FPS drop in low light even with manual focus?

[Hjones]

So this is a bit quirky and random, but it's really making me curious since I don't like the idea of not understanding something about my camera.. It's probably something really obvious that I haven't considered, but it just seems odd to me.

Even when autofocus is off in manual mode and the camera isn't focus hunting, it seems there's a major FPS drop on my 60D in the dark compared to when there's a light on. For example, when I point it towards a dark part of the room, it seems to get only around 1-3 FPS, but immediately when I point it towards my bright computer display, it goes back to the expected 5.3 FPS.. Why? Both images come out identically dark due to a shutterspeed 1/8000, but there's an audible drop in FPS. Since the photos are identically dark, I can't imagine that the camera is processing additional information on the dark frames.

Just curious--like I said--I like understanding everything I can about my camera; sure makes for less surprises when working.

[Joel Eade]

Do you have in-camera noise reduction turned on? Perhaps the metering is slower in the dark even though the camera is in manual mode the meter is still working, I am not sure of the reason, it does seem odd. Do you have an external flash attached?

[Hjones]

Do you have in-camera noise reduction turned on? Perhaps the metering is slower in the dark even though the camera is in manual mode the meter is still working, I am not sure of the reason, it does seem odd. Do you have an external flash attached?

I have noise reduction off and I don't have an external flash attached-- I feel like the most plausible explanation would be the meter like you said, but part of me feels like there couldn't be such a huge drop in FPS just from the meter trying to function. Though, like I said, this is an extreme case, since it's comparing a near-black room to a bright monitor screen.

[HDNitehawk]

I have experienced the same when testing other bodies. Not all files are created the same size. Start by comparing the file size of the two different shots, it might just be processing speed.

if you have learned one thing with this test it would be that your camera doesn't perform at its best when under exposing by 15 stops. Maybe a Nikon body would help with this problem.

[msowsun]

This FPS slow-down in low light conditions is due to Canon's iFCL metering which is in the 7D, 60D, 70D, 5D Mk III and probably all other newer Canon cameras. http://cpn.canon-europe.com/content/...CL_metering.do

To avoid this slowdown in low light, use the * button to lock the exposure if you are shooting in Tv, Av or P modes, or use LiveView and this will bypass the iFCL metering. In Manual mode you must use LiveView.

[Hjones]

This FPS slow-down in low light conditions is due to Canon's iFCL metering which is in the 7D, 60D, 70D, 5D Mk III and probably all other newer Canon cameras. http://cpn.canon-europe.com/content/...CL_metering.do

To avoid this slowdown in low light, use the * button to lock the exposure if you are shooting in Tv, Av or P modes, or use LiveView and this will bypass the iFCL metering. In Manual mode you must use LiveView.

Thanks for the info! I figured it had to do with the metering system. I doubt it'll ever become an issue, but I definitely learned something new about my camera nevertheless, which is a big plus. I never really knew the specifics of the iFCL metering system either, so that was a helpful read.