Homemade or modified eyepieces
and enhance or improve original eyepieces

 
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Improve 3X Barlow
Homemade Barlow
Improve 0.96" eyepieces
Make eyepiece of a camera
Make eyepiece of binocular
Build erecting eyepiece
Make 1.25" to 0.96" adapter
Homemade collimating cap

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0.96" cheap eyepieces

Improve 3X Barlow lens

It is a precision multi-lens all-glass optical system, just as an eyepiece is, and can actually improve the performance of many eyepieces.
However, the Barlow lens that cheap department-store or toy-store telescopes are terrible: uncoated lenses, shiny on the inside, the chrome part of the eyepiece also chrome inside! Also, the entire tube was shiny black plastic. Completely useless.
We can not change the lens, however we can remove all the shimmer hence lens edges, the tube and internal field stops can be blackened to reduce internal reflections and improve contrast.

  • Unscrew the barlow lens and use sandpaper on the inside (both sides). Make circular (like threading) movements or random, but never strait lines (from top to bottom). Be very careful that you do not thouch the lens!!
  • spray or paint the inside flat mat black. Do not forget the chrome part on the inside too!
  • Next, we need a baffle to reduce the glare even further. Unscrew the both parts of the Barlow and you'll see a little rim.
    That's the place we will put our baffle. I used a plastic ring and drilled a hole in the center of 10 mm. Paint it flat black on both sides and glue it against the rim.

  • Re-fit the Barlow.

Homemade: Make a 2X Barlow lens out of a 3X Barlow

A 3X Barlow is way to much for those cheap department-store telescopes. Building our own 2X Barlow lens and reducing the default magnification of a 3X Barlow is rather simple and will make it more useful (less blur, more contrast, shorter length and so easier to use on refractors). It will provide sharper images.
Prior to the type of lens used the magnification of a Barlow lens mainly depends on the distance of that lens to the eyepiece. So, to modify the Barlow is easy:

  • You need to do the same modification as stated above to remove the shiny interior.
  • We don't need the top part of the Barlow lens (where you put the eyepiece), but do not throw it away! Further in the text we will see how to use that part as a 0.96 inch eyepiece converter for a 1.25" telescope focuser. We gonna use the bottom part (where the lens is fitted).
  • Next, we need a baffle to reduce the glare even further. Lens edges and internal field stops are blackened to reduce internal reflections and improve contrast.
    You can make the baffle out of whatever you have around that fits the inside of the Barlow (+/- ...mm). I made the baffle out of a tiny piece of 5/8" PVC pipe and some double-sided adhesive tape. Saw about 5 mm of the 5/8" pvc tube. Then stick the tape in two layers on top of each other on the pvc-tube. Remove the adhesive around the baffle (else it will be virtual impossible to get it 1/3 inside the bottom part of the Barlow lens.
    Now paint the baffle mat black.
  • The outside of the bottom part of the Barlow lens is threaded. Ideal to screw our eyepiece holder onto it. So we need some PVC tube that nearly fits the thread with an inside diameter of 0.96" to fit the eyepiece. These are the measurements of the homemade/modified Barlow:

  • Finished "shorty" modify 2X Barlow

Improve old 0.96" eyepieces

There are many ways to improve the original eyepieces without buying new ones or replacing the focuser to allow fitting 1,25" eyepieces (Plösll are real good for their money).
Most 0.96" eyepieces that came with those cheap department-store or toy-store telescopes are terrible: shiny on the inside, the chrome part of the eyepiece also chrome inside, often plastic lenses etc.!
First and easiest thing we can do is to remove all internal reflections inside the eyepieces themself and (if needed) clean the lenses as well (read about it
here). None of those eyepieces I saw had any baffling or are even lacking flat black mat paint! Shiny black plastic isn't all that dark! Just keep it in the light, straight or under an angle, and you will clearly see the reflections. Any reflections are loss of light and can cause ghosting and glimmer. So get some matt black paint and paint the inside of the eyepiece (be careful not to touch the lenses!). The contrast will improve and reduce ghosting and glimmer. It will greatly improve observer comfort by minimising glare and providing sharper images.
0.96" eyepiece with the lenses removed to clean and to paint everything flat mat black. To clean the lens of your eyepiece you need to take care of a few things which you can read all about it
here.


1.25" eyepieces

Homemade 25mm eyepiece out of an old camera

I had an old (defective) analog film camera from where I removed the lens pieces. There was a wide angle lens combination (8mm-22mm) fully coated in it. Ideal to make myself a wide view 25mm eyepiece for my SkyWatcher telescope.


  • Get yourself a plastic 35mm film canister (black with gray lid and one with the black lid).

  • We will be using the 35mm film canister with the gray lid as the eyepiece holder

  • and the top of a second 35mm film canister with black top to use as a cover from where the lens will peep through.

  • We'll also need a piece of metal tube that fits inside the film canister. This will make it strong enough (of course you can use any other PVC tubing that fits your needs).
  • Paint the inside of the cansiter and the metal tube black or flock it.
  • Glue the metal tube inside the film cansiter.
  • Cut the bottom of the film canister (the one that had the gray lid on it)

  • Cut or drill a hole in the cover of the cover of the black covered 35mm canister so it will fit the smallest part of the film camera lens.

  • We mount the lenses in a way that the smaller part of "peeps through" the back film canister hole.


Make a eyepiece out of binocular lens

  • I had a cheap 10$ binocular which I had no use for...except...to experiment with the pieces for homemade eyepieces!
    This 12x25 binocular has achromatic lenses, coated eyepiece lenses and two erecting prisms.
  • So lets make an 10mm eyepiece from thbinocular eyepiece
    Tip: you can even keep the erecting prism if you want upright images. The roof prism design employs silvered surfaces that reduce light transmission by 12% to 15%. The prism does create light loss and some less contrast.
  • The binocular with the eyepiece removed which also clearly shows the roof prism.
  • The old 35mm film canister comes in place (again). To give it more strength I used some metal pipe that fits snuggly inside. "Luckely" the binocular eyepiece fits the cansister perfectly. You can also modify the eyepiece to be used in those old 0.96 eyepiece telescopes too. Much better then the cheap plastic lenses that they often sell together with those cheap department store telescopes.

Make an erecting eyepiece out of the prism of a binocular

  • The prisms of this (same) binocular are ideal for making a rectifying eyepiece (puts everything right side up, like a diagonal).
    We need a 1,25 " diameter PVC tube and a piece of tube that has an inside diameter of 1,25mm (those connection pieces plumbers use to connect two pieces of tube together).
    The smaller part fits into the focusser and holds the prism. The larger tub fits over the smaller one and allows your eyepieces to be inserted.
  • First sand the inside of the two tubes and paint it matt black (or flock it)
  • roof prism mounted in canister This explains clearly how the erecting eyepiece is mounted and constructed from two tubes of PVC and the prism of the binocular.
  • Tip: the prism could also be used in your finder if you want an upright image
  • About the roof prism used here
    A Schmidt-Pechan prism is a type of optical prism used to rotate an image by 180°. They are commonly used in binoculars as an image erecting system.

    The prism consists of two glass prisms separated by an air-gap. Multiple total internal reflections of the light cause a vertical flipping of the image; a "roof" section of the second prism also flips the image laterally, together causing a 180° rotation of the image. The image's handedness is not changed.

    Compared to the double-Porro prism or Abbe-Koenig designs, the Schmidt-Pechan is much more compact. However, the large number of reflections and glass/air transitions of the light make the prism more lossy than the other designs. Some of the surfaces must be optically coated for efficient internal reflection, since the light is incident at an angle less than the critical angle.

Homemade 1.25" to 0.96" eyepiece adapter

Remember that old 0.96" Barlow we modified? Barlow lens
And the top part we didn't need? Well, we need it now to make ourself a homemade 0.96" to 1.25" eyepiece adapter. This will allow you to use your old lenses, barlow and diagonal with your telescope.

Saw the Barlow top to about 28mm in length (not critical) homemade 0.96" eyepiece adapter

You will need to file it down a bit to fit inside your telescope's 1 1/4" eyepiece holder (+/- 31mm), and voila, a 0.96inch eyepiece adapter.


Collimating cap

If you do not know what collimation is then please read this first. In short: Collimating a telescope is lining up its optical components (lenses, mirrors, prisms, eyepieces) in their proper positions.
If you have a cheshire collimation piece then you can skip this...but this is a cheap alternative...not as good, but still...
"collimating cap":
- if your scope has 1,25" eyepieces: out of a plastic 35mm film canister (black with gray lid). Drill or punch a small pinhole (+/- 4mm) in the exact center of the lid and cut off the bottom of the canister. Replace the lid.
- if your scope has 0,96" eyepieces: use an protection lid that came with your scope (like one of your diagonal or the one used to protect the eyepiece holder). This is of transparent material. Drill or punch a small pinhole (+/- 4mm) in the exact center of the lid. Draw a diagonal with a thin black permanent marker.
This device will keep your eye centered of the focuser tube. The next thing to improve things:

More to follow, so please visit again soon.


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