ISO upper limit possible in movie mode ? - Feature Requests - CHDK Forum supplierdeeply

ISO upper limit possible in movie mode ?

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Offline vit40

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ISO upper limit possible in movie mode ?
« on: 04 / February / 2009, 04:15:44 »
Similar question by other member was moved to  "Hello, I'm a NEWBIE - HELP!! (Newbies assistance, User Guides and thank you notes)", but I'll try to explain my point of view, if something could be done about it

So, possibility of limiting max. ISO in video mode would be very useful for me. I'm using my digicam to record some sport dance competitions. Everything was fine with A620. Now I bought A650, which has optical image stabilization and better zoom (more steps, not so noisy, no obvious refocusing after zooming). But there's a big problem - auto exposure control in movie mode is considerably worse on this camera. In case of high contrast (brightly lit dance floor and very dark background), it tends to boost ISO to maximum (which is considerably higher than on A620 btw), producing very noisy picture and blowing bright parts of the picture. So a possibility to limit maximum ISO, somewhere in the menu (like for photo mode), would be quite useful with this camera.

For now, there's only a possibility to lock the exposure, including ISO, and then manually correct exposure time with left/right keys. It is usefull, but there are several drawbacks: after zooming, exposure is unlocked and changed to new value (usually brighter or darker), manual change of exposure is also quite visible on the final video, and it's not easy to set correct exposure, looking the picture on the LCD ...

Other problem is sometimes fluorescent lighting on some dance classes. We have 50 Hz electricity, and frame rate is 30 fps. So, under some circumstances, there's very strong flickering in recorded video, because of interference. That's why PAL camcorders have 25 fps. Here, it would also come handy to limit ISO, then lock the exposure and manually correct exposure to "+" (longer exposure time), which reduces this flickering. Of course, 25 fps movie mode would be a better solution here, but I suppose it's not possible (although Ewavr mentioned a possibility of different frame rate several months ago) ...

Maybe Ewavr has some magic solution, like always?

BTW, manual exposure correction seems to go only to 1/40 (instead to 1/30), at least in some circumstances
« Last Edit: 04 / February / 2009, 06:46:36 by vit40 »


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