AzPicLady Loc: Behind the camera!

Several years back I was in a camera store, and the clerk was showing me a particular lens. I had a 5D in my hand, and she put it on that camera. Another clerk corrected her immediately that it would ruin the contacts on the 5D because it was a cropped-frame lens. I only own EF lenses, so don't worry about it much. Recently, a friend purchased a Tamron wide angle lens. I don't understand their nomenclature, and there is no where on the lens to say if it's EF or EF-S. So, I've been hesitant to put it on my 5D or 1DX. Should I be? What will happen?

RichardTaylor Loc: Sydney, Australia

Worst case scenario is that you may damage the mirror on your full frame body.
What is the full designation of the Tameron lens? You can check with Tamaron to find out if it is compatible.

https://www.tamron.com/faq/products/checker.html

CHG_CANON Loc: the Windy City

Only Canon creates lenses using the EF-S mount. These EF-S lenses extend 'deeper' into a Canon cropped-sensor DSLR than an EF lens. If an EF-S lens were able to attach for an full-frame EOS body, the flapping mirror of the DSLR would strike the back of the EF-S lens due to how deep the lens extends into the body. The mirror strike will damage the camera, the lens, or both.

The EF-S mount is identified by a white square rather than the EF red circle. That EF-S mount position of white square on body to white square on lens are used to align and position the lens properly for mounting. There is no alignment position for an EF-S lens to mount to a full-frame EF camera. The only way to mount a Canon EF-S lens to an EF camera is to force (aka break) either the lens or camera body.

Third-party lenses can be designed for specifically cropped-bodies, Tamron has many of them. However, the third-party lenses use the EF mount position; and technically, the DX-style third-party lens can mount to both EF and EF-S style EOS bodies, via the EF mount alignment. The third-party lenses do not extend as deeply into the camera body as Canon's EF-S mount, so there is not the risk of damaging the FF camera. However, the resulting vignette is typically beyond acceptable. Here's a classic example of the result of using a third-party DX-style lens on a full-frame camera.

AzPicLady Loc: Behind the camera!

That's obviously something I do NOT want to do, right? I got all the info from her one day and looked it up. I didn't learn much! Nothing was said in the description about whether it was EF or EF-S mount. I sure wish everyone would use the same nomenclature!

AzPicLady Loc: Behind the camera!

Aha! That clarifies it nicely. Thanks.

Notorious T.O.D. Loc: Harrisburg, North Carolina

Technically you can mount an EF-S lens to a Canon full frame body using an extension tube. The question then becomes what would be the purpose in doing so. Maybe there is one somewhere but I have not found it...

BebuLamar

When you use an extension tube you can only focus at close distance only but the degree of vignetting is lesser. I believe when you get to 1:1 magnification all the vignetting would be gone.

Notorious T.O.D. Loc: Harrisburg, North Carolina

Perhaps but is there really a reason to do it...

imagemeister Loc: mid east Florida

Yes, it is safe to mount with a tube - AND - the vignetting will also go away ! So, for close-up is OK.

AzPicLady Loc: Behind the camera!

Interesting. Thanks.

AzPicLady Loc: Behind the camera!

So that would work for doing macros, but not for landscapes. Right?

PHRubin Loc: Nashville TN USA

Or, to put it simply, a Canon crop sensor lens (EF-S) will damage the camera, another brand will not.

AzPicLady Loc: Behind the camera!

Good to know. Thank you.

gouldopfl

I know that with Canon EF/EF-s to RF you can use all of your EF-S lenses. I suspect that is because the flange for EF/EF-S does not come close to the 20mm distance for the RF mount.

AzPicLady Loc: Behind the camera!

Also good to know, should I ever go to mirrorless.