On Thu, 6 Nov 2003 23:14:45 -0000, Jim Easterbrook
wrote:

My measured focal lengths were generally quite close to the stated
values except for my 38mm Surplus Shed Erfle, which measured 31mm. Has
anyone else with one of these eyepieces had a go at measuring it?
-snip-

Not at all uncommon with many, many eyepeices. Never tried
that one personally myself, but ai remember a chat I had with Al
Nagler on the hill at Stellafane many moons ago, whent he first
"clones" (wink, wink, nudge, nudge) of his Naglers came out.

He told me, without naming any names, measure any of his
eyepieces,a nd you will see his measurements are exact and true.

Then he told me to accurately measure other brands, exactly,
and see if the reported focal lenght is accurate.

You see, if you are out even a wee bit, your claims for apparent feild
of view are out too.

So do not be too surpized, but it is worthy point to note.

anytime
joe



http://www.oneilphoto.on.ca