Rodenstock 360mm f4.5 eurygon from 1945-1951

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Originally Posted by arri

I have a 300mm and a 240mm Eurygon lens. Yes, this lenses are three element types but not like the Cooke Triplet.
The Cooke lens, the Meyer Trioplan, the Zeiss Triotar, Rodenstock Trinar were lenses made in the max. possible quality of three elements. For this the distances between the elements are very important and have to be very exactly.
When you change the distances between this elements in any kind the lens is getting softer.

I find three categorys of three element triplets
1. are like the Cooke Triplet, first descriped by E.Abbe
These are 100% anastigmat lenses
2. portrait anastigmat like the Eurygon
This lens has small but visible chromatic and spherical aberations but the astimatism is corrected. Stopped down, 1-2 steps the aberations are not visble anymore.
3. Emil Busch Nicola Perscheid lens.
The lens has large spherical and smaller chromatic aberations, much more than the Eurygon has. The astigmatism is not corrected anymore, thats why the lens is not named as an anastigmat! Here you have to stop down the lens 2-4 steps to getting sharp images. It is in relation to the fastest speed and the focus length of it. Busch made different lenses, a 160mm f/6 and one in f/4.2 f.ex. Most lenses have f/4.5

The distance from the lens flange to the film is getting shorter the more aberations the lenses have.
My 360mm Nicola Perscheid has around 290mm flange focal distance. The 300mm Eurygon ~ 280mm and the 360mm Trioplan 355mm or better exact the awaitable 360mm.

End of the day the Eurygon lenses are one of the best portrait lenses you can find. At full aperture it is slight soft with very small halos in areas with high contrasts. Stoped down you have a sharp lens. It has no focus shift like the most soft focus lenses have like the Imagon, Verito or the Perscheid lens.

It has no cemented elements and the glass lenses are not so thick. That´s makes it very good usable for wet plates.

Last year we testet some different lenses for wet plates and the Eurygon is nearly 1 stop faster than a Tessar style lens and 1 1/2 step faster than a Dagor style one.
The reason is that the Eurygon let pass a lot of UV light which will be blocked by the lens cement of the other lenses.

I`am sure that you will love this lens. You are a lucky guy to find one in 360mm focus. All of this lense are very rare.

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Thank you for the info. I love it. I did 2 plates at f4.5 and I found the lens perfect for my needs.


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What a great find - this is a really impressive lens.

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Originally Posted by arri

1. are like the Cooke Triplet, first descriped by E.Abbe

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Tell me more, Arri ... about Abbe
PM me if you don't want to divert this thread.

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Originally Posted by Mark J

What a great find - this is a really impressive lens.



Tell me more, Arri ... about Abbe
PM me if you don't want to divert this thread.

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Thank you. Yeah. I was lucky to get it


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Quote:

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Originally Posted by Mark J

What a great find - this is a really impressive lens.



Tell me more, Arri ... about Abbe
PM me if you don't want to divert this thread.

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Ernst Abbe from Zeiss were the first who described that it is possible to realise an astigmatism corrected lens with only three lens elements but I guess it were Mr. Lee from the Cooke company who realised it in practice a couple of years later.
Abbe were not a designer of photographic lenses, he developed microscope lenses and made a lot of theoretical and calculation jobs.
He realised that it were impossible to measure the parts in the needed precision, so first he had the develope measurement gears and tools to measure and adjust the machined parts of the lenses.

I read it in a journal about lens makes and designers, but maybe you can find further information in the net.

I can believe that Abbe could work this out. I wonder when that was ?
The Cooke triplet was by H. Dennis Taylor at Cooke, I believe the UK patent was from 1893, and the US patent from 1895, but he would have been working on it earlier.
The 1893 patent already has three distinct examples, if I remember correctly.
The first one is the classic type of triplet with symmetrical or nearly-symmetrical spacings, the above Eurygon is of this type ( as are most others) and these are better for wider apertures like f/3.5 to f/4.5 and 'standard' field of view.
The second one used a thin doublet in the central element and which seems to be of debatable benefit.
The third one is interesting and became the Cooke Series III ( and others later ) . This is the one with elements 1 and 2 close-spaced and then the stop further back, followed by lens 3. This later had a new lease of life as the Rodenstock 'Geronar' in the 1980's/90's. It was shown I think as f/6.5 by Taylor and 55 to 60° field. It doesn't work as well at wider apertures, needs stopping down quite a bit, but does have lower field curvature at small apertures.

Lee I think came later and certainly designed the f/2 Opic at Taylor Hobson which was a development of the Planar.