Wide Angle vs. Fisheye Lens...?

[Alex_B]

Yes it is full frame so my 24mm is actually 24mm. No crop factor to take into account.
My polarizer (and ND filter) are standard ie not slim line, but even without a filter i can see a hint of vignetting on certain images.
Not enough to bother me but i can see it.

Out of interest does anyone know at which focal length vignetting will start to appear??

i use a slim polarizer on my full frame body only.

if you get vignetting or not does not simply depend on the focal length, but also on the built of the lens. And it depends on your aperture.

even at 17mm on full frame I can get rid of most vignetting if I just close the aperture a bit.

as i understand, there are two reasons of vignetting, one is thatsomething shades off part of the light which comes at the outermost angles, might be a lens hood, a filter, ot part of the lens barrel/filter mount itself. This sort of vignetting is often the most pronounced, and can be easily reduced by using small apertures.

the other type of vignetting results from the light at the edges of the image hitting the film or the sensor at a much shallower angle, especially if you use ultra wide angle lenses. as you then have less intensity per area unit on the sensor or film, it will appear darker than in the centre of the image. sensors are even a bit more touchy as their sensitvity itself depends on the angle... which then pronounces the effect even more than on film.