Canon EF-S 24mm: Brilliantly high image quality affordable APS-C lens

Miki Nemeth wrote:

I was looking for a small, high quality, modern (vs legacy), 20 - 30mm (APS-C), auto-focus prime lens for my Sony A5100. Despite I am a (Sony) mirrorless fanboy, I decided to pick a Canon EOS lens. I have a nice collection of Canon FD lenses, including the FD24mm/f1.4L, but I've always wanted to own a Canon EOS lens, too. I ordered a Viltrox EF-NEX (electronic) adapter and I visited a local shop and I tried the EF-S 24mm (adapted) on my A5100. The adapter worked fine, but I immediately found that the AF is very slow, very accurate/precise, though. I was a bit hesitant but eventually I bought the lens.

The EFS 24mm is a perfect fit on a small mirrorless camera.

Another shocking experience was the lag in the manual focus-by-wire. It's really frustrating at first, it took me a some time to learn. Huh, focus-by-wire is really bad on Sony lenses, too. Now I know that manual focusing Canon's STM lenses is not fun, either. Eventually, the brilliant focus peaking with touch-to-magnify of the A5100 made MF quite doable/applicable.

After the shocking experiences (very slow AF on the Voltrox adapter, and laggy focus-by-wire) came the good news: the image quality on the 24M Sony A5100 was exceptional. So sharp that I immediately fell in love with this lens. I have the lens on my A5100 since then.

I love so much the EFS 24mm, that I started thinking of buying a Canon APS-C camera just for this lens in order to get normal speed AF. Maybe Canon's EOS-M4 (if ever made) could be such a body; I am not in a rush.

I use my Sony A5100 + EFS24mm combo these days as slow AF and tricky-to-MF fixed-lens camera.

As far as I know EFS lenses cannot be used on Canon full-frame cameras, but they can be used on Sony FF bodies.

Maybe next time I'll buy a 40mm or 50mm STM. I expect that adapter makers will improve the AF, too. If not, I may buy a (mirrorless) Canon body in the future when they will have 4K video.

I gave 4.5 stars because of the laggy focus-by-wire, which, of course, is not an issue for AF-only photographers.

Am I the only one amused that the adapter is about the same size as the lens?  Maybe the 24mm's "hood" would've visually balanced things.