12.5″ Orion Deep Space Explorer Dobsonian

The Orion 12.5″ DSE is an outstanding telescope. I hated to sell it but when my back started giving me trouble from lugging this light bucket around I decided it was time to scale back a bit. The telescope fully assembled with base and optical tube weighed almost 100 lbs. The weight of the scope was one reason for selling it, the other was portability. The DSE’s large size made it difficult to transport and after selling my pickup truck I really had no way to haul this big scope around.

I purchased the telescope new from Orion Telescopes & Binoculars in 1996. It was one of the last “early model” DSE’s to be made. I know this because I remember the scope being delivered to my house and then a few days later receiving the new Orion catalog with the “all new and improved” 12.5″ Premium DSE on the cover. I kept telling myself that if I just would have waited a month to place my order I could have had the new premium DSE. That sulking lasted only until I got the scope under a dark sky. The views this scope provided under dark sky conditions were truely amazing. I have to admit there are times when I wish I hadn’t sold it but that’s usually about that same time that my back starts aching.

While this telescope was sold by/under the Orion brand name, the scope was actually manufactured and the mirrior figured by Discovery Telescopes. Sadly Orion no longer sells the 12.5″ DSE. They presently make the Skyline 12″ Dob which has some upgraded features but it’s not the same as the old “Discovery” DSE.  The Discovery PDHQ Dobsonian Telescope line would be the latest incarnation of the former Orion 12.5″ Deep Space Explorer Dob.

I enhanced the DSE performance by adding a large sheet of Ebony Star Laminate (better known as Ebony Star Formica) to the base plate on the mount and additional Teflon bearings. This really helped the smoothness of the mount. I also fashioned a lead shot counter weight (bean bag) and used a Velcro strap attached along the back of the OTA for balance. This worked out perfectly for adjusting the balance of the scope as larger heavier eyepieces were added.

Believe it or not the vehicle I used to transport this massive scope was a little 1989 Geo Metro, 2 door subcompact car. This small hatchback actually worked well to transport the scope and myself. Of course that was about all it was going to hold but never the less it worked. I’d fold down the rear seats and front passenger seat and then fit the OTA in the car. It ran the length of the car from dash to tailgate. I’d then add the Dob mount beside the OTA in the back and fill in all the voids with assorted eyepiece cases, a step ladder and other observing necessities.

After trading in the Metro I purchased a small Nissan pickup thinking that hauling the big DSE would be a walk in the park compared to the Geo but that really didn’t turn out to be the case. The OTA was so big and heavy that I needed something to keep it from rolling around in the bed. This seems like an easy thing to fix and I explored several options but I ended up having a custom, heavy duty cardboard box and lid made special for hauling this scope around. The box worked great.

Specifications and Features of the Orion 12.5″ DSE Dobsonian

Optical Design: Newtonian
Aperture: 317.5mm (12.5″)
Focal Length: 1524mm (60″)
Focal Ratio: f/4.8
Maximum Practical Visual Power: 600x
Optical Tube: Sonotube
Telescope Mounting: Dobsonian
Primary Mirror: Soda-lime glass
Secondary Mirror Mount: 4-vane spider
Focuser: Low profile helical focuser accepts 1.25″ and 2″ eyepieces
Finder Scope: 9 x 50 achromatic finder scope
Illuminated Reflex Sight: Telrad ®
Total Net Telescope Weight: 98 lbs.

12.5″ Orion Deep Space Explorer Telescope Instruction Manual – PDF

4 thoughts on “12.5″ Orion Deep Space Explorer Dobsonian”

  1. Hi, I found an 8″ Deep Space Explorer online for sale for less than $100. I am a beginner stargazer. Would you recommend? Thanks.

    1. Hello David – Yes. The 8″ Orion DSE is a great first scope, and if you can get it for less than $100 all the better. I’d suggest a thorough inspection of the scope before you hand over the cash. Ensure that the primary mirror is not chipped, cracked or scratched and the finish is still in good shape. Likewise do the same for the secondary mirror. Cosmetic blemishes on the optical tube or mount are just that, cosmetic only, and should not effect the scope’s performance.

      Make sure the mount and optical tube work well together in both altitude and azimuth. Take the scope using your hand and move it in these axes (yes, axes is the plural for axis. I looked it up!) to ensure that it moves freely and stops where you point the telescope. Look through the focuser and make sure the secondary mirror is centered and the collimation is not horribly off. If it is or the secondary mirror is not centered under the focuser then you might want to ask some questions about why it’s so badly out of alignment. The collimation can be fixed in most cases but you might want to pass on it if you are in fact buying your first scope and don’t want to have to jump straight into the “deep end” exploring telescope collimation. Typically it’s a slight adjustment and you’re done however, if the scope it extremely out of alignment the easy “slight adjustment” can turn into a tedious learning experience that might even require assistance from a pro. Regardless, there are plenty of “how to” guides on Newtonian telescope collimation on the internet to aid you should you find yourself in this situation.

      Don’t be afraid to ask about the telescope’s history. Is this a one owner scope? How did the seller acquire the scope? How long have they owned the scope. Have they ever had any trouble with the scope? If so, what issues specifically were they dealing with? This line of questioning will help you learn about the scope’s past and in determining if you want to make the purchase. I hope this helps. Good luck and Clear skies.

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