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EF 400mm f/5.6L USM image quality

Started Jul 1, 2021 | Questions thread
Octopuss
OP Octopuss Regular Member • Posts: 344
Re: EF 400mm f/5.6L USM image quality
1

So I bought the lens and am really perplexed: I just refuses to focus. Almost literally.

When I watched videos and read articles about it, it was praised to no end about its autofocus speed, but that seems to be the exact opposite of what I'm experiencing.

I slapped it on my 80D and it was nothing short of ridiculous. Focusing on things within say 10m distance was ok (not particularly fast but it just worked), but anything in distance flat out didn't work. There was a red crane maybe 50m away. The lens just didn't focus on it at all. I kept the shutter half pressed for three or so seconds and virtually nothing happened. I had to repeat that two or three times before the damn lens finally focused. I tried other random stuff and fairly contrasty stuff (like some black poles on blue sky background) as well with the same result.
The focus limiter didn't seem to make any difference.

I tried it on the guy's 1Ds with almost the same result and he told me it was simply an old lens and that simply was the way it worked. I didn't know any better so I bought it anyway, because it's really in absolutely mint condition as if it was just brough from a store with all the paperwork. It was manufactured in 2010.

Any ideas?

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Canon EOS 90D Canon EF 16-35mm F4L IS USM Canon EF 50mm F1.8 STM Sigma 85mm F1.4 Art
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