© Baader Planetarium GmbH
15
Adjusting the image plane at the RASA 8
The adjustment itself is done on the starry sky. The FCCT is designed to maintain the
correct working distances when using the appropriate QHY camera and unmounted
31 mm / 36 mm or 2" (47.4 mm) Baader filters with 2 mm glass thickness, together
with one of the enclosed 0.5 mm spacer rings (
3
in the scope of supply on page 4).
The clear glass filter built into the RASA should be removed, as each additional filter
shifts the focus outwards by about a third of its glass thickness.
The second of the two 0.5 mm thick rings is used to compensate for manufacturing to-
lerances – only if a satisfactory result cannot be achieved when focusing on the centre
of the image. In this case, you can add the second 0.5 mm ring, or even remove both
rings (e.g. if you use filters from other manufacturers).
1. The camera sensor is aligned with the
filter drawer and the adjustment screws
as shown in the illustration on the left,
if it was installed according to this
manual. The orientation of the camera
to the RASA can also be rotated by 90°
without losing the orientation to the
axes of the mount. The numbers 1 to 3
mark the pairs of adjustment screws;
screw pair 1) is now opposite the filter
drawer.
2. For the adjustment of the image plane,
the stars in the
centre of the image
must first be focused as small and
round as possible. Only then each
corner of the image can be examined
separately and adjusted by moving the
respective screw pairs. The diagram
shows the function of the screw pairs: :
1
tilts the camera along the
Longitudinal axis
2
and
3
tilt the camera
the diagonal axes
3. Use the extra-long Allen key with hand-
le to align the camera by loosening
and tightening each pair of screws so
that the stars are as small and round
as possible, even in the corners of the
picture.
Do not overtighten the screws (see
next page)!
Please note: At f/2, even small changes
have a big effect!
3
2
1
2
2
3
3
1
1
