WO Binoviewer focus problems in 12" Revelation

[avtaram]

I can't get the WO Binoviewer to come to focus in my 12" Revelation Dob.

Has anybody had a similar problem and is there a solution to overcome this.

Avtar

[SimonfromSussex]

Hi Avtar,

I don't have exactly the same set up as you, I have the revelation binoviewers with a 16" lightbridge but I gather the focus can be a problem with newtonian telescopes and most binoviews.

I find with x2 25mm eyepieces and a x2 barlow I can achieve focus but it is right on the limit of inward focus.

If you haven't tried it with a barlow that is worth a go, one that screws on the end is best. 

The other thing to try is a low profile 2" to 1.25" adapter that means the binoviews sit nearer your secondary and hopefully give you enough inward travel.

Something like this: http://www.scopesnskies.com/prod/scopeteknix/accessories/low-profile/eyepiece-adaptor.html

Try taking out your existing 2" to 1.125" adapter and see if you can gauge how much inward focus you need by just holding the binos in the 2" gap.

As I say, not exactly the same set up as you so others might be better placed to advise, but hopefully there are some things to try there.

If you get it to work the views are really good with two eyes, particularly on the moon.

[brantuk]

Just an idea - not tried it myself - but try it with the 1.6x barlow removed from the bv nose piece. It may or may not work but I just have a feeling it might.

[avtaram]

Thanks Simon and Brantuk, I'll give those ideas a go next time we have some clear skies.

Avtar

[denis0007dl]

Hello,

I have 10" TS/ GSO deluxe dobsonian, and I simply cut down part of tube 8cm, and replace original focusser with Baader Low profile, so I can reach focuss with any binoviewer without using any GPC or simillar, so I have lowest possible magnifications!

[avtaram]

Hello Denis,

Thats an interesting idea but I'm afraid that sort of mod is beyond my capabilities.

Thanks for the reply.

Avtar

[denis0007dl]

Hello Denis,

Thats an interesting idea but I'm afraid that sort of mod is beyond my capabilities.

Thanks for the reply.

Avtar

No problem Avatar,

if you need any help in tuning dobsonian that you can achieve enough back focus, contact me any time

[avtaram]

Thanks for the offer of help Denis, I will take you up on that at some point.

Avtar

[Avocette]

I have the 12" SW Flextube Dob with standard single speed focuser (top hat style eyepiece tube fitting) and the WO BVs. To find focus without using a nosepiece Barlow lens, I have to shorten the Flextube truss tubes by 10cm (i.e quite a lot). The latest SW Flextube Dobs have extra detent holes in the truss tubes which, although not mentioned in the user manual, are probably intended for this purpose.

[denis0007dl]

I have the 12" SW Flextube Dob with standard single speed focuser (top hat style eyepiece tube fitting) and the WO BVs. To find focus without using a nosepiece Barlow lens, I have to shorten the Flextube truss tubes by 10cm (i.e quite a lot). The latest SW Flextube Dobs have extra detent holes in the truss tubes which, although not mentioned in the user manual, are probably intended for this purpose.

This is usefull in flextube dobsonians, but if you use this setup, you must using larger secondary 

if you want to have all light from primary in your eyes