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

[lkt <tan@cox.net>]

Gene,

 This is nice, but I would really like to go down to 100-200mm if
possible. Something which can be coupled with an ST10 and be able to
cover large objects like Simeis 147 which is larger than the entire Veil
nebula. Yes, I agree, there are 50mm or 60mm aperture Taks out there.
but their FL is still too long. 

Loke



Gene Horr wrote:
> 
> > 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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