Gentlemen,
this is my first post on reduser and I am the guy who is doing the CineD Lab tests. I am here to answer all your questions, and looking forward to a good technical discussion.
Phil has shared already our method (how we test) - thank you - and in the article I have clearly laid out the dilemma one has when trying to reduce DR to a single number.
https://www.cined.com/the-cinema5d-c...c-range-tests/
a) Judging DR only from waveforms is a good method, but subjective, as some may see more stops than others and it doesn't tell you if all those stops are usable are not. USABLE is the term here!
b) The Xyla 21 chart has to be shot at 3200K - agreed. Nevertheless we purposely expand the RGB information to 5600K to see if all color channels are still there. In the french test shared by Bastien (previous page) you can clearly see the lacking color information on the top 2 stops of the KOMODO. Why, because Komodo uses an in - built highlight recovery mechanism (as the first RED camera). In the facebook thread where our lab results are discussed (RED KOMODO group), the man behind the IPP2 image pipeline himself, Graeme Nattress has confirmed this behaviour for the KOMODO, see attached screenshot.
c) IMATEST is the only objective way to mathematically calculate signal to noise numbers for each patch and hence dynamic range. Is it perfect - no. Because as Phil mentioned, flares can have an impact on the result, etc.. But it is a way to quantify and compare cameras to each other. We are conservative and use the Signal to noise ratio = 2 as our definition of usable (but give you both SNR = 1 and 2 values for full transparency).
d) Of course, in-camera or post noise reduction has an influence on the calculated signal to noise numbers. With noise reduction, the signal stays the same but noise is reduced, leading to a higher signal to noise value thus higher dynamic range. THe same happens by downsampling from 6K to 4K or to FullHD. IMATEST themselves warn against using noise reduction, and suggest to use RAW files as pure as possible, otherwise results will be distorted - as has been pointed out earlier in this thread as well. Thats why we give you pure values straight from the file with no post processing at native resolution.
e) on shooting the chart wrong: here is the download link for the R3D HQ file shooting our Xyla21 chart, judge yourself:
https://we.tl/t-c1YhxlHqWj
f) and finally, we are also doing the latitude test, purposely over- and underexposing and bringing it back to see how usable the dynamic range is. To have a reference we choose a max. luma value of 60% for the subject's face. Which is hot for some cameras like the KOMODO but in the middle for others - the ALEXA for example has five usable stops above 60% Luma, the BMPCC6K has close to 4 stops, the C300MKII has 3 usable stops above 60% - that is just a matter how cameras distribute the stops across the range, which also depends on the ISO you choose e.g. for the KOMODO. And this test confirms that two stops above 60% at ISO800 the face cannot be recovered - that is exactly the stop from the waveform which has already clipped color channels but still looks good in the waveform (due to HL recovery - or soft roll off, however you want to call it).
Happy to answer any other questions you might have!
best regards, Gunther
Originally Posted by Noah Yuan-Vogel
