"Lurking Luser" wrote in message k.net...
Centro de Observação Astronómica no Algarve has a little program to make
diffraction gratings with a home printer. But it has some limitations. First
the resolution is maxed at 720 dpi and second the pattern is round wasting a
large amount of the transparency.

So I have several question for the group.

1. Is the idea feasible?
2. Is 1200 dpi achievable or even desirable?
3. Would I be better off use 600 etching per inch in both quality and
defraction of starlight?
4. Are you better of putting the grating at the eyepiece or the objective?
5. Is there a simple way or producing this pattern in PhotoShop?

Thanks in advance and clear skies,
James King

A good diffraction grating could be done by using spider's web:
Here are a few tips:
1. find a good old spider who does not mind to share
2. do not use strands that made for catching flys, but that used by
spider for walking on
3. do not try to put the strands parallel - it is almost imposible by
counting the diamer of it ~2.5mk, but put one after other and remove
each second later!

Of coarse it is hell of work and if it is too difficult, the rest of
the web could be used for cross-hair for eyepiece.
(-:
Regards, Yuri