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What is this optical formula?
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PostPosted: Sat Sep 12, 2020 8:23 pm    Post subject: What is this optical formula? Reply with quote

4 element 4 groups


PostPosted: Sat Sep 12, 2020 9:17 pm    Post subject: Reply with quote

Looks like a typical medium tele. 135mm


PostPosted: Sat Sep 12, 2020 9:23 pm    Post subject: Re: What is this optical formula? Reply with quote

cbass wrote:
4 element 4 groups


Leica Macro Elmar 90mm f4?


PostPosted: Sat Sep 12, 2020 11:16 pm    Post subject: Reply with quote

Guessing Ernostar. I wonder if concave rear element disqualifies?

Seen similar configurations in 105mm focal length, with convex rear element, however.


PostPosted: Sun Sep 13, 2020 12:31 am    Post subject: Reply with quote

The Konica Hexanon AR 135mm F2.5 has a similar optical diagram:

From: https://tinglilin.com/konicahexanon/telephoto/hexanon-ar-135mm-f2-5/


PostPosted: Sun Sep 13, 2020 2:12 am    Post subject: Reply with quote

It does sort of look like an Ernostar. The third element seems to have a unique shape in a Ernostar lens diagram that this lens does not have. The third element also seems to have a gap between the first and second element while these are closer. Does that still make it an Ernostar?


PostPosted: Sun Sep 13, 2020 9:19 am    Post subject: Reply with quote

It's the Nikon E-series 100mm 1:2.8
http://www.mir.com.my/rb/photography/hardwares/classics/emfgfg20/eserieslenses/htmls/100135mm.htm

screenshot:


PostPosted: Sun Sep 13, 2020 11:51 am    Post subject: Reply with quote

I does look like it was based on the Ernostar.


PostPosted: Sun Sep 13, 2020 2:47 pm    Post subject: Reply with quote

D1N0 wrote:
It's the Nikon E-series 100mm 1:2.8
http://www.mir.com.my/rb/photography/hardwares/classics/emfgfg20/eserieslenses/htmls/100135mm.htm

screenshot:


Like 1 small


PostPosted: Sun Sep 13, 2020 9:19 pm    Post subject: Reply with quote

From 85 to 135 mm lens F/2,8 to 4


PostPosted: Mon Sep 14, 2020 9:46 pm    Post subject: Reply with quote

Thanks for the feedback. I knew it was Nikon 100 f/2.8 E series. I was looking for a known optical formula description like ernostar. It looks to be a modified ernostar of some sort based on the feedback. It actually does look pretty similar to the Leica Elmar 90mm f/4.


PostPosted: Mon Sep 14, 2020 10:16 pm    Post subject: Reply with quote

Let's see
Ernostar:


Nikon-E 105/2.8


Tamron 135/2.5


All variations on the same theme

Komine 135mm 2.8 (v1)


PostPosted: Mon Sep 14, 2020 11:00 pm    Post subject: Reply with quote

D1N0 wrote:
Let's see
Ernostar:

...


Aperture place on that diagram -- if correct, makes the Nikkor not an Ernostar I think...


PostPosted: Tue Sep 15, 2020 9:06 am    Post subject: Reply with quote

None of them have the slightly concave front surface of the third element either. It is either convex or seemingly flat.


PostPosted: Tue Sep 15, 2020 11:33 am    Post subject: Reply with quote

Regardless, it is clearly based on the Ernostar design. I expect the designers took a look at the Ernostar type and updated using modern computer aided methods and materials.


PostPosted: Tue Sep 15, 2020 12:11 pm    Post subject: Reply with quote

From another topic

no-X wrote:
aoleg: The ZM has one more element (rear) Smile

Bruce: If you like these lenses, why to care, if they use Sonnar or Ernostar optical formula? Smile Btw. both of them were developed by the same man, Ludwid Bertele. Ernostar is earlier. Sonnar is very similar, but its purpose was increase of contrast by reducing the number of air/glass surfaces.

So, simply: basic Ernostar is triplet lens with one more element in the front group.

Basic Sonnar is Ernostar, whose 2nd element and the central (negative) element were cemented together (directly, or by adding one more element between them, as shown on the picture):



Many fast Sonnars and Ernostars have a bit more complex rear group (cemented doublet or triplet)

The simpliest Sonnar design is used by CZJ 135mm Sonnars and soviet 135mm Jupiters.

More: http://img12.abload.de/img/lens_scheme_tri_v5ev1i.png (scroll down)



Maybe by the time the Nikon-E came out the cemented group of the Sonnar was no longer necessary due to improved coatings. Also four single elements is cheaper to produce and more light weight. There was another Ernostar adaption which added an extra rear element like you can see in the Pentax-m 100mm 1:2.8



PostPosted: Tue Sep 15, 2020 7:50 pm    Post subject: Reply with quote

For those being able to read German: I had published a series of articles on the general development of lenses back in 2009, in the "Sony Fotospiegel". The corresponding - slightly modified - PDFs can be downloaded from my website:

http://www.artaphot.ch/zeiss

http://artaphot.ch/images/Technik/Zeiss/Tessar/FS141_History_ZeissTessar_150dpi.pdf
http://artaphot.ch/images/Technik/Zeiss/Sonnar/FS142_History_ZeissSonnar_150dpi.pdf
http://artaphot.ch/images/Technik/Zeiss/Planar-Biotar/FS143_History_ZeissPlanarBiotar_150dpi.pdf
http://artaphot.ch/images/Technik/Zeiss/Biogon/FS144_History_ZeissBiogon_150dpi.pdf

Even if you don't understand German, the lens diagrams therein should be uselful.

S


PostPosted: Tue Sep 15, 2020 7:57 pm    Post subject: Reply with quote

Stevemark,

So is it a ernostar or not?


PostPosted: Tue Sep 15, 2020 8:26 pm    Post subject: Reply with quote

stevemark wrote:
For those being able to read German: I had published a series of articles on the general development of lenses back in 2009, in the "Sony Fotospiegel". The corresponding - slightly modified - PDFs can be downloaded from my website:

http://www.artaphot.ch/zeiss

http://artaphot.ch/images/Technik/Zeiss/Tessar/FS141_History_ZeissTessar_150dpi.pdf
http://artaphot.ch/images/Technik/Zeiss/Sonnar/FS142_History_ZeissSonnar_150dpi.pdf
http://artaphot.ch/images/Technik/Zeiss/Planar-Biotar/FS143_History_ZeissPlanarBiotar_150dpi.pdf
http://artaphot.ch/images/Technik/Zeiss/Biogon/FS144_History_ZeissBiogon_150dpi.pdf

Even if you don't understand German, the lens diagrams therein should be uselful.

S


https://translate.google.com/translate?sl=auto&tl=en&u=http%3A%2F%2Fwww.artaphot.ch%2Fzeiss


PostPosted: Wed Sep 16, 2020 10:02 am    Post subject: Reply with quote

visualopsins wrote:


https://translate.google.com/translate?sl=auto&tl=en&u=http%3A%2F%2Fwww.artaphot.ch%2Fzeiss


Sadly the machine translation doesn't work for the articles themselves. I would agree to make a raw tranlsation, if someone of the native English speakers here would agree to do the necessary corrections, and then make a proper PDF with all the necessary images. Just PM me if you're interested to help.

S


PostPosted: Wed Sep 16, 2020 4:45 pm    Post subject: Reply with quote

You can copy the text from the pdf and paste into google translate. You can also take the pdf and run it through a converter to turn it into html if you want to share it on your website with the ability to translate.

Although the pdf's are informative that still doesn't answer the question about which optical formula it is. The best guess so far is ernostar.


PostPosted: Wed Sep 16, 2020 4:49 pm    Post subject: Reply with quote

I agree -- that one drawing of Ernostar has aperture in the wrong position.


PostPosted: Wed Sep 16, 2020 5:56 pm    Post subject: Reply with quote

cbass wrote:
answer the question about which optical formula it is. The best guess so far is ernostar.


No guess involved and the answer has already been given - it's a modified Ernostar.


PostPosted: Wed Sep 16, 2020 8:27 pm    Post subject: Reply with quote

cbass wrote:

Although the pdf's are informative that still doesn't answer the question about which optical formula it is. The best guess so far is ernostar.


Sure it's an Ernostar - even though the first "Ernostar" wasn't an Ernostar: In fact the Gundlach Ultrastigmat was the first lens to have the structure we today call "Ernostar".

S


PostPosted: Wed Sep 16, 2020 9:53 pm    Post subject: Reply with quote

stevemark wrote:
cbass wrote:

Although the pdf's are informative that still doesn't answer the question about which optical formula it is. The best guess so far is ernostar.


Sure it's an Ernostar - even though the first "Ernostar" wasn't an Ernostar: In fact the Gundlach Ultrastigmat was the first lens to have the structure we today call "Ernostar".

S


Gundlach Ultrastigmat was designed in 1916
Ernostar was designed in 1923

ref:

https://oldlens.com/ultrastigmat%2050mmf075.html\

and

https://oldlens.com/lenshistory.html