Loss of focus at distance

[thebeardedgroundsman]

I've recently started using my old Vivitar 75-210mm lens (from my old Olympus SLR) on my A7Rii - using the appropriate adapter.

The images of relatively close subjects are lovely, and the Bokeh very creamy.

However, I cannot get long distant subjects in focus - is this usual when using adapters?

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[Pieter]

Was it a cheap adapter? Can you manually focus to infinity? If not, sounds like it's slightly too thick.

[XKAES]

Are you saving the viewfinder image does not appear in-focus, or that the resulting image is not in-focus when you thought it was in focus and made the exposure?

Does the green IN-FOCUS confirmation LED light up?

Try a test.  Set the lens to infinity and take a picture of something a mile away set at 210mm with MAX f-stop.  That rules out your vision.

[thebeardedgroundsman]

I think Pieter is right, the adapter is rather thick so it is probably TOO thick. Hey ho - at least it's not a lens I need to use - so I'll just use it on closer shots.

[Thwyllo]

What make of adaptor are you using out of interest? I've quickly looked at a couple of OM/Sony options (Urth and K&F) and both specifically state they focus to infinity...a third (Fotodiox) doesn't say this but the user comments confirm it to be so. It's not a problem I'm aware of as regards mirrorless...the lack of infinity focus has always been an issue on third party lens adaptors on Nikon DSLRs but that's the only place I've seen it so I'm curious?

[FunWithCameras]

As further evidence: people add extension tubes to get macro focusing with non-macro lenses. These tubes move the lens away from the camera, and you lose infinity focus. If your adapter is thicker than it should be, then it's acting like an extension tube, and you may be able to focus a bit closer, but you will lose infinity focus. The more extra thickness it has, the more pronounced the effect.

[XKAES]

On e-mount cameras, focusing to infinity should not be a problem with any adapted lens.  There is plenty of space for any adapter.

That's not the case with a-mount cameras.  For example, Minolta lenses must have a corrective element in the adapter -- or the lens can only be used at less than infinity.  On the other hand, M42 lenses have a long enough flange focal length so that they can be adapted to focus to infinity without any extra glass.

Edited November 13, 2023 by XKAES

[Pieter]

14 hours ago, XKAES said:

On e-mount cameras, focusing to infinity should not be a problem with any adapted lens.  There is plenty of space for any adapter.

any adapter for (D)SLR lenses. Anyway, true as that may be, it's not uncommon that (cheap) adapters are built outside spec tolerances and thus make infinity focus impossible.

[tadwil]

On 11/13/2023 at 8:51 AM, Pieter said:

any adapter for (D)SLR lenses. Anyway, true as that may be, it's not uncommon that (cheap) adapters are built outside spec tolerances and thus make infinity focus impossible.

I don't know how common the cheap adapters are built out of spec tolerances but I have yet to run across a cheap adapter that cannot be focused at infinity and most of my cheap adapters are generic eBay purchases.  Aka, as cheap as possible.