Autofocus problem with RF 50mm f/1.2 vs EF 50mm f/1.4

[shadow]

Wondering if this is an unusual isolated case for RF to be inconsistent in spot focus. A bad RF lens? I ran into this newly posted video and was surprised at his results with the hunting and slower response time.

 

[koenkooi]

It looks like his camera has Lens drive when AF impossible set to 'stop focus search', which, as the name implies, stops focus search when things are very out of focus. On a f/1.2 lens, that will be most things in the scene
I suspect the DoF difference between f/1.2 and f/1.4 was enough to get AF to work on the f/1.4 lens. You can also see that the f/1.2 lens did focus when it wasn't under exposed 2 stops (dark pelican case in the shadows in a dark room vs brightly lit kitchen), I wonder if setting ISO to 'auto' would've improved the results.

I think it's not so much the lens that's the issue, but more the default settings combined with using M mode set to 2 stops under exposure. With exposure simulation enabled, AF takes a big hit when under exposing. This is an area when Canon can improve things a lot, but they don't like to do that. Just look at how they present HTP. HTP will just lie about the ISO value it shows in the EVF. It's the photographic equivalent of setting your watch 5 minutes ahead. But the description makes it seem like it will conjure some extra DR out of thin air!

 

[tangerine_sedge]

Holy thread resurrection Batman!

I've just bought a refurbished version of the RF 50 1.2, and it exhibits exactly the same behaviour as the one in the Youtube video.

I have an R3 and an EF 50 1.2, so could compare performance side-by-side.

The RF was slower and noisier than the EF and occasionally failed to focus completely. Placing the RF into Manual Focus mode, and this ALSO occasionally failed to allow me to manually focus (I believe it's an electronic link and not manual). The RF was more consistent in better lighting conditions but was still slow and noisy to focus. My old EF 50 1.2 performed flawlessly in all lighting conditions.

I played with the 'stop focus' setting suggested above and this made no difference.

My assumption is that this lens was sent back to Canon due to the above 'fault' then sent straight back out the door as a 'refurbished' lens. This lens will be going back to the shop, and I'll wait until I can find a better copy.

 

[danfaz]

I replied to one of the comments on that video. Never experienced that issue with mine, and I tried all kinds of scenarios to trip it up.
It was not a refurbished lens (though that really shouldn't matter), but perhaps you did get a bad copy.

 

[EricN]

Holy thread resurrection Batman!

I've just bought a refurbished version of the RF 50 1.2, and it exhibits exactly the same behaviour as the one in the Youtube video.

I have an R3 and an EF 50 1.2, so could compare performance side-by-side.

The RF was slower and noisier than the EF and occasionally failed to focus completely. Placing the RF into Manual Focus mode, and this ALSO occasionally failed to allow me to manually focus (I believe it's an electronic link and not manual). The RF was more consistent in better lighting conditions but was still slow and noisy to focus. My old EF 50 1.2 performed flawlessly in all lighting conditions.

I played with the 'stop focus' setting suggested above and this made no difference.

My assumption is that this lens was sent back to Canon due to the above 'fault' then sent straight back out the door as a 'refurbished' lens. This lens will be going back to the shop, and I'll wait until I can find a better copy.

Because it's refurbished, maybe it's the same lens...