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PostPosted: Sat Oct 19, 2013 3:41 pm    Post subject: Reply with quote
Orio wrote:
sichko wrote:

Oberkochen simply calls it a 5-element Gauss. See : http://blogs.zeiss.com/photo/en/wp-content/uploads/2011/07/en_CLB_40_Nasse_Lens_Names_Planar.pdf


John, it's not the same design. The Biometar has two cemented elements. The Planar in the scheme has 5 elements
in 5 groups.
Having that said, it's still possible that lens designers consider that a gauss lens. Definition depends on the way the light
is transmitted and not necessarily in the physical position of the elements. In order to know we should ask a lens designer,
but I don't know any Smile


Orio, I know that they are not exactly the same. However lots of people would consider then to be part of the same generic group : Gauss/Double Gauss. I don't think that the presence of cemented elements, or not, is important. The link I gave shows a picture with two Planar cross-sections side by side. Each has 5 elements. One is 5/5. The other is 5/4 with a cemented doublet. This doublet is at the front. However Zeiss has patent designs where the cemented doublet is the second group, as in the Biometar. These arrangements, the Oberkochen 5-element Planars, the Jena Biometar and the Schneider Xenotar are often placed under the umbrella of Gauss/Double-Gauss.


PostPosted: Sat Oct 19, 2013 4:33 pm    Post subject: Reply with quote
Check out sticky post if one want to do revision on the lens design.
http://forum.mflenses.com/list-of-lens-diagrams-triplets-planars-and-hybrid-lenses-t22934.html


PostPosted: Sat Oct 19, 2013 10:09 pm    Post subject: Reply with quote
iangreenhalgh1 wrote:
Sickho, please DO NOT ruin yet another thread with pointless pedantry.


Pedantry ? Ruining a thread ? How so ?

Ian, please read this thread ...

http://forum.mflenses.com/standard-lenses-40mm-60mm-must-haves-t61167,start,45.html#1342091

where Orio said...

Orio wrote:
iangreenhalgh1 wrote:

I'm thinking of the Sonnar 2/50 and 1.5/50 and their Russian copies and a good Triplet like the Meyer Trioplan 2.9/50.


Yes, they're part of the "different scheme" concept like the Tessar, which I mentioned as an example, but the same is valid for Sonnar, for a Triplet, for a Biometar (Sonnar-Gauss hybrid), even for a Meniscus for that matter Smile


3 minutes later, you said

iangreenhalgh1 wrote:
So we're in full agreement then! )

BTW, isn't the Biometar a simplified double Gauss?


So you say something which is presumably useful or informative. I say virtually the same thing in connection with the Biometar, to the same person, in this thread - which is about the Biometar, and you attack me ? Why ?


PostPosted: Sat Oct 19, 2013 10:17 pm    Post subject: Reply with quote
calvin83 wrote:
Check out sticky post if one want to do revision on the lens design.
http://forum.mflenses.com/list-of-lens-diagrams-triplets-planars-and-hybrid-lenses-t22934.html


Thanks for the link. The OP placed the Biometar in a "hybrid group" but admitted that there might be a case for describing it as something else. You yourself have described it as a Planar (an example of a Gauss/Double Gauss)

calvin83 wrote:
iangreenhalgh1 wrote:
calvin83 wrote:
iangreenhalgh1 wrote:
So we're in full agreement then! )

BTW, isn't the Biometar a simplified double Gauss?

Yes. And so with the Xenotar with the rear doublet replaced by single element.


My understanding is that the Biometar, Xenotar and Planar fitted to the Rolleiflex are all simplified double Gauss, in the case of the Biometar, the simplification is removing one element in the front group, and with the Xenotar, it is as you say - removal of one element in the back group. Wray's Unilite is also a simplified double Gauss.

To be precise, the Biometar, Xenotar and 5 elements Planar are simplified five element Planar type from the six element planar designed by Paul Rudolph. The original double-gauss design is 4e/4g. It seems most people refers the Planar when they think about double-gauss type lenses.


from ...

http://forum.mflenses.com/standard-lenses-40mm-60mm-must-haves-t61167,start,45.html#1342091


PostPosted: Sat Oct 19, 2013 10:59 pm    Post subject: Reply with quote
sichko wrote:

Orio, I know that they are not exactly the same. However lots of people would consider then to be part of the same generic group : Gauss/Double Gauss. I don't think that the presence of cemented elements, or not, is important. The link I gave shows a picture with two Planar cross-sections side by side. Each has 5 elements. One is 5/5. The other is 5/4 with a cemented doublet. This doublet is at the front. However Zeiss has patent designs where the cemented doublet is the second group, as in the Biometar. These arrangements, the Oberkochen 5-element Planars, the Jena Biometar and the Schneider Xenotar are often placed under the umbrella of Gauss/Double-Gauss.


Well, I think that we can at least agree that the 5-elements design and the presence of a cemented group in the front part of the
lens without a symmetrical equivalent in the rear, are more similar to Bertele's original Sonnar concept than to the
original symmetrical double Gauss concept - can we?

The classic Planar, the Biotar, all classic double Gauss design are symmetrical. When the 7-lens asymmetrical double Gauss
design became popular, it was in the modern-day-Planar form, without cemented elements.
And I think that this is another thing that we can agree upon.

Aside from all that, only a technician who can read and understand the light transmission properties of the elements can say a valid
and final word on the subject.


PostPosted: Sun Oct 20, 2013 2:22 am    Post subject: Reply with quote
I am not jumping into the the discussion but give some facts I have gathered...

Charles G.Wynne in Wray design the Unilite 50mm F2 in 1944. One of the first simplified Double Gauss patented.

US. Patent US002499264 for the simplified Double Gauss design by Charles G.Wynne. Look at the first page with drawing and the descriptions.
http://pdfpiw.uspto.gov/.piw?docid=02499264&PageNum=1&IDKey=D867B612FF48&HomeUrl=http://patft.uspto.gov/netacgi/nph-Parser?Sect2=PTO1%2526Sect2=HITOFF%2526p=1%2526u=/netahtml/PTO/search-bool.html%2526r=1%2526f=G%2526l=50%2526d=PALL%2526S1=2499264.PN.%2526OS=PN/2499264%2526RS=PN/2499264

and we can also have a look on how Nikon describe the design of the AI Nikkor 105mm f/2.5

Quote:
...

Take a look at the cross-section of the AI Nikkor 105mm f/2.5 lens (Fig. 2.). This design is based on the Xenotar-type lens (5 lenses, 4 groups) with thick, convex lenses, rather than the Sonnar type with its many asymmetric components. From the left, there is a convex lens, a cemented lens consisting of a very thick convex lens and a concave lens, and then a convex and concave pair after the stop.

Compared to the previous model with Sonnar type lens construction, ....

Source http://imaging.nikon.com/history/nikkor/5/

and more about Wray Unilite in Germany:
http://taunusreiter.de/Cameras/Wrayflex.html


PostPosted: Sun Oct 20, 2013 3:50 am    Post subject: Reply with quote
Orio wrote:
sichko wrote:

Orio, I know that they are not exactly the same. However lots of people would consider then to be part of the same generic group : Gauss/Double Gauss. I don't think that the presence of cemented elements, or not, is important. The link I gave shows a picture with two Planar cross-sections side by side. Each has 5 elements. One is 5/5. The other is 5/4 with a cemented doublet. This doublet is at the front. However Zeiss has patent designs where the cemented doublet is the second group, as in the Biometar. These arrangements, the Oberkochen 5-element Planars, the Jena Biometar and the Schneider Xenotar are often placed under the umbrella of Gauss/Double-Gauss.


Well, I think that we can at least agree that the 5-elements design and the presence of a cemented group in the front part of the
lens without a symmetrical equivalent in the rear, are more similar to Bertele's original Sonnar concept than to the
original symmetrical double Gauss concept - can we?


I’m sorry but I don’t think that we can. Sure, the front of a Sonnar with a positive element first, followed by a negative group made up of two or more cemented elements resembles the front of a 5-element Gauss/Double-Gauss with a positive element first followed by a negative cemented doublet. However I think that this is almost accidental.

The essence of the Sonnar is that it is made up of three groups in a “positive, negative, positive” (or “+,-,+” arrangement. A Gauss/Double-Gauss has a “+,-,-,+” arrangement.

The Sonnar arrangement is discussed by Kingslake : http://books.google.co.uk/books?id=OJrJrEJ-r9QC&pg=PA110&lpg=PA110&dq=sonnar+kingslake&source=bl&ots=YZ7j7NA-aA&sig=flxjXoTdT5TzGf1D__qeX1nq5t8&hl=en&sa=X&ei=30djUseZAaes0QX3jYCADQ&ved=0CFQQ6AEwBQ#v=onepage&q=sonnar%20kingslake&f=false

Kingslake also discusses the Gauss/Double-Gauss arrangement : http://books.google.co.uk/books?id=OJrJrEJ-r9QC&pg=PA121&lpg=PA121&dq=planar+kingslake&source=bl&ots=YZ7j7NA14x&sig=fWT0RMcxASULUjC3voBoUvbGL9o&hl=en&sa=X&ei=aEhjUsj2LIGm0QWm6YGwCA&ved=0CE8Q6AEwBQ#v=onepage&q=planar%20kingslake&f=false

In the original Alvan Clark “Double-Gauss” each of the inner negative groups comprises one element. Rudolph used cemented doublets for each of these groups to give the famous 6/4 Planar. Note that it’s still a Double-Gauss with 4 groups in a “+,-,-,+” arrangement.

Charles Wynne working for Wray recalculated the lens for 5 elements. Again the “+,-,-,+” arrangement is retained – see the annotation on the lens schematic provided by Calvin (thanks Calvin); the full patent is given here : http://www.google.com/patents/US2499264 . An earlier patent by Wynne is found here : http://www.google.com/patents/US2487749 .

The Wynne patents are referenced by a number of Zeiss and Schneider patents. For example…

http://www.google.com/patents/US2799207 Carl Zeiss, Heidenheim, 5-element design - cemented doublet at the back (3rd group) – described as “Gauss objective”

http://www.google.com/patents/US2968221 Carl Zeiss, Jena, 5-element design – cemented doublet at the front (2nd group) – described as “modified Gauss”

http://www.google.com/patents/US2683395 Schneider, 5-element design – cemented doublet at the front (2nd group) – described as “of the Gauss type”

I offer no particular insight. I’m simply trying to understand and adopt the descriptions used by the designers/manufacturers. Calvin’s reference to the Nikon article is useful in showing how they see the difference between Sonnar and Xenotar (a Schneider 5 element design). They make a similar comparison for one of their “fifties”.

Note : I have used the term “Gauss/Double-Gauss” since the individual terms are often used interchangeably.


PostPosted: Sun Oct 20, 2013 3:52 am    Post subject: Reply with quote
calvin83 wrote:
I am not jumping into the the discussion but give some facts I have gathered...


Thank you.


PostPosted: Sun Oct 20, 2013 5:04 am    Post subject: Reply with quote
OK guys, you have convinced me Very Happy Very interest paper that of Wynne! So in fact, he's the father of the Biometar type.


PostPosted: Mon Oct 21, 2013 6:45 am    Post subject: Reply with quote
Back to what the lens was designed for.
Here are a couple of images taken recently both wide open @ f2.8.
Pentax K-10D and re-sized in Lightroom.
OH




PostPosted: Mon Oct 21, 2013 8:41 am    Post subject: Reply with quote
Nice work, I like the first one.
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