[AZ-Observing] Re: Eyepiece religions

Steve,

You may learn some from plain old graph paper like distortion, chromatic 
aberration and softening in the corners, but there is much more that can 
be measured using the appropriate test targets. Below is a link to a web 
site put together by Norman Koren, an ex Hewlett-Packard engineer and 
fine photographer, with tons of great information on everything 
technical you may want to learn about film and digital photography. You 
may even learn some things that will cause you to spend more money on 
better equipment, but as you well know, good equipment is worth it.

http://www.normankoren.com/Tutorials/MTF5.html

This link will take you to his lens testing page, but I'm sure you can 
figure out how to find the rest of his wonderful site. I've spent many 
very worthwhile hours absorbing what he presents.

Enjoy Learning,
Rick



-------- Original Message --------
Subject:        [AZ-Observing] Re: Eyepiece religions
Date:   Wed, 16 Apr 2008 20:19:30 -0700
From:   Steve Coe <stevecoe@xxxxxxxxx>
Reply-To:       az-observing@xxxxxxxxxxxxx
To:     <az-observing@xxxxxxxxxxxxx>



Brian, et al;

I would seem that the makers of eyepieces want it that way. I don't know 
enough of the science of optics to speak too much about using an optical 
bench. But, in the era of the digital SLR camera could not a 
knowledgeable person aim the eyepieces at a flat sheet of graph paper, 
take an image and learn quite a bit from that image?

Just thinking out loud;
Steve Coe


-----Original Message-----
From: az-observing-bounce@xxxxxxxxxxxxx
[mailto:az-observing-bounce@xxxxxxxxxxxxx] On Behalf Of Brian Skiff
Sent: Wednesday, April 16, 2008 4:06 PM
To: az-observing@xxxxxxxxxxxxx
Subject: [AZ-Observing] Re: Eyepiece religions

It's too bad the marketplace has made it difficult to  determine actual 
facts about the eyepiece designs as actually sold, so as to allow the 
discussion to be brought into the realm of quantitative comparison 
rather than "religion". The US magazines (at least) provide no such 
information, and without a pretty good optical-bench set-up, it would be 
a lot of work (and expense) to reverse-engineer the commerical products. 
Maybe some patent searches would turn up actual specs you could run into 
an optical-design program to yield details about image quality, color 
aberrations, field curvature, distortion, etc. I know this was done for 
the original Nagler design (it was in an issue of 'Telescope Making' 
back in the 80s), but what about the many newer styles that have come 
out since then?


\Brian



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