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Author Topic: Digital backs offer more DR than 35mm sensors?  (Read 9831 times)
John R Smith
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« Reply #20 on: January 29, 2010, 06:33:56 AM »
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I rather suspect that most people, when they are talking about DR, are really referring to the film or sensor's ability to hold in highlight detail rather than anything else. Certainly that has always been my concern when shooting for B/W prints using digital sensors, or scanning B/W film for that matter. In colour, perhaps we are rather more concerned with shadow detail, because dead black shadows don't look very good in a colour print, whereas in B/W that's probably OK (at least with me). So control of highlights is very much the issue in B/W. Whether DR is 8 stops, 10 stops or 12 stops is rather a moot point - what really counts is the ability to make an exposure which will just give detail in the brightest parts of the scene that can be retrieved in the eventual print (specular highlights excepted). That's the tricky bit. A larger DR will help, of course, but no camera or film or sensor yet made can see things as the human eye does. So shooting tight in towards the sun on a bright day will always involve some compromise - do I keep the clouds and lose the shadows under those trees, or lose the clouds and open up the shadow areas? Since Fox Talbot, it has ever been thus.

John
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ziocan
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« Reply #21 on: January 29, 2010, 07:22:38 AM »
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Quote from: bjanes
Of course, I have neither camera and would like someone with both cameras to demonstrate the practical DRs of each instrument.
Exactly.
That was the only line worth writing on your post.
« Last Edit: January 29, 2010, 07:31:08 AM by ziocan » Logged
Jack Flesher
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« Reply #22 on: January 29, 2010, 07:15:43 PM »
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Quote from: ziocan
Exactly.
That was the only line worth writing on your post.

Perfect!          
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BernardLanguillier
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« Reply #23 on: January 29, 2010, 10:14:17 PM »
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One thing to keep in mind in this discussion is that many photographers still think that DR is measured by the amount of blown highlights they manage to recover with their favorite raw converter...

Cheers,
Bernard
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Daniel Browning
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« Reply #24 on: January 29, 2010, 10:23:10 PM »
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Quote from: bjanes
According to the DXO measurements, the Phase One P65+ has 11.51 EV of dynamic range at base ISO and the Nikon D3x has 12.8 EV of DR at base ISO. The Phase One does have better resolution and enables bigger prints, but I have yet to see photographic evidence that it has better DR than the D3x.

Great post, Bill. Spot on, as always. In addition to the resolution and other MFDB advantages you mentioned, another thing it has is improved color depth in the upper part of the dynamic range. The increase in tonal gradations is easy to measure, but I think the visual effect would be subtle.
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David Saffir
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« Reply #25 on: January 29, 2010, 11:17:11 PM »
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You can look up the DR for most 35mm DSLRs, some compact, and selected digital backs, along with other quantitative info at: dxomark.com.

David Saffir
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Abdulrahman Aljabri
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« Reply #26 on: January 30, 2010, 06:05:09 AM »
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Since people are debating whether DR would show up in shadows or highlights let me provide an example



My understanding is that extra DR would show up on both ends and would help where the red spots are placed. For each spot there is a light source shinning directly in the frame. The original shot was a jpeg file with some details blended back in with a -2 underexposed file. Obviously my mistake is using jpeg instead of RAW, but even with RAW this problem will still be there. Don't MF cameras show more details in the original file much like a 35mm file would after digital blending?

And since we are at it, how do people counter this problem? It is clear from the picture that I failed to restore details to the desirable level. In fact I resorted to a trick by painting detail with a color brush just to make those areas appear to hold detail.


Feel free to critique the picture if you like. Thanks in advance!
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Jeremy Payne
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« Reply #27 on: January 30, 2010, 06:46:05 AM »
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Quote from:  Abdulrahman Aljabri
Since people are debating whether DR would show up in shadows or highlights

Really?  I just thought people were yet again discussing how many angels can dance on the head of a pin.

That's what it sound like to me ...
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Graeme Nattress
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« Reply #28 on: January 30, 2010, 06:46:13 AM »
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DR is typically noise limited. Indeed, you can think of sensors only having more and more range in the shadows as the top end is fixed by it's clip point. However, that does not mean you should only look for extra DR in the shadows as it all depends where you place mid grey in the range the sensor offers, and hence how many stops above and stops below you can record.

Given that different cameras sensor sensitivities are different, you can't just put a similar lens and set the same shutter and f-stop on each camera and expect a fair comparison. You might see one didn't clip some highlights, but the other did, and conclude the first had more DR. However, the first could be less sensitive. The second camera might have much more shadow detail and hence could have been easily allowed to be under-exposed by a stop, recover the highlights and get a wider DR by bettering the first in the shadow department.

That is why real world scenes are not so good for measuring DR, and why calibrated backlit wedge tests are good, because it doesn't matter where on the scale you clip, as long as you clip near enough the top that you can count down into the noise floor at the bottom.

Graeme
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tho_mas
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« Reply #29 on: January 30, 2010, 06:57:43 AM »
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Quote from:  Abdulrahman Aljabri
And since we are at it, how do people counter this problem?
http://www.luminous-landscape.com/tutorial...-blending.shtml
http://luminous-landscape.com/forum/index....showtopic=40761
http://www.luminous-landscape.com/tutorial...exposures.shtml
http://www.luminous-landscape.com/forum/lo...php/t24466.html
http://www.luminous-landscape.com/forum/lo...php/t35171.html


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Abdulrahman Aljabri
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« Reply #30 on: January 30, 2010, 07:19:20 AM »
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Quote from: tho_mas


Thanks man, I am familiar with a couple of those, in fact the first link was the first tutorial I read about the subject when I was still new to photography several years ago. I have used those techniques with landscape images with very excellent results. For some reason, however, they don't seem to provide the same results with interior shots. Taking the highlight area in underexposed shots produces very dark tones which cannot blend with original picture tones. Also the transition in underexposed shots becomes very severe. Drop the exposure more and you get overly overexposed edges. Very weird, perhaps its the very high DR lights in frame require versus typical landscape scenes. I guess its like trying to paint back details in the sun.
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CBarrett
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« Reply #31 on: January 30, 2010, 08:42:44 AM »
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To Graeme's point, revisit my post   http://luminous-landscape.com/forum/index....8&hl=sensor

In a test where the camera position, lens and lighting remained constant, my P65+ showed greater detail in hilights and shadows than my D3.  It's not, however, enough detail to make up for the extreme contrast of many interiors scenes.  You frequently have blown out light fixtures in the shot which may be the only area that isn't rendered with detail.

Sometimes I let these go, and sometimes I find them too distracting and will bracket for later compositing.  Even if I have people in the view, I find that I can process a single P65+ file +1.5 and -1.5 with little to no loss in quality and then composite those images to achieve far greater tonal range than any recovery sliders can render.

In the past I've used the above linked technique, and I also like Photomatix, but I don't find that either yields a result that I can call final...  I often blend the offensive areas (windows or fixtures) into a straight exposure that has nice contrast overall.

Will there ever be a sensor that has "enough" dynamic range?  I truly have no idea.  But I'm practically giddy to have twice the DR I used to have with chromes and don't mind a little compositing...    for now.

Parting thoughts:   RAW RAW RAW!  Jpegs have less tonal range than an 8 bit Tif.  Raws have more detail than a 16 bit Tif.  Which do you think you should be shooting?  Actually it often astounds me how much detail is there in the hilights of raw files if you play around with exposure and recovery.  You just have to massage it out and into your Tifs.

To address your image specifically, I feel like the sconce and the ceiling niches are fine but the wall feature lights are very harsh and definitely need to be softened.  It feels quite yellow overall and the shadow areas seem heavy.  In the ceiling I would remove the speaker, the access panel, the can light on the top edge and the dead can light to start cleaning things up.  Lastly, your shot is a little out of square.   You needed to swing left a little more  : )


-CB
« Last Edit: January 30, 2010, 08:52:38 AM by CBarrett » Logged
Abdulrahman Aljabri
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« Reply #32 on: January 30, 2010, 08:52:42 AM »
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Thanks man, I am going through the link as we speak


Quote from: CBarrett
Parting thoughts:   RAW RAW RAW!  Jpegs have less tonal range than an 8 bit Tif.  Raws have more detail than a 16 bit Tif.  Which do you think you should be shooting?  Actually it often astounds me how much detail is there in the hilights of raw files if you play around with exposure and recovery.  You just have to massage it out and into your Tifs.

And, your shot is a little out of square.   You needed to swing left a little more  : )


-CB



yeah I got so used to using jpeg because they are mostly sufficient that I miss opportunities to shoot RAW when there is a real benefit to using it such as in this picture. Back when I used to live in Chicago I used to photograph the forest preserves in Palos Heights and I always used RAW for landscape. I would open the file in Photoshop RAW make zero adjustments and open the file as a 16bit jpeg. From there I would set the white and black point as I please and play with contrast.
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bjanes
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« Reply #33 on: January 30, 2010, 09:16:28 AM »
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Quote from: BernardLanguillier
One thing to keep in mind in this discussion is that many photographers still think that DR is measured by the amount of blown highlights they manage to recover with their favorite raw converter...
Bernard
Bernard,

Quite true, but a camera that has a lot of room for highlight recovery is not desirable. Highlight recovery is possible because the red and blue channels of a typical sensor are less sensitive than the green channel. This results in a white balance multiplier for the red and blue channels. For the Nikon D3 with Solux illumination, the red and blue multipliers are 1.55 and 1.61 respectively, as shown in the Rawnalize screen capture shown below. The green channel here is just short of clipping.

[attachment=19853:16_Rawnalize.png]

If we render this image in ACR at defaults, the image appears overexposed.

[attachment=19854:16_ACR_Default.png]

Using negative exposure, we appear to be recovering 1.05 stops of overexposure. However, there was actually no overexposure but merely a hot tone curve in ACR (which has a baseline exposure of +0.5 EV and a default brightness of +50).

[attachment=19855:16_ACR_MinusExp.png]

With more actual exposure of this image, the green channel would clip first but the blue and red channels would be intact and allow highlight recovery. However, there would likely be color shifts. The blue multiplier of 1.6 corresponds to approximately 0.69 stops, and this would be the maximal highlight recovery for this camera. It would be desirable if the blue and red channels had the same sensitivity as the green channel. Some photographers place a magenta filter over the lens to hold back some of the green light and balance the channels, allowing increased dynamic range.

Since the response of a CMOS or CCD sensor is linear, it makes no sense to talk about highlight and shadow dynamic range on either side of mid gray. If you expose for mid gray (18% saturation), the highlights will be 2.5 stops to the right. However, for digital exposure it does not make sense to meter from the midtones, but rather one should place highlights that must not be clipped just short of clipping. Shadow noise and effective DR will then be determined largely by the read noise of the sensor for a given full well. I'm sure you know all this, but others may be interested.

Finally a few words on DR. Dynamic range is defined as the full well capacity/read noise (both expressed in electrons). This is the engineering definition, and photographers may set the noise floor higher.  For a recent MFDB sensor (the Kodak KAF 50100), the full well is 40,300 e- and the read noise is 12.5 e-, giving a DR of 11.7 stops, about the same as the Canon 1D MII (Roger Clark). The current champion of DR for dSLRs is the Nikon D3x due to its low read noise and decent full well capacity. I do not have the actual figures for that camera, but DXO reports the DR at 12.84 stops (screen), and they report 11.07 stops DR for the 1DMII (similar to Clark's data). This is per pixel DR, reported as "screen" on DXO. The screen DR for the Phase 1 p65+ is 11.51 stops. If one normalizes for a given print size, the DRs for the D3x, P65+ and 1D MII are 13.65, 12.97 and 11.11 stops respectively. I prefer these scientific data to subjective impressions DR derived by looking at pictures of clouds.  

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BernardLanguillier
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« Reply #34 on: January 30, 2010, 10:32:19 AM »
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Quote from: Graeme Nattress
DR is typically noise limited. Indeed, you can think of sensors only having more and more range in the shadows as the top end is fixed by it's clip point. However, that does not mean you should only look for extra DR in the shadows as it all depends where you place mid grey in the range the sensor offers, and hence how many stops above and stops below you can record.

Given that different cameras sensor sensitivities are different, you can't just put a similar lens and set the same shutter and f-stop on each camera and expect a fair comparison. You might see one didn't clip some highlights, but the other did, and conclude the first had more DR. However, the first could be less sensitive. The second camera might have much more shadow detail and hence could have been easily allowed to be under-exposed by a stop, recover the highlights and get a wider DR by bettering the first in the shadow department.

You are refering to the fact that DR depends on sensor true sensitivity, and that sensor sensitivity being different with different bodies, it is difficult to compare DR.

True enough, but it doesn't change the fact that there is one and only one method to measure DR with digital sensor, and that method has absolutely nothing to do with mid-tones.

That correct method is to expose to the right (brighest significant highlight not blown in any channel) and measure shadow noise.

That method isn't just mathematical, it is closely related to the way digital cameras need to be exposed for optimal results.

Regards,
Bernard
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CBarrett
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« Reply #35 on: January 30, 2010, 10:56:45 AM »
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Man, this all makes my head hurt.  I just wanna make pictures.
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« Reply #36 on: January 30, 2010, 11:33:43 AM »
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Quote from: CBarrett
Man, this all makes my head hurt.  I just wanna make pictures.
  +1
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« Reply #37 on: January 30, 2010, 11:50:17 AM »
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I hope it will be figured out or abandoned once and forever and the topic will be pinned to the top.
I'll go make some photographs in the meantime as well.

All those generic tests and mathematical calculations make no sense to me. One can only decide if IQ, DR, body design etc. suits him or her by examining his/her own real work produced with the equipment in question.

Best of luck to you anyway.
Alex
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Graeme Nattress
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« Reply #38 on: January 30, 2010, 12:58:49 PM »
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Practically though, it's hard to adjust a camera to be "just" under clipping, so we allow them to visibly clip in the chart and then we can measure from that point downwards. We do the same thing, just a bit easier to "prove" that we have captured the full range possible.

Graeme

Quote from: BernardLanguillier
You are refering to the fact that DR depends on sensor true sensitivity, and that sensor sensitivity being different with different bodies, it is difficult to compare DR.

True enough, but it doesn't change the fact that there is one and only one method to measure DR with digital sensor, and that method has absolutely nothing to do with mid-tones.

That correct method is to expose to the right (brighest significant highlight not blown in any channel) and measure shadow noise.

That method isn't just mathematical, it is closely related to the way digital cameras need to be exposed for optimal results.

Regards,
Bernard
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« Reply #39 on: January 30, 2010, 03:15:53 PM »
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Given the number of workshops that take place each year, between Michael's groups here and Jack and Guy's groups over on getdpi, I would think this matter could easily be put to rest if the same landscape were shot under identical lighting conditions with a 22 megapixel digital back and, say, a Nikon D3x, using the best glass of equivalent focal lengths on each camera.  After all... it is often claimed that even the 22 mp digital backs will clearly beat the best of the 35mm offerings.  Shoot the damned images at = iso, process in Capture One (or whatever the best software may be for the that given camera) and print them out at 24x36" on fine art paper.  Dot gain will level the field somewhat... and the resulting images should clearly show whatever advantage one might have over the other.  This subject has photographers so polarized that nothing short of a visual test on paper will ever settle the issue.  Make the prints and label them on the back.  Don't disclose the camera until the opinions are in.  What better way than to let your eye's decide between two images shot under identical conditions?
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