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How-to Optimize YourSkyView Pro Mount


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Optimizing Your SkyView Pro Mount

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

Double Cluster - 2nd Attempt, Center Crop

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

M45 17 by 300 SVP

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.

Back
Front
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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