
How-to Optimize YourSkyView Pro Mount
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Optimizing
Your SkyView Pro Mount
The
SkyView Pro German Equatorial Mount (GEM) made by Orion is a nice light
weight,
portable and stable mount which is categorized as a “Vixen
Clone”. It
has a saddle which accepts a
standard 1.75 inch dovetail bar. On
my SVP I have installed the Dual Axis Drive package which
gives motorized control over the RA and DEC axis with a small hand
paddle. You can
select between Northern and
Southern operation as well as 2X, 4X or 8X drives rates for slewing.
Tracking is done at
sidereal rate only.
Out of
the box the mount perform perfectly for visual operation. The user can
disengage the
drives to
manually operate the axis for centering an object and then reengage
them for
tracking and fine adjustments with the hand control. With my 66SD on
the mount, objects stayed centered for
over
an hour with a 26mm Plossl. When
I
tried some prime focus photography I came to the realization that the
SVP could
not do better than 30 second sub-exposures with out some work. The RA
axis had a
significant amount of
periodic error as well as backlash and lacked the ability to be
autoguided. Two
major drawbacks to
a long exposure photographic mount. I really enjoy using this mount and
set out on a mission
to improve its
photographic ability.
The first
thing I did was to mechanically overhaul the mount. I started by
reading the Modifying the
SkyView Pro
Mount article
on Andy’s Shot Glass.
An
excellent web site with a wealth of information pertaining to Orion
products. The
article can be found
here:
http://www.andysshotglass.com/SVPmods.html
I
followed the instructions to the letter and it made a huge difference
to the smoothness
of operation in both the RA and DEC axis as well as reducing the PE and
backlash. I
received the most
benefit from these 4 steps:
1. Disassemble
the entire mount and degrease everything. I used an environmental
friendly organic degreaser used by
bicycle
mechanics (my other hobby!). Quite
effective and available from Performance Bicycle.
http://www.performancebike.com/shop/profile.cfm?SKU=358&subcategory_ID=4205
2. Using my Dremmel rotary tool and a small wire wheel, I deburred the entire leading edge of the supr gears. This helps the worm mesh and ride more smoothly around the spur
3. Re-lubricate all appropriate surfaces with white lithium grease. This is easily obtained from any general hardware store. I used just enough to evenly coat the surfaces.
4. Reassemble
the mount paying extra attention to the worm-spur mesh and the drive
motor gear
mesh. I spent
multiple nights
getting this just so. I would adjust the mesh, set up the imaging
equipment,
take a few test shots. Then
evaluate the stars and repeat as necessary until I could no longer see
any
improvement. This
was a critical
part of the rebuild and I believe is reason I can achieve 300 second (5
minute!) sub-exposures without any sign of trailing or elongation. Here
are 2 examples of
what I was able
to achieve after this procedure and adding autoguiding capability to
the mount
Now that your
SVP is mechanically capable of long
exposure, you will need to make it capable of being autoguided. This is
a relatively
simple process
that you can complete as follows:
1. Modify
the Dual Axis Drive hand controller to add a ST-4 port. I used an
excellent Step-By-Step
instruction written by Doug Anderson at Shoestring Astronomy which can
be
downloaded from:
http://www.store.shoestringastronomy.com/eq_mod.pdf
2. Purchase and install a Shoestring Astronomy GPUSB guide port interface module. This will connect to the ST-4 port you added to your handbox in step 1 above.
3. Rig
up a guide scope and camera to your SVP mount, download and install PHD
Guiding
by Craig Stark at:
http://www.stark-labs.com/phdguiding.html
You are now
ready for long exposure astrophotography with
your Super SVP Mount!!!
The following
are some examples of long exposure
photography using the modified mount
.
The
Double Cluster in
Persius.
Imaged with a
300D through a William Optics ZS66SD with
0.8 FR.FF
Guided with a
DSI Pro I and a Sigma 55-200mm lens
Sigma Clip
stack of 17, 3 minute ISO 800 Exposures
The Seven
Sisters in the Pleiades
Imaged with a
Canon 300D through Sigma 55-200 lens
Guided with a
William Optics ZS66SD and a DSI Pro I
Sigma Clip
stack of 21, 5 minute ISO 800 Exposures
Here are
some pictures of my new and improved SVP mount and the side by side
mounting platform
for my imaging and guide optics. The mounting plate is made from a 3/8
inch piece of
aluminum sheet stock
drilled out to mount my optics. The plate was then bolted to a
8” 1.75 inch
dovetail bar. Any
brand will do. I
selected a solid version for extra
rigidity.
Following
these relatively simple steps will convert your SkyView Pro into a
Super
SkyView mount capable of performance you will not believe.
Good luck
with your modifications and feel free to contact me with any questions.
You can PM me here on CN
or email me a
djrLX90@optonline.net
Clear
Skies,
David
Rosenthal
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