Lunt 1.25" Diagonal Blocking Filter Shorty Conversion Kit for Imaging and Barlows

Lunt 1.25" Diagonal Blocking Filter Shorty Conversion Kit for Imaging and Barlows

3d printable eyepiece cup and eyepiece extension for the Lunt Solar Systems diagonal blocking filters.  

I recently acquired a Lunt LS50THa hydrogen alpha telescope with a B600 diagonal blocking filter, and was disappointed to find that the range of travel on the focuser was so limited that not only was imaging impossible, my inline barlow lenses couldn't even achieve focus.  Upon analysis, the only place that I could find to reasonably remove distance was in the T2 mount attachments on the blocking filter.  I initially set out to find pieces on amazon to shorten the optical path, but I couldn't find any 1.25" inserts with female T2 threads and the shortest eyepiece cup that I could find only shortened the path by 11mm.

So, an idea was born.

I created the shallow eyepiece cup as the primary component, which shortens the optical train by up to 16mm, depending on the depth of your eyepiece/barlow.  If needed, the forward extension can eliminate another 2mm of optical path. The eyepiece cup is designed to use the same compression band and thumbscrews as the original Lunt eyepiece cup.  The forward extension requires the use of an eyepiece 1.25" aluminum extension.  I chose to do this for reliability.  I have confirmed compatibility with the extension from the Celestron universal T adapter and several Meade plossl eyepieces.  Other eyepiece extensions may work, but I haven't tested them.

Recommended Material:

PLA Pro is an absolute minimum. Given that these are intended for use on a solar telescope, ASA or PA is preferred. If you plan to use these for imaging, ASA-GF, PA12-CF, PA12-GF, PC-CF, or PC-GF with proper annealing is STRONGLY RECOMMENDED for maximum stiffness.

Recommended Print Settings:

• 0.16mm layer height
• No Supports
• 5 Top/Bottom layers
• 5 Walls
• 99% Concentric infill

Notes:

These files are shared under Creative Commons – Non-Commercial – Attribution.   Print and use at your own risk. CVA Buck assumes no risk or liability for the use or misuse of the files.

If you use and enjoy this kit, please consider buying me a coffee: https://www.buymeacoffee.com/cvabuck