Re: ATM help asked with design focal reducer

["B. Pepin" <atmjedit@conceptsnet.com>]

Subject: ATM help asked with design focal reducer

You might call Lichtenknecker Optics N.V. for information on glass and
filters manufactured in your area. They are nice people and very interested
in amateur astronomy.

They manufacture a full line of unmounted optics of all kinds. The RG 715
filter is recommended for reducing solar IR (probably too dark for your
application), but they seem to have a full list of other cutoffs made from
Schott glass. They also make a Shapley focal reducing lens (0.6) with long
back-focus which will reduce a focal length of 3500, for instance, to 2100
with full corrections. 57mm dia. Part #3422.

Kuringersteenweg 44, or Grotebreemstraat 21
B-3500 Hasselt
Belgie
Phone:  11-25-30-26



Barlow



----- Original Message -----
From: Johan Vanbeselaere <jvb@digilife.be>
To: atmlist <atm@shore.net>
Sent: Friday, September 08, 2000 3:38 AM
Subject: ATM help asked with design focal reducer


>
> Hello,
>
> a couple of friends of mine here in Belgium are busy designing and
> manufacturing with off the shelf optics a focal reducer for their
CCD-camera
> on a 60cm Cassegrain reflector.
> Because this CCD is sensitive into the infrared they need to know how far
> their focal reducer is giving acceptable images in order to adapt an
> IR-blockingfilter.
> We were only able to find refractive indexes up to the r-line (706 nm).
> Anyone any idea how to obtain this indexes in the 700-850 nm range or
> perhaps up to 1000 nm  for BK7, BaK4, SF5 and SF10 ?
>
> They asked me and I told them this list should be able to help them, so
> don't disappoint me ;-)
>
>
> Vanbeselaere Johan
> ACG vzw Belgium
>
>


>
> Hello,
>
> a couple of friends of mine here in Belgium are busy designing and
> manufacturing with off the shelf optics a focal reducer for their
CCD-camera
> on a 60cm Cassegrain reflector.
> Because this CCD is sensitive into the infrared they need to know how far
> their focal reducer is giving acceptable images in order to adapt an
> IR-blockingfilter.
> We were only able to find refractive indexes up to the r-line (706 nm).
> Anyone any idea how to obtain this indexes in the 700-850 nm range or
> perhaps up to 1000 nm  for BK7, BaK4, SF5 and SF10 ?
>
> They asked me and I told them this list should be able to help them, so
> don't disappoint me ;-)
>
>
> Vanbeselaere Johan
> ACG vzw Belgium
>
>