Do all roof prism binoculars have 4 lense objectives?

[orbitaljump]

Id like to pick the brains of all the roof prism historians out there.

If not when did the 4 element objective hit the scene....and when did they become widespread?

Thanks!

Porrofan

[orbitaljump]

Also what types of prisms do most roofs use?

Abbe Koenig
Schmidt-Pechan

Aparently the Abbe Koenig is pretty rare.....is this true? What do the old Leicas use. The binocular that I can say without a doubt uses the Abbe Koenig is the old Zeiss 7x42 and 10x40 B/GAs.

Thanks again!

[henry link]

I'm probably forgeting something, but I can't think of any 4 element objectives (three fixed and one moving focusing element) before the Leica Trinovid BA about 1990. As I recall Zeiss followed shortly after with the Night Owls and Nikon sometime in the late 90's with the LX/HG. Swarovki SLC (except the 2 element 8x30) and EL use only 3 elements (2 fixed and 1 focusing). Zeiss 8x56 and 10x56 FLs use 5 elements (3 fixed and a doublet focusing lens). I have an old Kern 7x50 Focalpin Porro from the 80's which used a three element objective very similar to current roofs (a fixed air spaced doublet and a moving focusing element).

Only the 7x42, 8x56 and 6x42 Dialyts used AK prisms. The 10x40 and all the others used Schmidt-Pechan. The Current 42mm and 56mm FLs and the 40 and 50mm Conquests use AK. The original Leitz Trinovids used Uppendahl prisms, made by cementing three prisms into a monoblock. That was apparently an expensive prism to make, with no big advantage over Schmidt-Pechan.

[ceasar]

My Leitz (Old Leica's) 7 x 42 Trinovid BN has Uppendahl Roof Prisms. I don't know if they were ever used extensively by any other binocular manufacturers. They look like this: (see comparison with Abbe-Koenig)
http://www.google.com/search?hl=en&client=firefox-a&channel=s&rls=org.mozilla:en-US:official&q=Uppendahl+prism&start=30&sa=N
Bob

Here is an interesting list of Leitz Binoculars:http://www.europa.com/~telscope/leitzbin.txt

[orbitaljump]

Well I just read that my Pentax 8x32 SPs use a 4 element objective.....then checked the Meopta Meostar and it too had a 4 element objective. Thus prompting my interest...and thus questions.

Pentax had 4 elements in 3 groups listed.

http://www.samys.com/product_detail.php?item=7302

The Meoptra site had a cutaway diagram of the Meostar....which I read too quickly aparently....reading and looking again its 5 elements.

http://www.meopta.com/?id=176

Thanks for the prism information and clearing up my faulty info on the 10x40 B/GA.

[orbitaljump]

Here the Minox BD 8x32...

4 lenses in 3 groups

http://www.amazon.com/Minox-BD-8x32-BR-Binocular/dp/B00017LUKQ

[henry link]

The Meopta labeling is not so clear. The objective appears to be 4 elements, a cemented doublet up front, then the moving focusing element and then the fourth objective element quite unusually placed just in front of the prism.

All of the others you are referencing use the typical arrangement, a fixed triplet consisting of a cemented doublet and a singlet at the front and a moving focusing element behind, thus 4 elements in 3 groups.

[orbitaljump]

So that is the standard configuration today, henry?

4 elements 3 groups.

How about a Nikon roof from the 80s....like the 9x30.

[orbitaljump]

Here we have the Pentax DCF HS 8x36....

Objective Lens: 2 elements in 1 group;
Eyepiece Lens: 3 elements in 2 groups

http://www.opticsplanet.net/62600.html

[Kevin Purcell]

In general and excluding the focuser elements which some include in the objective to give a bigger count (bigger being better right).

Most likley is two: the classic achromatic doublet.

Next is three: sometimes in an "Apo" triplet (focusing three wavelengths of light to a single point rather than just two in the achromat).

And some have 4: the Zeiss Dialyt is named after the four element Dialyt lens that they use for their objective (it has a long history!) the design of two meniscus lenses facing "out" and two facing "in" helps reduce spherical and chromatic aberration but of course costs more to make (more lenses) and puts a bigger emphasis on getting them made accurately and aligned accurately (otherwise you don't get the useful cancellations). I beleive the current Zeiss FLs use the same scheme and suspect (but only suspect) the Victory range did the same thing. A Zeiss expert could correct me on that one ;)

http://en.wikipedia.org/wiki/Dialyt_lens

I'm not sure if the focusing element is separate with a dialyt objective. I believe it is.

Schmidt-Pechan is used in most roof prisms bins. AFAIK Zeiss is the only one to use the Abbe-Konig but then again Abbe worked for Zeiss ;). The AK makes for longer bins too which counted against it but relied on total internal reflection so it has very high transmission and advantage over older SP. With dielectric mirrors the SP now can do almost as well. All roof prisms need phase correction to work best.

The wikipedia has pretty good articles on the roof prisms (given I wrote big chunks of the SP article ;) )

http://en.wikipedia.org/wiki/Roof_prism
http://en.wikipedia.org/wiki/Abbe-Koenig_prism
http://en.wikipedia.org/wiki/Schmidt-Pechan_prism

The other thing to look at is the number of elements in the EP. Typically it's 4 though some of the "fancier" EPs go to 5 with an aspherical element (e.g. the Pentax SP).

Pentax with the HS reduced the number of elements: I rather wonder if they went to 3 with one of them being aspherical (rather than going back to a plain Kelner or reversed Kelner design). The view has some odd edge darkening that is rather like the SP when you don't get the exit pupil aligned quite right. It also has a very flat AFOV (that is only about 50-odd degrees). Perhaps it's cheaper for them to make a reversed Kelner with an aspherical lens and so reduce the lens count in the EP along with coating, assembly and testing costs but still get a flat AFOV and reduce aberrations. Interesting idea if it's true!

That would also explain the "S" in "HS". ;)

[ThoLa]

....AFAIK Zeiss is the only one to use the Abbe-Konig but then again Abbe worked for Zeiss ;).

And so did Dr. Albert König. He joined Zeiss in 1894 and stayed there for more than 50 years. He was a long standing director of the department for "Earth Telescopes" (= binoculars, etc.)

T

[bralk]

Here are some good illustrations of different types of prisms
http://www.tecplusplus.de/ManualLu/prisms.htm

cheers
Tom

[Tero]

As much as I enjoy trying different models, have not enjoyed the Abbe-Konig experience with the Conquests. The sharpness was no better than Pentax SP and I think there was more CA. Something in any case I did not enjoy in the view. It is possible they were brighter at dusk.

[henry link]

In general and excluding the focuser elements which some include in the objective to give a bigger count (bigger being better right).

Most likley is two: the classic achromatic doublet.

Next is three: sometimes in an "Apo" triplet (focusing three wavelengths of light to a single point rather than just two in the achromat).

And some have 4: the Zeiss Dialyt is named after the four element Dialyt lens that they use for their objective (it has a long history!) the design of two meniscus lenses facing "out" and two facing "in" helps reduce spherical and chromatic aberration but of course costs more to make (more lenses) and puts a bigger emphasis on getting them made accurately and aligned accurately (otherwise you don't get the useful cancellations). I beleive the current Zeiss FLs use the same scheme and suspect (but only suspect) the Victory range did the same thing. A Zeiss expert could correct me on that one ;)

I'm not sure if the focusing element is separate with a dialyt objective. I believe it is.

The other thing to look at is the number of elements in the EP. Typically it's 4 though some of the "fancier" EPs go to 5 with an aspherical element (e.g. the Pentax SP).



Kevin,

I think the focusing lens is included as an objective element because of it's position in the optical train as one of the image forming elements in front of the objective focal plane.

I'm not sure why Zeiss chose the "Dialyt" trademark. The name was long used by Hensoldt for their AK prism binoculars, so perhaps Zeiss just kept it when they began, in 1964, to use the Zeiss name on roof prism binoculars made at the Hensoldt factory. As far as I can see from examining internal views in various old Zeiss brochures the Dialyt camera lens design was not used in the Zeiss Dialyt binoculars. The objectives are conventional doublets. There are no internal focusing elements. The CF Schmidt-Pechan models focus by moving the objectives and the AK models work just like Porros by moving the eyepieces. The one odd ball is the IF Schmidt-Pechan 8x30 Safari which uses moving eyepieces.

Current FLs and the earlier Victories use a triplet in front (cemented doublet separated by an air space from a singlet) combined with a singlet focusing lens (doublet in the 56mm FLs)

Binocular eyepieces range from three to seven elements.

Henry

EDIT: Here's a drawing of an old Hensoldt "Dialyt" design showing a doublet objective.

http://zeun.info/hens_prism.htm

[henry link]

So that is the standard configuration today, henry?

4 elements 3 groups.

How about a Nikon roof from the 80s....like the 9x30.

I'm not sure I would say there is standard configuration for roof objectives, but AFAIK most "4 element" objectives are fixed triplets with a moving singlet focusing lens.

The only Nikon roof from the 80's I'm sure about is the 8x40DCF. It was the high end Nikon roof model of the time. It had no separate internal focusing element. Focused was done by moving the entire triplet objective. Unlike the Zeiss Dialyts that focused that way the Nikon maintained water tightness by using a flat protective glass plate to seal the front of the binocular

Henry

[Kevin Purcell]

I'm not sure why Zeiss chose the "Dialyt" trademark. The name was long used by Hensoldt for their AK prism binoculars, so perhaps Zeiss just kept it when they began, in 1964, to use the Zeiss name on roof prism binoculars made at the Hensoldt factory. As far as I can see from examining internal views in various old Zeiss brochures the Dialyt camera lens design was not used in the Zeiss Dialyt binoculars. The objectives are conventional doublets. There are no internal focusing elements. The CF Schmidt-Pechan models focus by moving the objectives and the AK models work just like Porros by moving the eyepieces. The one odd ball is the IF Schmidt-Pechan 8x30 Safari which uses moving eyepieces.

I could swear I saw a cutaway that looked like a dialyt (lens) to me in Zeiss bin but now I can't find it. Perhaps an overactive imagination? ;)

This Zeiss Victory FL 8x32 cutaway shows the optical set up a bit more clearly: EP 5 lenses in 3 groups and triplet objective with a single lense (plano-concave) focuser. Baffling is rather simple two: two knife edge apertures and a stepped baffle just in front of the prism.

http://www.birdforum.net/attachment.php?attachmentid=140172&d=1210880423

I see Zeiss do include all the lens at the objective end of the tube together e.g.

Victory 8 x 56 T* FL and 10x 56 T* FL These high-performing models feature a 5-lens objective and are the “light giants” of the FL class.

I didn't realize the AK Zeiss bins moved their eyepieces ... that explains the "waterproof vs waterr-resistant" Zeiss Dialyt arguments. I have to say I'm amazed that I never noticed the porro-oid external focusing system on the old Dialyts. In this BVD photo it is so, so clear. Not seeing the wood for the trees (or in this case, the trees for the wood).

http://www.betterviewdesired.com/images/mitclassic.jpg

Regarding focusing you can: move the objective lens; move a focusing lens before the prism; move the focusing lens after the prism; or move the eyepieces. I think different companies have done all of these at one time or another.

One thing that struck me about the current Pentax HS recently is the exterior of the "objective lens" is flat. Initially I though they had a fixed flat plate and were moving the objective lens inside the barrel (as you can see the moving focusing element that's the "full width" of the barrel) but some light bouncing seems to indicate this external element is plano-convex on the inside. But the comment above that "Objective Lens: 2 elements in 1 group" could be that arrangement or a doublet behind a flat plate. I'd like someone else to check that. Perhaps it is just a flat plate and they move a doublet objective inside the barrel. It would make the bin work with relatively few elements. And it does work rather well. Though one might have thought it would be JIS 6 rather than JIS 4 with so few moving parts.

[orbitaljump]

Henry, Ive got a book here that has a cutaway diagram of the Kern Focalpins. Ill see if I can snap a photo and post.

[elkcub]

... I'm not sure why Zeiss chose the "Dialyt" trademark. The name was long used by Hensoldt for their AK prism binoculars, so perhaps Zeiss just kept it when they began, in 1964, to use the Zeiss name on roof prism binoculars made at the Hensoldt factory.

Henry,

It may have to do with the nature of the original prism patents. It would appear from this 1932 S&A catalog that the prisms were originally patented as "Dialyt-prisms" by Hensoldt (Swift & Anderson was their sole US distributor from 1926.) There is no mention of A-K, a designation that appears to have been introduced by Zeiss decades later. I guess one might question the primacy of "A-K," since Mr. Dialyt wasn't there to defend himself. :)

Note on pg. 3 "...The only Prism Binoculars in which the prism system may be removed intact, cleaned and replaced in case of emergency." These festideous people thought of everything. Any idea what $70 in 1932 would be worth today? :eek!:

Ed

[orbitaljump]

Here you go, Henry.

[elkcub]

OJ,

What book or catalog is that from?

Ed

[henry link]

Thanks, orbitaljump

Here's a little more detailed view of the Kern Focalpin optics, showing the air-spaced objective. Interesting design ideas for the time, but unfortunately the actual binocular is only adequate optically, nothing outstanding.

Henry

[orbitaljump]

Binoculars and Scopes

and their uses in photography for:

Astronomers
Sportsmen
Birdwatchers
Hikers and
Nature Lovers

Robert J. and Elsa Reichert


Modern Camera Guide Series

Chilton Company - Book Division

Copyright 1961

LOC Catalog no. 61-5626


I have a signed copy with both Robert's and Elsa's signatures. I think these folks are affiliated with Mirakel, out of New York.

[henry link]

I didn't realize the Focalpin design went back as far as 1961. That makes it an even more interesting design for it's time.

I only recently bought a Kern 7x50 Focalpin after years of wondering just how good it was. Unbelievably, I ran into one that was actually NIB from the stock of a long defunct camera store in California. It dated from the last days of Kern in the late 80's and included an instruction booklet (printed in 1973), a yellowing warranty card to return to the long gone importer Karl Heitz in New York and, of course, a beautiful leather case and strap. All was apparently untouched as if from a time capsule..

[orbitaljump]

Sweet!

[henry link]

Henry,

It may have to do with the nature of the original prism patents. It would appear from this 1932 S&A catalog that the prisms were originally patented as "Dialyt-prisms" by Hensoldt (Swift & Anderson was their sole US distributor from 1926.) There is no mention of A-K, a designation that appears to have been introduced by Zeiss decades later. I guess one might question the primacy of "A-K," since Mr. Dialyt wasn't there to defend himself. :)

Note on pg. 3 "...The only Prism Binoculars in which the prism system may be removed intact, cleaned and replaced in case of emergency." These festideous people thought of everything. Any idea what $70 in 1932 would be worth today? :eek!:

Ed

Ed,

$70 in 1932 would be $1000 now according to one inflation calculator I Googled. Not cheap binoculars!

Henry

[Kevin Purcell]

Henry,

It may have to do with the nature of the original prism patents. It would appear from this 1932 S&A catalog that the prisms were originally patented as "Dialyt-prisms" by Hensoldt (Swift & Anderson was their sole US distributor from 1926.) There is no mention of A-K, a designation that appears to have been introduced by Zeiss decades later. I guess one might question the primacy of "A-K," since Mr. Dialyt wasn't there to defend himself. :)


From the monocular history side that Henry posted has this comments:

http://zeun.info/history/mono-history12.htm

Hensoldt deserves the award of being the first to make Penta-Prism-Monocles. They had a higher light transmission, allowed bigger objectives, and were made with flat hosuings with rounded corners. The prism is mounted on a cast-in prism-cage or later on a detachable prism-chair. The "Dialytic Pent-Prism Monocular" has two objective lenses - hence. dia-lyt (cf. later Dialyts).

Hmmm, so two elements of two lenses perhaps in the original Dialyt lens?

Also

http://zeun.info/history/mono-history15.htm

shows a couple of interesting things:

a porro monocular that focuses with the objective.

http://zeun.info/cz8x30co.htm

And perhaps an explanation for the odd placement of the tripod mount on the body of the prism housing rather than the end of the hinge. It was not common with porro monoculars!

http://zeun.info/atco6x30.htm

[elkcub]

Thanks, Kevin. That gives me some background on my own Zeiss monocular, as hijacked and shown below.

I'm planning to use it as a booster. Okay Henry? |:d|

Ed