Explore Scientific TWILIGHT Series, Manual

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13
ED TRIPLET ESSENTIAL SERIES
COLLIMATION
Although the optics in your telescope were carefully aligned in our quality control
department prior to leaving our facility, the shipping process could have caused slight
shifts in the positions of the three lenses. In case such a slip should occur, your telescope
is equipped with a three-point push/pull collimation cell that can be used to realign
your optics for optimal performance. Before using your telescope for the first time, it
is important to check the alignment of the optics. To do this, find a bright star with your
lowest power eyepiece and center it in the field of view. Next, put in a high power eyepiece
and defocus the image slightly until it begins to show a ring pattern. The image should
look very similar to #3 in Figure 1. Now bring the image to its sharpest focus. Doing so
should reveal your target star as a bright tiny dot (called the Airy disk) surrounded by one
or more rings (called the Airy pattern) that look similar to #4 in Figure 1. If the images in
your eyepiece reflect the same uniformity as those pictured, no collimation is necessary.
However, if the image in your eyepiece looks more like #1 or #2 in Figure 1,
collimation is required. To begin the collimation process, remove or retract the dew
shield (depending on your model) and take off the dust cover to access the three sets
of collimation screws. On the 80mm, 102mm and 127mm models, there will be one
adjusting screw and one locking screw located at each of the three points. On the 152mm
model, there will be one adjusting screw and two locking screws at each point. Using a
low power eyepiece, center a bright star in the field of view. Place a high power eyepiece
in and defocus the image until the star develops distinct rings. Be careful not to throw the
image too far out of focus because you may lose the rings. To align the lenses, you will
need to manipulate the push-pull tilt system by making adjustments at one or more of
the three points. To loosen and tighten these screws you will need a 2.5mm hex wrench if
you have a 80mm or 102mm model, a 3mm hex wrench if you have a 127mm model or a
4mm hex wrench if you have a 152mm model. Determining which set of screws to adjust
first is usually a trial and error process, although the shadow method described below
can help. To make an adjustment, you will need to loosen the locking screw(s) at the
chosen point and then turn the adjusting screw a quarter turn. Gently secure the locking
screw(s), being careful not to over-tighten. Recheck your image. If additional adjustments
are needed, follow the same procedure. To streamline the process, have someone else
make the adjustments to the screws while you keep your eye on the image. Once your
image looks like #3 or #4 in Figure 1, your telescope is collimated. As mentioned above,
the collimation process can go quicker if you use the shadow technique to determine
which screws to adjust. To do this, have someone else point their finger towards the
center of the optics so that their finger radiates out from the center like a spoke on a
bicycle wheel. When you look at your defocused star, you will see the shadow of their
finger as a dark line stretching from the center of the field of view to the edge. Have the
person assisting you move their finger around the optic so that the shadow reaches the
point that is most out of collimation (either the thickest or thinnest section of the star will
work). Their finger should be aiming in line with one of the sets of collimation screws,
and that is where you should begin your adjustments.