StubScope - 70mm Telescope with 2" Crayford Focuser

by StubMandrel Aug 15, 2018
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Oops! Should have posted that as a reply...

Good evening.

Everything are printed and assembled but I am unable to have a good fous.

I only have Omegon K10mm and K 25 mm in 1,25 inches.

Which are the good oculars for the Stubscope?

Looks like my reply disappeared, sorry!

Make sure the lens is the right way around, the groove around the lens should be closest to the face of the lens at the FRONT of the scope. The full moon is great target for testing things out.

Check the focal length of the lens by using it to project a distant light/scene on a shaded wall. you need to be able to focus the shoulder of the eyepiece both closer and further away than this. If you can't you may need to adjust the tube length.
10mm and 25mm will be fine but something like 6mm might work well for higher magnification. This is a good scope for larger objects like the moon, andromeda galaxy and wandering through the milky way in Cygnus, Cassiopiea and Perseus.

You can use very short eyepieces for smaller objects. I would suggest 4mm is probably as short as you want to go, or use a 2x or 3x barlow with your 10mm eyepiece for more comfortable viewing.


Prints are finished!!!

What is the thickness of the teflon square?

Excellent, my teflon was only about 2mm thick. you could use a bit thicker.

You didn't have problems to print with overhang without support for scope baffle and lens cell?

No, if you print them in the correct orientation (lens cell big end down, baffle small end down) they will not need support.


You talk about dewshield, but no file is named dewshield.
Which is the dewshield file?

Sorry! The Dewshield is in one piece with the lens cell.

After some feedback I have modified the baffle so that it isn't so narrow, it now has fewer steps and is a little shorter as well as being wider at the open end.

A test on the moon last night gave lovely views but as it is short focal length the moon did not fill the field of view.

Why don't you print the main tube?

Only because I had a suitable aluminium tube already. Same with the 2" to 1.25" adaptor.

In fact, all the bits were chosen from things I had 'in stock' already. If I make a second I will probably print the tube and maybe just use a 1.25" focuser.

I'd also add a place for an M6 screw to act as a focus lock.

Thank you for quick reply.

If I can I must print a tube of 76 mm outer diameter and 70 mm inner diameter with a total length of 204,1 mm (With the lens you recommend)?

Thank you for quick reply.

Another question : If I can I must print a tube of 76 mm outer diameter and 70 mm inner diameter with a total length of 204,1 mm (With the lens you recommend)? Is it OK?

In principle yes, but lenses vary, I would experiment using a cardboard tube first to get the right length.


Great design.
Is this lens to order?

Achromatic lens, coated, bi-convex
Diameter: 70.0 mm
Focal length: +280.1 mm

N° 566OAL at 15,96 pounds?

That's the one!