Finderscope Guider

[mickw]

I am about to turn a right angled finderscope into a guider using a QHY5 (cheers Jim)

After removing the "prism" am I right in saying that I should try to get the CCD the same distance from the back of the scope as the eyepiece element ?
That would make it about 95mm which seems way too much compared with what I've seen.

[Rocket Pooch]

I allways wanted a right angle finder and your killing one

[RobertM]

Mick,  The ccd chip will be much closer, probably just outside rear after unscrewing the back.  The only way to is to try it out focusing on a distant object - move the camera until you get rough focus then you know where it needs to be.

I wouldn't butcher a good finder or one that has spring adjusters for the alignment.  The filter finder will need to be very tightly held by the adjustment screws on the mounting brackets so it doesn't move.  Also the brackets will need to be bolted to whatevery you will be mounting it on.  I had heard that someone makes a QHY5 to finder adaptor which might be worth checking out.

Robert

[Ian]

I've seen one of those adaptors, although I would think that they're aimed at straight finders, not right-angled ones. If I can remember where I've seen them I'll let you know.

I'm not convinced a right-angled finder is smart for a guidescope, you'll either have to take the prism off making the tube really short, and possibly hard to connect the camera to, or if you leave it on there will be a significant torque on the finder mount from the offset camera.

The CCD will need to go where the eyepiece field stop is usually mounted.

I would think that's where your 95mm comes from...

[Tony G]

Mick,

I don't know if this helps...............http://mbsastronomy.com/2009/03/30/finderscope-turned-guidescope/

Tony G

[mickw]

I allways wanted a right angle finder and your killing one

Chris, don't take it personally - I'd kill it even if you didn't want one  

I've ditched the prism and had a peek just holding the eyepiece up to the open tube and it comes to focus a lot nearer than 95mm

Time to knock up a trial adapter.

Can't get anything out of the QHY at the moment though  

Busy, busy, busy

Thanks Tony, thats the same idea - I've ditched the bracket though,  I'll sort out rings later.

Also found some 3mm ally plate which I can laminate as a mounting plate

[The Thing]

I did a post on converting my Meade finder. But that was straight through. Didn't you have a straight finder on your etx Mick?

[RobertM]

The only difference between a right angle and a straight through will be the length of body after you've unscrewed the back.  You'll just need longer pumbing fittings thats all.  The important thing is getting the QHY5 to be a tight fit so there's no chance of movement.

[mickw]

I did a post on converting my Meade finder. But that was straight through. Didn't you have a straight finder on your etx Mick?

No, I've always used an angled finder, I am the wrong shape to see through a straight finder 

Knocked up an adapter out of plumbing bits and shoved an 1 1/4  eyepiece in it - seems to be OK, once I get the QHY working I can try it properly then make it look pretty 

[The Thing]

Why not make the whole thing out of plumbing bits and make a fitting to hold the the lenses section on the end? Then you wouldn't need to mess up the right angled finder and could swap the lens bit back on to the finder tube when needed.

[mickw]

DOH

Too late