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About Airplanes & Rockets

Kirt Blattenberger, Webmaster - Airplanes and Rockets

Kirt Blattenberger


My Engineering Web: RF Cafe

Carpe Diem! (Seize the Day!)

Even during the busiest times of my life I have endeavored to maintain some form of model building activity. This site has been created to help me chronicle my journey through a lifelong involvement in model aviation, which all began in Mayo, MD ...

Airplanes And Rockets Copyright 1996 - 2026

All trademarks, copyrights, patents, and other rights of ownership to images and text used on the Airplanes and Rockets website are hereby acknowledged.

My Main Modeling Websites

Academy of Model Aeronautics (AMA) - Airplanes and RocketsAcademy of Model Aeronautics

Tower Hobbies logo - Airplanes and Rockets

Tower Hobbies

Horizon Hobby logo - Airplanes and Rockets

Horizon Hobby

Sig Manufacturing - Airplanes and Rockets

Sig Mfg

Brodak Manufacturing - Airplanes and Rockets

Brodak Mfg

JMI MotoFocus for the NexStar 8SE Telescope

Focusing at high magnification on my Celestron NexStar 8SE telescope is a little difficult because the single-fork mount is not as stable as the dual-arm mounts. It is possible to get an excellent focus, but it usually involves making a small turn of the focuser know and then removing your hand to allow the image to steady, then do it again if necessary. An electric focuser seemed like the answer based on reviews I read on astronomy forums. A brand new JMI MotoFocus costs around $180, which was more than I wanted to pay, so I started watching eBay auctions. A MotoFocus made for the older Celestron C8 appeared and I won the auction for $105. I knew it would require some modification, but for a $75 savings I figured it was worth the trouble. All it took was fabricating three small brass brackets and cutting about 1/2" off the end of the plastic MotoFocus body. The entire process took about an hour. The result was exactly what I needed! Now it is possible to get a perfect focus without any shaking at all. The focuser hand controller has a potentiometer that allows you to set the speed. A standard 9V battery powers it.

I have since bought a new Celestron CPC 800 Deluxe HD telescope (dual arm) and installed a FeatherTouch dual rate mechanical focuser on it and do not need the electric focuser anymore.

Modified JMI MotoFocus for Celestron NexStar 8SE telescope - Airplanes and Rockets

Modified JMI MotoFocus for Celestron NexStar 8SE telescope.

Brass mounting brackets mounted on stock focuser retainer plate - Airplanes and Rockets

Brass mounting brackets mounted on stock focuser retainer plate. #2 sheet metal screws used to attach MotoFocus to the brackets.

JMI MotoFocus for C8 adapted for use on the NexStar 8SE - Airplanes and Rockets

JMI MotoFocus for C8 adapted for use on the NexStar 8SE.



Posted October 2, 2012

Model Aviation Magazine, AMA - Airplanes and Rockets