To: atm{at}shore.net
From: "Matthew L. Brown" 
Reply-To: "Matthew L. Brown" 



>Marco,

  I'm no expert, but my dog-eared copy of Sam Brown's "All About
Telescopes"
  http://www.telescope.com/jump.jsp?itemType=PRODUCT&itemID=462
has a couple of nice chapters on astrophotography.  There are 4 basic
methods: A) direct from objective to film (no eyepiece nor camera lens) --
this is simplest
B) Afocal: focus eyepiece by eye and set camera to infinity focus: works
well with autofocus cameras
C) Projection with a positive lens where the eyepiece goes and no camera lens: can
  easily multiply effective focal length 5x
D) Projection with a negative lens closer to the objective than an eyepiece
(like a Barlow) and no camera lens: multiplies EFL like C but more compact

Your problem is making precise focus, and for this, I suspect, your best
bet will be to mark your focus tube and take several test photos and be
very repeatable thereafter.

Note all methods other than B do not use the camera lens, so you may be
able to make use of an inexpensive SLR camera body without a lens at a
rummage sale.  In the end this might be cheaper than all the ruined test
photos.

=Matt


>Hello all.
>
>Strictly speaking this is not a scope making question, but I would
>really appreciate some help.
>
>I would like to take some shots of the moon with some sort of lash up
>in front of the eyepiece of my scope.(8.75in F5.7). The thing is I have
>old Rollei 35mm camera (not SLR) which has a manual focus adjustment.
>It also has manual shutter speed and aperature settings. Also the aperture
>looks like
>it opens to about 12mm. I think the lens is an F3.5   40mm.
>The problem is I do not know where to set the focus, and aperture to take
>the shot.
>Do I set the camera at infinity, or at the f.l. of the mirror (about 4ft),
>or at the closest focus possible?
>
>I am presuming that I must first focus the scope to have a sharp image and
>that the camera be as close to the eyepiece as possible.
>
>Incidentally my eyepieces are 8mm, 26mm, 40mm plossls.
>
>Thank you
>
>Marco Miglionico
>
>www.geocities.com/telescopiman

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