Officina Stellare RH200 User manual

RH200 AT and MARK II AT COLLIMATION
MANGIN, FRONT LENS AND TIP TILT
Thanks for purchasing our RH200, simply the best astrograph on the market!
As with any professional instrument, it needs a proper adjustment to be used.
In this manual you will learn how to adjust the:
-Primary mirror (Mangin)
-Front lens
-Tip tilt
VERY IMPORTANT: normally, only primary mirror collimation is required. If you are not satisfied with your
result, please contact Officina Stellare or your Dealer to get further assistance before making any further
adjustments. An improper adjustment of the front lens or tip tilt will cause a dramatic telescope’s
performance degradation vs. bad collimation.
PRIMARY MIRROR (MANGIN) COLLIMATION
The first step is to collimate the telescope, as you would do with any other scope using a mirror to collect
and focus light. The RH200 is equipped with 3 screws on the backplate to adjust collimation. This is
analogous to an SCT, Newtonian, or RC in that you use the 3 regulation screws to center the secondary
mirror shadow. Stars must be extra focal and always in the center. You should always make very small
adjustments of a 4th a turn or less.
Using the 3 regulations screw on the backplate
FROM
TO
Collimation
screw
Collimation
screw
Collimation
screw

Now you have the telescope collimated, it’s time to take some images to check the rest of the system. You
need to take one image at focus and another just a little bit out of focus.
FRONT LENS ADJUSTMENT
Now look at the out of focus image. If the stars appear deformed then there is too much stress on front
lens from mechanics. This could be caused from a prior poor adjustment and/or a big temperature
change after adjustment. While you can collimate the telescope using the collimation screws on the back
(as noted above), the front lens can also be adjusted with a very different effect. The front lens will
control the stars shape roundness and can remove or introduce aberrations (most common one is
astigmatism).
For example, if the stars look like the two below, that means you have the front lens under too much
tension which is introducing astigmatism and needs to be fixed.
If you get round stars like the ones below then you shouldn’t touch the front lens.
NOTE: to check the front lens, images must be taken in intra-focal position and always in the center,
meanwhile collimation is done with extra-focal stars.
To adjust the front lens, take the allen screws provided and follow instructions in next page.
Stars are deformed:
the front lens is tensioned

1) Unscrew about ¼ or ½ a turn the following screws indicated from the blue arrow:
These screws will reduce tension on the front lens from the front ring (the one with writings).
2) Take another image of the same star. If the shape is more round, but still not perfect, you can try
another ½ turn. Never unscrew more than 1 turn in total. If you loosen the front ring too much, the
front lens will be free to fall dawn. To check if the front ring is too loose, gently tap on it with a finger.
If you hear the front ring tapping on the front lens that means there is no contact between them and
the screws need to be tightened a bit more.
3) If after loosening the screws the stars shape is still deformed then it’s time to collimate the front lent.
To collimate the lens, follow the steps as displayed on the next page:

Under the pull screws (blue arrow) there are cup springs to keep collimation. If these screws are/or
become too tight, you need to unscrew them. Start by unscrewing all pull screws 1 turn. This will reduce
compression on the front lens cell from the cup springs. Then take another image to see if the star’s shape
has changed.
You need to bring the star
NOTE: If 1 turn is not enough to reach to the goal, you can do a second turn on the pull screws.
Pull screw
Push screw
Pull screw
Push screw
Pull screw
Push screw
FROM
TO

Now gently tighten the push screws to lock the front lens. After collimating the front lens, you need to go
move focus to extra-focal and collimate the primary mirror again as shown in the first part of this
manual.. Every time you touch the front lens you MUST re-collimate the primary mirror.
Let’s recap:
-With the collimation screws on the back you can collimate the primary (mangin) mirror as you do in
most telescopes
-You MAY need to use the collimation screws on the front lens tochange the star’s roundness to
remove aberrations like astigmatism
We always carefully collimate the telescope before shipping. However different variables (like large
temperature change or mishandling) could require a deeper adjustment instead of the classical collimation.
If you have any questions about collimating your RH200, always contact Officina Stellare or your Dealer to
get the proper assistance: this is a professional instrument and very sensitive!
TIP TILT REGULATION (AT or classic version)
Take a look at the image below: you can note the imaging train is completely tilted on the focal plane and
this is causing a massive star deformation. As a result, you see a part of the field you will not see when the
imaging train is proper tilted on the focal plane.
Focal plane seems to be centered here. In
the ideal situation each corner is flat. Tip
tilt adjustment is required.
Completely deformed stars, as this is an
off axis distance you will not see when the
telescope is settled up rightly