Binoviewer with 6" Dob?

Benboy (Ben) · #1 23-03-2011, 12:17 AM

Hi guys,

I'm thinking of getting myself a binoviewer for my 6 inch Dob. Probably something along the lines of the ones Williams Optical sells or similar. I've read that binoviewers don't work so well with dobs. So what do I need to do to get them to work properly? Will the 1.6x barlow nose piece that comes with the WO pair be enough to allow them to work in my Dob?

Any help appreciated.

Cheers
Ben

P.S If you have a second hand pair for sale let me know

dannat (Daniel) · #2 23-03-2011, 07:24 AM

You will probably need to shift the mirror up the tube as well to reach focus with the 1.6x oca , something like 3.5-5cm. Get some longer bolts

Benboy (Ben) · #3 23-03-2011, 11:28 AM

Oh, I really don't want to have to mess with the mirror - I'm not that confident just yet. Surely there must be another way?

Osirisra (Ken) · #4 23-03-2011, 04:39 PM

you have to shorten the focal length by moving the secondary or primary. My dob is collapsable breed so I just don't fully extend it by a couple of inches and it it's all good. for the binos.

Keep in mind that you will loose some light with the Binos and this could be a serious consideration with 6"

dannat (Daniel) · #5 23-03-2011, 04:46 PM

There is anothervway, but more expensive. Siebert optics in the US sell an oca just for newts

Osirisra (Ken) · #6 23-03-2011, 04:55 PM

Quote:

Originally Posted by dannat

There is anothervway, but more expensive. Siebert optics in the US sell an oca just for newts

OCA's sure cost a bit that' s for sure.

Benboy (Ben) · #7 24-03-2011, 12:28 AM

So I guess the next question is how easy is it to replace the bolts?

PCH (Paul) · #8 25-03-2011, 12:36 AM

When I bought a binoviewer, I got the Stellavue item from Peter at SDM telescopes. This model was very reasonably priced and came with the additional glass tube thingies that enable it to focus when installed on a dob.

The thing is, - I can't see them offered for sale now on his website. You could send him an email to clarify whether he's still offering this item for sale I suppose. It would certainly be better than mucking around with your mirror position I would have thought. Worth a call

Benboy (Ben) · #9 25-03-2011, 03:01 AM

Thanks for all the responses.

I've got myself a burgess optical 24 coming to me in a couple of weeks from the states. It comes with a 1.9x corrector. (Is that the glass tube thingy your talking about PCH?) I've been in contact with Harry Siebert as well and think if this thing doesn't come into focus with the corrector I'll probably take that route (lucky its tax return time in NZ!) I figure I'm into astronomy for the long haul so might aswell invest in it for future bigger dobs aswell!

Ben