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Binoviewing with a camera?

astrophotography binoculars DIY
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#1 texcoco

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Posted 13 August 2019 - 03:51 PM

Anyone use a camera in one side of their binoviewer?

 

I'm looking to record exactly what I see in an eyepiece simultaneously, to the best of my ability, with a camera.

 

I could use a flip, but I already have that built into the back of my MAK and the different focal lengths makes focusing a real chore and I can not afford to mess around with a flip when time is of the essence.

 

I was thinking of using a beam splitter, like the one in the heart of the 1.25" Coma beam splitter (https://www.adrianol...olo.asp?ID=4135) by Adriano Lolli until I realized, I already had something like that in an old microscope head I have sitting around. Wait...I wonder if a binoviewer would do the trick?

 

So, this sounds like a good excuse to obtain an entry-level binoviewer...and enjoy it as a binoviewer as well. I have a pair of matched 5mm Celestron X-cels coming my way...sooo...why not? (be using them for Jupiter)

 

I have searched the forum, doesn't seem like anyone uses a camera in one side of their binoviewer.

 

Any major hiccups come to mind? I would appreciate your recommendations. I don't want to go out and just buy the lowest-cost used binoviewers and end up in disappointment.

 



#2 photoracer18

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Posted 13 August 2019 - 04:35 PM

 The spacing between the eyes in a BV is not enough room to use any kind of camera and one eye except maybe a P&S digital. Too close together for a DSLR and a dedicated astro-imager would likely not have the same or near focus range as the eye with an eyepiece. Unitron used to make a thing called a Duoview which was a beam splitter with 2 viewing tubes that went out  at 90 degrees and had separate focusers for 2 observers.

The item you are suggesting seems to have coma correction in it which is going to mess up the coma free views in your MAK. With a bino-viewer there is a limit on how much focus travel each eye has as the mount's focuser does most of the focusing. With dissimilar equipment you will likely have wildly different focal planes such that one will likely not focus unless it has the ability all by itself, which is why I suggested a point and shoot digital. But while it will see the same thing as you it might not be the same view as you depending on magnification.

Not to mention binoviewers need a LOT of backfocus and will not come to focus in a MAK without some kind of Barlow to extend the focus point back farther. This is going to make the view even dimmer to the camera side. This also applies to a beam splitter to some degree also.

Its possible an action cam like a Hero might have enough room but the focus point is going to be an issue.


Edited by photoracer18, 13 August 2019 - 04:38 PM.


#3 texcoco

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Posted 13 August 2019 - 05:13 PM

photoracer18, I imagined that focusing would be the biggest issue. Regarding space for the camera, that was also a concern and I imagined using an  ASI120MM-S (mono) or a mini in place of the left eyepiece and viewing with my left eye in the right eyepiece. With the microscope head I can see that being physically possible. I'm not looking so much for extended viewing as much as occasional glance to check on things without disturbing the equipment.

 

If it gets too complicated, I'd just set up a second scope in parallel on the same mount, but I am trying to avoid that.

 

I imagined that the backfocus on the MAK would be adequate...but I don't really know how much it has.

 

Celestron's web site https://www.celestro...ed-focus-issues gives me the impression the backfocus on the MAK might be serviceable. "Schmidt-Cassegrain telescopes (SCTs) typically have generous back focus distances of approximately 5 in. Similarly, Maksutov-Cassegrains (Maks) also have large back focus distances."

 

Would any binoviewer, in theory, be able to accomplish what I am looking to do?



#4 Wild_Willie

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Posted 14 August 2019 - 11:30 PM

I'm going to try using my Iphone. Just bought the Celestron NexYZ mount. My goal is stacking video for photo's with this setup (mount on the right optic). Will give it a run this weekend : )

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#5 Eddgie

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Posted 15 August 2019 - 12:50 PM

The biggest obstacle to success will be a virtual doubling (+) of the exposure time.

 

Since the beam splitter will only send half the light to each eyepiece, this means an f/18 scope would be working with light equivalent to f/36.  That is pretty huge difference.  (The increase in focal ratio to f/18 is going to be caused by the needed back focus and half half the light accounts for the double of that figure.)

 

So, not that it can't work, but at the kinds of focal lengths involved, the exposure times will be quite lengthy and guiding errors will be another obstacle, unless you already have a very good mount. 



#6 texcoco

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Posted 19 August 2019 - 10:38 AM

How'd things go Willie?



#7 Wild_Willie

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Posted 19 August 2019 - 10:02 PM

Cloudy and some stuff came up so I didn't have a chance to give it a shot. Maybe this weekend.



#8 noisejammer

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Posted 06 September 2019 - 12:36 PM

The biggest obstacle to success will be a virtual doubling (+) of the exposure time.

 

Since the beam splitter will only send half the light to each eyepiece, this means an f/18 scope would be working with light equivalent to f/36.  That is pretty huge difference. ...

I don't think that's quite correct.

 

Suppose you had a f/18 system at focus. Let's guess it's a 6" scope so the effective focal length is 6*18 = 108".

 

Now split the light in two, so that each aperture is 0.7*6" = 4.2". (The 0.7 comes from 1/sqrt(2) .) The f-stop (indicating the depth of focus would remain f/18 but the T-stop (indicating image brightness) would be 4.2/108 = T/26 (ignoring losses due to reflectivity, obstructions etc.)

 

Nevertheless, image brightness goes with the square of the T-stop and things could be very dim.

 

Fwiw, I did try this using a binocular microscope and a modified webcam. It worked to an extent but it needed a very bright light source and achieving simultaneous focus was a real p.i.t.a.




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