topic Re: EF 50mm 1.8 on DSLRs: Accurage AF without fine-tuning? in EF & RF Lenses

EF 50mm 1.8 on DSLRs: Accurate AF without fine-tuning?

damatka5 — Sat, 29 Nov 2025 14:18:28 GMT

Is accurate AF possible with this lens? I am on my second copy. Second more accurate than first, but still not brilliant. I can't fine-tune the AF on my 5D Mk I.

Other lenses focus well on this body, but none of the Canon 50mm lenses I've tried - the 1.8 II, the 1.4 USM and now this - do. I don't want a Sigma Art lens that is as big as a zoom.

I like the 50mm field of view, and the fast aperture comes in useful in the gloomy UK. But I might have to return to the 40mm 2.8 pancake, which has excellent performance - it's just a bit too wide and 2.8 is sometimes limiting. (Yes, I know the 50mm 1.8 isn't sharp wide open. I often close the aperture down. The problem is AF accuracy - often back focusing.)

It is worth trying another copy? Or is this lens meh?

Re: EF 50mm 1.8 on DSLRs without AF fine-tuning.

shadowsports — Wed, 12 Nov 2025 10:36:47 GMT

Greetings ,

I only owned one EF50 f1.8 which I used occasionally on my 6D Mark II. It's focus did not require any adjustment.

Are you buying new lenses or used? It's unusual that two identical lenses would both behave the same way when others are working fine.

Re: EF 50mm 1.8 on DSLRs without AF fine-tuning.

Anonymous — Wed, 12 Nov 2025 13:10:23 GMT

It's the luck of the draw whether you get one exactly right for your camera or not.
For a camera model still in service you could sent both lens and body to Canon to adjust, maybe some repairshop in your neighbourhood can still do this for the 5D?
Other than that there's only third party lenses with a dock to try(or upgrade body😉).

Re: EF 50mm 1.8 on DSLRs without AF fine-tuning.

stevet1 — Wed, 12 Nov 2025 13:44:40 GMT

damatka5,

I have the 50mm STM f/1.8 that I use on my T8i, and it's pretty darn good.

Steve Thomas

Re: EF 50mm 1.8 on DSLRs: Accurage AF without fine-tuning?

ebiggs1 — Tue, 18 Nov 2025 15:28:28 GMT

"It is worth trying another copy?"

You will never find a solution to a problem if you continue to look in the wrong places. The ef 50mm lens all versions have a stellar IQ reputation. The odds of getting two copies that have not been damaged that perform under par is very small. That means there is likely an issue elsewhere. Without additional info, I don't have an answer but a good place to start is to show some examples of what you are seeing with both lenses.

The 5D (there is no Mk I) is also an excellent camera. A full reset to factory default is a good place to start.

Re: EF 50mm 1.8 on DSLRs: Accurage AF without fine-tuning?

atam1 — Wed, 19 Nov 2025 06:40:31 GMT

I happen to have a 5D and f/1.8 STM like you. I have no problem with it. I have been using it since that iteration came out. AF has always been spot on. If you are sure it's back -focusing, try the lens first on another body and find out if the problem still persists.

Re: EF 50mm 1.8 on DSLRs: Accurage AF without fine-tuning?

stevet1 — Sat, 29 Nov 2025 14:17:19 GMT

damatka5,

I remember that I took this with a 50mm. I stopped the lens down to f/2.8 and turned into a calendar for October that I put on my refrigerator.

Steve Thomas

Re: EF 50mm 1.8 on DSLRs: Accurate AF without fine-tuning?

Waddizzle — Sat, 29 Nov 2025 22:06:18 GMT

I assume that you are using the EF 50mm f/1.8 STM, which uses a metal camera mount.

i have found that lens works best in One Shot AF mode. Even so,I found that I could not always rely on focus always being tack sharp on the first focus lock. Holding my position and getting a second lock helped.

This brings up another point. Your camera holding technique needs to be “better than most” when shooting with wide aperture lenses. This applies to side to side motion, and front to back motion. The latter is a common cause for OOF photos.

I suggest that you test the camera and lens combo. If you have an available tripod, use it. Set up a focus target at a distance of 50x the focal length, or about 8-9 feet. Don’t have a focus target? Use a cereal box. Frosted Flakes are great! (Cereal boxes are the perfect size and can stand on their own.)

Align the camera so that it’s as close to perfect horizontal as you can. Position the target within the field of view, as well as you can center it.

Take several test shots by triggering the shutter in different ways. Defocus the lens between shots! You should see the best results using the builtin shuttet delay timer.

Using the OVF should be the priority. Capturing a few shots using Live View, with and without mirror lockup will provide food for thought.

Be meticulous. Take your time. If possible, use incandescent lighting indoors or bright sunlight outdoors,

Re: EF 50mm 1.8 on DSLRs: Accurate AF without fine-tuning?

ebiggs1 — Sun, 30 Nov 2025 16:43:28 GMT

And what good is that going to do? As I recall my 5D does not have micro focus adjustment, AFMA, so the OP can't make corrections. AFMA was featured on the 5D Mk II if I remember correctly.

Re: EF 50mm 1.8 on DSLRs: Accurate AF without fine-tuning?

Waddizzle — Sun, 30 Nov 2025 17:10:37 GMT

“ And what good is that going to do? As I recall my 5D does not have micro focus adjustment, AFMA, so the OP can't make corrections. AFMA was featured on the 5D Mk II if I remember correctly. “

——————————

Who said anything about making a focus adjustment besides you?

” I suggest that you test the camera and lens combo. If you have an available tripod, use it. “

Re: EF 50mm 1.8 on DSLRs: Accurate AF without fine-tuning?

ebiggs1 — Mon, 01 Dec 2025 16:14:46 GMT

"Who said anything about making a focus adjustment besides you?"

The OP did, that's who! " I can't fine-tune the AF on my 5D Mk I."

The point is, if it is found to be true there's nothing the OP can do about it. So, what good will that do unless you just like messing around with tripods and cereal boxes. ? Plus even if found to be true, I doubt it is cost effective if sent to Canon, they still will do a camera/lens adjustment and correction on a 5D. Some early models (ef 50mm f1.8) have such large increments in the AF motor that adjustments aren't even possible. The vast majority are fine as is.

Re: EF 50mm 1.8 on DSLRs: Accurate AF without fine-tuning?

Waddizzle — Mon, 01 Dec 2025 17:39:22 GMT

” I suggest that you test the camera and lens combo. If you have an available tripod, use it. “

As mt esteemed colleague pointed out in earlier post, the odds of getting two lenses with near identical flaws is pretty small.

There is something else going on. Test your gear very carefully.