RE: [ccd-newastro] Equipment dilema :-(
- Imaging is the more challenging task, so I'll only consider it when making a
The key question here is what focal length do you want to image at? Are you
interested in wide-field imaging -- then the FSQ-106 is probably the best
choice and it will work on almost any competent imaging-grade mount (EM-10;
EM-200; NJP; AP 400 GTO, etc.). Is portability the critical issue? Then the
Sky90 is smaller and lighter, and with the f/4.5 field flattener it works
very well with CCD cameras.
Do you want to "go long" and use a longer focal length so that you can take
portraits of deep-sky objects? If you want a longer focal length, say
1000mm, then a 5" or 6" refractor is your ticket. A 5" refractor will get to
1000mm at about f/7 or f/8, and run between $4-6k, squeezing you somewhat on
the mount. The Tak FS-128 (or a used FC-125) would be ideal and have a nice
large flat field. The AP130 would also work well with the size of the chip
in your current camera, but starts showing elongation from curvature of
field with chips like the KAF-1602 and KAF-3200. I would look at the EM-200,
a used AP 900 GTO, and a Mountain Instruments MI-250 as your primary options
for mounting a 5" refractor for imaging.
If a 5" refractor pushes the budget too hard, then a 4" will have to do it.
Your choice is either among the fast wide-field scopes previously mentioned
(to which one could add scopes like the TV NP101 and various TMB scopes),
or an f/7 to f/8 4" or smaller refractor that will give you longer focal
lengths and a narrower field of view (FS-102, TV 85, etc.). You'll need
longer exposures with the slower focal ratio, but anything f/10 or under is
reasonable with CCD cameras.
author of The New CCD Astronomy
From: audibeasta42001 [mailto:dan.sevcenco@...]
Sent: Tuesday, April 02, 2002 7:36 AM
Subject: [ccd-newastro] Equipment dilema :-(
I am having an equipment dilema and I would appreciate any advice you
can give me on this one, as it is "killing" me :-)
Here is the data:
* Budget: $10,000
* Want a refractor on an equatorial mount intended for both visual
and CCD use. I'd say about 50% of the time for each.
* The CCD camera is not part of the budget as I already have it (FLI
* The budget must include the OTA, mount, tripod / pier and anything
else that is neccessary - field flattener, dovetail and rings for
mounting the OTA, etc.
So, given the above, which would be the configuration you would
choose, in terms of brand, model and price distribution per item.
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- Hi Dan,
Another scope for serious consideration if the Vixen 114m f/5.3 ED
apo refractor. With the I have one and I'm sure you saw its review
in the most recent S&T. It is a great scope and the cost is about
$2000 (I got mine for $1850). You can get it from Orion or perhaps
another international dealer. Its forte is wide field
astrophotography, but it is a wonderful visual scope as well. An
option is an f/4.4 focal reducer for photography. The Vixen gives
great wide field views and no color on the Moon, Jupiter or Saturn.
The S&T review was accurate and fair (and I think very favorable for
the Vixen), but there was one point of possible misunderstanding.
The reviewer noted that a number of his eyepieces did not come focus.
I have many premium oculars (Naglers 3 to 6 zoom, 7mm and 9 mm Type
6, 17 mm and 20mm; Orion SW Lanthanum, Pentax XL, UO 40 and 25 mm
Konigs MK70, All UO 1.25 Konigs; 6mm through 55 mm Clave Plossls from
the late 1970s)and a number of other mid level eyepieces. WITHOUT the
field flattener (not needed for visual use) and WITH a 2 inch
diagonal they all easily come to a beautiful focus. I don't have
Panoptic but a post on the Vixen Yahoo group after the review
appeared from a reliable source indicated that the 35mm Panoptic also
comes to focus with the above configuration. I think all eyepieces
will come to focus using a 2 inch diagonal and no field flattener
(just screws in and out very easily). The reviewer noted that the 2
inch set-up was the best, but I was left with the impression that
this was a real problem, which it really isn't. I have both a
Losmandy G11 and GM8 mount and an SBIG STV which is mated for the
Losmany controls and autoguiding. A pier is available. Both of the
mounts are excellent. The G11 is better for imaging but GM8 is
somewhat more portable. With you budget, however, you probably can go
to an even higher quality. BTW Vixen has another, supposedly ever
higher quality, apo available - a double ED (DED series). It comes
in 108mm f/5 and I believe a 130mm (not sure of the f/# but it is
probably f/5 as well). For what its worth the DED had a very
positive post on the Vixen Yahoo group. With these items, I have
used about 1/2 of your budget.