doghouse_94545 wrote in post #6578537
guys and gal i really appriciate the help and the pictures too!!!
so is there some lens similar to the Tokina 10-17 with 2.8?
No, it is the only one of its kind. All other fisheyes are designed for APS-C or FF, and will only provide work well with the format size they are designed for. Because teh tokina 10-17 is a zoom, and designed to work with a bunch of APS-C cameras, the distance from flange to sensor is large enough to be able to accommodate the swing of any Canon dslr mirror, which is why it can be used on any Canon (d)slr, including FF ones.
Furthermore, it is designed as a true 180 degree diagonal fisheye for an APS-C dslr. Now, Canon's APS-C implementation is slightly smaller, sensor wise (hence 1.6 crop), than a true APS-C design (1.5 crop). This is why a Canon APS-C dslr captures just a little less than 180 degrees at 10 mm. It would need 9.5 mm to see 180 degrees.
Because the image circle gets bigger when zooming, it gets large enough at some stage to cover an APS-H sensor (at ~12 mm) and a FF sensor (at 15 mm). This is why it works well with any Canon dslr and will still have a 180 degree diagonal view of the world, and a little bit less on a 40D (or XSi, etc.).
just to clarify things here, what is minimum MM lens that would work on the 40D and
180 degree diagonal view: 9.5 mm
180 degree circular view: 4.2 mm or less (in the latter case the image circle would be even smaller than the sensor height))
180 degree diagonal view: 16 or 15 mm
180 degree circular view: 8 mm or less
i am just a lil confused!!
i was told to look the lowest aperture as possible something like a 2.8,
the Tokina is f/3.5-4.5, is it worth to get it or get some other ones that 2.8
F/3.5 is only 2/3 f a stop difference, which especially with a fisheye is neither here nor there.
BTW, I use my Tokie 10-17 on both a 40D and a 5D . And indeed, on the 5D at 15 mm it gives a slightly wider view on the world than at 10 mm on the 40D.
You can still get a wider view from it, by removing the built-in lens hood, but that is a non-reversible tricky surgical operation. You'll get about 193 degrees diagonally on a 5D that way.
Kind regards, Wim