Guider 2 Lecture - Mechanical Implementation an Setup.

For this lecture, I've created a GIF format drawing, GUIDER.GIF
to further illustrate the optical layout of this new tracking
system.  

Mechanical Implementation.

To fully use the Arizona On/Off Axis guiding system, the small
guiding mirror was made two axis adjustable.  A thin bar of
aluminum was epoxied to one end of the mirror on the back
unaluminised surface, and protrudes on each side slightly.  Then
two 4-40 allen head cap screws with epoxy dipped tips were
installed on the protruding bar portions for tilt adjustment.  A
small drop of epoxy on the opposite end of the back of the mirror
acts like a ball pivot.  This three point system is then
installed on the main diagonal in about the center, and held in
place with two rubber bands stretched around it and the main
diagonal.  

Several phenolic pieces with "V" grooves are epoxied to the
extreme outside ends of both diagonals to keep the rubber bands
from slipping off and maintain the proper tension.  To prevent
any lateral or side movement in the small mirror, two tiny steel
flat washers are epoxied to the surface of the main diagonal
itself, centering the 4-40 adjust screw tips within them.  The
small diagonal completely installed reflects light to the second
focuser next to the main one.  

A slide focuser is all that is needed for the second guiding
focuser.  It performs its task with a minimum of expense and
flexure.  The angle of this focuser, some three inches from the
main focuser in which the camera is attached was determined by
looking through it with no eyepiece installed and adjusting the
tilt such that the small guiding mirror is centered up in it. 
This also collimates the guiding system, and is now ready for
use.

The System In Actual Use.

When we are scanning the skies in the normal visual mode, and
desire to photograph what we see, the small diagonal is clipped
in and secured with two heavy duty rubber bands.  (astronomical
quality)  The camera is installed next, carefully focused and
rotated to compose the field in the most pleasing fashion.  With
a low power ocular inserted into the guider focuser, the area
around the subject is then inspected for potential guide star
candidates.  Scanning all around the subject is possible by
carefully reaching in and turning the adjust screws on the second
small guiding diagonal.  We have found that unlike conventional
off axis guiders where guiding on the subject is impossible and
locating easy guide stars is always a problem without highly
decentering the subject, we are now faced with a new absurd
problem:  Which one of the dozens of bright guide stars do we
choose from!  It has never taken us any longer than about two to
three minutes with this system to select a suitable bright guide
star, and we don't have to worry about decentering the subject in
the camera field to center the guide star.  

Once a suitable star is "dialed up", ( Pierre wanted to call this
system the "Picadilly guider", since it allows you to Pick - a -
dilly of a guide star...)  a 2x barlow and 12mm dual red reticle
eyepice is installed, and the rest is routine.  We are strong
advocates of using red illumination on the cross hair to keep the
contrast high between the guidestar and the lines.  

The Final Results.

Since we have been using this system to guide for the past half
dozen years, the ratio of excellently tracked shots has
escallated remarkably.  With normal off axis guiders or flexure
prone seperate guide scopes our success rate for perfect tracking
was about 25 %.  With the new Picadilly guider, tracking leaped
to nearly 95 percent perfection.  with the addition of a cable
controlled shutter in the main camera focuser to shut off only
the camera, the rate is now an even 100 %. In other words, we
never have had a shot ruined by guiding itself since we have
switched to this system.  Pierre Schwaar now incorperates this
guiding system as an option in every "Bigfoot" telescope he makes
comercially.  

It is so very reasureing that any very carfully guided shot will
show pinpoint images, without finding out in the darkroom later
that your hours of hard work at a distant mountain observing site
came out as trailed blobs. 

Additional Notes:

Since this article was written four years ago, we have continued
to improve the system.  It is now refered to in literature as the
"Arizona ON/OFF Axis Guiding System", and has enabled hundereds
of aspiring astrophotographers first starting out, to produce
stunning perfectly tracked shots for the first time.  Although
many will find it too much to bear to glue steel washers on the
secondary mirror with superglue, their obstruction is so slight
as not to be noticed visually.  Pierre now glues a bracket with a
spring clip to the center of his diagonals on the scopes modified
for the guideing system, and has eliminated the rubber bands.  I
still use them because I dont have the nerve to permanently
contact cement a sizeable base for the clip to my diagonal.  

It is hoped that some of you out there will benifit from this
sytem, perhaps modified for your own scope.