Canon 50mm f2.5 Macro - Does it have a hard stop at infinity?

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Ichthyophthirius
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Canon 50mm f2.5 Macro - Does it have a hard stop at infinity?

Post by Ichthyophthirius »

Hi,

I'm currently testing a Canon 50mm f2.5 Macro lens https://www.canon.co.uk/lenses/ef-50mm- ... acro-lens/

My copy seems to have a hard stop at infinity in the same way that older manual lenses used to have. It that the case here or a defect? The lens is so old that reviews don't mention this feature and the few that do are contradictory. The distance indicator stops exactly at the centre of the infinity symbol on my lens.

I'm asking both because I hadn't seem this on autofocus lenses before and because the lens is soft at infinity (objects on the horizon about 1 km away) at f2.5 - f4. Only at f5.6 does it get very sharp for distant objects.

Regards, Ichty

Pau
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Re: Canon 50mm f2.5 Macro - Does it have a hard stop at infinity?

Post by Pau »

My copy seems to have a hard stop at infinity in the same way that older manual lenses used to have. It that the case here or a defect? The lens is so old that reviews don't mention this feature and the few that do are contradictory. The distance indicator stops exactly at the centre of the infinity symbol on my lens.
I own this lens and it behaves the same, but actual infinite focus is realized a bit before the end of the focus ring travel, at the beginning of the infinite symbol

I find it a nice lens, AF is slow and noisy for today standards but pretty accurate. Now the sun is almost gone here, if you want I could test sharpness tomorrow, too much time to recall its infinite performance.
Pau

Ichthyophthirius
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Re: Canon 50mm f2.5 Macro - Does it have a hard stop at infinity?

Post by Ichthyophthirius »

Hi Pau,

Thanks. If you find the time to test it, that would be very helpful. My feeling is that my copy of the lens falls JUST short of reaching infinity focus wide open.

Cheers, Ichty

Pau
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Location: Valencia, Spain

Re: Canon 50mm f2.5 Macro - Does it have a hard stop at infinity?

Post by Pau »

Here you have my results:
At f2.5 it is somewhat poor: a bit fuzzy and some CA, at f3.2 it clearly improves and at f4 it is well corrected, about the same as at f5.6 or at f8
18Mpx EOS 7D, 100% crops near the center. AF or MF deliver the same results.

Raw processed with DPP with sharpness 2 (low value)
Judge yourself

F2.5
EF compact macro 50 F2-5.jpg

F4
EF compact macro 50 F4.jpg

F8
EF compact macro 50 F8.jpg
Pau

Steve S
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Re: Canon 50mm f2.5 Macro - Does it have a hard stop at infinity?

Post by Steve S »

Takes me back to the old days, when Canon lured me from Nikon with the 5D, introduced when Nikon was still stolidly insisting that APS-C was all that would ever be needed.

I bought the 50mm f/2.5, and the focusing ring had a hard stop at about 5-10m, IIRC. Objects at infiinty were definitely OOF. I sent it off to Canon service, and it was returned with the mount shimming changed, and the lens then performed properly.

Edit: Now I recall I received a lens with the above malady from B&H and returned it as defective, and when the replacement was just the same I sent it on to Canon for repair, wondering if the lenses, designed for film, had been deemed so sharp that they were set up to allow for the slight bulge of film away from the pressure plate. Rubbish hypothesis, probably.

Ichthyophthirius
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Joined: Thu Mar 07, 2013 5:24 am

Re: Canon 50mm f2.5 Macro - Does it have a hard stop at infinity?

Post by Ichthyophthirius »

Hi Pau, Hi Steve,

Thank you for the test, Pau. That looks very similar to the resuts from my lens. I conclude that the "hard stop" is normal for this lens and not a defect.

It would be reassuring if it went slightly past infinity (like later lenses) so the user could be sure that objects at the horizon are in focus. However, it gets very sharp at f4 or f5.6 even at infinity, so overall I'm pleased with the lens as an all-purpose minimalist setup.

Regards, Ichty

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