I-R-Lab's reviews

Canon EF 17-40mm f/4L USM

Some notes on alternate hoods for crop format DSLRs:

The EW-83J (for the 17-55 f2.8) and the EW-83H (for the 24-105L) both work nicely on this lens when used on a 1.6x crop body. The J hood is about 60mm deep. The H hood is a little shorter, and provides a little less coverage.

I have tested the EW-83J on my 20D and the 1Dmk3 we have here in the I-R lab. On the 1Dmk3 (a 1.3x crop body) there seems to be a hint of vignetting. The H hood might be a better choice on the 1Dmk3.

The J hood vignettes badly on a 5D (full-frame body), as one would expect.

The J hood is now permanently on my 17-40L / 20D. And, for the record, the J hood is also an improvement over the H hood on my 24-105L (with a 1.6x body).

As always, your mileage may vary.

-Luke