I don't mean to beat a dead horse, but if you own an A7 or A7r and are looking

Started Dec 24, 2013 | Discussions thread
120 to 35 Senior Member • Posts: 1,273
Re: Getting back to the initial objective of this thread...

osv wrote:

120 to 35 wrote:

Adapters could cause problems with lenses that contain optical elements that move relative to one another. There are two problems:

1. The whole adapter is too short and the focus ring show the wrong distance when in focus. This translates to the what is called "focus past infinity". What happens here is you don't get an image that is perfectly focused both in the center and the edges. I don't know about the internal design of the particular lenses discussed here but I have checked old Canon 35mm and 50mm lenses that suffered from a short adapter.

This phenomenon has been confirmed recently in the forum with an expensive wide Nikon zoom (2.8/14-28 ED) that showed soft corners with a short adapter and performed perfectly with an expensive Novoflex adapter that had the precise length. See this thread:

http://www.dpreview.com/forums/thread/3590395

A short adapter has no adverse effect on image quality when the lens optics move together as one unit when the focus ring is turned.

those statements are conflicting with each other... you can't say that a short adapter has no adverse effect on image quality, then turn around and say that his problem was caused by a short adapter.

You read half a sentence. There are two types of lens as I mentioned. Those with relative movement and those without.

one thing to note about that thread is "minor play in the adapter"... which, if it's not rotational slop, is easily fixed, he should have tried doing it... rotational slop won't affect how square the lens is to the camera body flange.

these adapters all require perfect flange distances; i confirmed with a micrometer that the barrels are all equal thicknesses, but i haven't yet tried measuring the flanges in relation to the barrel end surfaces... i expect that it's not going to be an issue.

the cheapo adapters that i have all focus past infinity, thank goodness, it's a real blessing, because with live view/magnify, there is no doubt when you are in focus... with that technology, the distance markings on the barrel are largely obsolete and unnecessary, unless perhaps you are in a video rack focus type of a situation.

Your cheap adapters might be good for your lenses. You did not understand the post. Instead of wasting time here, go to the linked thread and see the evidence.

i am sooo glad to be done with optical viewfinders and barrel markings, lol!

Thank you!

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dan

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