Instead of two refracting lens barrels why couldn't a catadioptric or newtonian optical system be used in binoculars? What problems would have to be overcome?
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Why couldn't a catadioptric or newtonian optical system be used in binoculars? (1 Viewer)
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WJC
Well-known member
They ARE used in larger sizes
Both concepts just adds a lot of unnecessary work to the process.
From Jurassic Park: Just because you CAN do something, it doesn't follow that you should. You can get from NYC to LA via Miami, but who would WANT too?
Bill
Here you go.... configured as a reverse binocular. If I understand the way they work correctly you view looking away from the target with the 10" or 16" reflectors pointing over your shoulders.
http://www.company7.com/jmi/rbseries/rb10_data.html
http://www.company7.com/jmi/rbseries/rb16_data.html
David
http://www.company7.com/jmi/rbseries/rb10_data.html
http://www.company7.com/jmi/rbseries/rb16_data.html
David
jan van daalen
Well-known member
Taking Dennis his muscular cricket bat posture in consideration, this should not be a problem.
WJC
Well-known member
Wonderful, isn't air travel great!
Cheap flight and free visit to NYC, with Iceland thrown in. They used to have a great duty free at that airport, so you could reinvest your savings.
Awesome. Now if they could make them smaller for birding. It would be a simpler optical design than having ten lenses in each optical tube of a binocular like they are now. No CA without having ED glass and all that stuff. These would be fantastic for astronomy. $5K for the 10 inch isn't bad. I would imagine alignment could be a nightmare though.
"A professor and several of us serious astronomers spent the night trying to find words to describe what we were seeing. We were dumbstruck, blown away, astonished...it's unspeakable. The views are beyond the power of mere mortals to put into words The RB-10 changes everything. It is the greatest piece of optical equipment I've ever looked through." (Paul Carmody, RB-10 owner and customer of Company Seven who traded up from his 6" RB-66)"
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WJC
Well-known member
That is WAY oversimplified!
Forget the fold mirrors. A Newtonian system would require a FAST paraboloidal mirror, a Schmidt would require matching 4th order curves, and a Mak would require a meniscus setup. In addition, lenses converge light meaning other elements could be smaller. In a Maksutov system, the light leaving the corrector diverges, meaning some elements would need to be larger, thus adding weight. Finally, the secondary in both the Schmidt AND the Maksutov would have to be MATCHED to the main mirror. This is no simple task on bigger instruments and the problems multiple as the scale shrinks.
Bill
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I guess you would always have to deal with the fact that there has to be a secondary mirror somewhere to bring the image to the eyepiece and usually in a reflector it is in the light path which is going to degrade the resolution a small percentage which is ok in an astronomical telescope but would not be good thing in a birding binocular where you want resolution. Even an astronomical refractor has better resolution than an astronomical reflector. I would bet those big astro binoculars with 16 inch diameters would be something to look through on a dark sky say in the southern skies trained on the Magellanic clouds. Probably incredible.
Here's a pair of relector binoculars for $200. So it is possible.
http://www.aliexpress.com/store/pro...ing-Portable-Binoculars/909845_620106498.html
http://www.aliexpress.com/store/pro...ing-Portable-Binoculars/909845_620106498.html
Gijs van Ginkel
Well-known member
Dennis,
If you dive into the history of binoculars you will detect that diferent mirror type binoculars were made. A very famous one is the Bouwers design from Old Delft/Delft instruments, but only a few were made, since the consumers were not ready for it, I assume (if you want to read more about it, look at my powerpoint of Binoculars made in Holland and Belgium between 1600 and the present time on the WEB-site of House of Outdoor). Leitz also made a hybrid mirror binocular which involved the use of a mirro combined with a roof prism (te Amplivid 6x24 with a field of view of 214m/1000m).
Gijs
If you dive into the history of binoculars you will detect that diferent mirror type binoculars were made. A very famous one is the Bouwers design from Old Delft/Delft instruments, but only a few were made, since the consumers were not ready for it, I assume (if you want to read more about it, look at my powerpoint of Binoculars made in Holland and Belgium between 1600 and the present time on the WEB-site of House of Outdoor). Leitz also made a hybrid mirror binocular which involved the use of a mirro combined with a roof prism (te Amplivid 6x24 with a field of view of 214m/1000m).
Gijs
. The Yukon 30×50 binocular is a folded refractor. I have it and like it a lot, it has really excellent resolution but the transmission is low because of rather poor coatings. It is a bit heavy. The objective is probably a bit longer focal ratio than normal with binoculars.
Later they made a 20×50, but I don't have this.
They also do spotting scopes in 50 mm, 60 mm and 100 mm aperture that are also folded refractors.
As to the craziness of life, it was cheaper to send a letter from Scandinavia to England then back to Scandinavia, than it was to send it internally in Scandinavia. Also the postal language was French, but nobody in the main post office spoke French or understood it.
I'm not sure if investing in Iceland is a good idea. Our local Council lost £35 million doing exactly this, and we are still suffering the consequences. They are overpaid councillors who are not capable of running a corner shop let alone a council.
A British optical specialist completed half of a 12 inch Maksutov binocular, possibly the main mirror was F/1, I cannot remember. Unfortunately he did not live long enough to complete the instrument. I saw the half that he had made.
The Ampliivid 6×24 is a very nice and usable binocular which fits in your pocket. It has a wide field of view that is fully usable although the edge performance is not that good. The transmission is low so the images are a bit dull. It is a pity they don't make it nowadays with modern coatings.
Later they made a 20×50, but I don't have this.
They also do spotting scopes in 50 mm, 60 mm and 100 mm aperture that are also folded refractors.
As to the craziness of life, it was cheaper to send a letter from Scandinavia to England then back to Scandinavia, than it was to send it internally in Scandinavia. Also the postal language was French, but nobody in the main post office spoke French or understood it.
I'm not sure if investing in Iceland is a good idea. Our local Council lost £35 million doing exactly this, and we are still suffering the consequences. They are overpaid councillors who are not capable of running a corner shop let alone a council.
A British optical specialist completed half of a 12 inch Maksutov binocular, possibly the main mirror was F/1, I cannot remember. Unfortunately he did not live long enough to complete the instrument. I saw the half that he had made.
The Ampliivid 6×24 is a very nice and usable binocular which fits in your pocket. It has a wide field of view that is fully usable although the edge performance is not that good. The transmission is low so the images are a bit dull. It is a pity they don't make it nowadays with modern coatings.
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WJC
Well-known member
I doubt that the F/1 mirror would have killed him, as he didn't make mistakes. If it was an F/1 mirror it would have been corrected to work. He lived till an old age.
Schmidt Cassegrains usually have F/2 or F/1.95 mirrors and Maksutovs F/2.5.
A fellow expert made an ellipsoid mirror, I can't remember but maybe it was F/0.35. I cannot remember exactly but it was fast and military.
From memory, the fastest refractive lens is about F/0.57.
Schmidt Cassegrains usually have F/2 or F/1.95 mirrors and Maksutovs F/2.5.
A fellow expert made an ellipsoid mirror, I can't remember but maybe it was F/0.35. I cannot remember exactly but it was fast and military.
From memory, the fastest refractive lens is about F/0.57.
WJC
Well-known member
Sky and Telescope's & Telescope Making's Bob Cox "didn't make mistakes" either. But although he was a professional optician, he died before his personal 9-inch Schmidt would render a satisfying image. Some projects are life suckers.
Bill
Probably the longer focal ratio aids the resolution and gets rid of a lot of CA.
I have heard the Amplivid 6x24 are good binoculars. Sometimes they come up on Ebay and usually fetch a high price for their collector value.
I have actually thought about it. Such a binoculars should lack the CA problem as conventional binoculars suffer from, but would demand a larger aperture for a given brightness because of the central obstruction.
Apart from that a large exit pupil does not work good with a small eye pupil, so during daytime or when use against bright light sources more than 3-4mm exit pupil should cause a hazy image with the feeling of a diffuse obstacle in the way for the eye.
Apart from that a large exit pupil does not work good with a small eye pupil, so during daytime or when use against bright light sources more than 3-4mm exit pupil should cause a hazy image with the feeling of a diffuse obstacle in the way for the eye.
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