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 p.2 #19 · p.2 #19 · Call for help - building sensor readout speed database | |
Grenache wrote:
Naive, and sincerely not sarcastic, question: assume you have all of these numbers, what would be the use of the data? I have only encountered one situation where having even a global shutter would have materially impacted my image quality, and that was photographing fighter jets that were approaching the speed of sound.
Cheers,
Jim
snapsy wrote:
Determining rolling shutter distortion likelihood for fast-moving subjects/cameras (both stills and video) and whether banding will occur for a given lighting cycling frequency. It also helps in reverse-engineer how many samples the AF system will see and also what refresh rates LV can be driven at (if you use the 10-bit video mode rates since that's likely how the sensor is sampled for stills LV). It also helps reverse-engineer the sampling modes used for video, including which are oversampled and which employ line-skipping/binning. which has implications for video IQ.
chiron wrote:
Great project and very useful and interesting to me. My concern with sensor readout speed has to do with avoiding banding from LED or other flickering lights while shooting with any form of electronic shutter, which has become a major problem as these lights have become more ubiquitous.
I personally have never had a problem with flickering/banding with either the A1 or the A9, the two cameras on your list that I own. I have never shot billboard lighting or theatrical lighting, which may be more difficult cases.
Since the A9 reads out at 1/152 of a sec and the A1 at 1/256 sec, that suggests that readouts well short of a global shutter (with its compromises in dynamic range and perhaps colors) are sufficient to avoid banding with electronic shutter under flickering lights.
This makes me wonder if the A1II, whenever it finally gets here, will simply speed up the sensor readout rather than try for a global shutter. This would keep the cost down, the image quality and versatility up, and make the camera more attractive for many of us.
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snapsy wrote:
Thanks. Unfortunately there are some LED lights that cycle very quickly, particularly if they're dimmed below 100% due to PWM. For example here's a photo from the Z9 on a Kasa Smartbulb I own that cycles at 1920Hz:
https://photos.smugmug.com/photos/i-mpRPL5X/0/Cmk59Mj7VMTNSpggWshjqfq3hjMH6NjmxbTgWxFwD/L/i-mpRPL5X-L.jpg
Here's that same bulb shot with the global shutter on my Nikon D40:
https://photos.smugmug.com/photos/i-49cTBxX/0/3rB9jnKDrQBZf8gPPgh6rSm5ZknN5r3QCHpmG6fZ/L/i-49cTBxX-L.jpg
While I don't shoot with stacked sensor cameras, rather the Canon R6 and R6II, I've found Canon's high speed flicker compensation in the R6II quite useful for some stage lighting situations. In my case, corporate events. The spots used at these are LED and often dimmed quite a lot because they're used in smaller venues and the corporate execs doing the on-stage presentations don't like bright stage lights in their eyes... At the most recent event I did, the flicker compensation feature indicated these spots operated at 1200Hz. The e-shutter banding in these situations with the R6II was fairly faint, but still noticeable if you looked for it because there were numerous bands. My guess is the a1/Z9 would still see some banding but it would be quite broad and probably disguised by the scene unless there are a lot of blank, even-toned surfaces. Based on the calculations in the above example of the LED at 1920Hz, the scenario I was in, if shooting with an a1 or Z9 would likely have resulted ~9 bands across the frame.
FWIW the high speed flicker compensation feature works very well, but is an additional step that has to be done (camera analyses the light and sets/recommends the correct shutter speed).
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you know what I mean
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