Canon EF 100-400 f/4-5.6L IS "Soonish" [CR2]

[Loswr]

Let me put it this way - Canon's viewpoint is that the crop factor impacts the 1/focal length rule. With a 200mm lens on a 5DII in Av mode and Auto ISO, the camera will maintain 1/200 s (reciprocal of focal length) and increase the ISO, and only after hitting ISO 3200 will the shutter speed begin to drop lower than 1/200 s. In the same situation on a 7D, the camera will maintain 1/320 s (reciprocal of 1.6 x focal length) until ISO pegs at 3200.

 

[Lee Jay]

One thing is different however; circle of confusion is smaller on an crop sensor because we enlarge more for any given print size. Is that the actual physical phenomenon at play... when the angular motion that occurs during the exposure is larger than the CoC we begin to see the blur?

Bingo.

 

[tral]

Figures. I just bought one in August. Love it, but really do wish it had a twist zoom instead of push/pull.

With the current 100-400L model, what is the minimum shutter speed you need at 400mm with IS to get a decent keep rate for your picture? I assume it would be less then 1/400. Maybe 1/200 with the current IS? Any thoughts as to how much of an improvement a new IS version would make using these parameters?

I was always afraid that at 400mm and f5.6, even with IS it must not be always obvious to get great shot on a cloundy day?

I've used it in some adverse lighting conditions and been able to use shutter speeds as slow as 1/30 at 400mm and get usable results, but not the *best* keep rate. Settling for 1-stop darker photos for lightening in post or balancing that change with ISO, I got consistently great results with 1/60.

When I bought it, I expected to only be able to use it in blazing sunlight. But I've used it in all kinds of circumstances now, and have been really happy with the results.

Edit:
Here is an example. This was taken on my backup camera, a Rebel XTi. 400mm, F5.6, 1/50. This is a shot of the woman as reflected in a mirror. I can't take credit for the image myself, it was taken by one of my contract photographers during the course of our shoot that day. Very reasonable quality coming from an older entry-level camera, a long lens, and less-than-ideal lighting.