Guidescope help

[milan]

Seen a guidescope for sale to use with the QHY5 (ordered yesterday) but it doesnt come with a star diagonal, eye piece or finderscope (finderscope is no realy biggy).

Question is, do we really need the 1.25'' star diagonal and eye piece to complete the kit? presume its needed to focus? (have a celestron nexstar 6SE that used a 1.25" star diagonal, so could we use that?)

Thanks

EDIT:

Does the guidescope camera typically go straight in the back of the guidescope, i.e. not using star diagonal etc? are we likely to need an extension tube?

[steppenwolf]

For guiding, you will not want to use the diagonal as this is a potential source of flexure - you want the light train to be as simple as possible and that means 'straight through' although you will need an extension tube to make up for the 'loss' of the light path through not using the diagonal.

[milan]

thankyou :-)

How would we work out what length extension tube?

[steppenwolf]

Aim at the Moon, adjust the focus tube so that it is just under 50% extended and roll up a piece of paper into a tube using an eyepiece as a former then carefully hold the eyepiece in front of the focus tube using the paper tube as a guide and although it will wobble like mad, adjust the distance of the EP from the end of the focus tube until you get a half reasonable focus then measure the distance from the focus tube end to the EP where the 'chrome' part finishes at the lens end. Or, about 3 inches will be fine!

[martin_h]

I used a variable lenght extension adaptor for my guide scope/QY5. I found one on astroboot at a good price.

AstroBoot

[milan]

Thanks both

[ollypenrice]

If you have an old Barlow then you can remove the lens and just use it as an extender.

Olly

[Merlin66]

I use a 50mm extension with the ST80 and QHY5

Ken

[MarkF]

If you have an old Barlow then you can remove the lens and just use it as an extender.

Olly

Ooooh, smashing tip, I was using a diagonal and didn't realise about flexure, just so happens I have a 15 year old celestron standard barlow spare.

[milan]

Some great tips in here! unfortunately still being new to all this we have spare nothing!

[spacebloke]

sorry to drag up this old thread, but how have you attached the guidescope to the 6se ota?