Canon FF cameras incompatibility with APS lenses.

Started Oct 3, 2012 | Discussions thread
OP Ma55l Contributing Member • Posts: 805
Re: Canon FF cameras incompatibility with APS lenses.

x-vision wrote:

Ma55l wrote:

My question is 2 part

1. what is the real reason (just because light fall off would be seen with APS lenses on a FF sensor or was there indeed a mechanical problem)?

I think they did it on purpose, so that you don't use EF-S lenses on FF bodies.

EF-S lenses cannot project a FF image circle, so no point in using them on FF anyway.
But Canon's usual segmentation tactics are in play here as well.

2. Can APS lenses be used on the new 6D?

No (at least not without mods).

Well there are several points to using a APS lens on a FF as all the other camera makers let you do this. For instance the Sony and Nikon do that automatically - they process the image in camera to the size of an APS sensor when an APS lens is in place. In a 24 MP sensor the APS equivalent would be about 10 MP and about 15 mp in the 36 MP format. At that size the camera works faster shots per second in burst and has a deeper buffer. For instance I believe the Sony a99 runs burst at 6 FPS in FF and 10 FPS in APS size and I think you can even change via camera controls to an central APS size while using a FF lens. That yields a 1.5 X magnification so a 200mm lens has the aspect of a 300 mm lens just like APS.

I believe Canon would not forego those benefits especially when the other makers have it in place. So the real reason must be a mechanical problem - like the mirror hitting the back of the lens.

And lastly the image circle changes with aperature and zoom settings. So although it would be hard to get a 100% coverage for Full Frame perhaps at certain settings you could achieve a 30 mm side to side image circle and a 1.2 crop factor. I tried that on a Sony a700 and you can see the fall off in light there - but at different aperatures and zoom settings it gets wider and in some rare instances fills the whole image area.

Post (hide subjects) Posted by
(unknown member)
Keyboard shortcuts:
FForum PPrevious NNext WNext unread UUpvote SSubscribe RReply QQuote BBookmark MMy threads
Color scheme? Blue / Yellow