First of all, you must learn how to move (tip-tilt) the primary mirror. Take a look to the images in
this page and familiarize yourself with the tip-tilt screws of your primary mirror.
In “big” scopes (i.e. 50 cm and above) you must follow this procedure to operate on the three big screws that control the tip-tilt
movements of the primary mirror. This screws are rotated using a metal bar or a big screwdriver (1, left image). But before you can
operate them, you have to remove the black cap (2, left image) and remove the external locking “bolt” (3, left image). The tool to do
so has been provided with the scope. Once you have removed the external locking bolt, you will see the
internal
locking bolt (2, center
image). Use a small hex wrench to move it a bit
inside
the scope (1, center image). Just rotate it 4-5 turns. The bolt must move
away
from the back plate, i.e. go
inside
the telescope. The big tip-tilt screw can now be operated using a metal bar or a big screwdriver
(right image). Please note that even in big scopes each screw turn will move the mirror just one millimeter. Collimation screws are
spring loaded (using cup springs in big scopes) so there is no need, when you tight one screw, to loose the other two or vice versa.
When you have set the tip-tilt position of the primary mirror, bring the internal locking bolt again in contact with the back
plate of the scope
and put back in position the external locking bolt and the black cap. There is no need to apply too much force on
the internal locking bolt. Just rotate it until it stops against the back plate of the telescope. It is the external bolt that does the real job.
In smaller telescopes there are three big screws to set the tip-tilt position of the primary
mirror (number 2 in the photo at left). If your telescope has also the safety set screws (1)
loose them 4-5 turns before to operate on the big screws using the specific tool (3),
included with the scope. When you finish, tight the safety set screws. Do not apply too
much force. Just let them touch “gently” the internal mirror cell.
Please note that in all Officina Stellare telescopes each collimation screw turn will move
the mirror just one millimeter. Collimation screws are spring loaded, so there is no need,
when you tight one screw, to loose the other two or vice versa.
Now go back to our defocused star, where the shadow is not in the middle of the white circle and...
go to the next page!
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