Saturday, 28 November 2009

Odd Phenomenon with Canon 7D at High ISO

This evening I decided to play around with the noise reduction settings for high ISO. The ultimate aim was to try to determine whether it would be better to switch the noise reduction off and control it in Lightroom instead and the tests would also determine for sure whether noise reduction had any effects at all in the RAW files, even if in theory it shouldn't.
It was full darkness and heavy rain, with the street lit by artificial lighting (i.e. street lights). I was using the Canon 50mm f/1.4 at 1/50th sec handheld on ISO 6400. Because I wanted to test the detail level, I was trying to focus on areas without the risk of blown highlights and as a consequence the contrast was quite low, making it a challenge for the AF system.
However, I didn't get as far as testing the detail level, as I noticed on the screen, that the camera just didn't focus properly when high ISO noise reduction was set to Standard, if it was compared to the focus when it was switched off.
While this is a static scene and therefore can't be extrapolated to wildlife such as birds in flight, it does make me wonder if this is one reason why there have been reports of some 7Ds not coping very well with birds in flight. Also, I can't judge whether it occurs at all ISO settings or just at higher settings. I do know though, that until I've tested further, I will be keeping the high ISO noise reduction switched off until I can test further.

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