that use of the EDR may result in more shadow noise.

I have decided to turn mine off permanently. The k20d metering already does a great job of preventing overexposure. Also, so much of my shooting is indoors at high ISO, and the last thing I need is more shadow noise.

[augustmoon]

Originally Posted by WMBP

I don't think anybody has offered an answer to the question I asked earlier: does this feature in the K20D do anything that I can't do myself, by exposing to the left in order to avoid clipping, and then bringing the exposure back up on the computer?

Will

No, there is no magic, just convenience. If you shoot RAW, and have a capable RAW editor, and take care in your methods, you can accomplish what the EDR offers you and more. Even if you don't normally use Lightroom or Photoshop ACR, the ACR engine does a terrific job of restoring clipped highlight information...As long as there is at least one of the RGB channels that is NOT clipped, then ACR can restore the highlight info.

Still best to back off the exposure to the left so you don't clip anything, though. You don't want to go too far left, because when you bring up the shadow detail, or try to, you'll get a lot more noise and banding in the shadows. So expose left enough so you just barely aren't clipping any highlight detail, or just have a few dots blinking (turn on the exposure warning in the preview) Remember that your preview in the LCD is based on a JPEG conversion, and does not represent the actual RAW file, but the JPEG processing parameters you have selected.

So, expose left enough so you don't blow or completely clip your highlights, but careful not to move more than necessary into the shadows . Increase your ISO (which is what EDR does). Increasing the ISO should give you some more room in the shadow area. Bracket if it is a still scene, or not if it is a moment to be captured.

Then process your RAW file. In RAW conversion, (at least ACR/Lightroom) take the default contrast from 25 to 0 to start with, you can bring this up later after you get the most range out of your photo, contrast reduces the range so that a flat photo is more dynamic, but you are starting here already with an overly dynamic image. Also make sure that your point curve (again in ACR/Lightroom) is set to medium contrast or even linear, medium looks better than linear but if it is a tricky shot you might have to use linear, avoid strong contrast as this just pushes more into both over and under exposure.

First of all, obviously, make sure your white balance is the way you want it before making the following adjustments..

Next bring up the exposure just so it isn't clipped or just barely clipped, use the recovery slider to the point that nothing is clipped (hold down the option key while you move the exposure and recovery sliders to see where clipping starts) Then back down on the "black" again holding down the option key so you can see what is being clipped. If there is any black clipping, then you can use the shadow slider to bring life back into those areas. if you have any room left over on either end (more room to go with the exposure and recovery sliders, as well as the black and shadow slider) and you want a little more punch, you can bring some contrast back up, as you do so,, you will need to check the exposure clipping and black clipping again and adjust those or give some more push to the recovery and shadow sliders.

The last tone adjustment will be the brightness, and this is to taste and affects the midtones, so use this to give the image a more high-key or low-key look. Then with your input sharpening, don't go crazy sharpening all over the board, but you can sharpen so that you actually can perceive more highlight detail, just make sure that your masking is set to cover the shadow areas (again in ACR/Lightroom) holding down the option key while looking at the image at 100% will show you were the mask (dark area) is applied and thus no sharpening there, so adjust the masking slider so that it covers your shadow areas and leaves your highlight areas open, then your sharpening will only affect the mid and high tones, giving the appearance of more detail in those areas, (and less blown looking) while not increasing your noise in the shadows. Then finally, if there was a lot of noise picked up in your shadow area when that got adjusted the way you want it, is to use your favorite noise plug-in in your favorite photo editing app (I use noise ninja in Photoshop).

[WMBP]

I know how to expose shots while shooting and how to deal with difficult exposures in post-processing. The reason I asked if the EDR feature was doing anything special is that it seems to me that it could possibly do something special.

Imagine that the sensor is an egg carton with a dozen cups in it. And imagine that the light being captured is represented by letters of the alphabet. If the exposure looked like this:

ABCDEFGHIJKL

- that is, the first dozen letters of the alphabet - then it would fit perfectly into the dozen cups of the egg carton. But exposures often look more like this:

ABC F HIJ MN PQR

and you normally have to decide whether you're going to capture A-M, or F-R, or something in the middle. What I was hoping was that the EDR feature had some really clever way to turn

ABC F HIJ MN PQR

into this:

ABCFHIJMNPQR

In other words, a dozen different positive tonal ranges from high to low, captured in the dozen cups of the egg carton. Or to put it in a nutshell rather than an egg carton: in-camera HDR.

I don't know much about how sensors work, and perhaps this simply isn't possible. But it doesn't strike me, in my ignorance, as out of the question. I know that the shutter and aperture are mechanical aspects of exposure that can't be monkeyed with, but the EDR feature seems to be playing with ISO, and ISO on a digital sensor seems to involve a lot of math. The sensor "sees" what it sees when the shutter is tripped. I thought perhaps there was a way for it to take it all in, then do some math that looks for the "gaps" - the places where the exposure level could best be compressed - and that it would do that. As I said, in-camera HDR.

But apparently not. So never mind. ;-)

Will

[flyer]

to WMBP.
Right now, it doesn't seem possible, but in a short while. I'm pretty sure the problem will be resolved. Samsung has applied for patents addressing the subject and Kodak is also working on the subject.Kodak has also developed (or is developing) a sensor that generates an electric signal when it doesn't receives light, instead of the other way around. That solution, by itself, should reduce noise by a big margin. So, we are not done seeing improvement in the sensor department.

[ivanp]

Originally Posted by flyer

Pentax stated that EDR was at the expense of noise.

Where can I read that information ? In the manual ?

[PentaxPoke]

Originally Posted by ivanp

Where can I read that information ? In the manual ?

Starts 3:00 in to the video.

YouTube - Pentax K20D

[ivanp]

Originally Posted by flyer

When you take pictures with EDR "off" and "on" and look at the histogram, you can clearly see the histogram has been moved to the left giving more "room" for highlights. So, to me EDR seems to help preserving highlights.

Strange, I can see something different - the histogram is moved slightly to the right, except highlights that are "compressed", i.e. highest highlights are indeed moved to the left thanks to EDR which dynamically lowers ISO here. (and for this reason ISO100 is not available with EDR ON)

[flyer]

Maybe I don't look or interpret my histogram like you. You know, sometimes those French Canadians...

[ivanp]

Originally Posted by PentaxPoke

Starts 3:00 in to the video.

YouTube - Pentax K20D

I think it is misunderstanding. The guy in video does not claim that EDR leads to higher noise, but that with activated EDR "the minimum ISO is increased to 200 and it may give more noise in shadow details".

As I understand it, you can either
compare apples to apples = pictures with ISO 200+EDR OFF and ISO 200+EDR ON (and the noise will be the same),
or compare apples to oranges = pictures with ISO 100+EDR OFF and ISO 200+EDR ON (and the noise will be different, but not because of EDR, but because using different ISO speeds).