Unpacking the Finder Scope
Again the packing of the parts leaves nothing to be desired. Poly bags and bubble-wrap ensure a safe journey.
The Finder Scope arrives pre-installed in its main bracket, and this is very easily placed into the dovetail holder on the telescope tube, and locked into position by tightening the knurled thumbscrew on the dovetail holder.
In the photo you can see the Focusing Lock Ring at left hand side. The finder can be focused by loosening the lock-ring and then turning the front barrel. It is a very fine focus adjustment requiring several turns to move in or out of focus, so initially it can be difficult to tell whether to rotate clockwise or anticlockwise, and by how much to achieve the desired focus for your vision.
Focusing is therefore best done initially during daylight hours against a distant object. You can then tweak it more finely on a bright star at night.
Notice the small knob on the top of the Finder Scope - this is one of two alignment screws, the second being on the other side of the scope.
If you wear glasses, you might also bear in mind whether to focus the Finder Scope with or without your glasses. This depends in part on whether you need to wear your glasses when viewing through the main Telescope Eyepiece (some spectacle wearers find they can focus through the telescope eyepieces without needing their glasses). Focusing for the correct situation can save time having to constantly swap between wearing or not-wearing your glasses when moving between Finder Scope and viewing Eyepiece.
After focusing, tighten the lock nut again, then you can then move on to aligning the finder.
Aligning the Scope
Obviously the finder scope must be aligned accurately with the main tube for proper use.
The chrome-plated cylindrical object lower down the photo is the spring-loaded Tensioner. This does not perform any kind of adjustment, it just holds the body of the finder, which is free to pivot in the finder scope bracket, in contact with the two alignment screws.
Again, alignment of the finder scope with the main telescope tube is something best done during daytime, and against a distinct object at least 1/4 of a mile away, such as a telegraph pole (you cannot focus on anything much closer).
After positioning the view in the main telescope using the 25mm eyepiece (or 10mm for more accuracy), use the adjusting screws on the Finder Scope to align the crosshairs with the object that the main telescope tube is aligned to. Now move the telescope again, but this time use the finder to locate some point and centre it on the crosshairs, then look through the telescope eyepiece to check that the object you aimed at is located centrally in the eyepiece view. Repeat this process until you've got it spot on.
Note that the image in the telescope view will appear upside-down as is usual with Newtonian reflectors, compared to the view through the Finder Scope which is made normal by the right-angle image corrector.
The Dovetail Holder Thumbscrew provides a sufficiently firm grip, and holds the Finder Scope accurately enough that provided the thumbscrew is tightened firmly, the Finder generally does not need re-aligning if it is removed, and then later re-attached to the telescope (e.g. storing the finder scope indoors in the warm, can help reduce "dewing up" of the eyepieces for a little while longer than if you keep it attached to the scope in a cool place).
Even if it does need re-alignment, which it is recommended you check this before each viewing session, this is very easy to do even in the dark (you just need to make sure not to bump or move the main tube aligned on a star, while you make small adjustments to the Finder Scope alignment screws to bring the cross-hairs back onto the star).
Warning: Make sure you screw the dovetail holder thumbscrew up tight otherwise if it loosens, when the telescope is pointed vertical the finder scope could fall out of the dovetail holder onto the ground!
Other Topics in the Assembly section: