Here is some more feedback on the latest July 25-th build for the 100D concerning the other croped modes. All tests were performed in the "Framing" preview mode with the 95 MB/s SanDisk Extreme Pro SD-card (64 GB).
1) "2.5K 2520x1304" and "3K 3096x1320"
(*) 14-bit lossless works just fine, with bright screen and WySiWyG preview, no corrupt frames;
(*) 10 and 12-bit lossless modes provide corrupt footage;
(*) 10, 12 and 14-bits uncompressed work too but there is no in-camera playback for 10 and 12 bits uncompressed (black screen);
(*) as expected, the 3K mode needs new focus pixel maps.
PROBLEM:
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The WySiWyG preview works fine only when the camera is cool. As soon as the indicated temperature exceeds 50 deg. C, the preview becomes scrambled and this makes framing and focusing impossible. Camera needs to cool down before the preview becomes normal. This is not the case with the "2.5K 10bit 2520x1304" mode in which 5x-preview continues to work even when camera temperature reaches 61 deg. C. This is probably due to the fact that the screen stays pretty dark in that 10-bit mode.
2) "2K 2520x1080p"
This is the best working and most stable mode, with bright screen, WySiWyG preview and no corrupt frames in all compressed and uncompressed modes. At 8 ... 11-bits and 12-bits LL compressed and proper exposure it provides continuous recording at 24 fps. In this condition, the write speed is between 52 and 58 MB/s meaning that a 128 GB card can accommodate about 35 minutes of footage. If the scene is exposed to the right, the exposure slider can be pushed down by one to two stops in MLVApp which provides very clean shadows, beautiful colors and superb overall image quality. This mode is very good news for those who like shooting at 2,35:1 aspect ratio.
3) "3x3 720p"
This mode is not working properly which is seen also in the preview screen. A horizontal line splits the frame into two parts with different exposures and some greenish/bluish color cast on the upper part. The same behavior is observed also when the footage is opened in MLVApp. The good news is that at the maximum resolution (2520x1078)@24 fps, this mode provides stable WySiWyG preview, continuous recording at 8 ... 11-bits and 12-bits lossless and in-camera playback. All that needs to be done for it to work properly is to fix this split image.
4) "4K 4056x2552" (14-bit lossless)
In this mode, I also noticed some instability. Although the write speed indicator was green, indicating about 45 MB/s write speed or less - well below the 59 MB/s limit, I was unable to get continuous recording at more than 3 fps. Even at this FPS rate, recording was continuous only after I pushed the INFO button which kills the framing preview and provides a scrambled screen. With the framing preview active I was able to get only 1 frame recorded, no matter what I did.
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5) I also would like to mention that the Normal uncroped mode at 1736x976 resolution as well as the Movie Crop Mode at 1800x1012 resolution also work very well at all compressed and uncompressed bit rates. No surprises here. At the 8 ... 11-bit lossless, 1736x976 resolution and 24 fps, the Normal mode writes at less than 32 MB/s when filming a normally lit and properly exposed scene. This provides about 1 hour record time on a 128GB SD-card. Therefore, with appropriate power supply (a fully charged quality battery or external power supply), the 100D is appropriate for filming even events. I tested this with a 64 GB card and let the 100D film until card was full. I did not observe camera overheating (temperature did not exceed 50 deg. C) and recording with sound was perfectly OK. Another wonderful feature of the Normal mode which makes it usable for Slow motion shots, is that one can increase the frame rate to 42 fps and still get stable recording at the maximum 1736x976 resolution with the 8 ... 11-bit LL setting. This is possible due to the SD-overclocking feature (thanks A1ex and Danne !!!). Record time at the 42 fps rate is about 8 sec. You can go up to 44 fps but this is the edge and recording is not very stable. At 45 fps, you get corrupt frames. In the 2520x1080 mode (5x-magnification), FPS rate can be increased to 36,7 fps.
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PLEASE NOTE: Although this build is quite stable, random crashes in the high-resolution crop modes still occur now and then and they are impossible to reproduce. Mostly they happen after changing modes, preview or FPS settings. It is advisable, after these settings have been changed, to turn camera OFF and On again and then start recording.
I hope, this helps the developers continue their work on this most capable build. If they manage to fix the dark screen and WySiWyG preview without reducing record time too much in the "2.5K 10bit 2520x1304" mode, the 100D will be ready to shoot 2,5K RAW video under real-life filming conditions.
