Can't focus with GSO Newtonian

[freespace]

Hi,

Took delivery of my GS-530 (150x1000mm) yesterday, and after a herculean effort to get the end cap off (it was stuck in there good!) I took it out for a spin.

Immediately I found that I couldn't rack the focuser out far enough to any of my eyepieces, from 32-12 to focus. So I checked my collimation using a laser collimator, and it looked good, and then I verified I can focus by manually pulling the eyepiece out slightly.

So I pulled converted one of my into a barlows into an extender tube, and got focus that way, and enjoyed the rest of the night. But is this normal? I would have expected to be able to focus without any modifications.

Cheers,
Steve

[dannat]

did you purchase it new? or secondhand..some of the scopes these days are sold with a 35mm extension tube for visual use..and for photography focus no extension tube is needed - i would have thought the retailer would have let you know

[freespace]

Bought it new from andrews. There was no mention of an extension tube when I called to order, or looking at the website. Should there have been one? *confused*

EDIT
OK, Luke from andrews just called me back about another matter, and I mentioned this problem to him. He is going to send me an extension now too :D :thumbsup: to andrews.

That should be the end of this problem hopefully.

Cheers,
Steve

[rmcpb]

My GS 8" needs an extension tube for some lenses. I tend to leave it in for all lenses for ease of use.

[freespace]

Cool, I feel better now knowing that :)

[middy]

It's funny this post should appear just now. I have recently replaced the rack and pinion focuser on my 8" Saxon/Skywatcher Dob with a Crayford focuser and I have exactly the same problem. I now don't have enough outward travel to reach focus. Like Steve, I can pull the eyepieces out slightly to reach focus but this is not ideal.

I was thinking if I wind the primary mirror collimation screws so the primary is as close to the end of the tube as possible then I might get an extra 5 mm to play with. Failing that I might need an extension tube.

[freespace]

If you have a spare barlow lying around, it will do if you remove the lens :)

[Terry B]

Or us a a diagonal.

[freespace]

That's the first thing I tried actually, but it didn't seem to work. Maybe using the diagonal gave me too much out focus and I needed to rack in. Will try again tonight.

Would have preferred to use a diagonal, the newt gets into awkward positions on an EQ mount. Made me wish I was a gymnast!