Cleaning SCT Optics

daughterduckUrban and Civil

Nov 15, 2013 (3 years and 10 months ago)

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Cleaning SCT Optics

Ways to Prevent from
Cleaning your Optics

Don’t let your optics get dirty!

Keep them covered when not in use.

Use a Series 6 Skylight filter on the
eyepiece end of the telescope to
prevent contaminates from entering the
tube.

A Skylight filter also increases lunar and
planetary contrast.

TO CLEAN OR NOT TO
CLEAN

Make Sure Your Optics Need
Cleaning

Specks of dust or pieces of lint do not
impair the visual or photographic
performance of your telescope.

Excess cleaning can cause small
scratches which scatter light, this is very
harmful to optical performance.

Telescopes, used nightly, generally
need to be cleaned only every six
months to a year.


When Cleaning is Needed

Keep children and pets away.

Clean off dust and dirt by using
compressed air.

Never apply cleaning solution directly to
optical surfaces.

Never rub or apply pressure when
cleaning optics.

Cleaning Solution and
Materials

½ cup distilled water


DO NOT USE TAP
WATER

1 cap full of 70% Isopropyl Rubbing Alcohol

1


2 drops of dish soap

Cotton Swabs


useful for Stubborn particles
and for cleaning eyepieces.

Cotton Balls


general cleaning

Acetone


useful in cleaning sticky materials
such as tree sap from the corrector. DO NOT
USE ACETONE ON MIRROR OR
SECONDARY.

Cleaning Stroke

What tools do I need to
perform a collimation?


Two or three eyepieces that offer a range of
magnification from about 200x to 600x.

An Allen wrench or screwdriver appropriate to
the screws that you will use to set collimation.

A flashlight in case you need to look closely
at the collimation screws.

Patience!


Collimation

Guidelines


Always put the eyepiece directly into the
visual back of the telescope. Never use
a diagonal. You want the straightest
possible light path for collimation.

Make one adjustment at a time.

Always (repeat:
always!
) re
-
center the
star after every adjustment.

Be patient!

Setting up for Collimation


To start collimation, point your telescope at a
moderately bright star.

Place an eyepiece that gives you about 200x
in the visual back, and center the star in the
field of view. Defocus the image slightly.


You need a slightly out
-
of
-
focus star image to
work with during collimation. The image at
right shows what you
don't

want: an almost
solid doughnut of light.


What does collimation look
like?


The image at right shows what a mis
-


collimated scope will look like. The


diffraction rings are not concentric
--

they are
pinched or bunched up in one direction.

The image at right shows the proper amount
of defocus you are looking for. These
diffraction rings are concentric, and show the
ideal state: a perfectly collimated telescope.

Air turbulence will no doubt result in


diffraction rings that move and shimmer


QUESTIONS?