Homemade eyepieces, finder scope, and other misc accessories
 

On this page you can find instructions and ideas on how to make telescope eyepieces, finder scopes and other misc accessories.
A great source of inexpensive, surplus optics is Surplus Shed

7x50 finder scope for 12$

Parts needed

This is a 51 mm diameter, 180 mm focal length , achromatic objective lens. Cost : 6$


Originally  made as a projection lens, it makes a very good 25 mm focal length eyepiece. Cost: 5$


A scrap piece of 50 mm PVC tubing (drainpipe) about 20 cm long, and a 50 -> 32 mm reduction fitting  Cost: 1$

The lens body has an outer diameter of 25 mm. To convert it to a standard 1.1/4" eyepiece size, cut a cardboard strip, and glue it around the bottom (widest) part of the lens. Take a Kodak film canister, and cut of the bottom . Now put the lens inside the film canister.

This lens is also good as a telescope eyepiece. If you have a smaller telescope with a 0.96" focuser, you can use this lens as a primary eyepiece. A minute with fine sandpaper on the focuser inside, and it will fit perfectly. Optically, it is by far superior to the usual H20 plastic lenses eyepiece, originally received with the telescope.


 		 To assemble the finder scope, first measure the length of the 50>32 mm fitting with the eyepiece lens inside.
Leave 5 mm spare, for fine focus.
Total length of the finder scope for focus at infinity should be 218 mm, from objective lens, to eyepiece end, so cut the 50 mm tube accordingly.
Connect the plastic tubes, paint the inside flat black, and the outside in any color you please :)

You can fasten the objective lens at the front by simply winding a few turns of electricians tape around the lens edge and tube.

The finished finder scope mounted on the telescope. You can fine focus the finder scope by moving the eyepiece inwards or outwards inside the 32 mm tube. This is usually referred to as a draw tube focuser.


Illuminated finder scope

Can't see the black crosshairs against the dark background of space? A ready made illuminated finder is too expencive?
All you need is a 3$ reticule, a LED, 2 AAA batteries, and some electronic components from the "junk bin"
Even just two hairs instead of the reticule will work perfectly

26 mm super Plössl eyepiece

This is the "26 mm SuperPlössl eyepiece kit" from Surplus Shed  Cost is 6.5$
They are in "like new" condition and make a great eyepiece for very little money

Materials needed :
 

26 mm SuperPlössl eyepiece kit
32 mm PPR fitting
2 Kodak film canisters, black electricians tape, superglue
This is a 32 mm PPR water pipe fitting. The inside diameter is 30 mm, and it needs to be bored to 1-1/4" (32 mm) A Forstner bit is ideal for this. It can also easily be done on a lathe if you have access to one.

The felt pads are temporary, they are used not to scratch the PPR fitting in a vice or lathe while drilling.

With a sharp utility knife , we cut off the upper rim of the film canister (around 5 mm), and a 30 mm piece.
The bottom is discarded. These will make lens holders.

On the second canister we cut out a 40 mm middle section. The rest is discarded. This will be the eyepiece barrel.
If you want a nice, metal, filter threaded barrel, you can order one here for 4$
   

Conveniently enough, the achromatic lenses fit perfectly inside the film canister, and the film canister fits perfectly inside the PPR fitting Use the 30 mm canister section and place the achromatic lenses (thick ones) inside......

...then put the canister part with the lenses inside the PPR fitting. Use some electricians tape for a snug fit if necessary......

..now put the eye lens (single lens) on top, with the flatter side turned upwards, then add the top part of the film canister as a lens retainer. Use a drop of superglue on the upper rim of the canister. Now, insert the 40 mm , barrel section on the bottom side, use electricians tape and a drop of superglue to secure. Done :)

 Lenses orientation in the
"26 mm SuperPlössl" eyepiece

 

 

This eyepiece has a generous eye relief of aprox 20 mm and has aprox 55°apparent field of view

19 mm Plössl eyepiece



Even simpler is the 19 mm Plossl eyepiece kit .
It costs 5.50$

Lenses orientation in the 19 mm Plossl eyepiece.

Cut a 5 cm strip of black electricians tape, put it on the desk with the adhesive surface facing upwards.

Roll the 2 lenses over the tape and it winds itself around. Put the lenses in the PPR fitting. Plug the fitting into a Kodak film canister with the bottom cut off. Done :)

In addition to the lenses you receive from Surplus Shed you only need a 20->25 mm PPR fitting adapter, a Kodak film canister, and a bit of black electricians tape.


The finished 19 mm Plossl. It has around 50° apparent field of view, and about 12 mm of eye relief. Sharp images!

©  1999-2005 Berislav Bracun
Amateur telescope making, star charts, planisphere, astronomy software, eyepieces,  findescopes, observing accessories