Questions re Skyliner 150p Dobsonian

[chrisbk]

Hello - I'm new to this forum and have a couple of questions about the above scope that you may be able to help me with.

I'm thinking of buying Skyliner and substituting a homemade mirror which I'm about to start.

Firstly, I wanted to make sure that my mirror would fit the mirror cell - mine is 155mm in diameter and 25mm thick.

Secondly, Can anybody tell me the distance from the side of the tube to the 1.25" eyepiece flange when the scope is in focus.

The reason I ask is that I may substitute a low profile focusser for the stock one and would therefor plan to make the mirror focal length a bit shorter than the nominal 1200mm.

Many Thanks in anticipation.

Chris

[NGC 1502]

Hi Chris, the focuser on my 200p is the same as the 150p, and is about 135mm high, from the tube wall, when in focus, but some eyepieces require more in or out travel to focus. The 150p is listed in my Optical Vision catalogue as having a 153mm diameter mirror, but I wouldn't treat this as gospel, as when I had a 250PX it was listed at 254mm dia but was actually 258mm, (measured when I washed it) If the new mirror is thicker/thinner than the original, you may be able to adjust the mirror retaining screws to fit. The mirrors in these mass produced scopes are usually very good, so it will not be easy to make a better one yourself. Hope this helps, Ed.

[chrisbk]

Many thanks for the response.

Looks like I'll be able to cut the focal length a couple of inches if I use a low profile focusser - keeping the flat to focus shorter will help with the fully illuminated coverage of my lowest powered eyepiece.

I made a couple of mirrors about 30 years ago which were not too bad and, as I have taken early retirement, I thought it would be a nice little project.

It used to be the cheap option but not now with inexpensive Chinese imports. By the time I've had the mirror alluminised it'll cost about 2/3 the price of the whole 150P!

Regards

Chris