The inside focus image of a very bright star at 202X (10 inch Dob/1.83 inch second. f5.9) has pronounced "spikes" which radiate fairly uniformly (but not with exact periodicity) around the disk. The spikes are evident at focus (which is pretty snappy) and diminish as you go outside focus (i.e. the focuser is racked further out from the secondary). There may be around 20 to 40 of these spikes which dance and swirl some with time. They don't look like the air turbulence patterns in the book and they don't look like the roughness patterns. The inner diffraction rings are pretty well defined and contrasty both inside and out of focus though there is a significantly darkened area inside of focus which corresponds well with the secondary obstruction and increases directly with increased obstruction (I hung a roll of masking tape over the secondary bolt for this simple experiment.) If I had to guess (and it is little more than that) could it be that I have a rough outer zone/ rough edge? I looked at the mirror around the edge with a 10X loupe and it looks pretty smooth to my inexperienced eye. Oh yes, the spikes "stick out" of the disk on the inside focus side about 1/4 the angular extent of the disk and the eyepiece is a 7.4 mm Plossl Televue. The mirror was recently purchased from a commercial source.
Since last night I noticed that my eyepiece was very dirty (probably a fingerprint smudge on the surface closest to the eye. Also, the inside of the scope is still not darkened - raw cardboard. For lack of real understanding, I guess I will try a mirror aperture mask. I would like to get an experienced eye to look at the machine and will try to do so.
So doctor(s), can you diagnose over the phone? (and better yet issue perscriptions?) Or is it more like the butler in the library with a rolled edge?
TIA,
Steve