Canon EF Lens to RF-mount speed booster ultra 0.71x questions

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p.1 #1 · p.1 #1 · Canon EF Lens to RF-mount speed booster ultra 0.71x questions

Hello all,

I would like to know if anyone has had experiences with this adapter.

- Auto focus: Does it work flawlessly in still or video? All I need is a reliable auto focus.
- Sharpness: If center sharpness is good, I am ok with that.

Other stuff like information display are non significant to me.

I am shooting mainly still, 90% photos and 10% video.
Canon R5 and lenses to be used with this are EF 300/2.8 is ii, EF 70-200/2.8 is ii and maybe EF 400/2.8 is ii or iii

Thank you.
Hai

Oct 24, 2023 at 12:42 PM

selski
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p.1 #2 · p.1 #2 · Canon EF Lens to RF-mount speed booster ultra 0.71x questions

I think the Canon 0.71x adapter is meant for crop sensor cameras, so that it can get close to the same focal length of its intended purpose. Are you planning on using crop modes on your R5?

I briefly used the 0.71x on an EOS R I had before, just so my EF lenses would be close to there designed focal length when shooting 4K video (since the EOS R had 4K crop). It did work like the regular Canon EF-RF adapter in terms of AF, but i can't be certain if it degraded the quality of image. I didn't really do a comprehensive test.

But I did notice using the 0.71x gave a stop or so lower ISO values given the same exposure compared to a regular adapter. So, the speedboosting part was working, even though I couldn't set it visually in the display (F2.8 lens should be reading F2, but it remained F2.8)

Oct 26, 2023 at 04:40 PM


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