exposure difference between shots

[Glenn Aronwits]

Using my MK2N in AV mode, AI servo I seem to get exposure differences between shots in rapid fire mode. It is fairly consistant with the first shot exposed properly and the 2nd shot under exposed buy an increase of shutter speed. I use AV mode for shooting soccer. Also using Cfn 4,3. Here is an example of a static subject. Any ideas?

1st Shot ss 1/200 f4.0

2nd Shot ss 1/250 f4.0

 

[Michael Mouravi]

Framing changed just a tiny bit between the shots, which could have triggered the change since in the evaluative metering mode a zone could have picked up more of a bright part of the image.

It would probably be best to put the camera on a tripod and shoot a static scene, just to be sure

 

[Don Lashier]

I always shoot manual exposure when in motor drive. (for that matter, I always shoot manual regardless, but it's pretty much a given in motor drive if you want consistent exposure).

- DL

 

[Glenn Aronwits]

I'll give the tripod a try to confirm it is not the camera. When shooting sports I do not use a tripod, typically a monopod or hand holding. I have experienced this quite often and it is consistant with the exposure decreasing on the 2nd shot.

 

[Glenn Aronwits]

I always shoot manual exposure when in motor drive. (for that matter, I always shoot manual regardless, but it's pretty much a given in motor drive if you want consistent exposure).

- DL

For sports in changing light conditions going manual does not cut it. If the light is consistant I typically shoot in manual. I never heard of an exposure issue with using motor drive in modes other than manual. Can you point me to a resource about this?

 

[Don Lashier]

> For sports in changing light conditions going manual does not cut it.

For a split sun/shade venue I agree, but otherwise I shoot manual.

> I never heard of an exposure issue with using motor drive in modes other than manual.

I think the possible issue is that to avoid the horrid first shot focusing delay, many people will half-press a little ahead of time, and unless you've changed your CF's, this will lock exposure and meanwhile the scene changes a bit. After the first shot the camera will AE for following shots. It would be easy to test by shooting a sequence of a static scene while on a tripod and see if the first shot exposure still varies.

- DL

 

[Will_Perlis]

"It would be easy to test by shooting a sequence of a static scene while on a tripod and see if the first shot exposure still varies."

Yes. IMX Canon's evaluative metering is very sensitive to changes. It will almost jump through hoops to avoid blowing out highlights even if they're quite small areas of sunlight on chrome, etc. That's mostly good but it's difficult to keep overall picture brightness consistant across a series.

 

[Nill Toulme]

If you use CF4-1 you'll get a consistent exposure throughout the burst; AE is locked on the half shutter press. I prefer CF4-3 because it *doesn't* lock the exposure; you get a new AE reading for each frame. Because in soccer we're so often tracking players through changing light conditions — in and out of sun and shade, etc. — I find this to work better.

Nill
~~
www.toulme.net

 

[Glenn Aronwits]

Nill,

Thanks for the insight as usual. I also prefer to use CF 4-3 to get the exposure at the decisive moment in changing lighting conditions, but have need to keep the exposure locked at other times. One thing that is strange the 2nd shot is underexposed most of the time as in the example on the OP. I did know the metering is so sensitive. Another item to keep a mental note about and remember to change when it is needed.

If you use CF4-1 you'll get a consistent exposure throughout the burst; AE is locked on the half shutter press. I prefer CF4-3 because it *doesn't* lock the exposure; you get a new AE reading for each frame. Because in soccer we're so often tracking players through changing light conditions — in and out of sun and shade, etc. — I find this to work better.

Nill
~~
www.toulme.net