Sigma 35mm HSM ART Autofocus on RF

Hi all,

I'm currently considering to adapt the Sigma 35mm HSM ART for Ef mount on my R5.

I tried it out in a store next to the RF 35mm 1.8. As expected it was sharper wide open, but the AF was slow. So slow, that I first thought the camera was in video mode and the AF slowed down due to that. But no. Tbh I don't think I had a slower focusing lens on a camera ever.. The RF 35mm was way quicker..

Now the question: has anyone used this lens adapted to an RF body and could comment on the AF performance? My main use case is shooting an erratic toddler (and therefore later small child running around).

The guy in the camera store said he had no issues photographing his kids, but he uses the E mount version with the built-in adapter. No idea if this is any different..

I searched the forums but only found discussions on its image quality, so I'd appreciate any input.

Did you test it in the store on your R5? I don't have experience with the 35, but I have the 85 Art adapted on RF bodies, and the AF is noticeably faster and more confident than the lower end RF stuff (35, 50, etc.).

Yes, I directly tested it on my own R5 in the store.

I also took a few video samples to check for audio pick up of the AF motor noise, but had no time to check them yet..

Comparison
https://youtu.be/Nmni8zEzf3U

hunk wrote:

Comparison
https://youtu.be/Nmni8zEzf3U

Doesn’t compare AF performance, only IQ.

I don't have the 35, but I have a number of Sigma Art lenses and they all focus pretty quickly. But note that the Sigma Art lenses can be hooked up to the dock and one of the settings you can change is focusing speed, at least for some of them. Not sure about the 35.

antonio-salieri wrote:

I don't have the 35, but I have a number of Sigma Art lenses and they all focus pretty quickly. But note that the Sigma Art lenses can be hooked up to the dock and one of the settings you can change is focusing speed, at least for some of them. Not sure about the 35.

Interesting, thank you, I wasn't aware of that.

By any chance, do you know what default value the lenses are programmed to, usually ? Is it the quickest?

MasterWayne wrote:

antonio-salieri wrote:

I don't have the 35, but I have a number of Sigma Art lenses and they all focus pretty quickly. But note that the Sigma Art lenses can be hooked up to the dock and one of the settings you can change is focusing speed, at least for some of them. Not sure about the 35.

Interesting, thank you, I wasn't aware of that.

By any chance, do you know what default value the lenses are programmed to, usually ? Is it the quickest?

Again, not sure about the 35, but I believe the default value is medium speed, to be a balance between accuracy and speed. But on mirrorless faster might be about as accurate.

I have never used the 35, but the 50 is about the same age and focuses fast for me on my R5. It's also possible the copy you tested at the store was off.

Apparently one of the firmware updates for the 35 dealt with a slowdown glitch in continuous AF. So that could be it, too.

For all Sigma GV (Art, Sports, Contemporary) lenses, you can use the USB dock to adjust settings and update firmware. Firmware updates are infrequent, but of course can be useful. Also, note that firmware 2.0 for the early art lenses (such as the 35) added support for in-camera corrections on Canon cameras. It's a little awkward to need to get the dock, but it's definitely somewhat useful. It can also be used to calibrate focus accuracy, but this is only relevant for DSLRs. (Also, note that IBIS will only work if you turn off the full time MF override setting. You can still manually override, but you can't do it while holding down AF, if you want IBIS enabled — weird quirk, but not a problem, as I just have a button mapped to prevent AF, and can MF anytime that way; similarly, if you use BBAF, it will always work with IBIS and MF override)

All I know is all my other Sigma primes work great on the R5. Though maybe I'd want a different individual copy than the one you tested!

antonio-salieri wrote:

MasterWayne wrote:

antonio-salieri wrote:

I don't have the 35, but I have a number of Sigma Art lenses and they all focus pretty quickly. But note that the Sigma Art lenses can be hooked up to the dock and one of the settings you can change is focusing speed, at least for some of them. Not sure about the 35.

Interesting, thank you, I wasn't aware of that.

By any chance, do you know what default value the lenses are programmed to, usually ? Is it the quickest?

Again, not sure about the 35, but I believe the default value is medium speed, to be a balance between accuracy and speed. But on mirrorless faster might be about as accurate.

I have never used the 35, but the 50 is about the same age and focuses fast for me on my R5. It's also possible the copy you tested at the store was off.

Apparently one of the firmware updates for the 35 dealt with a slowdown glitch in continuous AF. So that could be it, too.

For all Sigma GV (Art, Sports, Contemporary) lenses, you can use the USB dock to adjust settings and update firmware. Firmware updates are infrequent, but of course can be useful. Also, note that firmware 2.0 for the early art lenses (such as the 35) added support for in-camera corrections on Canon cameras. It's a little awkward to need to get the dock, but it's definitely somewhat useful. It can also be used to calibrate focus accuracy, but this is only relevant for DSLRs. (Also, note that IBIS will only work if you turn off the full time MF override setting. You can still manually override, but you can't do it while holding down AF, if you want IBIS enabled — weird quirk, but not a problem, as I just have a button mapped to prevent AF, and can MF anytime that way; similarly, if you use BBAF, it will always work with IBIS and MF override)

All I know is all my other Sigma primes work great on the R5. Though maybe I'd want a different individual copy than the one you tested!

Again, thanks a lot for this great advice! I'll look into the topics you mentioned.

I have used the 35mm Sigma on an R6. I just sold the Sigma. It would autofocus very quickly but it often missed focus. Sometimes it would back focus, sometimes front focus. No fault of the camera, just the lens.

I would rather get the 35mm f1.8 STM. It shouldn't be any less sharp.

I have a bunch of Sigma glass and they all AF fairly quickly on the R5.

rmexpress22 wrote:

I have a bunch of Sigma glass and they all AF fairly quickly on the R5.

Same here. The 40mm is the fastest, the 28 and 105mm are also very fast focusing. The 85 and 50mm are a tad slower. I don't own the 35mm.  All lenses focus very accurate, with the 85 and 50mm showing a ever so slightly lower hitrate maybe.