[JJ_SO]

Distortion and perspective basically are independent at first, I think. But of course, in the case of ultra wide angle, both begin to interact together noticeably. Thanks for the great explanation, Scythels.


In other words, using a 500 mm lens and taking the same picture with a 50 mm but remaining on the exact same place and aiming at the exact same target and using the same aperture, the perspective will not change if I crop a frame out of the 50 mm picture. Saying the focal length is changing perspective, is untrue and a very old false assumption in photography. The whole "perspective change" only is true, because wide angles do give the opportunities to choose a closer point of view to the target. But in that case, not the wide angle is changing the perspective. This is only done by using your feet, not your zoom ring!

[Scythels]

Correct, a 500mm lens and a 50mm cropped to "500mm" would look the same, provided the entrance pupils are located in the same place (and if you're shooting something at infinity, it'll be close enough that no one can tell). 

 

The aperture will not change perspective, as entrance pupil *location* is important, the size never enters into the geometry until you get into telecentric or hypercentric systems.

[nuke12]

Hi all, 

I intend to get an ultra wide angle lens, however I am not sure to which format should I go:

Using 30D for almost all my  shots and slowy  5D only with prime lenses for portraits.

I intend to get an ultrawide angle lens however I am not sure for which format I should get the lens:

a nice 16 or 17-XX prime or zoom for 5D or a 10-XX prime or zoom for APS-C

which is better especially from perspective view side

 

Not being a big time landscape shooter, I'm no expert but I do use the Samyang 14mm f/2.8 on my FF. I find it quite sharp and a remarkable lens for the price. A fair amount of vignetting wide open but stepped down to f/4-f/8 it can become quite sweet. The vignetting goes away and the sharpness jumps.

[Rainer]

I am not sure for which format I should get the lens

 

Well, eventually one important question is this:

What are the situation where you will use this lens? ... Which of

your cameras will you usually have with you in these situations.

Eventually it turns out, you will need the UWA only when you have

one certain camera with you ... in that case, you have an anwser.

 

If I compare images that I did with the EFs 10-22 on a 300D to

those I have from an EF 17-40 on a 5D, I usually prefer the latter,

but I couldn't really blame the lens for it.