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Is there a market for astronomical binoscopes?

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#51 Oberon

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Posted 20 February 2015 - 05:15 PM

This is good; I'll keep my eyes out for a couple of TV Widefield 32s.



#52 Oberon

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Posted 20 February 2015 - 05:36 PM

i dont think the market would be there for 100 units - im guessing you'd be sitting on that inventory for 20 yrs

i would have that that moving 10 might be doable - but you have to compare with the APM 100ED, which is a fairly known quantity & a dealer people know.

 

Andy jackson [plyscope username] is about to build a 5" istar bino  - that will be an interesting build , having one of his ply constructions it is beautifully built [and very lightweight -the 5" f12 is under 7kg for the OTA -much ls than istar supplied tube]

 

Thank you for this. The APM looks like a very nice binocular with a very nice objective. But it is limited to 1 1/4 eyepieces and has at least 3 internal reflections.

My bino is also ply construction, and shares similar techniques to my "Merope" telescope (see my signature). I don't think it would appeal to someone who wants an APM style of binocular; it won't be nitrogen filled and will need looking after and tweaking etc more or less like a Newtonian Dob. And it could very easily cater for a variety of objectives and focal lengths, some of which are cheaper than eyepieces. In my design it would be feasible to swap objectives rather than (or as well as) eyepieces. Basically you could use a 100mm f/5, a 127mm f/5.5 or a 152mm f7.5 or longer, although having all those options together in the one package obviously one couldn't pack it into a carry-on-luggage suitcase.



#53 plyscope

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Posted 20 February 2015 - 06:23 PM

My binocular project is fairly basic and kind of a trial to see if I like it. My inspiration came from Mr Bill and his bino box.

 

I am trying to make it even simpler by using offset objectives and thus getting away with only one diagonal mirror per side. The IPD will be fixed at my own 68mm IPD.

 

The focusers are simple helical units from Baader with limited travel. More or less like a normal IF binocular. Just enough focuser travel to allow fine tuning. For eyepieces I will be limited to ones with similar focus point to the 24mm Panoptics. This will include 19mm Panoptics, type 6 Naglers and TV plossl's.

 

I am aiming to keep costs down. I hope to make some more progress over the next month or so.

 

IMG_1047 - Copy.JPG



#54 MartinPond

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Posted 20 February 2015 - 06:30 PM

Thanks, Jon;   the factor of exit pupil makes sense, to advance binoculars' realm a bit farther.

 

Jochen: that was a very informative description of your experience of 'stacking'.   Even though you cannot trace it

             to some exact phenomena, I know what you mean now.   If I were to speculate on how the cognitive

             psychology works, I would guess that it is a combination of slight differences all across the fields that

             that allows the cortex to understand it is stitching two images together...especially something sweeping

             in effect, like a very slight difference in power.  This would allow a sort of 'image fitting' to happen, figuring

             out what third thing must be behind the other two.  That would have a stronger noise reduction effect

             than just averaging nearby points.   A strange sort of test would be to have more and then less perfect

             matching between the two sides.  Some slight mismatch would give you a better result than none.

             Exceptions may 'prove the rule' (the true object).


Edited by MartinPond, 20 February 2015 - 06:31 PM.


#55 Mr. Bill

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Posted 20 February 2015 - 06:43 PM

Been lurking....

 

Spend a night with me under Bortle 1 skies mid summer in central Nevada viewing the overhead Milky Way with my homemade 5 inch f/5.5 binocular and a lot of this back and forth would be academic.

 

:shocked:



#56 KennyJ

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Posted 20 February 2015 - 06:46 PM

I've visited hundreds of markets in my lifetime, and have been occasionally fascinated by the range of goods on sale.

 

That said, I've yet to visit a single one selling Astronomical Binoscopes.

 

Kenny



#57 Mr. Bill

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Posted 20 February 2015 - 06:52 PM

I've visited hundreds of markets in my lifetime, and have been occasionally fascinated by the range of goods on sale.

 

That said, I've yet to visit a single one selling Astronomical Binoscopes.

 

Kenny

 

A niche market to be sure.....

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#58 TomCorbett

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Posted 20 February 2015 - 08:01 PM

Been lurking....

 

... a lot of this back and forth would be academic.

 

:shocked:

 

I was thinking ping pong--but hey, I am here to learn.

 

...Bob


Edited by TomCorbett, 20 February 2015 - 08:05 PM.


#59 Oberon

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Posted 20 February 2015 - 08:22 PM

Been lurking....

 

Spend a night with me under Bortle 1 skies mid summer in central Nevada viewing the overhead Milky Way with my homemade 5 inch f/5.5 binocular and a lot of this back and forth would be academic.

 

:shocked:

 

Excellent. Trip to Nevada here we come!

So...what is your widest APOV field eyepiece and what is your widest TFOV?



#60 Jon Isaacs

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Posted 20 February 2015 - 08:54 PM

Been lurking....

 

Spend a night with me under Bortle 1 skies mid summer in central Nevada viewing the overhead Milky Way with my homemade 5 inch f/5.5 binocular and a lot of this back and forth would be academic.

 

:shocked:

 

I suspect some objects would be better seen in your 5 inch F/5.5 Binoculars and some in your 15 inch F/5 Discovery.. 

 

But I would like to join you to look through the binos.. 

 

Jon



#61 faackanders2

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Posted 20 February 2015 - 09:29 PM

For me I decided YES.

For a long time I also thought about using 5" or even 6" achromats, but I would not have been happy with the CA and poor contrast at all. Magnifications above 75x would not have been to funny.

 

So I am currently building a binoscope using two Borg 125 ED refractors and the wonderful Matsumoto EMS binobacks.

This Instrument will be usable for deepsky, planets and even the sun in whitelight or together with two coronados :-)

Weight ans size of the DoubleBorg is extremely small, together with a fast cooling down of the doublets this scope will be used a lot, even for short sessions.

 

I am sure that I will love this instrument and my question is more if there is a need for a bigger binoscope using two 14" f/5 mirrors.

I think this could be really breathtaking...

 

Best wishes Jochen

Then you may like JMI's 10" or 16" bino (reflector) telescope



#62 GlennLeDrew

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Posted 20 February 2015 - 09:39 PM

Nearly 20 years ago I built a 5" f/5 bino for a friend. It used 3 mirrors per side (hence mirror-reversed images) and used 2" helical focusers fixed at a 62mm IPD. With 30mm 80 degree AFoV eyepieces the TFoV is 4 degrees. In spite of the achromatic objectives, passable lunar/planetary views are had at 130X. On-the-fly collimation is via a pair of thumb screws per side, they adjusting the 90 degree mirrors which first intercept the light.

I could only enjoy a hint of their binocular performance due to the pupil clipping at my IPD of 67mm.

About image summation. In our brain this works very like the average combining of CCD images. Signal to noise is increased by the square root of two, or a factor of 1.41. This amounts to an equivalent gain of 0.37 magnitude. I find not a darkening of the sky, as noted by some others. Rather, the view just becomes more definite, with a more lively presence. The same gains are realized with the unaided eyes as for a small bino or a huge bino. That is, the qualitative improvement found by opening the other eye after gazing naked-eye with just one is the same as the enjoyed after uncapping the second objective on any binocular; the same 41% improvement in signal to noise obtains.

#63 Oberon

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Posted 20 February 2015 - 10:01 PM

What would you or the market pay for a compact binoscope with the following features?

 

1. 5" f/5.5 Istar objectives (or similar, option to upgrade or supply own) 

2. 2" Moonlite or similar quality focusers suited for up to 17mm Ethos, 24mm Panoptic or 32mm Erfle

3. Up to 3 degree unvignetted field of view

4. Portable; able to break down and fit into carry on luggage sized suitcase for aircraft including with stand

5. Setting circles on very stable alt az mount

6. able to be used from a table or its own stand

7. IPD adjustable from 56mm to 75mm

8. Single reflection (better throughput but inverted image not suited for terrestrial use)

9. Option to fit 3rd focuser for camera use (one side remains available for eye)

10. General fit and finish to similar engineering standard as Moonlite focusers, ie, would look nothing at all like any available commercial binocular

 

Why do I ask? I'd like some for myself, I have roughed out a design to the point of making a prototype, and I'm wondering how big the market might be for a portable instrument with these features.

 

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#64 schang

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Posted 20 February 2015 - 10:02 PM

My binocular project is fairly basic and kind of a trial to see if I like it. My inspiration came from Mr Bill and his bino box.

 

I am trying to make it even simpler by using offset objectives and thus getting away with only one diagonal mirror per side. The IPD will be fixed at my own 68mm IPD.

 

The focusers are simple helical units from Baader with limited travel. More or less like a normal IF binocular. Just enough focuser travel to allow fine tuning. For eyepieces I will be limited to ones with similar focus point to the 24mm Panoptics. This will include 19mm Panoptics, type 6 Naglers and TV plossl's.

 

I am aiming to keep costs down. I hope to make some more progress over the next month or so.

 

attachicon.gifIMG_1047 - Copy.JPG

Have you looked into using pentprism/porro prism combination for the binoscope? This may be a simple design as well ...though the actual scope construction of all designs will not be easy both from aesthetic and precision standpoints.  To this end, I opt using my giant binocular (straight thru) based on the economic and  time consideration.  Maybe one of these days...


Edited by schang, 21 February 2015 - 08:58 AM.


#65 Scott Beith

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Posted 21 February 2015 - 08:06 AM

Joe Castoro was making these for years...  even had a dual Tak binoscope. Seems the market isn't really there.

I think I remember seeing a photo of the side by side Tak's.  I thought it was pretty neat.  They were FS102's if I remember correctly.

 

 

Dang I scrolled through the rest of the thread and Mr. Bill posted a pic.  I am a bit slow this morning.  ;)



#66 Mr. Bill

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Posted 21 February 2015 - 11:12 AM

 

Joe Castoro was making these for years...  even had a dual Tak binoscope. Seems the market isn't really there.

I think I remember seeing a photo of the side by side Tak's.  I thought it was pretty neat.  They were FS102's if I remember correctly.

 

 

Dang I scrolled through the rest of the thread and Mr. Bill posted a pic.  I am a bit slow this morning.   ;)

 

 

Hi Scott

 

This is a pair of Tak 150 f/8s.....took this at the 2011 Okie-Tex SP. 

 

Impressive views but I would't trade it for my BinoBox.

 

Different horses for different courses.... ;)


Edited by Mr. Bill, 21 February 2015 - 04:17 PM.


#67 Mr. Bill

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Posted 21 February 2015 - 11:15 AM

 

Been lurking....

 

Spend a night with me under Bortle 1 skies mid summer in central Nevada viewing the overhead Milky Way with my homemade 5 inch f/5.5 binocular and a lot of this back and forth would be academic.

 

:shocked:

 

I suspect some objects would be better seen in your 5 inch F/5.5 Binoculars and some in your 15 inch F/5 Discovery.. 

 

But I would like to join you to look through the binos.. 

 

Jon

 

 

The BinoBox is perfect for viewing large scale MW structure, which is my interest these days.

 

The 15 inch is great for touring summer MW "eye candy"



#68 Mr. Bill

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Posted 21 February 2015 - 04:21 PM

 

Been lurking....

 

Spend a night with me under Bortle 1 skies mid summer in central Nevada viewing the overhead Milky Way with my homemade 5 inch f/5.5 binocular and a lot of this back and forth would be academic.

 

:shocked:

 

Excellent. Trip to Nevada here we come!

So...what is your widest APOV field eyepiece and what is your widest TFOV?

 

 

24mm Pan.....about 2.33 degrees. Big enough to show structure while still seeing detail.



#69 Gordon Rayner

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Posted 22 February 2015 - 01:04 AM

Plyscope:

You show two Baader focusers. Do they hold 2 inch diameter oculars?

Would two of those focusers interfere at 65mm. IPD. If so might a lune(?) be cut away from one or both to provide clearance?

Are they multiply threaded, with shallow truncated thread forms, ff. military binocular tank optics, binoculars, ship binoculars, Fuji, Nikon, Kowa, Toko, Nikko, WW II Busch,, Zeiss, Leitz, etc.?

Or, are they just single thread, deep thread form wasters of nose space, as are most/all of focusers for the monocular telescope business, in which there is no need to consider a space budget
between two eyepieces of a binocular instrument?

#70 plyscope

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Posted 22 February 2015 - 02:42 AM

Hi Gordon

 

These Baader focusers are 1.25" only. They have a fine thread and total travel is probably only 1/4". Two of them do not interfere at 68mm, I think 65mm would be fine also. I can confirm that in a weeks time when I'm home again. They are designed to screw onto the T2 thread of a Baader diagonal or other T2 accessories.

 

Once you have the eyepieces in them then the nose clearance is fine.

 

Here is a link;

http://www.teleskop-...2-to-1-25-.html



#71 nicknacknock

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Posted 22 February 2015 - 03:33 AM

 

I have only used it down to f6 and I would consider the view very acceptable, but I will soon try it on a f5.5 telescope and see how it performs there.

 

thank you. That would be terrific.

 

 

Although the thread has changed in respect of eyepieces to be used, I did check the Edmund Scientific 32mm last night with my 60mm f5.5 Doublet. Not that I expected any different as I use this eyepiece with an f10 telescope but the results are as follows:

 

1. Massive field close to 7.5 degrees, slightly larger than my Nagler 31mm which I used for reference. So, the field stop measurement of 42.7 appears to be fairly accurate.

 

2. It definitely helps with balancing since this eyepiece is much lighter, but at the expense of requiring more focus travel to the outside as the body of the Edmund is such that the lens group is nearly flush with the diagonal insertion point.

 

3. Views up to 50% from the center are fantastic and then field curvature comes into play. By 75% you think that stars are orbiting a black hole and by 90% you think that the stars are about to fall into the event horizon of that black hole.

 

The point being that with such a massive field, I didn't care much about field curvature and will definitely use the eyepiece in the summer with this scope to enjoy the Milky Way. But I would really think about using such eyepieces for a binoscope. They would yield 3.5 degrees TFOV but at the expense of the views from 50% out, meaning that at this FOV, field curvature will become distracting. 



#72 Oberon

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Posted 22 February 2015 - 04:36 AM

Thank you Nick that was very helpful.



#73 Jon Isaacs

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Posted 22 February 2015 - 06:15 AM

 

 

3. Views up to 50% from the center are fantastic and then field curvature comes into play. By 75% you think that stars are orbiting a black hole and by 90% you think that the stars are about to fall into the event horizon of that black hole.

The point being that with such a massive field, I didn't care much about field curvature and will definitely use the eyepiece in the summer with this scope to enjoy the Milky Way. But I would really think about using such eyepieces for a binoscope. They would yield 3.5 degrees TFOV but at the expense of the views from 50% out, meaning that at this FOV, field curvature will become distracting.

 

Field curvature in a 60mm F/5.5 doublet will rather extreme.  I calculate that the focus at the edge of the field with a 42mm field stop will be 2.0mm further in than at the center.  In the 5 inch F/5.5 it will be slightly less that half that and since the area of the defocused star is what we see, it will be much less apparent. 

 

But in evaluating the difference between these two eyepieces at F/5.5, the issue is the astigmatism, not so much the field curvature because the field curvature is a function of focal length.  What did the edge views look like when the edge was brought to focus rather than the center?

 

Jon



#74 nicknacknock

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Posted 22 February 2015 - 07:46 AM

 

 

 

3. Views up to 50% from the center are fantastic and then field curvature comes into play. By 75% you think that stars are orbiting a black hole and by 90% you think that the stars are about to fall into the event horizon of that black hole.

The point being that with such a massive field, I didn't care much about field curvature and will definitely use the eyepiece in the summer with this scope to enjoy the Milky Way. But I would really think about using such eyepieces for a binoscope. They would yield 3.5 degrees TFOV but at the expense of the views from 50% out, meaning that at this FOV, field curvature will become distracting.

 

Field curvature in a 60mm F/5.5 doublet will rather extreme.  I calculate that the focus at the edge of the field with a 42mm field stop will be 2.0mm further in than at the center.  In the 5 inch F/5.5 it will be slightly less that half that and since the area of the defocused star is what we see, it will be much less apparent. 

 

But in evaluating the difference between these two eyepieces at F/5.5, the issue is the astigmatism, not so much the field curvature because the field curvature is a function of focal length.  What did the edge views look like when the edge was brought to focus rather than the center?

 

Jon

 

 

Pretty severe Jon. Actually astigmatism rears its head even more than field curvature with this eyepiece, hence my reference to stars about to drop in a black hole's event horizon. 

 

Should have been clearer about it - my bad. Whereas field curvature appears at 50% and is not so distracting, at 75% the mix of curvature and astigmatism is a bit too much. At 85% out astigmatism takes over completely and as you approach the field stop, stars appear as elongated streaks orbiting the center of the eyepiece, even in focus.

 

I originally got this eyepiece in anticipation of getting a long focal length refractor  to be used with lightweight eyepieces and I got my 90mm f10.1 a week ago. I was lucky enough to have clear skies on Friday and tested the combination.

 

Obviously no field curvature and astigmatism in that scope showed up only on the last 5% - 7% of the view, which considering the expansive AFOV of the eyepiece, this is very acceptable!

 

There is a reason why well corrected wide field eyepieces are bigger and weight more. More glass is required to correct the image. Ultimately, I guess it depends on the user and what is acceptable for each person, but to invest a significant amount of money on a binoscope only to not get the best out of it, is not a value proposition for me.

 

Keep in mind that the Edmund 32mm easily outperformed my Nagler 31mm on axis. By easily I mean that the amount of detail on the Leo Triplet was clearly better in the Edmund (visibility of NGC 3628 as a test) and the number of stars visible in M67 was higher again in the Edmund. OK, not a tremendous difference, but certainly something which could easily be seen.



#75 nicknacknock

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Posted 22 February 2015 - 07:52 AM

And for those unfamiliar with the Edmund 32mm RKE eyepiece, a couple of photos of the eyepiece with friends.

 

 



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