RobertG. said:
Eldar, thank you for posting this panorama in full size. I always wondered if this 5DsR is really as good as some people claim. The level of details and sharpness is!
I shoot mainly landscapes and hate the noise of the 5D II, especially in the sky. No matter which ISO I choose, there is always some noise. Often I use grad ND filters and later one need to brighten up parts of the sky by a 1/3 or even 1 stop. Then noise can become a problem for a pixel peeper....
Now I saw that your pano was shot at ISO 100. So I took a crop to compare it with a shot from my 5D II. For this purpose I converted with Canon DPP one of my Raw files into a JPEG (just a conversion, nothing else done in DPP). I have no full size JPEGs out of came available and it's late at night. So a Raw to JPEG conversion must do. Attached is the comparison of the sky at 100% view.
BTW Eldar, a 242.5 MP pano is very impressiv. I guess you can easily print it several meters wide without noticing any noise at all. The details and sharpness of this pano are amazing. With Photoshop I reduced the size from 30548 to just 12000 pixel long (with auto rendering applied). With 37 MP it still has amazing details and sharpness and now the noise is comparable to my 5D II. So your picture was very useful for me to make some tests. Thank you.
Are you normalizing the images before comparing crops? At native size, the 5Ds has considerably smaller pixels. You need to first normalize the images (downsample the 5Ds image to the 5D II size), then crop and compare. While I am not sure that will actually result in the 5Ds being cleaner than the 5D II, it should certainly reduce the amount of noise your seeing in comparison, possibly make the two images look the same (as far as noise goes). We can actually calculate what the results might be.
The 5D II is gathering more light per pixel, so the signal is stronger in each pixel, and the noise is in relative terms less (noise = SQRT(signal)). If the 5Ds has 1000e- signal in a sky pixel, it's noise is (ignoring RN for the moment) 31.63e-. That is an SNR of 31.63:1 (again, ignoring read noise). Now, if the 5D II has 4000e- signal in a sky pixel, it's noise is 63.25e-. Seems like it's higher...the key is, that's an SNR of 63.25:1. The RATIO is larger with the 5D II, so the image looks cleaner. Downsampling the 5Ds image will average pixel data together. That will increase signal strength, thus increasing SNR, and the differences should drop.
Now, there is read noise to contend with in the real world. The 5D II has 30e- RN at ISO 100, and an FWC of 61072e-. Assuming the blue sky is somewhere around a mitdone gray level, the signal strength of a blue sky pixel in the 5D II would be 30536e-. The SNR would be 30536/SQRT(30536 + 30^2), or 172.23e-:1, which in terms of decibels is ~44dB (out of a maximum of 47.8dB). The 5Ds on the other hand probably has (using 7D II data for now, since we don't have Sensorgen.info for the 5Ds yet and that the 5Ds non-normalized SNR is very close to the 7D II non-normalized SNR), 13e- RN at ISO 100, and an FWC of 29544e-. An 18% midtone blue sky is going to have a signal strength of 14772e-. So SNR would be 14772/SQRT(14772e + 13^2), or 120.85:1, ~41.5dB.
The 5Ds is newer technology than the 5D II. We should hope that, at the very least, Canon has improved the sensor technology between the 5D II and now. I suspect at the very least there will be an increase in Q.E. and a reduction in dark current (which is generally negligible these days anyway, so I'm not accounting for it here.) The 5Ds should actually be gathering more light PER UNIT AREA than the 5D II, so it has the potential to produce better normalized images. I can't say that for sure, and Canon's noise characteristics are usually less than ideal, so only an actual test will say for sure. However, theoretically...
Once you downsample, you should see an improvement, a solid improvement. The ratio of pixel areas between these two cameras is 2.44x (6.4^2/4.1^2). So, if we do: (14772 * 2.44)/SQRT(2.44 * (14772 + 13^2)), we get an SNR closer to what a downsampled image would have. In this case, it's 188.77:1, or 45.5dB. That
is actually better than the 5D II! Well, it would be, if this was actually using 5Ds statistics...I substituted the 7D II statistics, so, I can't say for sure. It is marginally better, we aren't even talking a third of a stop here. Plus, how much the data improves often depends on the scaling algorithm, and there are a lot of those out there (Photoshop will just do a basic BiCubic).
Anyway...the increase in noise with the 5Ds is probably because you are comparing crops of sky at native size. Normalize the images, then crop, and the results may actually tilt in favor of the 5Ds.