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copyscope by Ron Wagner (GIF for text browsers) |
copyscope by Ron Netzley (GIF for text browsers) |
A copyscope is a refractor built from a surplus photocopier lens. These lenses generally have a short focal length and flat fields. Photocopier lenses are generally found mounted in an aluminum or steel cell. Copycopes similar to those described here, have previously been described in Astronomy magazine, May 1986, page 74 . Stillwater Stargazers members drew from the magazine article for inspiration in building their copyscopes.
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copyscope by Ron Wagner (GIF for text browsers) |
copyscope by Ron Netzley (GIF for text browsers) |
In general, the following parts will be needed to create your working telescope. The telescopes which will be created will perform as a wide field, low magnification instruments. Do not despair, the use of high power is seldom needed in astronomy.
Lenses for copyscopes can be difficult to acquire at times. Although everyone who wanted to build a copyscope in our club was able to find a lens, I have personally not seen any lenses recently. The good news is that the original supplier mentioned in the Astronomy magazine article is still in business (although they've changed their name). URL and addresses will be given later.
The selection of a lens for this project is best undertaken with knowledge
of the entire project. The use of PVC pipe and fittings to create the telescope
lends itself to knowledge of PVC sizes. If you acquire a lens which does
not fit into standard PVC fittings, it will be more difficult to create your
copyscope. I went to the local hardware store and measured several PVC fitting
in an attempt to simplify your process.
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4 inch fitting is about 4 1/2 inch inside diameter |
3 inch fitting is about 3 1/2 inch inside diameter |
2 inch fitting is about 2 3/8 inch inside diameter |
To make mounting the lenses easy, find a lens which is just smaller than the inside of a PVC fitting. It the lens is too small for the fitting, wrap the lens with quality duct tapes, or carefully glue paper strips to the cell of the lens with epoxy glue. If your lens is too large for the fittings, you will need to enlarge the fitting. Be careful that you don't weaken your PVC fittings by removing too much plastic while you enlarge the fitting. Again, it is best if you can get a good fit between the lens and the PVC pipe to begin with.
The lens specifications for the project are fairly open. For ease of mounting,
the best lenses will be ones which are mounted in some type of cell. The
focal length and diameter are fairly forgiving, but the f-ratio should be
between 4 and 6 for best results. If the f-ratio is not given, it can be
calculated as follows: Focal length of the lens divided by the diameter of
lens.
Example: 50mm diameter lens, with a 200mm focal length. 200 divided by 50 equals 4. So lens is f4
The last item about the objective lens is, that it should be achromatic.
That is to say, if you are not using a copier lens then your best choice
would be a color corrected (achromatic) lens. With a non-achromatic lens,
you will notice a colored halo around the objects you are looking at. Depending
on the power your copyscope ends up being, this will be anywhere from
unnoticeable to somewhat annoying.
Supplier originally mentioned in the Astronomy magazine article (new name) is:
American Science & Surplus
3605 Howard Street
Skokie, IL 60076
(708) 982-0870
Mention you are looking for optics.
Here is another surplus shop on the net who also has lenses. The address is:
Surplus Shack
407 U.S. Route 222
Blandon, PA 19510
610-926-9226
A Canadian company I found on the web also has had lenses. The address is:
Gnome Technologies
541 Jarvis Avenue
Winnipeg Manitoba Canada
R2W-3B2
(204) 586-1604
I have no personal knowledge of the above mentioned companies, use your own good judgment.
There is a very large surplus dealer close to Troy, Ohio. I have done walk in business there often. At time they have lenses. The address is:
Mendelson Electronic Company Inc.
340 E First St.
Dayton, Ohio 45402
937-461-3525
I am not endorsing MECI, nor do I have any connection with them. Use your own good judgment when dealing with surplus dealers.
A source, which should not be overlooked, is you local eyewear shop. The lenses are often available to be purchased if you know what to ask for. I will elaborate further on this subject after I again touch base with the local shop where I live. I have purchased lenses from my local shop before, but I need to get the correct "jargon" down. When I get it all together I will add it to this page. A disadvantage with these lenses is that they will almost always show some color abrasions. On the other hand, they are substantially lighter, easier to acquire, and often cheaper then copier lenses.
The process of assembling your copyscope includes mating the lens with the PVC fittings. This is basically different for each copyscope built. Some general guidelines include:
Assemble your parts on a table without the PVC pipe to get and idea how long your scope needs to be. This can be a bit tricky, but will assist in knowing what lengths of PVC to buy.
Measure and write down your layout, and head to the store to buy the PVC fittings. Take your lens with you, so that you can "fit it up".
If you are using a diagonal, take it with you as well. Use it to find the correct 1 1/4 inch adaptor.
When you arrive home with your parts, begin by laying and fitting the pieces together without glue. In some designs, it may not be necessary to use glue. The scope that I built, has only the lens glued in with a hot glue gun. The rest of the scope is friction fit.
After the fitting stage, you are ready to glue the pieces together. I personally like hot glue guns for this part. Hot glue seems to hold well but is not as permanent, smelly or messy as the PVC cleaner and glue.
Don't get into a hurry during this stage. Glue the objective (front) lens into place (or otherwise affix it to the PVC). Then try assembling all the other pieces. Friction fit the parts and make sure that things are the length they need to be. Make any adjustment to your configuration. Make sure that the entire "system" can be focused with the eyepieces you plan to use.
When you are satisfied that the pieces are correct, glue (or otherwise) connect the remaining pieces.
A difficult part of this project will be mounting the copyscope to a tripod. Most people choose a camera tripod which they may already own. The copyscope will need another "foot" so that it can be quick released as if it was another camera.
Most people will drill a hole in the PVC and run a 1/4-20 tap through the hole to thread it. This hole then becomes the location where the foot is attached. This is the method I personally prefer.
Some copyscopes builders (generally those with heavier lenses) will use hose clamps (from the automotive or plumbing department) to attach a piece of wood or metal to the copyscope. For the metal, a 1/4-20 thread is tapped and used to attach the scope to the foot. On the wooden ones, a T-nut (I hope this is the correct term) is used for the foot attachment. The top of the T is against the scope, and the tail of the T is pushed through the hole and attaches to the screw of the foot.
Ron Netzley (being a machinist) took still another avenue. Ron took a small square piece of aluminum and cut a grove with a ball end mill. He then drilled and countersunk 2 holes for hex head bolts. The bolts attach into the PVC of the copyscope. A third hole was drilled and tapped to accept the foot from the tripod.
To focus your copyscope you will need to move the eyepiece toward and away from the objective (front) lens. This can be accomplished in a couple of ways. I personally use a diagonal with a set screw. The scope is built so that the eyepieces focus just a little "up" from the bottom of the diagonal. In this way, I can install an eyepiece in the diagonal, and then pull up on it until focused and use the set screw to lock the eyepiece in position.
Another way to focus your copyscope is to push and pull on the 1 1/4 inch pipe reducer (adaptor). The reducer usually has a nylon washer and a plumping pipe nut. The nut can be loosened and the diagonal (or eyepiece it you are not using a diagonal) will slide in and out to achieve focus.
Clear skys, the Stillwater Stargazers.
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