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12-25-2014, 01:32 PM - 1 Like   #1
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K-3 Shadow Recovery Ability - a Test

Hello all. Did a quick shadow recovery test with the K-3 today. I underexposed by five stops and lifted the shadows in LR5 using +2 Exposure and +100 for both Blacks and Shadows. Played with curves from there and viola. Shadows show considerable noise in the very darkest areas, but results are impressive compared to my last digital body (7D). I've inserted both the original image and the PPed image below for reference.





12-25-2014, 01:39 PM   #2
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Very impressive.
I usually get 2 to 3 EV back, but didn't try this interval.
12-25-2014, 01:42 PM   #3
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The first time I did this, I nearly fell over. It is shocking how much you can pull out of a black image.
I wish, sometimes, that the same could be done for highlights in the image.
12-25-2014, 01:49 PM   #4
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QuoteOriginally posted by Zygonyx Quote
Very impressive.
I usually get 2 to 3 EV back, but didn't try this interval.
I definitely did not have to push it as far as I did to achieve a usable end product. A -2 or -3 EV bias would've given much cleaner shadows. I just had to go -5 for the sake of, ya know, science!

12-25-2014, 02:15 PM   #5
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Powasky, did you use a fixed WB? I had an issue with leaving the camera in Auto-WB when I did a 4 stops boost test with a K-5:

https://www.pentaxforums.com/forums/61-post-processing-articles/234154-invest...-boosting.html

BTW, check out this 4.77 stops boost with a 645Z. Phip Bloom gave the camera to someone to take an important group shot (Phil's the one in the dark singlet holding the video camera) and they grossly underexposed:

Shadows and Detail: A love letter to the Pentax 645z | Philip Bloom
and finally this…and this is a biggy…just how much shadow information it holds is terrifying!!
Below are two screen grabs from Lightroom 5. The first showing a hopelessly underexposed image. This would be junk for every other camera I know. I thought it was too…then I pulled up the exposure to almost 5 stops more and brought the shadows up 100% and my mind was blown. The photo was there and it was clean! No noise. This I have never seen before and this for me is the single greatest feature of this camera. How it holds information in the shadows is voodoo!!!
Before:


After:


LR 5 settings used:



Also check out Philip Bloom's example of the recovery of a backlit scene taken with a 645Z. I was impressed with the IQ and colour he got out of this:

https://www.storehouse.co/stories/o061f-shadows-and-details

Dan.

Last edited by dosdan; 12-25-2014 at 07:52 PM.
12-25-2014, 02:31 PM   #6
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Wow. Just wow. Very impressive powasky and Dan.
12-25-2014, 03:06 PM   #7
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Very impressive. With low ISOs noise is not too bad.
12-25-2014, 07:39 PM   #8
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OK I am sufficiently impressed

12-25-2014, 08:01 PM   #9
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This begs the question of what is "correct" exposure for a sensor. One could make an argument that the 645Z should be routinely "underexposed" by 1 or 2 stops to avoid blown highlights, which it can't recover so well. Pentax has made a choice, but the photographer doesn't have to adhere to it. The other advantage of this "move the goalposts" policy is that it makes it possible to hand-hold more shots.

It is also worth pointing out that the processing software used makes a difference. When the 645Z first came out, Adam posted some RAW files on PF. I downloaded a couple and processed with Aperture (Apple's Digital Camera RAW processor), and it definitely lost detail in deep shadows that LR (Adobe's Camera Raw) managed to recover. Overall, I prefer Aperture to Lightroom (notwithstanding the former's imminent demise), but in this regard LR/PS wins.
12-25-2014, 08:08 PM   #10
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QuoteOriginally posted by Paul the Sunman Quote
This begs the question of what is "correct" exposure for a sensor. One could make an argument that the 645Z should be routinely "underexposed" by 1 or 2 stops to avoid blown highlights, which it can't recover so well. Pentax has made a choice, but the photographer doesn't have to adhere to it. The other advantage of this "move the goalposts" policy is that it makes it possible to hand-hold more shots.

It is also worth pointing out that the processing software used makes a difference. When the 645Z first came out, Adam posted some RAW files on PF. I downloaded a couple and processed with Aperture (Apple's Digital Camera RAW processor), and it definitely lost detail in deep shadows that LR (Adobe's Camera Raw) managed to recover. Overall, I prefer Aperture to Lightroom (notwithstanding the former's imminent demise), but in this regard LR/PS wins.
I think this will help kill "ETTR" for me. Interesting that you say that Pentax has made a choice...I think it is also reflected in the fact that they offer highlight clipping warnings in LV and during review, but no shadow clipping warning. I am going to continue to experiment with this.
12-25-2014, 08:19 PM   #11
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QuoteOriginally posted by powasky Quote
I think this will help kill "ETTR" for me. Interesting that you say that Pentax has made a choice...I think it is also reflected in the fact that they offer highlight clipping warnings in LV and during review, but no shadow clipping warning. I am going to continue to experiment with this.
Agreed! ETTR never made much sense to me, especially in harsh Australian sunlight. Too many irrevocably blown highlights if you're not very careful.
12-25-2014, 08:30 PM   #12
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Generally, most digital cameras in raw mode won't have much headroom before clipping. Since the visible effects of over-blowing are so noxious (e.g. grey areas on foreheads or cheeks), with DSLRs that have good shadow noise performance it pays to usually apply a little negative EV Comp.

Some manufacturers choose a lower metering level (see * below), which can allow more headroom, at the expense of a little more noise in the shadows. Also, if you shoot in JPEG you are applying a Tone Response Curve, and these TRCs often have a bend near the top that makes the camera appear to tolerate very bright situations better.

* Note: "K" is the reflected-light meter calibration constant. Each manufacturer has some latitude in deciding what K value they'll use in setting their metering level for what they consider a correct exposure. K=11.4 was originally used; nowadays K=12.5 (Canon, Nikon, Sekonic) and 14 (Pentax). Higher K numbers mean that exposure levels are slightly greater today, because the brightness is higher. The increase is 0.13 stops ( K=12.5) and 0.3 stops (K=14). Interestingly, Pentax light metering uses a K which is outside the ISO 2720:1974 standard recommended range for K of 10.6-13.4.

Dan.

Last edited by dosdan; 12-25-2014 at 08:39 PM.
12-25-2014, 09:28 PM   #13
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Even the K-5 ain't bad. Here, the flash didn't fire. I really don't know how to use LR so my recovered image might be better when done by someone who knows what they are doing.
Attached Images
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PENTAX K-5  Photo 
View Picture EXIF
PENTAX K-5  Photo 
12-26-2014, 01:34 PM   #14
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QuoteOriginally posted by Paul the Sunman Quote
Agreed! ETTR never made much sense to me, especially in harsh Australian sunlight. Too many irrevocably blown highlights if you're not very careful.
After some further thinking, it's really "ETTR until highlights are blown". After all, more photons = less noise. So ETTR as far as you can in a scene (which may be -3 EV) before highlights are blown.
12-26-2014, 03:31 PM   #15
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QuoteOriginally posted by powasky Quote
the PPed image below for reference.
dxo optics pro, using the prime mode, would clean that noise up... on sale for $149

https://shop.dxo.com/login_product.php
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