Astrophotography with the SF1
As already described in the SF1 section, the mount is a bit too small for focal
photography through the big Starfinder OTA. This is primarily due to the
mounting straps which hold the OTA on the wedge.
The SF1 doesn't have a standard prism mounting system. That's not too bad
because therefore You can build Your own adaptions without almost any costs!
The wedge, made of Aluminium, can easily be machined by a handy electric
drill. You should drill four holes as seen below:
The distance of these four holes should match the holes in metal mounting plates which You
can buy in any store for carpenter's needs.
This plate will be tightened with four winged screws. The wedge with the rounded scope bearings
is ideal for this because it ensures a stable position of this plate and keeps distance to the wedge
so that You can fix any scope onto it:
Here the same seen in side view:
This gives a good base for mounting the tube rings of, e.g., my 5-inch Newtonian:
On these rings, I fixed a ledge of Aluminium with two more holes holding
the guide scope ring:
Here You can see both, the rings for the Newtonian and the one for the guiding scope:
Equipped with both scopes, it looks the following way:
In my case, the upper refractor (d=70mm/f=700mm) is the focal instrument. This is, because
with the Newtonian (d=130mm/f=900mm) I don't reach the focus without a barlow lens.
So I take the Newtonian as the guiding scope.
With this setup, I could get
photos with 15 minutes and longer exposure times. The mount really doesn't see
those two scopes on it's back! You don't need any counterweight for these totally
5kgs! (5" Newtonian, 3" refractor and camera).