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New Product - Special Introductory Price!
Many users
find the primary mirror focusing mechanism of Schmidt-Cassegrain telescopes
(SCT) cumbersome to use. There is some amount of image shift and precise focus
cannot be found easily. This is inconvenient for visual use and a serious
problem for astrophotography. GSO's (Guan Sheng Optical) latest Crayford
focuser model is a gorgeous, all-black, rotatable focuser for Schmidt-Cassegrain
telescopes that elegantly solves these problems.
CNC machined from aluminum and anodized black, this focuser
will screw on to the rear cell of any SCT telescope sold by Meade and Celestron
having a standard SCT thread. The standard SCT rear cell
thread is an (approximately) 2-inch diameter male thread.
This single-speed Crayford focuser is a
joy to use and you will wonder how you ever lived without it once you install
it! By design, SCT Crayford focusers eliminate the annoying backlash and
image-shift that plagues many SCTs. You will experience very smooth and precisely
controlled focuser motion.
The inner drawtube glides on 4
precision bearings and a roller shaft. The inner barrel is baffled and painted
a flat black to minimize reflections for maximum contrast. This barrel
is also black anodized and features a laser-etched mm (millimeter) scale. It provides 1" of focus
travel which is more than adequate for SCTs. You first use your SCTs focusing
knob to achieve coarse focus and then switch to the Crayford focuser for finer
focus and control. Depending on your range of eyepieces and accessories, you
may never need to touch your SCT's main focuser again!
The 2" focuser barrel features a brass
compression ring and can accept standard 2" refractor-type diagonals and other
accessories. Also included is a 1.25"-2" adapter with brass
compression rings and threads to accept standard 2" filters. This deluxe model features a 360-degree rotatable ring that
allows you to orient the focuser (and hence your diagonal/eyepiece) to the most
comfortable viewing position.
GSO's rated load capacity for their
Crayford focusers is a little less than 6 lbs (2.7 kgs) and I have no problems
using this with a 2" dielectric diagonal and several heavy 2" eyepieces on my
Meade LX200 SCT.
The focuser also has two large
thumbscrews. The thumbscrew on the telescope side can be used to lock the
focuser, allowing the use of heavy accessories or cameras without fear or
slippage or losing focus. The other thumbscrew on the eyepiece end can be used
to adjust the tension of the focuser to achieve a focusing "feel" that you
like. At the easiest (lightest) setting,
the focuser moves extremely smoothly. At tighter settings, you can still use
heavier accessories without sacrificing much of the smooth focuser action.
Please note that some larger Meade and Celestron SCTs (11"
and larger) have a larger rear thread, so please make sure that you have an
adapter that reduces that larger 3"+ thread to the smaller 2" SCT thread. If
you have a standard 1.25" SCT visual back, all you need to do is unscrew the
visual back and screw on the SCT Crayford focuser in its place. The focuser is shipped in a foam-fitted box.
Specifications:
- Minimum focuser height (with 1.25" adapter) = 4.29"
(109mm)
- Maximum focuser height (with 1.25" adapter) = 5.28"
(134mm)
- Minimum focuser height (without 1.25" adapter) = 3.90"
(99mm)
- Maximum focuser height (without 1.25" adapter) = 4.88"
(124mm)
- Tube travel = 0.99" (25mm)
- Focuser weight (with 1.25" adapter) = 1lb-10.5oz (751gm)
- Focus knob diameter = 1.57" (40mm)
- Microfocus knob diameter = N/A
- Maximum outer barrel diameter = 3.3" (84mm)
-Thread: Standard SCT female thread
- Millimeter markings on focuser drawtube: Yes
- Rotatable: Yes
- Dust plug: One 1.25" dust plug included
Description copyright: Agena
AstroProducts (2008). Reproduction without permission prohibited.
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