£3 Guidescope

[JKB]

Well I finally got round to going to the local Recycling centre last weekend and lo-and-behold in the stuff for sale was a Celestron f900 60mm scope and EQ1 mount.

After paying the princely sum of, you guessed it, £3 I got thinking.

Could I use it as a guidescope? Well considering it was much longer than my 150p I thought I would probably not bother.

Then thinking some more I wondered if I could shorten the scope

So I did!

Essentially I took the lenses out and using the sun and a broom handle I measured the focal length of the first objective (omitting the second) and burnt a hole in a piece of paper. (That reminded me of my childhood and magnifying glasses)

So I cut the tube to suitable length (around 300mm) and put it all back together. Have achieved focus with a 25mm EP easily and am not worried about CA.

Just need to find a way of mounting guide cam and make some mounting rings to hold it in place.

Will keep you updated!

Pic of modified scope

[synapse]

An impressive piece of re-engineering.

[WayBig]

...and when you're done with it you can sell it as a "rare" Celestron 60 WideView

[JKB]

Like it Chris

[yesyes]

hmmmmm, interesting. I have a similar scope lying around that I wanted to use as a guide scope at some point in time.

So you have taken the main objective lens, measured its focal length, then cut the scope down to that the focal point is just outside the focuser/draw tube? And you've not used any other lens?

[bamus]

I have got same scope and allways thought there is only 1 lens inside with fixed focal lenght. how can it be reduced to 300?

[JKB]

There were 2 lenses, air spaced at the objective end. The second one was discarded and the first kept and measured the FL using the lens taped to a broom handle and piece of card.

The exact tube length was shortened to the FL - length of focuser - 30mm allowing for a little back focus if the ccd is too far back with adaptor ring etc.

HTH

[yesyes]

Thanks. I'll see if I can do the same to mine. Being shorter should remove some flexure and generally increase stability, hopefully.

[JKB]

Just in case heres a non scale diagram!

[MikeWilson]

Great job. Well done, I'm quite keen to see your results!

60mm of aperture is probably just right for a light guidescope

[jnp]

An optically superior solution to reduce the focal length is to use an additional lens as a focal reducer, but for £3 thats a cheeky bodge.

Wonder if you can get away using it for guiding? You could try using a bit of cheap plastic film to reduce CA?

[bamus]

it really works!!! I have done the same to my celestron power seeker and quick test during day and night time showed that picture is fine. I will use it as guide scope, just need to get guide rings:

[JKB]

Bamus Excellent! Perhaps I can start a new craze?

I tested mine, finally, the other night and was actually really surprised what was visible and the fact I got great focus on my SPC900.

Well done. How will you be guiding? I only have EQ3/2 mount so will be doing the Controller Mod. Until I can afford a better mount.

As for Guide rings I have a mate at work making me a set out of acrylic. Hopefully have them this week.

[bamus]

I have got eq5 goto synscan so mount is not a problem. I have actually some success with SW finder and unmodded web cam:http://stargazerslounge.com/imaging-discussion/125230-unmoded-webcam-guider.html#post1663012

but extra 10mm in lens diameter will give some more light gathering, which will help with my unmoded webcam

[Herbig]

Wish I could find that sort of gear in my re-cycling centre!

Great mod by the way.

Regards

Pete

[JKB]

Herbig.

I only wanted a Flymo from the Re-cycle centre! Never thought I would end up with a Scope, which in turn would lead me down this path!

[yesyes]

I think I should have a stroll down the recycling centre... I never actually considered *taking* anything from there. ;-))

[JKB]

Well here you are. My Chopped £3 guidescope mounted on the 150p.

Thanks go to Rich at work for making the rings. I used the spare Dovetail and bolted it on top of OTA Rings.

Now all I have to do is build the guiding hardware to control the motors..

Clear Skies all

[RikM]

That looks a proper job. Hope it works out nicely for you.

[Beyond_Vision]

Now that's a bargain, ingenious stuff

Regards

Kevin