Greyscale test on D90 - Can you help?

<p>Hi,<br>

I have recently entered the DSLR world and have bought a Nikon D90. I have also begun an online photography course. My lastest assignment tought me how to produce a greyscale test and asked me to produce a Zone ruler for the D90.<br>

I have struggled to reach RGB 000 at the darkest end of the scale. I have tried many times to produce a fully black image, but the closest I can get to is RGB 111. I have even used the max shutter speed (1/4000) at f.22 while aiming at a black subject and still not managed to get closer than 111.<br>

While this is very close to full black it is also very concerning as all camera's should have a range of 000 (Black) to 255 (White). I am concerned that my sensor may have a defect.<br>

Has anyone (using a D90) tried to produce this test? Did you manage to reach RGB 000?<br>

Many thanks,<br>

Richard.</p>

 

<p>Have you tried changing the ISO? Low number, 100 or so, may help.</p>

<p>RGB 111 may be the lowest you can go on that sensor. the difference between 000 and 111... to say it's negligible would be an overstatement. This is not a defect, but it is interesting... Perhaps the scale at the high end goes to 256-256-256? In which case, 1-1-1 is probably the same exact thing as the 0-0-0 you are being asked to reproduce.</p>

<p>Richard your result may also depend on the raw converter and/or the post processing after raw conversion that you used. Different converters (or the converter in your camera as well as in camera settings) will "interprete" your image in different ways, out of principle or out of settings ^^ .</p>

<p>You did not say if you looked at raw files or jpg files.</p>

<p>A range of 0 to 255 indicates an 8bit resolution. Obviously you did some sort of processing. Your sensor does not record 8 bit images. The bit resolution will be more like 12bit in 16bit data format.</p>

<p>Even at low ISO numbers any image from your camera should contain noise. How did you evaluate the rgb values? Did you look at individual pixels? Are all pixels 111? That would be very surprising.</p>

<p>By the way: keeping the lens cap on might be a better idea than to shoot at f22, though you follow the logic well.</p>

 

<p>Have you tried shooting in dark room with the lens cap on with a fast shutter speed.</p>

<p>Lol Brian I thought similar and had the sentence in then erased it, saying that even with a lens cap some light might get in ^^. Double safety never hurts.</p>

<p>Hi All and thank you for your responses.</p>

<p>Peter, thank you for clarifying that the difference between 000 and 111 are so insignificant.</p>

<p>And Walter, thank you for the detail you have given. This was very useful. In answer to your questions, you are right to point out that i did not conduct this test in Raw, mainly because i could not find a densitometer tool in the free Nikon editing software and I am unable to open NEFF raw files in Photoshop Elements 6 for some reason.</p>

<p>Therefore it could be due to processing like you say.</p>

<p>I was concerned that the camera was over exposing as it is also not reproducing vibrant colour reproduction.</p>

<p>A few things:</p>

<p>First, turn off Active D-Lighting. If it's on, it will change your exposure on you and will also boost shadows. I.e. black won't be black.</p>

<p>When you metered on something black, what metering mode did you use? If it's not spot metered, your metering may not be as accurate, as background stuff may affect metering. Switch to spot metering and meter off of Zone 0 on your Zone Ruler, then reduce exposure by 5 stops (Pure Black is supposed to be 5 stops below mid-tone).</p>

<p>If you're in spot metering mode and Active D-Lighting is indeed off, and you meter off of Zone V without any compensation, but you don't get Pure Black (RGB = 0,0,0), then that means that the D90 has wider than 11 stops dynamic range.</p>

 

<p>Thanks Vinh,</p>

<p>I have tried turning D-Lighting off as you suggested and it has done the trick. JPEGs are now coming out at 000. I've taken some test shots and can see how impressively D-Lighting works to maintain detail in the highlights and shaddows.</p>

<p>I think there is a downside to the technology though. It seems to render vibrant colours a bit washed out looking.</p>

<p>If correct, you received a small cap with the camera to cover the viewfinder.<br>

Some light might leak through the viewfinder, maybe try blocking the viewfinder with the cap.</p>

 

<p>Forget about the difference between zero and 1 level - it's really nothing. And level zero shouldn't be used as a baseline reference anyway, since the step from 0 to 1 represents an infinite jump in brightness while from level 1 to 2 represents only a doubling of brightness (assuming unity gamma).</p>

<p>Actually, I'd forget about all that greyscale stuff too, and about trying to use the Zone system in any form with digital. The whole point of the Zone system is to achieve an end result that matches your pre-visualised picture. The Zone system was necessary when using film because of the delay between taking the shot and seeing the negative or print. Digital's instant review makes all that redundant. Now you can just look at the camera back and/or histogram and make an informed judgement on any exposure adjustment. Shooting RAW is the digital equivalent of using the Zone system, and a RAW file <em>never</em> contains the RGB values 0,0,0 unless your camera is broken.</p>

<p>Don't waste your time testing and re-inventing what Nikon's R&D department have already done for you. Just get out and take pictures!</p>

<p>Richard,<br>

Curious about the online photography courses that precipitated your initial question...........can you direct me to the site where that hosts the courses, and are you happy with the quality of them?<br>

Thanks, James</p>

<p>Hi James,</p>

<p>I signed up with the Photography Institute as they have an online course that was within my budget (£450). It is a 6-12 month course at your own speed. I would say it is like reading a really good photography book but with a test/assignments at the end of each chapter, of which there are 12. There is also online tutorial advice via email.<br>

Here's a link: <a href="https://www.thephotographyinstitute.co.uk/">https://www.thephotographyinstitute.co.uk/</a><br>

Rodeo,<br>

Thanks for your input. I'm a little confused though... Since downloading camera raw and being able to open my RAW files I have retested and Zone 0 does come out at RGB 000. This is a result that I have been tought is correct, not a result of a broken camera.</p>

<p>Cheers guys. </p>

 

<p>Hi all,<br>

Like Richard, Im with Photography Institute as well and doing this assignment at the moment. these information's very useful to me as i am beginner in this photography world.<br>

thanks</p>