Quote:
Originally Posted by chaffingbuttock
There's an entry in wikipedia (which doesn't make it fact)
http://en.wikipedia.org/wiki/Canon_EF-S_lens_mount
My understanding is that focal length is focal length irrespective of what the lens is being mounted on, so to say that it is 200mm it is 200mm. The crop factor is to calculate the effect of having a smaller sensor, which in the case of APS-C is 1.5-1.6X. The mount (EF Vs EFS) is just the connector for the lens to the camera body, which is independent of the focal length. It just means that you can connect an EFS and EF lens on the EFS body (backward compatible), but you can't connect an EFS lens on an EF body because it is designed to take into consideration the smaller sensor. If you could, I assume you'd just get an image with a really large black border. |
Yeah cool, I learned something new!
I used to have a 500D and I could swear my EF 50mm f1.8 was considerably longer than the long end of the EFS 18-55mm but it wouldn't be the first time my memory didn't match reality.
Also I have an EFS 4.5mm Sigma fisheye at work that I can still fit on my 5DmkII as it doesn't protrude too far into the body and it just gives a lot of black around the image.