Upgrading to a GSO "crayford style" focuser

freespace · #1 08-02-2010, 02:10 PM

Hi everyone!

I have a F/5 102mm skywatcher refractor [1], and would like to upgrade the focuser to the GSO "crayford style" from andrews communications.

My first concern is that the standard focuser has a finder scope mount, and I don't know if the GSO one does. I will have to call up andrews and ask - perhaps some one here has one and can tell me?

If it doesn't have a finder scope mount, what is the best way to fabricate one?

My second concern is that it won't have sufficient in or out travel to achieve focus for both optical and photography use. Has anyone performed a similar upgrade and can offer some advice?

All advice on this planned upgrade are welcome

Especially if you think I should just save my money and get a better scope instead

Cheers,
Steve

[1] http://www.skywatchertelescope.net/s...1=1&class2=105

TrevorW · #2 08-02-2010, 02:16 PM

It should state how much travel in the drawtube, it should be about 80mm

freespace · #3 08-02-2010, 02:18 PM

Quote:

Originally Posted by TrevorW

It should state how much travel in the drawtube, it should be about 80mm

Andrews does say for some, but not the others. Guess I will have to call them and ask

multiweb (Marc) · #4 08-02-2010, 04:00 PM

No the GSO doesn't have a shoe for the finder attachment. Its total travel is 72mm. It will sag if you draw the whole tube out. It will also not hold heavy weight. But all in one it's a good focuser for a small scope and it does the job. I have one on my ED80 and it will hold a QHY8 + 2" extension tubes (~500g). It works both for visual and astro-photo. You will reach focus.

TrevorW · #5 08-02-2010, 04:13 PM

Your other option although a bit more expensive is the WO Crayford focuser, I've had one on a 120 f5 SW prior to selling it and they are VG IMO

freespace · #6 08-02-2010, 08:48 PM

That's out of my budget, but thanks for the recommendation Trevor.

Marc: thanks for the info

So what is the best way to add a finder bracket to an OTA? The thought of just drilling holes and screwing one in worried me...

En1gma (Robert) · #7 08-02-2010, 10:23 PM

the GSO focusers acually have a single bolt to attach a Finder dovetail.

Although the issue you will have is the GSO dovetails are slightly smaller then the SW dovetail base so you will need to grind.

Will take a pic and show you what I mean.

Rob

freespace · #8 08-02-2010, 11:32 PM

Rob,

Thanks! That information really helps

Look forward to the pictures, thanks for all the effort you are putting in

Cheers,
Steve

multiweb (Marc) · #9 09-02-2010, 09:22 AM

Quote:

Originally Posted by freespace

So what is the best way to add a finder bracket to an OTA? The thought of just drilling holes and screwing one in worried me...

You'll have to open the back of the tube anyway so all you need is to get an 8x50 with its shoe. Drill two holes in the tube and bolt it through before you put the new focuser back in.

En1gma (Robert) · #10 09-02-2010, 10:09 AM

Pic as promised.

freespace · #11 10-02-2010, 12:32 AM

Robert: Thank you! That has helps immensely!

Marc: That's true. I would have to do it with the scope standing up, mirror up, and probably pack some news paper in there to stop any debris from flying up and getting lodged eh?

Actually having looked at the prices for a newtonian with the same kind of focuser, I might just get a new scope instead...