This will enable you to insert and eyepiece between a sony camera's e-mount and the 1.25" eyepiece socket on [designed for] a vintage celestron 8" SCT.
You still need to print the 3 three pieces that make up the actual sony e-mount adapter which
com from the most excellent design of thing 3641973 by vbatusov. all my parts are derived from his originals and just manipulated vertices in maya (dont judge) and then scaled.
print .15 layer height
no supports or rafts
dont be like me -- have black plastic on hand and then use it.
anything lighter than black will most likely need to be painted in order not to let
stray light in.
if you like it let me know -- if you dont -- don't
The white(vanilla) plastic is just what I used for prototyping (also, it was all I had on hand) and is too translucent to function properly. I covered all threads with masking tape and painted a few coats of matte black krylon. I will eventually reprint it in black PLA.
My Celestron 1.25 12.5mm Eyepiece needed an extension to hold it closer to the sensor.
i just electrical taped in the extension and the mounted in the holder
and then into the adapter [which is more for a 40mm eyepiece originally]
using an 8" SCT which is fl=2032 f/10. the eyepiece when inside the cup and atached to the sony a7iii sits approximately 47mm from the sensor. I used this a FL calculator found here:
according to https://starizona.com/tutorial/eyepiece-projection-calculator/
It predicts my new focal length at 5608 f/28.
and using the formulas I found here:
( 47mm - 12.5 ) / 12.5 = 2.76x larger
eye piece goes in the adapter.
cup threads on over adapter.
you may need to put an extension tube on an eyepiece with greater magnifications shown here on a 12.5mm
first attempt using a less than desirable 12MP camera