Re: [APML] Need for a 300 mm "CCD scope"; was: (OT) IC1396 CCD with Schmidt-like FOV

["Bert Katzung" <katzung1@attbi.com>]

Hi Gene:
Thanks for the input---that Tak scope and its price are a very useful
yardstick! Is that no longer available? And I know what you mean about
focusing with fast systems.  I would prefer an f4 or 4.5 over an f2.8. But
focussing is one place where I find CCD  really eases the process compared
to film. Being able to check the focus with an actual image, half-flux
diameter, etc *immediately* makes a big difference to me.
Bert

Bert Katzung
katzung1@attbi.com
www.astronomy-images.com



----- Original Message -----
From: "Gene Horr" <genehorr@texas.net>
To: <astro-photo@seds.org>
Sent: Tuesday, August 06, 2002 9:52 AM
Subject: Re: [APML] Need for a 300 mm "CCD scope"; was: (OT) IC1396 CCD with
Schmidt-like FOV


> > Sean's estimate of $5-6K 300 mm apos would be way outside my comfort
zone because
> > I already have so much invested in equipment. But I sure would
> > be interested in one that sold at $2 to 2.5K
>
> IMO that is doable.  Tak used to sell their 76mm f/4.5 triplet set for
around
> US$2k.  That gives you 342mm FL and full 35mm coverage (they claimed 6x4.5
> coverage, but the corners were pretty bad.)
>
> But keep in mind that focus at f-ratios faster than f/6 starts becoming a
> real b*tch to keep up with.  Camera lens aberrations tend to hide
> a lot of the problems that start becoming obvious at these faster speeds.
> You have to plan on refocusing when changing filters and between
> exposures.
>
> Gene Horr
> genehorr@texas.net
>
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