The equatorially mounted Starfinders


In my opinion, the equatorially mounted Starfinders are the most interesting memebers
of this family, because they combine the possibilities which come with a rock solid
German equatorial mount and the optical possibilities of splendid aperture of not less
then 6 inches! And all this for an affordable and reasonable price!
The SF1 is dimensioned to carry the 10-inch tube with 1140mm (45inches) focal length
(1150mm tube length and 34cm tube diameter) without any problems. The 8- and 6-inch
tubes should be carried with additional equipment!
My own SF1 carries a 130/900-Newtonian and a 70/700-Refractor for photographic purpose
with ease, for this equipment, the counterweight wich came with hte 10-inch tube is
definitely too heavy, also, if it is in the innermoust position of the Dec-Axis! On the other
hand, the 10-inch tube with a guider-scope would only be applicable under the condition
of absolutely no wind! More about this in the section Astro Photography.

The outfit

The Starfinders EQ come with the mount including a quartz controlled tracking
motor and the matched counterweight. They also have an achromatic 6x30mm-
finderscope in two three-point-bearings which can be very well adjusted. The
finderscope's crosshair is quite thick which looks a bit strong at the first glance.
However, in practical use, the thick crosshair is quite obvious even under dark
skies, a real advantage over finders with thin crosshairs. The finder can be
focussed.
The primary mirror is, of course, a real parabolic mirror, not only a spherical one.
The over all quality of the Starfinder mirrors is quite good, I have never heard of
a bad one. They're made of Pyrex, not plate-glass, so that thermal expansion
isn't of any significance. The Aluminium lies under a quartz coating.
The mirror cell is an open one machined from aluminium so that the mirror
can come to a thermal equilibrium in quite a short time. The 6-, 8- and 10-inch
mirrors have a three point cell, the much bigger 16 inch has a nine-point mirror cell.
The mirror cell can be adjusted very precisely due to extremely massive pairs
of screws.
The secondary is fixed with a minimum of obstruction: the mirror is clipped to a
elliptical piece of metal fixed with a four-arm spider made from steel ribbon so
that the spider and vane don't induce any further obstruction.
The only disadvantage is, that the screws for adjusting the secondary are a bit
fumsy to reach. One of them is quite good to reach, the other two are hidden
by the spider's arms, so one must put in the screwdriver a bit obliquely.
The workaround to fix this I did, was to cut a bit of the shorter side of the tool.
The focusser is the worst thing coming with a Starfinder. It is 2inch with a
reduction to 1.25" and T2-winding, but it focusses very rough and unprecisely!
The tolerances of the focuser are, simply spoken, too big, much too big.
The best thing would be, to replace this part by a real focusser.
The 26mm-Superplossl eyepiece, shipped with the Starfinders, is an excellent
eyepiece with very good sharpness to the edge of the visible field, which extends
to 52 degrees. The contrast of this eyepiece is very good and I have never seen
any reflexions in this eyepiece.
In one word, You could say, the Starfinders are quite serious scopes and they are
recommendable. They have their little weaknesses, but not more than any other
scope of any other manufacturer would have.