[LRFlex] Re: APO vs Asph
- From: "Neil Gould" <neil@xxxxxxxxxxx>
- To: <leicareflex@xxxxxxxxxxxxx>
- Date: Tue, 15 Feb 2005 07:53:45 -0600
Hi all,
> From: Charles Cason <cec@xxxxxxx>
> Subject: [LRFlex] Re: APO vs Asph
>
> Thanks Doug,
> I always thought APO was a specific kind of element much like the
> aspherical. So this means that Leica does not designate a specific
> lens as APO until they know how it performs?
>
I'm in "digest mode", so it's possible that I've missed a response that
defines 'APO'... if so, please excuse the redundancy. Much of this I
learned from an extensive discussion on this topic in the medium format
equipment newsgroup, rec.photo.equipment.medium-format.
The term "APOchromatic" is used to describe a lens that creates the exact
image for 3 separate colors. The implication is that lenses capable of
doing this will have superior performance, rendering images with less
color aberation than "Achromats", which create only two identical images.
Unfortunately, there apparently is no specification as to which 2 or 3
color images are being resoloved, so a lens that resolves one color image
in the visible light spectrum, one in the ultraviolet and one in the
infrared range would be technically called an "APO", but may perform less
well than an achromat that resolves 2 color images in the visible light
spectrum.
That said, from my *very* limited experience, Leica has established a
quality level such that lenses they designate as "APO" will be excellent
performers, and should be better than their non-APO versions of that lens
(I can't verify this personally). I do like my 100 mm APO Macro-R a lot,
though!
Regards,
Neil Gould
--------------------------------------
Terra Tu AV - www.terratu.com
Technical Graphics & Media
------
Unsubscribe or change to/from Digest Mode at:
www.horizon.bc.ca/~dnr/lrflex.htm
Archives are at:
www.freelists.org/archives/leicareflex/
Other related posts:
