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Old 25-11-2018, 10:06 AM
garymck (Gary)
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A dirt cheap fast astrograph

Hi,
Due to a serious health issue (heart surgery), I've had to scale down the size of scopes I use - particularly for portable use, as I just can't carry what I used to. I thought I'd share some experiences with others of a seriously cheap scope that has fabulous potential as a short focal length wide field imager. The scope is the Skywatcher 130PDS, a 130mm F5 Newt, which combined with a Skywatcher .9X F5 Coma corrector which drops the speed down to F4.5 (I verified this with plate solving)

The scope only requires one mod - a shortening of the focuser tube by 10-12mm as it protrudes into the light path. I also added a ring to the bottom of the focuser to stop it coming off the focuser bearings.

The standard 2 speed focuser is fine with light/medium weight cameras and does NOT require replacement, although Moonlight makes a version to fit it if you wish. Nor does the scope tube flex under the weight of a camera.

Attached is my first real try at imaging with it - not a fabulous image, but enough to show the scopes potential. This was only calibrated and stretched, no sharpening applied as I wanted to see what the scope was able to do.

249X60seconds, taken from a red zone in Geelong, calibrated with bias and flats. ASI071MC

One note, the coma corrector nominal spacing is 55mm, I found that I had to reduce this to 53.5mm to clean up stars at the edge.

So for around $600, you have a 130mm F4.5 astrograph with a focal length of 585mm focal length. Starts to make expensive apos look, well, expensive...

Happy to link the full calibrated but unstretched image to pixel peepers, via Dropbox. PM me for link. The heavily shrunk jpg doesn't really represent the image.

There is a 92 page thread at stargasersloung, where I first encountered this scope:
https://stargazerslounge.com/topic/2...130pds/?page=1

Hope it's useful to someone
Gary
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  #2  
Old 25-11-2018, 10:30 AM
VPAstro (Andrew and Cam)
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Great review Gary. Sounds like a fantastic scope. All is going well here, but still waiting for a clear night...lol
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Old 25-11-2018, 04:10 PM
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ChrisV (Chris)
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Sounds great Gary. Especially with getting such a good field of view at F4.5 on an aps-c sized sensor
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Old 25-11-2018, 04:30 PM
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Hi Gary,

Sorry to hear about your health problems..
All the best!
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Old 26-11-2018, 07:40 AM
garymck (Gary)
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Quote:
Originally Posted by bojan View Post
Hi Gary,

Sorry to hear about your health problems..
All the best!
Thanks Bojan, all OK now - just one of the several on here who it seems needed their hearts reconditioned....
Gary
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Old 26-11-2018, 08:36 AM
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netwolf
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Hey Gary sorry to hear of your health issues, hope your road to recovery is smooth.
Long back i came accros a similar review but for a 8" GSO vs TEC apo not as compact as the 6" though.
http://msfastro.net/articles/gso_tec...c_compare.html
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