Can't get enough inward focus... What to do?!

[rocketandroll]

Hi folks

So, I'm at my local astro society and were trying to get focus on my dslr attached to the observatory scope.

Now the scope is a 10", 1 ton Victorian refractor.

We can't swap the focuser for a new one as it's integral to the scope... and focus for the camera is about an inch or two further in than it can actually reach.

Is there anything we can add, a focal reducer or barlow or something to optically bring the focal plane further out?

Thoughts?

Ben

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[Rossco72]

You answered your own question really, a barlow or some sort of glass path corrector as used with Binos will probably be required.

If it's a big long refractor, a focal reducer might be worth a try as it's likely to be of more use than a barlow.

[RobH]

Hello Ben.

It sounds like a fascinating instrument....any chance of a few pics

Putting a barlow in will bring the focal point a bit further out, and even then it may not be far enough, but will make it much trickier to do anything other than planetary or lunar photography with the scope as you describe it.

A '1 ton Victorian Refractor :)' is unlikely to be on a high enough quality mount to do any deep sky imaging anyway though.

An accurate mount for something that weight would cost as much as a house!

A focal reducer won't work. That will put the point of focus even further into the tube, as I've found with my 6 inch refractor.

If you can't get focus with a barlow, how about trying eyepice projection?

Cheers

Rob

[Rossco72]

Good point Rob, you could get one of those EP's which can attach directly onto a T-Thread and hence your camera.

[rocketandroll]

You'd be surprised about the mount :-)

It's on a 2ton cast iron equatorial mount on top of a 50ft solid brick/concrete pillar :-)

Its also got an RA drive, the original one was clockwork but its now electric.

No one has ever taken an image through it so, after 120 years its about time someone tried!! :-)

I'll have a look at the ep projection adapter idea... Wasn't sure though if a barlow or a focal reducer was gonna help... couldn't get my head around the optical implications of either :-)

Cheers

Ben

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[ncjunk]

It will be great to see some images of the mount and also some dsos!

No pressure...but..i want to see some images!

Looks like it might be very entertaining.

[gary1968]

Could you not move the primary mirror up the tube a bit?

Gary

[Cornelius Varley]

Could you not move the primary mirror up the tube a bit?

Gary

Not on a refractor .

Peter

[gary1968]

Not on a refractor .

Peter

OOPS! That'll teach me to speed read through posts.... lol

Gary