Which vintage lens mount is most suitable for EOS cameras? [duplicate]

Question

I've been doing some research on vintage lenses to buy with the focal length of 24mm or 28mm as an alternative to the more expensive canon 24mm F2.8.

Best options I found were the FD version of the same lenses, Tokina 28mm F2.8, and Yashica 28mm F2.8. I found people selling the adapters for these lenses to an EOS camera on Amazon, but many articles on the internet do not recommend buying certain adapters since the quality will drop.

Are there certain brands or lens mounts that I should stick with that would not cause focusing problems, like not being able to focus at infinity, and that would not cause quality to drop?

Answer 1

Forget using Canon FD lenses on EOS cameras. You can't get infinity focus with those lenses without adding additional optics.¹ This is because at 42mm the FD mount has a shorter registration distance (a/k/a flange focal distance) than the 44mm of the EF mount. If you insist on using non-EF lenses on EOS cameras, lenses made for mounts with longer registration distances than the EF mount would be preferred. The 44.5mm Minolta A-mount is out due to mechanical clearance issues. Ditto for the Olympus OM mount. That leaves Nikon F and Pentax K as the most likely candidates.

But you'll still be giving up a lot by using a Nikon F or Pentax K lens instead of a native Canon EF lens.

I never recommend adapting lenses cross-brand² when there is a native lens for a particular mount available. YMMV.

If you are using an APS-C EOS camera, the EF-S 24mm f/2.8 STM sells for around $130 new from authorized dealers.
If you are using a FF EOS camera, the EF28mm f/2.8 goes for $470.

Some third party lenses in the Canon EF mount (for both APS-C and full frame):
Yongnuo 35mm f/2 (with AF) - $90
Samyang (Rokinon) 24mm f/1.4 (MF) - $380

_{¹ Those additional optics also act as mild teleconverters, which kind of defeat your stated purpose of a fast, wide-angle lens. TCs make a lens longer and slower.
² Something like EOS EF to EOS-M is bit different, as both mounts use the same protocols, the only difference is the RD.}

Answer 2

There are now four lines of Canon EOS cameras (excluding a few models that don't quite fit the pattern).

• EOS #D – DSLR with full-frame sensor. Uses lenses with EF mount. FFD = 44mm.
• EOS ##D/###D/####D – DSLR with APS-C sensor. Uses lenses with EF or EF-S mount. FFD = 44mm.
• EOS-M – Mirrorless camera with APS-C sensor. Uses lenses with EF-M mount. FFD = 18mm.
• EOS-R – Mirrorless camera with full-frame sensor. Uses lenses with R/RF mount. FFD = 20mm.

The major factor to consider when adapting lenses is the flange-focal distance. If the distance for which the lens was designed is shorter than that of the camera, it's generally futile to attempt adapting it. The flange-focal distance of the FL/FD mount is 42mm, so it would be reasonable to adapt it for use on EOS-M (18mm) or EOS-R (20mm) bodies. You can search your favorite shopping sites for adapters.

The EF and EF-S mounts are generally not suitable for use with adapted lenses because of the long flange-focal distance (44mm). You should stick with a native lens. Since the EF mount was introduced so long ago, in 1987, many third-party and "vintage" lenses are available at numerous price points.

If you still want to adapt a lens, adapters are available:

• M42 (45.46mm) and Nikon F (46.5mm) – maintain infinity focus.
• Tamron Adaptall – also maintains infinity focus.
• Pentax K (45.46mm) and Olympus OM (46mm) – "slim" adapters should be able to maintain infinity focus, but care should be taken with full-frame cameras because mechanical linkages on the lenses may block the mirror.
• FL/FD without optic – allows close-up/macro use, loses infinity focus.
• FL/FD with optic - magnifies image by 1.2x to 1.4x.