Saturday, March 21, 2009

Making my Ranger a motorized "Pronto"?

Tonight, I have a very strange idea.

Actually, the Ranger is inside my closet and I will never part with it due to emotional reason. It's my first serious scope, and I just have so much great memories with it. However, it's 1.25" focuser is limiting its function... It couldn't accomodate a binoviewer without a corrector as well. Wide field scanning is still great with my 20mm Widescan Type III, it gives more than 3 degrees of true field, but more is definitely better. Let say if it has a 2" focuser, I could use my Pentax SMC XL 40mm which will give more than 5 degrees!!!

Another point that I'm not using it any longer is that, it lacks a motorized focuser. I found motorized focusing very convenient when solar imaging is concerned. That's part of the reason why I'm using my Borg 45ED II more actively now.

So I guess if I could use my Ranger with a motorized 2" focuser, it would be great!

I pulled my Ranger out tonight, to see if I could remove the focuser, again, it's hard... I guess it takes some tricks to do so. Then I looked at the draw tube, it's close to 2"... 48mm to be exact, so if I could remove the draw tube, I guess I could attach my NGF-S there?

I turned my Ranger upside down, I saw a slot which governs the drawtube travel, so I know that there must be a pin there guiding the motion, and at the same time, to stop it from getting out completely! So, I know that I could remove the drawtube easily as long as I could remove that pin! After some work, I got it done!

Therefore, now the next step is to make another draw tube for it... And at the end of this draw tube, I shall make an adapter to connect to the NGF-S! That would:

1. enable the Ranger to use 2" eyepiece!
2. enable the Ranger to do solar imaging again with a motorized focuser!

Before doing that, I will need to check the focuser travel, to see how long a draw tube that I should make. Frankly, I could make it exactly like the original draw tube with the helical focuser, but then I know I want to make it slightly shorter to save some weight. A longer draw tube should cause vignetting.

I shall also see if I could accomodate a binoviewer without corrector. And at the same time, I would want to be able to use a reducer in this setup, and if possible, to bring down the focal length to around that of my Borg 45ED II so that I could do full disc solar imaging as easy as before.

A very nice project really!

The design of the draw-tube with NGF-S should look like this:

However, that M57P0.75 side should become 48mm (outer diameter) instead, and how long it should be is pending design.

I'm very excited about this idea!!! If it's done, I could sell my Borg 45ED II and my equipments could be further consolidated, better yet, it saves my Ranger and gives it a new life!

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