Re: Celestron Fastar - pros and cons

On Oct 11, 7:43 am, Quadibloc <jsav...@xxxxxxxxx> wrote:
Jack wrote:
What are the disadvantages of this setup?

Upon reflection, I realized that I left out the *most important*
disadvantage of that setup.

Given the (relatively minor) disadvantages I pointed out in my other
post, the most serious problem is that enduring those disadvantages is
unnecessary.

That's because the *detector* in most CCD cameras - until you get up
there to the *very* expensive kinds of detector - are pretty small.
Which means that one can, without problems of vignetting, simply
shrink the image produced by the telescope at the normal eyepiece
position for fast photography.

And, in fact, image reducers of this type (noted as for imaging use
only, since they would not work well visually with long focal-length
eyepieces) are available.

Meade has an f/3.3 reducer has a T-mount adapter, so it only works
with film cameras, but either Meade or Celestron has a strong reducer
billed as designed for one of their CCD cameras specifically.

John Savard

Well, depends on your definitial of "expensive," but larger detectors
are getting into the hands of more and more amateurs all the time.
Something along the lines of the ST2000 camera could definitely
benefit from Fastar,

Fastar itself? I don't think Celestron discontinued it specifically
because of the "disadvantages" you mention, but simply because they
were not selling many of the corrective optics packages. I suppose the
number of serious imagers and the subset of serious imagers interested
in trying Fastar was just not large enough.

As for the disadvantages? I've been surprised that people turn out
amazing images by hanging a DSLR on the corrector via Fastar. No, you
can't guide off axis, but most folks aren't doing that much anymore
anyway. The chance of damaging the corrector IS very real. Me? I'm
sticking with a Meade 3.3 reducer--even if I'm not too happy with it.

;-)

.