Archived posting to the Leica Users Group, 2001/02/24

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

Subject: [Leica] Lense testing...
From: "Austin Franklin" <austin@darkroom.com>
Date: Sun, 25 Feb 2001 02:54:04 -0500

I decided to find out what the REAL effects of a UV filter are on image
degradation.  I arranged for an afternoon of test time at a high end optical
testing facility in Cambridge MA.

I am bringing my Hasselblad 110/2 and Leica 75/1.4 with their respective
Hasselblad and Heliopan UV filters, and will obviously test them with and
without the UV filters.  They suggested as tests, both MTF and resolution.
Center and out to the edges.  I also want to test focus shift.

If anyone has experience with doing such testing and has some CONSTRUCTIVE
input on the testing procedure, I welcome it.  Those who think this is
silly, well, given that this only costs $175/hour, and one filter is near
$100, I think that if I find out filters are useless, it'll easily recoup my
money by selling all my image degrading UV filters.  If I find out filters
do not degrade the image such that it is perceptible, well, then I won't
waste my time debating this subject, as I will have facts to back up my
conclusions, and that will be well worth the effort and expense.

I will publish the raw test results, no matter what they are.  I fully
expect this to be quite controversial, and I also fully expect to find there
is 'some' degradation.  It is the significance of the degradation that will
have to be 'analyzed' in order to draw any 'reasonable' conclusion to
whether a UV filter does actually degrade the resultant image.

Replies: Reply from Jim Brick <jim@brick.org> ([Leica] Re: Lense testing...)
Reply from Mark Rabiner <mark@rabiner.cncoffice.com> (Re: [Leica] Lense testing...)
Reply from Rob McElroy <idag@pce.net> (Re: [Leica] Lense testing...)
Reply from Rob McElroy <idag@pce.net> (Re: [Leica] Lense testing...-corrected MTF)