Archived posting to the Leica Users Group, 1997/11/04

[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]

Subject: Re: Focussing 70-180 APO
From: Jim Brick <>
Date: Tue, 04 Nov 1997 21:09:57 -0800

At 10:11 PM 11/4/97 -0500, you wrote:
>I noticed that infinity is not infinity when used with the 2x APO extender.
>Atlanta's skyline is over 20 miles from Stone Mountain.  The picture was
>tack sharp when the distance indicator was on 300 feet.
>Even when used without the extender infinity is not exactly at the
>'mechanical end' of the lens.  Perhaps 1 to 2 mm from the end to be tack
>Is that something to worry?
>Regards Jorg

No. This is normal and proper. You see, there is no such thing as infinity.
It's beyond the farthest possible object. Telephoto lenses frequently focus
beyond what you might perceive as infinity. That mountain range over there.
If you stop and think about it, it makes perfect sense.