RPCrowe wrote in post #15386031
First off, the 12-24mm Tokina is NOT an EF-s lens. Although it is designed for 1.6x format cameras, it is an EF mount lens and can be used both on 1.6x cameras which don't have EF-s capability (D30, D60 and 10D) or on full frame cameras.
It will begin to vingette at shorter focal lengths when shooting with full frame cameras however, you can use it down to somewhere around 16mm or so. I don't shoot full frame so I never paid attention to the exact focal length.
I would not worry about Canon discontinuing the 1.6x format. But that's just my opinion...
This is true...
Only select Canon lenses are EF-S. They use the EF-S or EF-"Short" bayonet mount that only allows the lens to be fitted to the APS-C crop sensor cameras after the 10D (all Rebel series, plus 20, 30, 40, 50, 60D and 7D). All third party lenses (Tokina, SIgma, Tamron, etc.) simply use the standard EF mount, even though some of them are designed and intended for crop cameras only. The Tokina 12-24 is one of these.
Tokina and the other third party manufacturers use coding on their lenses to indicate if they are crop only or usable on full frame and crop. Tokina's codes are "DX" for crop only and "FX" for full frame capable (the same designations that Nikon uses, BTW). Tamron marks their full frame lenses "Di", their APS-C crop sensor lenses "Di II" and has started to introduce a third series for mirrorless cameras labelled "Di III". Sigma designates their full frame lenses "DG", their APS-C specific lenses "DC", and has begun to introduce some "DN" lenses for mirrorless cameras.
It's also correct that the Toki 12-24 "DG"", in particular, can be used to a limited extent on a full frame camera... Just out of curiousity I've tested the 12-24 on my 5D Mark II (though I bought it for use on 7D, 50D, 30D and 10D cameras) and can tell you that it will work to 18 or 19mm before it starts to vignette. There is some distortion and the corners of the image are softer than when I use the EF 20/2.8 lens that I prefer... but it works. I would be cautious of using crop-only lenses on full frame, though. In addition to vignetting the images, some lenses also use a retrofocus design that causes the rear elements of the lens to protrude into the camera body. This might physically interfere with and damage the larger mirror in full frame cameras.
The crop format is here to stay and continues to sell strongly. It's really a more practical format for most people. On forums like this one, where a lot of "gearheads" hang out and participate, you do get quite a few full frame fanboys chanting "go full frame or go home"... But out in the real world the vast majority of DSLRs sold continue to be some sort of crop sensor. Crop sensor cameras are considerably less expensive and lenses for crop cameras also can be less expensive, smaller and a lot lighter weight than what's required for full frame. Also, crop cameras can be used with both crop/EF-S lenses and full frame/EF lenses. Full frame cameras, for all practical purposes, can only be used with FF/EF lenses.
So, don't worry.... There will likely be plenty of EF-S/crop sensor cameras and lenses for many years to come.
If anything, DSLRs might be challenged in the future by EVIL cameras (Electronic Viewfinder, Interchangeable Lens) and similar. The Canon M-series cameras and lenses are one example, though it's lacks any viewfinder at all (uses the LCD monitor on the back to view the image). Canon is late getting into this type of camera, so they don't offer a lot of choices yet. But other manufacturers have developed similar, too, and this is likely to be a faster growing segment of the camera market compared to DSLRs.