After doing considerable testing with my Kendrick's SCT collimator I
have some mixed impressions with the complete workings of the collimator.
I have tested the unit with 5 different scopes and 3 times on my own. I
used a flashlight with a precision hole drilled with a number 78 bit into
4 thousands brass shim stock. The shim w/hole was mounted to a large
washer and taped to the flashlight. A target made from white cardboard
tape to the washer and concentric alignment rings drawn with a compass to
help center the halo or what I call "the meatball". I tested scope sizes
of 8, 10 and 12 inch model LX-200's. The 12" tested with a f/6.3 reducer
which caused a large blob on the wedge angle of the laser but retained
the alignment when removed and it left a smaller blob return to the wedge
plus moved it very close to the center opening where the laser beam
exits.
Alignments went pretty well on all scopes and I found my problem with
the changes induced by a guider rings set which was causing a torsion
between its forward and rear cell mountings. This was easily corrected
and most should not have this problem............the plus side of the
laser is it showed this problem, Jim Kendrick thought it might be caused
from the forks and heavy weights on the OTA but other scopes with similar
weights didn't show this problems. Balance would be important when
collimating with the laser. Another plus side of the laser is the use of
the artificial star and target and the laser will improve any small
alignment errors over doing the standard collimation, like the one in the
Meade manual. On all the test I used the Hartmann Mask (Kendrick's) to
check alignment by seeing if the out of focus stars comes together at the
same time, this was done before and after collimation to see if an
improvement was made. All the 8" scopes showed improvements.
I think using the Hartmann Mask and flashlight target will give you the
same results as using the laser but would take considerable longer to do
so. The laser spot that returns to the wedge of the laser on my scope
hits directly center of the laser which makes it impossible to place the
paper spot. I did notice on the other scopes tested that the return laser
spot to the wedge showed a small inner spot less than 3/16". I guess this
is what you would use to check and realign the collimation after you get
the best results from doing the target alignment. The instructions says
that after the first alignment the target./artificial star is no longer
needed but I could not see how this worked considering I couldn't put the
paper spot on the wedge of the laser. Maybe some of the others on this
list could give me some ideas plus..............what do they see on the
return laser spot??? Do you see the small inner dot of the laser on the
wedge????

ric
OPTAS President
San Marcos, California
OPTAS website http://members.aol.com/rlecker/optas.html

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