-
Welcome to BirdForum, the internet's largest birding community with thousands of members from all over the world. The forums are dedicated to wild birds, birding, binoculars and equipment and all that goes with it.
Please register for an account to take part in the discussions in the forum, post your pictures in the gallery and more.
Prisms! S-P, Uppendahl, Abbe-Koenig.. (1 Viewer)
- Thread starter wdc
- Start date
Chosun Juan
Given to Fly
wdc
Well-known member
..................... and I sure don't plan to join Brock and Joe down in the rabbit hole discussing irrelevant or fanciful objective designs or glass types "we know nothing about". -- Henry Link
Chosun, In examining your .sig, which I think you've had ever since I've been a member, it seems like a rather prescient statement with regard to this thread, wouldn't you say?... ;-)
Are we not just digging a new rabbit hole? Maybe we're doing a bit more homework...
I see it primarily as a learning opportunity, with no expectations. Bicycles can be 'built up' ,component by component, on a specified frame. Isn't that the service a company like Kamakura essentially offers? I do not expect miracles in this process...
Uppendahl, no (only one source, unless its all NOS, and no longer in production), Perger-Porro, nope (Leica patent rights)...
Abbe-? S-P? Porro? Only 3 options left.
Birding tomorrow! No more speculative optics fantasies for at least 24 hours...
-Bill
Chosun, In examining your .sig, which I think you've had ever since I've been a member, it seems like a rather prescient statement with regard to this thread, wouldn't you say?... ;-)
Are we not just digging a new rabbit hole? Maybe we're doing a bit more homework...
I see it primarily as a learning opportunity, with no expectations. Bicycles can be 'built up' ,component by component, on a specified frame. Isn't that the service a company like Kamakura essentially offers? I do not expect miracles in this process...
Uppendahl, no (only one source, unless its all NOS, and no longer in production), Perger-Porro, nope (Leica patent rights)...
Abbe-? S-P? Porro? Only 3 options left.
Birding tomorrow! No more speculative optics fantasies for at least 24 hours...
-Bill
Last edited:
I really do not think prisms are desirable optical components.
Lenses have symmetry, so they are relatively easy to align correctly and hold firmly.
Prisms are asymmetrical objects intolerant of misalignment. They have no place in the optical train imho, because mistakes happen all to readily and bumps are a fact of life.
At worst, the extra lens for an all lens system needs to be a lot faster. to keep the length down. That seems doable, considering what is possible in the camera lens world.
Lenses have symmetry, so they are relatively easy to align correctly and hold firmly.
Prisms are asymmetrical objects intolerant of misalignment. They have no place in the optical train imho, because mistakes happen all to readily and bumps are a fact of life.
At worst, the extra lens for an all lens system needs to be a lot faster. to keep the length down. That seems doable, considering what is possible in the camera lens world.
Hi Etudiant,
Camera lenses don't need to erect the images.
The image is upside down.
It is only needed for the viewfinder on SLRs.
On rangefinder cameras the viewfinders are Galilean reversed optics usually.
Relay lenses for binoculars make for a long instrument.
Regards,
B.
Camera lenses don't need to erect the images.
The image is upside down.
It is only needed for the viewfinder on SLRs.
On rangefinder cameras the viewfinders are Galilean reversed optics usually.
Relay lenses for binoculars make for a long instrument.
Regards,
B.
wdc
Well-known member
Interesting ideas. What has kept an all lens binocular from happening in the last 100 years or so? Especially considering the development of camera lenses in that time? Is it only image erecting issues, length of the optical train, or something else? AFAIK, SLR film cameras all used an erecting prism in the viewfinder, so the lens was providing an inverted image onto the film.
As for faster lenses, my only concern there would be an increase in CA.
-Bill
The thought is that a fast relay lens will address the length issue.
One sees lots of rifle scopes that are not excessively long, so I'm hopeful it is practicable.
I accept that CA for a fast relay lens is an issue potentially.
There are quite a few SLRs that use mirrors for the viewfinder rather than prisms.
Some such as the Wrayflex use just one mirror for a reversed image but very nice look and reduced height.
Others use two mirrors for a correct image but increased height.
Some cameras use mirrors to fold the light path onto the image for a very slim package.
I would think that high end mirrors could be used in binoculars, but few use these.
There are erect image eyepieces but these usually have small fields.
B.
P.S.
The Ucaflex from about 1950 uses a mirror and prism for a periscope effect.
It has a reduced height.
A friend had one, but it was too expensive for me to buy.
They are rather rare, but I don't know how much they cost nowadays.
Some such as the Wrayflex use just one mirror for a reversed image but very nice look and reduced height.
Others use two mirrors for a correct image but increased height.
Some cameras use mirrors to fold the light path onto the image for a very slim package.
I would think that high end mirrors could be used in binoculars, but few use these.
There are erect image eyepieces but these usually have small fields.
B.
P.S.
The Ucaflex from about 1950 uses a mirror and prism for a periscope effect.
It has a reduced height.
A friend had one, but it was too expensive for me to buy.
They are rather rare, but I don't know how much they cost nowadays.
Last edited:
The issue is not the prisms per se, but rather all the non axi-symmetric elements, whatever they may be.
The hope is to create a much cheaper and more robust device.
Omid
Well-known member
I too believe it is practical to make binoculars with lens-based erectors. There are premium-class riflescopes made by a [formerly] premium-class manufacturer which are only 30cm long:
https://www.schmidtundbender.de/en/products/police-military-forces/5-20x50-pm-ii-ultra-short.html
Gijs van Ginkel
Well-known member
Omid, post 70,
30 cm is at the long side for my theater binocular, I will be arrested probably when I try to use them in the theater.
Gijs van Ginkel
30 cm is at the long side for my theater binocular, I will be arrested probably when I try to use them in the theater.
Gijs van Ginkel
Chosun Juan
Given to Fly
John A Roberts
Well-known member
Prism-less Binoculars?
Why not dispense with prisms and just use lenses? Back at post #32 etudiant raised this question
By chance I’ve just come across a similar discussion in Cloudy Nights from March 2019: https://www.cloudynights.com/topic/653361-why-no-bins-in-rifle-scope-design/
Particularly see post #14 by the always informative Rich V, quoting from Greivenkamp and Steed
In brief, prism-less binoculars, even with very small objectives:
- were very long in use (see the image from G & S), and
- if designed to collapse for carry, there were considerable technical difficulties
In relation to the latter, perhaps akin to achieving a quality zoom binocular today?
John
And even with updated cosmetics, would you buy one? . . .
Why not dispense with prisms and just use lenses? Back at post #32 etudiant raised this question
By chance I’ve just come across a similar discussion in Cloudy Nights from March 2019: https://www.cloudynights.com/topic/653361-why-no-bins-in-rifle-scope-design/
Particularly see post #14 by the always informative Rich V, quoting from Greivenkamp and Steed
In brief, prism-less binoculars, even with very small objectives:
- were very long in use (see the image from G & S), and
- if designed to collapse for carry, there were considerable technical difficulties
In relation to the latter, perhaps akin to achieving a quality zoom binocular today?
John
And even with updated cosmetics, would you buy one? . . .
Attachments
Last edited:
wdc
Well-known member
Thanks for posting these pictures John. As to the question of a contemporary version, they don't seem physically practical at all unless the objective size was quite small. Perhaps a handheld mount in the manner of a modified stock might be the best way to use them, but then how would the focuser be accessed? The last question is whether the 2 lenses offer any advantage over a prism in terms of light transmission, CA, or field distortion. If not, then there may be no clear rationalization for modernizing that format.
Maybe weight is less with lens than prism? Binocular spotting scope on a mount?
They do have a steam punk vibe, so might find favor in that culture, for goth bird watching festivals (bats!)
-Bill
Last edited:
John A Roberts
Well-known member
Hi Bill,
Now that you mention it, . . . they just might very well be the perfect choice for some of those folks on Bat Forum (‘the forum for wild bats and bating’)!
John
Now that you mention it, . . . they just might very well be the perfect choice for some of those folks on Bat Forum (‘the forum for wild bats and bating’)!
John
