Sun Filter

This is a sun filter for my 10" LX200 using the Baader sun film. Although I do miss the yellow color that I get with the Orion sun filter on the ST80, it makes a very good and very inexpensive filter. You need the following supplies:

Baader sun film 12" x 12"

4 12" wooden embroidery hoops

2 13" x 13" cardboard sheets

double sided scotch tape

wood glue

The Baader sun film can be found through various astronomy sources on the net. The hoops can be found in most craft stores and the rest should be easy to find.

First I glued 3 of the hoops together. That provided a ring of just over 1 inch of depth to slip over the OTA. The 12 inch hoops fit over my 10 inch LX200 very snugly. In my case, I had to cut out a slot through the back 2 hoops to accommodate the rail holding my counterweights. If you do this, make sure the glue is very dry first.

Next I cut holes in the cardboard so that I had 11 inch diameter holes in the middle of each sheet. I placed double sided tape around the hole on one sheet (about 10 1" pieces). I laid the sun film flat on a table and pressed the cardboard with the tape down on top of it - tape side down of course. Then I taped the other piece of cardboard and pressed it to the other side so that the sun film is between the cardboard and the holes in the 2 cardboard sheets line up. You can see on the picture that the film is not tight or stretched. That prevents any stretching that might put pin size holes in the film. There is absolutely no distortion.

Finally I glued the cardboard assembly to the hoops, gluing the 4th hoop to the front (just to help protect that side of the film), and cut the excess film that stuck out around the cardboard. It won't matter if the cardboard is round, square, or whatever.

This may seem too simple but it really is that simple and it makes a very good sun filter. Of course, if your telescope is not the same, you'll need to adjust sizes accordingly. Adapting the techniques shown here, I also built sun filters for my binoculars and a new Meade ETX-70 (to use when I'm stuck in San Antonio).

WARNING: Never look at the sun and never point a telescope at the sun unless both the scope and finder scope have filters or caps on them. Always check a sun filter before using it. Look for pinholes of light coming through the filter. If you see any, do not use that filter.

Sun Finder

Even though I use a pier, I usually don't have my alignment exact enough for the LX200 to find the sun and put it in the eyepiece without doing a 2 star alignment. So I need a method that will allow me to guide the scope to the sun. This easy-to-make sun finder will do that. I remember that when I made my first one, I got the idea out of one of the astronomy magazines, so the credit goes in that direction. Be sure to look at the pictures so that the instructions will make sense. All you need for this is:

2 toilet paper or paper towel rolls 4 to 6 inches long

1 very small piece of plain paper

1 small piece of something transparent

glue

If you put 3 straight tubes together so that each is resting along the other 2, then all 3 tubes will be pointing in exactly the same direction, whether or not the 3 tubes have the same diameters. That is the principle in effect here.

First take the 2 cardboard tubes and bunch them together against a 3rd tube - your scope, another cardboard tube, or whatever you can find that will fit the requirement. See how they all come together. Now run a line of glue alongside one of the tubes, from front to back in a straight line. Put the 3 tubes back together so that the glue line is up against the 2nd cardboard tube, gluing the 2 tubes together. Hold the 3 together with a rubber band or something until the glue dries.

Now glue the plain paper to one end of one of the cardboard tubes. If one tube is slightly longer than the other, it will be easier to trim the excess paper. As you guessed, after the glue dries, cut the excess paper around the tube. See the pictures.

Now, to the other end of the same tube, glue the transparent material. On the sunfinder pictured by itself, that material is a piece of overhead transparency. On the other sunfinder pictured on the scope, it is a piece of plastic packaging material. After the glue dries, trim the excess and set the tube assembly on top of the 3rd tube just as if the 3rd tube was your telescope. Use the same orientation that you will use in practice. Now draw a cross across the very middle of the transparent material, as in the pictures.

Now you need to put the assembly on your scope and point it at the sun. Make sure that the sun finder is in the same orientation as when you marked the cross and make sure that the cross end is toward the sun. The sunfinder won't be any help to you this time so you'll need to find the sun the hard way, using shadows, trial and error, whichever way you can without damaging your eyes. When you have the sun lined up in the eyepiece (through the sun filter of course), you will notice that the cross is casting a shadow onto the plain paper at the back of the tube assembly. Check and make sure the sun is still in the eyepiece and then draw a cross on the paper overlaying the shadow of the cross from the front.

Now you have a working sunfinder. The next time you need to find the sun, just guide the scope until the cross on the back of the sunfinder overlays the shadow from the cross in the front. The sun should be in the eyepiece. Make sure that you always use it in the same orientation, meaning always on the top center of the scope, always on the side in the same place, whatever way you want to use it as long as that orientation is the same as when you drew the crosses. It should work every time and it's a quick way to find the sun.

Accessory Rail

Here's an easy to make accessory rail. This started out as a mistake. I purchased the Meade piggy-back camera mount with the intention of using it for a larger finder/guide scope. While the mount may be just fine for a small camera, it is not adjustable, it is too light-weight for larger uses, and it put the ST80 too far back which interfered with my head when trying to look through the LX200. The accessory rail that I made to use with the camera mount, though, has worked out very well. All you need to build one yourself (in addition to the camera mount) is:

1 6" x 1 1/2" x 1/8" aluminum plate

1 flat-headed bolt about 1 1/2" long

1 matching nut

1 matching wingnut

1 Teflon coaster

epoxy

To start off, you need to force the camera mount to point slightly downward at the front. I did this by folding up some aluminum foil to 6 thicknesses and placing it under the camera mount just behind the mount bolts (toward the back of the OTA).

Take the aluminum plate (which can be longer than 6 inches if you desire) and drill some 5/16" or 3/8" holes in it. Drill one hole about 1" and centered from the end of the plate. This end will attach to the camera mount. At the other end of the plate, drill a hole close to the end. This is the end where the bolt will be used. Also drill 2 or more holes in the plate to use for mounting your accessories.

Epoxy the nut to one side of the hole that you drilled at the end of the plate. Make sure that the bolt can still screw through the nut and the hole. While you have the epoxy out, use it to glue the wingnut on the bolt about halfway down the threads. When the epoxy dries, you will be able to turn the bolt using the wingnut into and out of the nut on the plate.

Now you need to scruff the top surface of the camera mount and the bottom surface of the aluminum plate (the same side that has the nut) around the first hole you drilled. This will provide a set of binding surfaces that will not allow the plate to turn on the camera mount when the mount screw is tightened. When you attach the plate to the mount, you will notice that the plate points slightly downward toward the front of the scope, due to that aluminum foil that was used under the mount. Turning the bolt at the front of the plate, you can raise and lower the angle of the plate. I use the Teflon coaster under the bolt head to protect the surface of the OTA. This assembly creates a structure that is sufficiently rigid and stable for the ST80.

Scope Rings

The rail shown before still did not have the adjustability to align the ST80 with the LX200. I needed a pair of scope rings. Searching the magazines and the internet, I found some but not with a price that I was willing to pay. Again, my father came to the rescue. He would make the rings if I just gave him the dimensions and instructions.

Fortunately as you can see, my father corrected for the minor mistakes in the drawing, like centering the holes at the top and bottom of the rings. There are several ways to put threads in the rings for the screws, inset nuts like in my drawing, insert threaded tubes into larger holes, or even thread the wood itself. Any of these will work as the pressure on the screws will always be light.

Since the nylon screws I got had flat heads and were hard to turn without cutting my fingers, I also got nylon nuts and screwed them up all the way to the screws heads, making them tight. It is much easier to turn the screws and adjust the ST80 this way. The combination of the rail and the rings has made an excellent base on which to mount the ST80.