Dedicated to my Canon EF 50 mm f/1.8 IS II lens, that by the price of its life saved my camera.

Purpose

Theoretical purpose was to get an eyepiece with a big exit pupil (relatively to my other eyepieces).

Materials

Broken Canon EF 50mm f/1.8 Lens

Barlow lens x2 from the telescope kit

Black paper

Sellotape or scotch tape

Step 1 : Disassemble 50mm lens

The first of all we need to disassemble lens to obtain 50mm doublet (as far as I remember the optical scheme service manual for these lens).

Step 2 : Disassemble Barlow lens

As you probably read in review to my telescope (https://suddenastronomy.wordpress.com/2019/09/02/my-meade-polaris-90-900-review/), kit Barlow lens are pretty much useless because of the quality. What do we want is use the metal part of it to make lens attachable to telescope.

Step 3 : Assemble eyepiece

Now we need to assemble all parts together.

Black paper is needed to make a kind of spacer between eye and lens.

When I tried for the first to watch into it I saw nothing. The point is that there is a proper distance when image seen through it has maximum field of view.

Step 4 : Use the eyepiece

Results:

Eyepiece has pretty narrow field of view ~1deg, that is almost the same as my 26mm kit eyepiece and 20mm Gloldline eyepiece (apparent field of view 66deg)

As for the brightness it is pretty bright and I was able to observe Andromeda Galaxy very easy



