***SPAM*** =?big5?q?Re=A1G=20[APML]=20Takahashi=20Epsilon-180ED=3F?=

[Paul Ng <paulimer@yahoo.com.hk>]

Wade and all,
I believe this scope is aimed at DSLR users' market,
therefore they came out with a 44mm image circle. With
a CCD/CMOS the resolution of f/2.8 can be more fully
utilized than E200 I guess.

Paul


--- "Thomas W. Earle" <twade@bmi.net> 說：

> This new scope from Takahashi looks pretty
> interesting.  I'm tempted
> in purchasing one; however, it's doubtful I'll do it
> for several
> reasons.  First, it's not quite as fast as one would
> think given its
> f/2.8 speed.  Since it has a central obstruction of
> 80mm this cuts
> out 20 percent of the light reaching the film giving
> an effective
> f-stop of f/3.5.  This is a decrease of about a 1/2
> stop.  Second,
> with an image circle of 44mm, it just barely covers
> 35mm format
> film.  Given this fact, it would take approximately
> four frames to
> equal one Pentax 67 frame using my current FSQ-106N.
>  Third, its
> focal length is very similar to the FSQ-106N (i.e.
> 500mm vs. 530mm);
> hence, I would not gain any focal length.  Finally,
> I've heard these
> scopes are very difficult to keep collimated.  I'm
> not sure if
> Takahashi has improved on this weakness or not. 
> Since I would be
> using it in a portable environment, I don't want to
> spend countless
> hour trying to collimate the scope in the field.  I
> see one good
> thing though when comparing it to my current
> telescope, the
> Epsilon-180ED does win in the resolving power
> department (i.e. 0.64"
> vs. 1.1"); however, at these focal lengths, it's
> debatable if one
> would even see a difference, especially using E200. 
> It will be
> interesting to see what's the next telescope in this
> new series.
> Hopefully, it will be just as fast, but with a
> greater image circle.
> 
> Wade
> 
> 
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> 


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