Bino viewer & fast dobs?

[sally1jack (Phil)]

I'm interested to see if anyone has had any experience with bino viewers & maybe a Denk bino in a fast dob?, also are they compatible with SIPS.
If anyone is going to SPSP & wouldn't mind me having a look & a chat that would be great, i will only be there on the Friday.
thanks phil

[gbeal]

Not sure what you define as "Fast", but I use a Televue Bino-View in my 10" f5 newt/dob, and with either a pair of 25mm TV Plossls or 12.5mm Vixen LV's.
On the moon, wow, there is no other way to do it. DSO's, hmmm, OK, but not (to me) with the wow factor that lunar gives.
Planetary I haven't really tackled too much, the seeing hasn't been too flash. I'm sure it will be like lunar.
Try it, but be prepared to pay, as once you see the lunar surface this way, you'll be hooked.
Gary

[astroboy]

Hi Phil
I use a Denk bino in my 24" F3.6 works great but I remove the parracor 2 first , I don't have the sips set-up but I would think the sips lenses would get in the way of the OCS or OCR or whatever they call the optics that allow the bino to come to focus.

Thanks
Zane

[sally1jack (Phil)]

Thanks Gary & Zane,
Gary my dob is f3.3 , i would love to have a look through a sub f4 scope with a bino viewer.
Zane i don't know if you remember i came down about a year ago & had a look through your scope to check out the size in the flesh & the views, i should have had a look then , anyway maybe another time.
phil

[astroboy]

Hi Phil
Yes I do remember sadly I've rented out the cottage now , it now gives a better income without the hassle of worrying what the weather is doing.

Thanks
Zane

[denis0007dl (Denis Levatic)]

I use my Mark V bino on 10" f/5 dob, so, for achieve lowest possible magnification I cut scope tube 8cm, put Baader low profile foccuser, and can achieve back focus with MkV without using any GPC or barlow!

[janoskiss (Steve H)]

Yes, binoviewers do work in Dobs. To maximise the fully illuminated true field of view, you need a corrector that gives an f-ratio equal to 2 x optical path length of the BV divided by the clear aperture of the BV. Typically this means about f/10. So an f/5 Dob will need a 2x OCA.

Most people seem to think that the main function of the OCA is to let the BV reach focus. Not so. It is essential to make use of the full aperture of the scope. But even then, you will be limited to medium to high powers. Something to keep in mind. It depends on the scope's aperture and f-ratio, but say in a 10" f/5, you will be able to use a BV from ~100x up but even then only the central ~50% of the FOV will be fully illuminated. This is not so obvious visually. People usually look for vignetting to decide whether there is loss of illumination. But this is a poor indicator as the human eye+brain only picks up vignetting when most of the incident light is blocked.

[bobson (Bob)]

Hi,

I have Bintel 12" f/5 Dob and William binos. What is 2x OCA and where I can get it?
I checked under resources acronyms and couldn't find it

cheers

[chrisp9au (Chris)]

G'day Bob,

I understand it to be Optical Corrector Adapter

Cheers

Chris

[MattT]

Andrews Communications sell the WO 2X OCA/ OCS. It's in the Williams Optics section for $30.

[bobson (Bob)]

Thanks Chris and Matt!

I found this one under William Optic section at Andrews, is this the one?

E-BINO-B2 1.25" 2x Barlow nosepiece for Binoviewers $39.00

cheers

bob