Quote Originally Posted by arri View Post
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.
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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