Ever tried a binoviewer on a Dobson?

[jonathank]

Hey,

Ever tried a binoviewer on a Dobson?
Easy question to know if a binoviewer is not to heavy on a Dobson (like a lightbridge).
A balance weight could be useful.
What do you reckon?:doh:

Cheers

[iceman]

There's certainly no problem using a binoviewer on a dob. Like you said, there may be balance issues, but that's easily sorted with a magnet or some other weight at the back of the scope.

[Harpspitfire]

im selling mine on ebay-- ill tell ya what- theres MANY times i almost dropped the whole contraption unless its kept upright- i got great moon views from it- but its hardly worth the effort anymore for how carefull you have be- another thing is the eye relief drove me crazy- seems the scope was no where near me!

[gbeal]

I do, and yes, there is a few balance issues you need to be aware of, but the views, lunar especially, make it worthwhile. Get the whole lot balanced with the normal cyclops setup. Then get it balanced with the bino viewer, and keep thaqt extra weight (like Mike said a magnet os something similar) handy for use when you bino. Great fun.

[casstony]

I keep a stack of speaker magnets on my Bintel dob eyepiece rack and apply as necessary to balance whatever is in the focuser. I dont use the springs to tension the bearings as I don't like applying the extra friction. The Denk is a bit heavier than my chinese binos, but you just need a few more magnets - I haven't found balance to be any problem at all.

[Ambermile]

Hmm - well I wouldn't be able to do it on the 22" because I'd need to cut three inches of the truss tubes to get to focus...

Arthur

[gbeal]

With my Denks, and the 2" OCS the focus point is very close to "normal" Arthur. Why would your trussie 22" be any different?
Gary

[Ambermile]

Well - you tell me what an OCS is and I'll let you know...

[Karls48]

Hi, could someone please comment on quality (or lack of it) of $200 binoviewers sold by Andrews or AOE. I cannot find any reviews on those.

[casstony]

AFAIK, the body is the same as that of William optics/Burgess/Stellarvue. The main problem you might run into is misalignment of the prisms making it difficult to merge images, but if you're within driving distance of the shop it would be easy to swap for another set. Also check that they have individual focus adjustments for each eyepiece - the WO sets do.

EDIT: you do need to use a barlow or corrector on refractors and dobs.

[wavelandscott]

While not an expert...I do have a Denk Big Easy Binoviewer and it seems to work fine in my reflector and refractor...from the OPT website a comment on the Denkmeir OCS...


" Product Information - About the Denkmeier 1.25" OCS

The "Optical Corrector System" (OCS) is a peripheral optical system that allows the Deepsky Binoviewer to reach focus in a telescope where the focal plane formed by the primary mirror or lens remains in a fixed position. While some telescope designs like Schmidt-Cassegrains have the ability to "push" the focal plane forward by moving a spherical primary closer to the concave secondary, the majority of telescopes cannot perform this maneuver. Therefore, a means must be implemented to place the focal plane far enough forward so that the eyepieces placed in a binoviewer can form a focused image where your eyes can intercept this image.

In the past, a barlow lens was used. A standard barlow lens will in fact allow the focal plane to be accessed for viewing with a binoviewer. However, the magnification when using a typical 2X barlow ends up being more like 4X when implemented for this purpose. This means that even a 40mm eyepiece would behave like a 10mm. This situation has prevented the proliferation of binoviewer use for "all of the time" observing, especially for deep-sky work.

This is why our patent-pending, multi-purpose 1-1/4" or 2" OSC has such important implications for the advancement of bino-viewing. Now, the OCS allows the binoviewer to operate at almost true power. Low power applications are now possible!

In the past, big Dobsonian owners cut their poles down or had two focusers with one in a much lower position. A much larger secondary mirror is needed for this to work. This is because the light cone is intercepted by the secondary when it is wider. The expense and hassle of rigging up such a dual configuration made it impractical and expensive. Furthermore, coma from the primary mirror is corrected with the use of the OCS. So, it is clear that there are many advantages to be realized through use of the OCS."


Hope this helps!

[Karls48]

Thanks for replies. I live close to Andrews shop so exchanging would not be problem. I need binoviewer for the experiment and I’m not sure if it is going to work, so I don’t want to spend too much money on it. I want to use binoviewer to merge images from two 102mm F5 refractors into one, for imagining. One of the problems is that eyepieces holders spacing would not be wide enough to fit two scopes side by side. I may have to use two diagonals on each scope. Then, I may not reach focus even with barlow. Collimation is another problem. I’m also looking at beam splitter cube in place of binoviewer.
What I hope to achieve with this aperture synthesis is to get resolution of 12” scope by using two 4” scopes.

[gbeal]

Arthur,
Wavelandscott has neatly summarized it for me. I have the Denk standards, and the 2" OCS, and in my f5 newt it works a treat, I can also use it on the refractors, with the 2" diagonal.
Gary

[Ambermile]

Ah - I see. Well, I think the OCS is likely going to come in at way too much for me to get one (I'll stick to the 80FD and no externsion tube :D ) although it does sound like at least *somebody* listens to what people are asking for out there!

Arthur

[Harpspitfire]

mine are celestrons (while i still have them) they seem to be the same as the BO,WO etc- i never had a collimaton poroblem on merging images, i doubt this would be an issue unless you get a bad pair- make sure you get them at a place that can collimate them if needed or return them