I have not been happy with the focuser on my VC-200L since the day I
received it and I have been examining my options for a couple of months now.

http://www.astroden.com/VC200L_Focuser/Original_Focuser.JPG



Well yesterday I decided to cut it up, I was first going to make a plate for
the back of the scope to attach a modified (shortened) AP 2.7" focuser but
that seemed like a lot of unnecessary work (plus it would have been a
problem to align the focuser and corrector together)



After taking the original focuser apart I figured out I could cut and
machine the housing to accept a AP 2.7" extension tube, which would then
open the door to many possibilities.



I started buy removing the focuser from the OTA and from it removing the
corrector lens and baffle tube

http://www.astroden.com/VC200L_Focuser/Original_Housing.JPG

I then placed the housing in the lathe and began to sawsall the front
section off

http://www.astroden.com/VC200L_Focuser/In_the_lathe.JPG

After getting the front cut off

http://www.astroden.com/VC200L_Focuser/Sawsalled.JPG

I went ahead and machined the face of the cut

http://www.astroden.com/VC200L_Focuser/Seat.JPG

Next step I did was to machine the inside to remove the original pads that
the old draw tube rode on

Unfortunately there are only two of these pads or I would have been able to
thread the inside but instead I had to install 3 - 6x32 set screws to attach
the AP ring

http://www.astroden.com/VC200L_Focuser/internal.JPG

A test fit shows it all seats nicely

http://www.astroden.com/VC200L_Focuser/AP_ext.JPG

Next I masked off the housing and painted the inside flat black

http://www.astroden.com/VC200L_Focuser/Blackened.JPG

A shot of the corrector back in the housing

http://www.astroden.com/VC200L_Focuser/Corrector.JPG

The housing back in the OTA

http://www.astroden.com/VC200L_Focuser/Back.JPG

Here is a shot with the AP compression ring on before I laser aligned it

http://www.astroden.com/VC200L_Focuser/AP_ring.JPG



Next step was to remove the secondary mirror

Before I did I marked the two housings with a pencil so I could align them
again when reinstalled

Also note that there are several washers behind the secondary so don't loose
them.



I placed the laser in the AP compression ring and turned it on with the
secondary removed

Note that the beam is off center to the front spider frame

http://www.astroden.com/VC200L_Focuser/Missaligned.JPG

A couple of tweaks and she is all aligned up

http://www.astroden.com/VC200L_Focuser/Aligned.JPG

With a little cigarette or cigar smoke blown into the OTA you can actually
see the beam to be sure it is dead on

http://www.astroden.com/VC200L_Focuser/Smoked.JPG



Next thing I did was to reinstall the secondary and then moved to the back
of the scope and backed off the push screws of the primary and tightened the
pulls screws so the primary was all the back flat against the rear cell, I
did this so I could collimate the secondary first.



After getting the primary mirror set in place I installed the Starlight
focuser that I will be using

http://www.astroden.com/VC200L_Focuser/Starlight.JPG

With an eyepiece in place I collimated the scope with the three collimation
screws on the secondary, one I was pretty happy with that I finished the
collimation on the primary

I then attached a Canon 20D camera to take a couple of test shots

I started with a quicky of Saturn (not much to look at)

http://www.astroden.com/VC200L_Focuser/Saturn.JPG

I then took a 30 sec shot of Sirius (mount is not aligned very well and
optics were still cooling)

http://www.astroden.com/VC200L_Focuser/Sirius.jpg

After an hour or two I tried Arcturus and the optics looked as though they
had settled down much better

http://www.astroden.com/VC200L_Focuser/Arcturus.jpg



I will get my mount aligned and give the STL-11000 a try to see how it works
out with this new arrangement.



Michael Downing

www.astroden.com <http://www.astroden.com/>







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