Does Active D lighting change the exposure?

[francisco_disilvestro]

<blockquote>

<p>if I shot everything with Active D-Lighting in the Low Setting and no flash, will my .NEF files be any different than if the Active D-Lighting was off? There is no exposure shift, but did it change any other characteristic of the file?"</p>

</blockquote>

<p>I have done extensive tests with a D300 and the answer is NO, there is absolutely no change in any other characteristics of the file.</p>

<p>Performed tests in controlled artificial lighting, matrix meter mode:</p>

<p>1.- Exposure with ADL ON HIGH Manual, according to the exposure meter (this was about -2/3 f/stop than ADL OFF)</p>

<p>2.- Exposure with ADL OFF Manual, according to the exposure meter and then another at -2/3 f/stop compensation</p>

<p>3.- Exposure with ADL ON HIGH Aperture priority Auto</p>

<p>4.- Exposure with ADL OFF Aperture priority Auto</p>

<p>All Raw (NEF) files were compared in three ways:</p>

<p>1.- Unprocessed RAW in Rawnalize - No difference other than exposure in the histogram</p>

<p>2.- Unscaled, undemosaized linear tiff from Dcraw and then viewed as logarithmic histogram in <a href="http://www.guillermoluijk.com/tutorial/histogrammar/index_en.htm">Histogrammar</a>, again, no other difference than exposure</p>

<p>3.- Used a trick with <a href="http://www.rawtherapee.com/">RawTherapee</a>, used the Dark Frame substraction function, using the ADL OFF frame as the DARK frame and the ADL ON frame as the image. The result: A completely black frame, so no difference between those frames. For this to work, I used the ADL OFF manually underexposed by the same factor than the ADL ON frame</p>

<p>My conclusion is that at least in the D300 there is absolutely no change other than underexposure in the RAW file</p>

<p>I don't have the test images at this moment, but I can post them later if anybody is interested.</p>

[graeme_finlayson]

<p>I never use the active D-Lighting setting as I shoot in RAW, and process in LR/CS5. I also turn off all of the other in-camera processing options as (so far as I know) they're not carried forward into LR, and it helps to maximise the buffer depth when shooting action in CH mode.</p>

[indraneel]

<p>To tie up loose ends, the meter underexposes only in matrix metering mode. There is no change in the spot and center weighted metering modes (tested with 35/2D on D700, single dynamic area AF, Aperture priority, auto ISO; I tested inside the room, so ISO was the only thing that changed, shutter and F stayed (appeared) the same).</p>

<p>The preview (postview?) image with ADL on has "better" contrast and saturated colors (picture control standard with no changes) not only in matrix metered shot (with no exp. comp.) but also spot and CW shots (again, no exp comp (the exposures are vastly different, but I'm comparing ADL on to off here, not matrix to spot)).</p>

<p>ADL auto results looked most pleasing to my eye. I'm going to leave it at that and keep in mind that it's on when in matrix meter mode (which is not always). I always shoot raw, so I'll also have a nice looking jpeg to share without going into NX2 everytime. Since I've started using auto ISO and most likely stepless shutter speeds and aperture when using the matix meter, I guess it can't hurt to also use ADL when on "all auto".</p>

[indraneel]

<p>I found some more information here:<br>

<a href="00OYaw">http://www.photo.net/nikon-camera-forum/00OYaw</a><br>

<a href="http://www.flickr.com/groups/nikon_d300_users/discuss/72157611112048962/">http://www.flickr.com/groups/nikon_d300_users/discuss/72157611112048962/</a><br>

Apparently the D300 does not have ADL auto, but I'm not sure...</p>

[dan_ded]

<blockquote>

<p>To tie up loose ends, the meter underexposes only in matrix metering mode.</p>

</blockquote>

<p>I was going to remark on that as well. If I want a meter reading I can comprehend, I need to use center-weighted or spot metering mode anyways. Who knows, exactly, what matrix metering is reporting. Its algorithms consider brightness in multiple segments, auto-focus points, distance information, etc. It does seem to work well: even better now than on my old 8008s, and it worked pretty well on that, too.<br /><br />So considering that, ADL settings could be viewed as one small manual control of matrix metering. No need to fear it any more than you would fear matrix metering to begin with.<br /><br />What's frustrating though, maddening even, is the lack of precise, definite statements about it in Nikon's documentation. Learning a camera's controls shouldn't have to be an exercise in emperical experimentation. I'm old enough (just :-) to remember when electronics manufacturers often used to include electrical schematics with their products. We don't need to go this far in the opposite direction.</p>

[studio460]

<p>Francisco said:</p>

<blockquote>

<p>I have done extensive tests with a D300 and the answer is NO, there is absolutely no change in any other characteristics of the file.</p>

</blockquote>

<p>Thank you for performing all those tests, and for sharing your findings! Very thorough! Excellent job!</p>