Dear Wayne, I plan on going back to very basic "stuff" tomorrow, among others, like shooting a plain vanilla ColorChecker 24 chart. This type of target ought to easily reveal any differences between the RAW file, as developed with CameraRAW, and the JPEG "in-camera" rendering. It's going to be very easy to compare both processed pixels values. This is still a mystery to me. I probably did something silly on my camera ... Best / Roger -----Original Message----- From: Wayne Bretl <waynebretl@cox.net> Sent: Friday, June 21, 2019 11:10 PM To: graxx@videotron.ca; 'Iliah Borg' <iliah.i.borg@gmail.com>; Colorsync-users@lists.apple.com Subject: RE: Exposure Value Dear Roger, Without further evidence, it is still a mystery why your original raw-file-only mode pictures show apparent underexposure, and the ones taken after choosing raw + jpeg do not. Is it possible you changed another mode setting, like going from Program to Full Automatic, or some other setting (matrix, spot, center average) that changed the exposure metering mode in your camera? Some modes may center the dominant exposure sensing on the in-focus point, for example. Some cameras also have an automatic tone curve adjustment (possibly enabled or disabled according to the exposure mode and/or in a menu somewhere) that attempts to recognize and compensate for various types of images. This is an opportunity for the camera to do things you don't like, as well as possibly rescuing some shots for the unknowledgeable person using full automatic mode. Another thing to note is that while the data in the raw file is supposed to be a mostly untouched rendering of the light falling on the sensor, the rendering output of the raw processor definitely is not so simple. The rendering is not even simply an application of a gamma curve to match the standard jpg 1/2.2 power. That sort of simple process was used in very early digital cameras adapted from video chips, such as the Sony Mavica, and was universally disliked compared to film. Now, raw processors always apply an S curve, mimicking film, because this provides the best looking result: an increase in contrast (at least for the mid tones) to compensate color appearance effects of the human visual system, and a gradual toe and shoulder to accommodate highlights and shadows without severe clipping. This is one example of the kind of behind-the-curtain processes, the details of which are buried in the camera profile and never revealed to the user by Adobe camera raw. Regards, Wayne -----Original Message----- From: colorsync-users <colorsync-users-bounces+waynebretl=cox.net@lists.apple.com> On Behalf Of Roger Breton via colorsync-users Sent: Friday, June 21, 2019 7:15 PM To: 'Iliah Borg' <iliah.i.borg@gmail.com> Cc: Colorsync-users@lists.apple.com Subject: RE: Exposure Value Dear Ilah, Thank you so much for applying your vast technical expertise to my humble problem. I realize, again, that there is so much to learn in digital photography, I feel ashamed to have neglected digging into this fascinating part of image processing for so long (It took me more than a few CPU cycles of my brain to figure Exposure Value, today)... For sure, I need to invest in a "new" gray card, I confess that this one has seen its share of "tales from the trenches". Having said that, I'm relieved to read in your analysis that my camera "light meter" isn't playing tricks on me or need to go back to the manufacturer under warranty. I *will* reshoot, for sure, as you suggested. It's an exercise worth every effort and probably investigate using one of your suggested software.. For now, I am not sure what to conclude from my experience? Tomorrow, I will probably experiment with shooting A) RAW alone and shooting B) RAW + JPEG. In "theory", there should not be any difference between the two modes of shooting but if there should be one, then this is going to prove interesting. Have you had a chance to take a look at my Excel sheet at all? To see whether I correctly applied the metering equations from measured Luminance and Illuminance? I think the calculations are sound. One last thing I have not tried and I *will* try is, to shoot with my antique D100, in RAW, to compare with shooting the same scene with the D810, in RAW, to test any potential differences between the two systems, in terms of exposure. One thing I wonder, as I was thinking about the experimental setup, something completely absurd (?), was, what that, could there be any difference in the underlying capture of the pixels between the two cameras? Suppose, on the D810, at 1/200s, F/5.6, ISO400, the histogram looks skewed to the left, suggesting some degree of under-exposure (see my earlier links)? Suppose further, on the D100, at the same 1/200s, F/5.6, ISO400 settings, the histogram looks "normal", with pixels distributed throughout the tonal range, from 0 to 255, then what? Until I'm convinced that there is nothing wrong with this camera, I figure I need to further test it, until I'm fully satisfied that there is nothing "wrong" with it. Best regards / Roger -----Original Message----- From: Iliah Borg <iliah.i.borg@gmail.com> Sent: Friday, June 21, 2019 6:33 PM To: graxx@videotron.ca Cc: Colorsync-users@lists.apple.com Subject: Re: Exposure Value Dear Roger, Based on your gray card NEF: You are in 14-bit mode, maximum is 2^14-1-black level (600) = 15873; average on the card (and the card seems to have some rather strong imperfections) is 1181 (you can check with RawDigger, trial version is enough). That puts the exposure at log2(1181 / 15871) = 3.75 EV below clipping; the camera is calibrated to produce midtone 3.35 EV below clipping, that means the exposure is 0.4 EV below the midtone. Nothing dramatic so far, provided that the card has a lot of wear and tear on it, it isn't shot out of focus, and not at an angle as it should be (see http://www.zonephoto.it/images/pdf/kodak-grey-card1903061.pdf ). The result is mathematically inconclusive - but from my experience I would be expecting something like the numbers above, given how the shot was taken, and would say that metering is calibrated OK. Of course, if you could re-shoot we will be able to come to a more definite conclusion. On Jun 21, 2019, at 6:03 PM, Roger Breton via colorsync-users wrote:
I will get to the Gray Card NEF in a few minutes, Ilah, but I thought I would try turning on Image quality = NEF + JPEG in the camera shooting menu?
And I got very different results? See this link: https://1drv.ms/u/s!AkD78CVR1NBqkLVK68wxOJ6dhvv2nQ
On the left hand side is the JPEG opened in Photoshop as usual, and on the right hand side is the RAW, opened in CameraRAW. The only thing that I could say is the Histograms are very different, this time, extending well into the highlights...
Thanks for you guys patience and help. I'm trying to contact Nikon tech support...
Best / Roger
-----Original Message----- From: colorsync-users <colorsync-users-bounces+graxx=videotron.ca@lists.apple.com> On Behalf Of Roger Breton via colorsync-users Sent: Friday, June 21, 2019 5:44 PM To: 'Wayne Bretl' <waynebretl@cox.net>; Colorsync-users@lists.apple.com Subject: RE: Exposure Value
I just tried with ViewNX2 and it is still too "dark"? So it is not coming from CameraRAW -- good news 😊
ViewNX2 link is here: https://1drv.ms/u/s!AkD78CVR1NBqkLVIL-cOCJBYIX0LuA
CameraRAW link is here: https://1drv.ms/u/s!AkD78CVR1NBqkLVJgBzv-yK7ygFD7g
The histograms are not lying, this is under-exposed.
Best / Roger
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-- Best regards, Iliah Borg LibRaw, LLC www.libraw.org www.rawdigger.com www.fastrawviewer.com _______________________________________________ Do not post admin requests to the list. They will be ignored. colorsync-users mailing list (colorsync-users@lists.apple.com) Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/colorsync-users/waynebretl%40cox.net This email sent to waynebretl@cox.net