Re: [OM] OT: New Sonie lens 20/1.8

Subject: Re: [OM] OT: New Sonie lens 20/1.8
From: Ken Norton <ken@xxxxxxxxxxx>
Date: Tue, 24 Mar 2020 11:33:29 -0800
> Some data from old Modern Photo reviews...
> They may be referencing back to this review. Where else are they going to get 
> accurate measurements?

I'm assuming that their tests were done at infinity focus? It's
actually a little more tricky with the measurements because a
traditional lens design that focuses through extension will generally
get a little longer as it is focused closer. But an IF (internal
focus) lens will get shorter (wider angle) as it is focused closer.
And then there are the various zoom lens designs which have a lot of
variation depending on what end of the range they are on.

Take the OMD 14-54 as an example. There are two crossover points where
the lens behaves quite differently. It's like three different lenses
in one. Depending on which of the three focal-length ranges you are
on, the lens will either get longer or shorter as it is focused.

Also, did MP measure the angle of coverage from corner to corner or
from side to side?

AG Schnozz
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