Converting a long focus doublet for AP with a DSLR
Posted: Wed Jun 17, 2020 5:17 pm
Impossible you say?
Impractical, perhaps?
Well you may have a point, but I have an old Celestron f6.3 FRFF in my sock drawer and wanted to see how it might be done.
I also have a C80, circa. mid-1990's, which is a very nice doublet. f11.3 and has a 910mm focal length - a beautiful scope for visual work on planets,DSOs and the moon. It has a newer 2" Crayford Focuser.
Wouldn't it be great to use this scope on an appropriate mount for some astro work?
The goal is to try to create an optical path that could be used forAP .
Problem 1. The Celestron f6.3 is made forSCT usage. Can it be adapted for a Crayford Focuser?
Problem 2. What is the sweet spot for the working length of this focal reducer? Can it be reached?
A1 - I think so, with the right adaptors. I looked to Scopestuff for this.
A2 - The working length may be around 106 mm (total from glass to sensor), but the beauty of the design of this FRFF is that you have some room to play. ~ 36mm of this is taken up within the body of the camera itself. Knowing this and having a few adaptors in hand, empircal testing is possible.
Here is the beginning of what I have put together. This image shows my D90 Nikon, but anyDSLR could be used here, with the right T-fitting.
Camera - t-mount - spacer + spacer - Cf6.3 FRFF - 2" scope insert. The approximate working length of this rig is ~ 100mm. I will need to test to see if I can bring the image to focus and go from there.
910mm reduced to 573mm and f7.2 is interesting... will be fun to see if this theoretical reduction is possible and practical.
Stay tuned as I develop this idea, thanks for reading to the bottom.
Impractical, perhaps?
Well you may have a point, but I have an old Celestron f6.3 FRFF in my sock drawer and wanted to see how it might be done.
I also have a C80, circa. mid-1990's, which is a very nice doublet. f11.3 and has a 910mm focal length - a beautiful scope for visual work on planets,
Wouldn't it be great to use this scope on an appropriate mount for some astro work?
The goal is to try to create an optical path that could be used for
Problem 1. The Celestron f6.3 is made for
Problem 2. What is the sweet spot for the working length of this focal reducer? Can it be reached?
A1 - I think so, with the right adaptors. I looked to Scopestuff for this.
A2 - The working length may be around 106 mm (total from glass to sensor), but the beauty of the design of this FRFF is that you have some room to play. ~ 36mm of this is taken up within the body of the camera itself. Knowing this and having a few adaptors in hand, empircal testing is possible.
Here is the beginning of what I have put together. This image shows my D90 Nikon, but any
Camera - t-mount - spacer + spacer - Cf6.3 FRFF - 2" scope insert. The approximate working length of this rig is ~ 100mm. I will need to test to see if I can bring the image to focus and go from there.
910mm reduced to 573mm and f7.2 is interesting... will be fun to see if this theoretical reduction is possible and practical.
Stay tuned as I develop this idea, thanks for reading to the bottom.