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$500,000 12 inch binocular vs. my 18 w/binoviewer?

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#1 Darren Drake

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Posted 23 January 2013 - 10:02 AM

Ok So Marcus and APM are now selling a half million $ 12-inch apo binocular. There is no question that this is an amazing instrument. I can't help but wonder however just how would a high power view compare to my 18 inch with excellent optics and a binoviewer and tracking. I suspect that the views would be similar but if seeing is extremely good my scope would show higher resolution. Brightness would be about the same. The area where the APM would totally dominate would be low power viewing. Even if I had shorter trusses to eliminate the need for a barlow the light concentrating power would only be half that as the binoculars as the exit pupil would hit the 7mm limit long before the they would in the APM. So there might on paper be a distinct advantage for each system. Or is this crazy and the APM would be just to good to compete with? I don't think so as I have seen mind blowing higher power binoviews of deep sky, lunar and planetary views with my setup. I however have yet to look through a high quality binoscope at least in recent years. Thoughts??? I post this here in reflectors amoung friends. I suspect a very different series of responses might come if I went to refractors... :smirk:

#2 GlennLeDrew

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Posted 23 January 2013 - 10:36 AM

At given exit pupil diameter, the true bino's image surface brightness is twice that of the BV-equipped cyclopean tube. At the observer's largest pupil diameter, the true bino will always then offer an image twice as bright, which can be of benefit under dark skies when ferreting out the really low contrast fuzzies.

This business of image surface brightness should always be the element of comparison at the forefront when comparing binos and binoviewers. Determining equivalences in other areas--such as stellar magnitude limits--is not nearly as meaningful.

If we amateurs get all hung up over differences in transmission/reflectance down to the 5-10% range, and pay premiums to obtain such improvements, surely a difference of a factor of two (!) cannot be ignored or waved off.

#3 Darenwh

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Posted 23 January 2013 - 11:13 AM

Besides, the owner of that half mil 12" apo bino has so much more bragging rights it's not even funny...
:yay:

#4 Qwickdraw

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Posted 23 January 2013 - 12:07 PM

I say buy the $500,000 binocular and compare the two side buy side.

#5 Darren Drake

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Posted 23 January 2013 - 12:21 PM

I once did a similar comparison. A buddy had a pair of Takahashi 20X60 binos and I put them up against my WO 80mm with binoviewers. Light grasp is similar and we used about the same power. Except for the mirror reversal in WO the views on terrestrial viewing were very close if not indistinguashable. This was far from a deatiled comparo but still interesting nontheless.

#6 Jarad

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Posted 23 January 2013 - 12:30 PM

The area where the 12" refractor binoscope will win is wide field. Since there is no CO, there is no downside to exceeding a 7mm exit pupil (you will still see the brightest image possible), where your reflector has problems due to the secondary (both with edge of field illumination and light loss due to the shadow of the secondary taking up more and more of the exit pupil that can fit into your eye).

At medium to high power, the extra resolving power of the 18" should win.

And your 18" has much less of a balance problem - there is still money left in your wallet to prevent you from falling forward onto it. ;)

Jarad

#7 Darren Drake

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Posted 23 January 2013 - 12:40 PM

Right looking through each eyepiece in the 18 is like looking through the scope with a 50% neutral density filter. So it's not possible to attain full brightness at the lower powers. And yes there is enough money left over to still have a house to live in lol.

#8 Jarad

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Posted 23 January 2013 - 02:22 PM

Right looking through each eyepiece in the 18 is like looking through the scope with a 50% neutral density filter.


This effectively makes your light gathering equivalent to the 12" true bino's. That's equivalent.

The low power issue is this:
In the 12" refractor bino, there is no CO. So let's say you want to look at the Pleiades at 30x to fit the whole thing in the field, that gives you an exit pupil of 10mm. If your eyes only open to 5mm, you effectively stop down the aperture to 6". But you are still seeing the view as brightly as possible for your eye with a 5mm exit pupil.

In your 18", you have a CO (let's say it's 3.5" for the sake of discussion, which equals just under 20%) that results in 70% illumination at the edge of a normal field. At 30x, your eye stops it down to 9", but it still has the 3.5" CO, so now your CO is up to almost 40% of the diameter that gets into your eye, and you are losing significantly more light to the CO. The field is wider, and the illumination drop off at the edge will now be very significant (in reality, with a 2" focuser it would 0%, but if you switched to a 4" custom one it would still be much dimmer at the edge unless you also made the secondary larger).

Jarad

#9 morceli

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Posted 23 January 2013 - 03:18 PM

I would like to know what kind of reflector one could buy for $500k. I would imagine a 60" f3 Starstructure with Lockwood mirror would be significantly less than that. Not sure what options would be for bigger than that.

#10 Jon Isaacs

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Posted 23 January 2013 - 06:59 PM

In the 12" refractor bino, there is no CO. So let's say you want to look at the Pleiades at 30x to fit the whole thing in the field, that gives you an exit pupil of 10mm. If your eyes only open to 5mm, you effectively stop down the aperture to 6". But you are still seeing the view as brightly as possible for your eye with a 5mm exit pupil.



There is one slight issue to consider... The binoculars have a 2300mm focal length. Assuming it has 2 inch focusers, the widest possible field of view will be 1.15 degrees. At 30x, this corresponds to a AFoV of about 35 degrees... A 41mm Panoptic provides the 1.15 degree TFoV at 56x with a 5.5 mm exit pupil.

If the skies are dark and clear, I am sure the views will be fantastic as they are in any scope when the skies are dark and clear.

Myself, it's looks too cumbersome to enjoy.

Jon

#11 norton67

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Posted 23 January 2013 - 09:06 PM

I just want to see a picture of it.

#12 norton67

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Posted 23 January 2013 - 09:06 PM

I just want to see a picture of it.

#13 Darren Drake

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Posted 23 January 2013 - 09:41 PM

http://www.cloudynig...5638471/page...

#14 Bill Weir

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Posted 24 January 2013 - 01:00 AM

Nice looking scope/bino but unless it's in a dark site doesn't seem worth the money. And to be clearer about the cost it's in Euro which at todays conversion rate = $665,754.95 USD

Bill

#15 norton67

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Posted 24 January 2013 - 04:48 AM

Thanks...does not look very portable...lol.

#16 Ed D

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Posted 24 January 2013 - 05:51 AM

I'm not sure that one would fit in the back of my Toyota. I'll pass.

Ed D

#17 killdabuddha

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Posted 24 January 2013 - 12:59 PM

In the 12" refractor bino, there is no CO. So let's say you want to look at the Pleiades at 30x to fit the whole thing in the field, that gives you an exit pupil of 10mm. If your eyes only open to 5mm, you effectively stop down the aperture to 6". But you are still seeing the view as brightly as possible for your eye with a 5mm exit pupil.



There is one slight issue to consider... The binoculars have a 2300mm focal length. Assuming it has 2 inch focusers, the widest possible field of view will be 1.15 degrees. At 30x, this corresponds to a AFoV of about 35 degrees... A 41mm Panoptic provides the 1.15 degree TFoV at 56x with a 5.5 mm exit pupil.


There is one other slight issue to consider, one which obviates the difficulties arising from such a comparison, and that's to simply build a 12.5" reflector bino at a cost which is less than its 17" BV counterpart. Sorry for pointing out the obvious, but...I'll be ready for Glenn and others to take the plunge eventually, especially once they do the math and see just how straightforward a proposition the reflecting bino is. Would that I were still in Chicago for you to compare, Darren, but we're in central NJ if anyone wants to see the difference and be convinced of the ease of owning yer own big bino.






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