[Prev][Next][Index][Thread]

Re: (IAAC) Planetary eyepieces


>quite apparent to critical observers of the planets. Al Nagler is one of
>these; he had much to say about this at Riverside, at the eyepiece panel
>that we were both a part of.
>
>Since the light transmission of Naglers is a few percent less than the
>Orthos, and the design is not as well corrected as orthos across the field,
>it may seem that the Nagler is "sharper, brighter, and clearer" than a good
>ortho - especially at low power on a fast scope, where other aberrations
>will overwhelm the correction of the ortho - but in reality the perception
>is nothing but fantasy.

Al Nagler has specifically stated to me quite the opposite, and I am
surprised that
he did a 180 degree reverse. In fact, he used his work in the field of
television/projection
as a specific example of how Nagler's hold more contrast. He indicated that
while working in the
field, one of the sharpest pictures had only 5% light transmission, but
such high contrast that the lgiht transmission was not an issue, as the
contrast was far more important. 

I personally, have tested Naglers directly against Takahashi LEs with one
ep in one side of the binoviewer, and the other in the other side... in a
daytime test, so this does not take into acct the effect of your internal
reflections. The light throughput was noticeably less in the Nagler, and
yet the image was as clear, if not more clearly resolved in the Nagler at
the same time. At night, similar performance was noted, to the degree that
I was not able to perceive the loss in light. HOWEVER< in a quick test
against a Pentax XL last week, I noted that the view seemed "cleaner" in
the Pentax 7, as opposed to the Nagler 7, but I couldn't put my finger on
it due to poor seeing and limited time. 

Similarly, I sold my 9mm Pentax Ortho and kept a 9mm Nagler after a quick
back and forth swap at the eyepiece last year.

Overall, I have seen very clearly the light throughput difference, and
agree there.
I also have seen internal reflections at times in the Naglers.
I cannot 100% for sure state at this point that I have noticed performance
differences to date
on Jupiter (as an example) and globulars (my other test target) through
other eps over Naglers, but
do believe it to be true. As a person that tests so many eps, I have found
it frustrating not being able to perceive an immediate difference in this
regard



Thanks!   -Todd

Todd Gross
Boston Meteorologist
homepage: http://www.weatherman.com
(617)725-0777
References: