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Author Topic: Proprietary info extracted by mfrs' raw conversion software?  (Read 4769 times)
David Eckels
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« Reply #20 on: May 27, 2013, 07:02:25 PM »
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Below, 100% crops of the LR4 conversions, I can't see much of any difference, as expected.
Jeff, I will bet you are rolling your eyes when you read this, but thanks for your patience and for The Digital Negative.
« Last Edit: May 27, 2013, 07:05:30 PM by David Eckels » Logged

Jack Hogan
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« Reply #21 on: May 28, 2013, 01:36:16 AM »
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Yes, hi David.

You apparently are the lucky owner of two of the world's most advanced cameras, a D800 and a D7100, both with usable Photographic Dynamic Ranges close to 11 stops, so your need for bracketing is minimized compared to someone who shoots with cameras based on older technology.  Add to this the fact that a completely functioning and adapted eye can see only about 12.3 stops of DR and one realizes that bracketing with cameras such as yours today is an infrequent exception for special occasions rather than the rule.  The same is not true for all current DSLRs, however.  Canons, for instance, are typically limited to about 9 stops of PDR.

So then the question for you shifts to a different one: most images are squeezed into 8-bit jpeg files and/or viewed on monitors/prints that can normally render 9 stops or less, with contrast ratios of around 250 or 8 stops being a high norm in practice. So what do we do with the extra couple of stops of DR that recent Nikon DSLRs capture - just let them get lost in the display medium's murky shadows?  Of course not.  You've got the information, use it at its best.  That's where ADL comes into the picture.

From now on, I will turn ADL off because it interferes a bit with my ETTR thinking and I can better compensate for high contrast scenes by bracketing....as the experts have said here all along! Sometimes, I learn slow

If you ETTR in 2013 you probably shoot Raw in full manual mode, setting shutter speed and f/number according to your artistic costraints of blur, DOF and retained highlights while selecting ISO for the desired balance of SNR, DR and SOOC output brightness.  If that's the case ADL does not 'interfere a bit with [your] ETTR thinking'.  It doesn't change anything in your Exposure.  All it does is intelligently process the 11 stops of your captured PDR to fit into a couple less.  It does an excellent job of it.  So good that I personally find it quite a time saver in PP to have the NEF look just like that when first opened by the raw converter (CNX2 in my case).  Not to mention the much better looking SOOC jpegs.

If you do not shoot in full manual mode, ADL is even smarter than that, but that's the subject for a different post.  So don't be afraid of ADL, it's just another advanced tool in your photographer's toolbox.  An excellent one at that, so study it and learn how to use it to your advantage, if at all.

Cheers,
Jack

PS Perhaps your other sources shoot with lower PDR cameras? Smiley
« Last Edit: May 28, 2013, 12:33:21 PM by Jack Hogan » Logged
jrsforums
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« Reply #22 on: May 28, 2013, 09:36:18 AM »
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If you ETTR in 2013 you probably shoot Raw in full manual mode, setting shutter speed and f/number according to your artistic costraints of blur, DOF and retained highlights while selecting ISO for the desired balance of SNR, DR and SOOC output brightness.  If that's the case ADL does not 'interfere a bit with [your] ETTR thinking'.  It doesn't change anything in your Exposure.  All it does is intelligently process the 11 stops of your captured PDR to fit into a couple less.  It does an excellent job of it.  So good that I personally find it quite a time saver in PP to have the NEF look just like that when first opened by the raw converter (CNX2 in my case).  Not to mention the much better looking SOOC jpegs.

If you do not shoot in full manual mode, ADL is even smarter than that, but that's the subject for a different post.  So don't be afraid of ADL, it's just another advanced tool in your photographer's toolbox.  An excellent one at that, so study it and learn how to use it to your advantage, if at all.

Cheers,
Jack

PS Perhaps your other sources shoot with lower PDR cameras? Smiley

jack, is what you say....ADL not interferring....true if one does not use Nikon raw converters?

I (think) I know what Canon does under the covers with HTP, what does ADL do?  How does LR/ACR handle it?

John
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John
FranciscoDisilvestro
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« Reply #23 on: May 28, 2013, 10:16:15 AM »
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The only effect for the RAW data in nikon NEF files if you use ADL is perhaps underexposure and this depends on the ADL level (low, high etc). I say perhaps because if you use the low setting it usually do not even change exposure.

This means that if you use ACR/LR, the only thing that you might have achieved by using ADL would be preserved highlights, nothing more. It would be just like using exposure compensation (In manual mode it just change the meter reading, again like using exposure compensation).

Nikon converters apply a propietary algorithm to images with ADL on, I presume it is more complex than just a curve, it looks a more advanced shadow/highlights adjustment.

You can achieve very good results with LR, especially with the new process 2012, playing with the whites/highlights/shadows/blacks sliders.

Going back to the OP, data such as focus point is not used by other converters, and you cannot use the Dust Reference photo either with any other software than Nikon.
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Jack Hogan
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« Reply #24 on: May 28, 2013, 12:32:23 PM »
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jack, is what you say....ADL not interferring....true if one does not use Nikon raw converters?

I (think) I know what Canon does under the covers with HTP, what does ADL do?  How does LR/ACR handle it?

In full manual metering mode ADL is just an advanced in-camera image processing algorithm applied to the captured Raw data in order to produce the SOOC image/jpeg (Nikon Raw converters use the same algorithm when first opening a NEF captured with ADL on): being smart, it does things like brightness/contrast corrections and tone mapping to obtain what it thinks is a pleasing OOC image given the captured Raw data.  In my opinion, for an automatic algorithm, it does an excellent job right out of the post.  It does not mess with Exposure - in full manual mode*. 

Non Nikon Raw converters start with the exact same Raw data in the NEF, but apply their own camera-specific yet generic recipes which tend to mimic Picture Controls (i.e. Lanscape, Standard, Portrait etc.).  But they do not use the information contained in the NEF connected to ADL nor do they attempt to do what it does.  Since ADL applies quite a number of adjustments, images taken with ADL on may appear quite different SOOC as opposed to as rendered from a third party Raw converter.  I like what it does so I keep it on 90% of the time (I turn it off for instance when I use flash).

Jack

*We need a separate post to deal with ADL used in conjuntion with an automatic metering mode.  See below.
« Last Edit: May 29, 2013, 01:57:54 AM by Jack Hogan » Logged
Jack Hogan
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« Reply #25 on: May 28, 2013, 12:56:41 PM »
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The only effect for the RAW data in nikon NEF files if you use ADL is perhaps underexposure and this depends on the ADL level (low, high etc). I say perhaps because if you use the low setting it usually do not even change exposure.

Alright so now let's talk about what ADL does in conjunction with an automatic metering mode (NOT in full manual mode, which was discussed in the previous posts).  With all this talk about ETTRv2013, wouldn't you like it if your camera Exposed for maximum information captured (i.e. maximized shutter speed, aperture, SNR and DR without clipping) but was also capable of processing that Raw information for a most pleasing brightness/tonality in the final image?  You guessed it, that's exactly what auto ADL does when you let it.

When auto ADL is used with Matrix Metering in P,A,S (+ auto ISO) mode for instance, it will evaluate the scene continuously as long as the meter is on before you squeeze the trigger.  If it figures that your histogram is going to be empty to the right, it will adjust exposure automatically up to about 1 stop to ETTR.  If it figures that your histogram is going to be too full to the right and you might be clipping some desirable highlights, it will adjust exposure automatically up to about 1 stop to shift the histogram to the left in order to let more highlights in.  And thanks to current cameras' outstanding PDR  it can do it without worries of 'underexposure'.  That's how auto ADL determines Exposure to capture the best information (IQ) possible in the Raw data, the NEF.

Next, when you squeeze the trigger, in the blink of an eye it (and V/CNX2) also processes that excellent IQ Raw data into a SOOC image with pleasing brightness and tones as described earlier.  If you now open the NEF in a third party converter which does not read ADL information, the rendered image may look off (too bright, too dark, too contrasty or whatever) because they simply apply their generic recipes as is.  It doesn't mean that you cannot get an image to look like the one OOC, but you have to work at it.  Work that I prefer not to do if I do not have to - because it's already been done for me Smiley

Jack
« Last Edit: May 28, 2013, 01:11:03 PM by Jack Hogan » Logged
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