EF & EFs lenes

So my 28-135 is good on FF or crop bodies? If I purchase a Rokinon 35 1.4 can i use it on both FF and crop? Have a 40D now.

Yes and Yes. EF-S on FF=no.

DanFrank wrote in post #15924802
So my 28-135 is good on FF or crop bodies? If I purchase a Rokinon 35 1.4 can i use it on both FF and crop? Have a 40D now.

You have not asked any questions about Canon EF-S lenses.

Neither of the lenses you listed are using the Canon EF-S mount and thus they will both mount to a "full-frame" Canon SLR or DSLR without any mechanical interference.

Both of the lenses are designed to fill the 24mm x 36mm frame of a "full-frame" camera.

There are many third-party lenses that are designed with conventional Canon EF mounts but they are designed to cover only the APS-C format with their projected images. If these lenses were used on a "full-frame" camera, you should expect significant vignetting around the images.

The reason im asking is im planning on buying the Rok 35. But plan on going FF in a few months. Says can be used on either format, just wasnt sure if i was missing something. Heard people using 28-135 on ff, whick I thought was only used on crop bodies.

DanFrank wrote in post #15925159
The reason im asking is im planning on buying the Rok 35. But plan on going FF in a few months. Says can be used on either format, just wasnt sure if i was missing something. Heard people using 28-135 on ff, whick I thought was only used on crop bodies.

Those are both lenses intended for full frame.

The 28-135mm was bundled with the a couple of crop bodies but it is still a full frame lens and the focal length demonstrates this.

dalto wrote in post #15925175
The 28-135mm was bundled with the a couple of crop bodies but it is still a full frame lens and the focal length demonstrates this.

How is that? There's no difference in the focal lengths printed on lenses designed strictly for smaller format DSLRs and those designed for so-called "full-frame" cameras.

SkipD wrote in post #15925190
How is that? There's no difference in the focal lengths printed on lenses designed strictly for smaller format DSLRs and those designed for so-called "full-frame" cameras.

I just meant that the focal range was one that is typically more common in full frame. I have never seen an ef-s or APS-C lens that had a similar focal range to 28-135mm.

SkipD wrote in post #15925190
How is that? There's no difference in the focal lengths printed on lenses designed strictly for smaller format DSLRs and those designed for so-called "full-frame" cameras.

dalto wrote in post #15925195
I just meant that the focal range was one that is typically more common in full frame. I have never seen an ef-s or APS-C lens that had a similar focal range to 28-135mm.

True. Back in the film days there were lots of 28 -"XX" or 35 - "XX" lenses. Anytime you see a zoom lens that starts at 28mm or 35mm you can be pretty sure it covers the Full Frame format.

Here's another tip

Canon lenses with red dots, to signify where the lens meshes with the camera body, are EF or full frame capable and can also fit and work on crop cameras.. Canon lenses with white dots are EFs lenses designed for crop cameras and will neither fit nor work on full frame cameras.

Some third party lenses such as the Tokina 12-24mm f/4 ATX with Canon mounts are designed for 1.6x cameras but, will fit and partially work on full-frame cameras. The 12-24mm Tokina will begin to vignette as you zoom to the wider focal lengths...