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Canon XF Series HD Camcorders
Canon XF305, XF205 and XF105 (with SDI), Canon XF300, XF200 and XF100 (without SDI).


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Old January 7th, 2011, 06:01 AM   #1
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Light sensitivity 720p

Hi

I don't own a XF300 (yet...) so I consider myself as a hangaround for the moment. I just checked this on Vimeo:


As I understand it, the light sensitivity is increased if using the 720P mode. Can any proud owner of a XF300/XF305 confirm that, and/or give an explanation to this behavior?

I own a XH-A1 today and is pleased with the light sensitivity on this camcorder as it covers my needs. If the light sensitivity is better on the XF3xx models, and also can be boosted a little bit more using 720P in certain situations, this will be another plus for these camcorders.


Regards,

/Bo
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Old January 11th, 2011, 08:20 AM   #2
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Hi Bo,

you're right – no light is lost switching between 720/25p and 720/50p. Unfortunately, switching from 1080/50i to 1080/25p looses almost one full stop (see Brian's Resolution Sensitivity Test when he switches between 720p and 1080p. Switching to 1080/50i would have resulted in no light loss compared to the 720/24p setting)

Also see this thread which I started a while ago:

Switching from 1080/50i to 25p loses one f-stop?

Cheers, Martin
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Martin Steimann is offline   Reply With Quote
Old January 23rd, 2011, 06:05 AM   #3
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Hi:

I don't own a XF300, I'm currently waiting for the XF100, anyway, I believe this is pure geometry:

In 1080p you have 1920x1080 or approx 2Mpixels, in 720p you have 1280x720 or approx 1Mpixels. If the camera takes advantage of the entire sensor, interpolating the data to produce 720p, you have the double light per pixel in 720p. That gives you one stop difference at the same framerate/shutterspeed.

Shooting 50i or 50p you have a shutter speed of 1/50 regardless, in 25p you can have a shutter speed of 1/25, giving one stop difference. 25p and 50p with a shutter speed of 1/50 should give the same exposure.

BR, Erik
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Old January 23rd, 2011, 06:35 AM   #4
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720p

Did not Alan Roberts say something about using noise control to improve, recover some of the lost resolution when using 720p?? This could be very useful indeed! Im looking for the relevant paragraph now..
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