Another lens: Ernemann Doppel-Anastigmat

[matti]

So I just help myself and bought this Ernemann Doppel-Anastigmat "VILAR" 1:6,8 f=16,5cm with working shutter at an auction site. I am having some problem finding info about it. Is it the same kind of lens as a Dagor? What could I expect of it? What kind of covarage?
/matti

 

[Ole]

This is from the Vade Mecum:

Vilar f6.8 on HEAG 11 (1920's), Bob V 1920. This has been described as excellent in a 1998 report, and said to be 5 glass: but a 4-glass seems more like. (Shutterbug, 1998) Frerk says it is a 4-glass dialyt type. It was one of the cheaper versions on the Heag 11, below Ernar and Ernon. It was noted as an 135mm lens at No82,89x on a 9x12cm Tropical. It was used in B.J.A. 1926, p676 etc. on Bob V rollfilm in several sizes such as VP, 2.25x2.25, 2.5x3.5in and 4.25x2.5in. (B.J.A. 1925, p698 on Bob V abd Heag VII,etc).

The 16,5cm version was made for "postcard size", or 10x15cm. So it should have good coverage for 4x5". Dialyte lenses (if that's what it is) of that age are generally very very good, although they have fairly low contrast due to the 8 air/glass surfaces they were sharper than just about anything else.

As this is an older German lens which is rather uncommon, I wouldn't trust anything the Vade Mecum says about it.

 

[JPD]

I saw that auction too. It doesn't look like a Dagor (the internal silvery reflections in a Dagor is similar to a typical Gauss), so it's probably a dialyte. But then again, the rear of the lens is larger than the front, so it COULD be a five element lens, but to know for sure one has to take the lens apart. Can't imagine that it's a 5/2 lens.

 

[Dan Fromm]

Folks, there are f/6.8 Doppel Anastigmats that are not 6/2 Dagor types. Goerz even made some. Most are dialytes.

Dialytes can be recognized by counting reflections. Four strong reflections, no weak ones in front of and behind the diaphragm = 4/4 dialyte or 4/4 double Gauss. The difference is that the double Gauss' elements are all menisci concave to the diaphragm [(( (( | )) )), where "(" is a surface and "|" is the diaphragm] and dialytes are a meniscus and a biconcave lens on each side of the diaphragm [(( )( | )( ))]. The 4/4 double Gauss' reflections all move together, the dialyte's don't.

6/2 lenses have two strong and two weak reflections on each side of the diaphragm. The weak ones can be hard to see. Dagors are 6/2 types, don't show the same pattern of reflections as 4/4 or 6/4 double Gauss; 6/4 more or less symmetrical lenses have 4 strong, 1 weak reflection on each side of the diaphragm.

JPD, I'm not going to do your homework for you, but look for Protar cross sections. I think you'll find that "Protar" includdes 4/2 and 5/2 types.

Matti, when you have your new lens in hand you'll be able to see for yourself what it is. Until then trust Ole and remember that dialytes were usually the cheap alternative.

 

[matti]

Thanks all!
I'll try to count the reflections when I get it.
/matti

 

[JPD]

JPD, I'm not going to do your homework for you, but look for Protar cross sections. I think you'll find that "Protar" includdes 4/2 and 5/2 types.

Yes, but would they call an asymmetric 5/2 design "Doppel-Anastigmat"? Maybe.

 

[matti]

Got the lens today!
When I count the reflections, I get two strong and two weak in each side of the iris. (That is when unscrew one of the parts and count the reflections. If I look at the whole lens, I see two strong, two medium and four weak reflections.) Both elements are convex outward and concave towards the iris. The inner element is slightly larger than the outside.

So what would that mean?

/matti

 

[JPD]

It means that it probably has four lenses. It you look at the lens from an angle, does it look like the picture 1 or 2?

 

[Frank R]

It would be really helpful if someone wrote an article with photos showing how to count reflections; with photo examples of each lens type. It would be a great reference source here.

 

[matti]

What is the difference between the pictures? I am not sure what to look for. Maybe it looks more like the first picture.
/matti

It means that it probably has four lenses. It you look at
the lens from an angle, does it look like the picture 1 or 2?

 

[Dan Fromm]

It would be really helpful if someone wrote an article with photos showing how to count reflections; with photo examples of each lens type. It would be a great reference source here.

Have you ever tried? It isn't difficult.

 

[JPD]

What is the difference between the pictures? I am not sure what to look for. Maybe it looks more like the first picture.
/matti

You can see the shape of the elements (or cemented group).

Picture 1. is a dialyte. A Tessar or simple triplet would also look like that:

() )(

Picture 2. is a Dagor. It has three cemented elements in front of the shutter, and the group in one piece looks like this:

( (

A gauss design looks similar as the Dagor, but on them you would see two reflections bowing outwards.

(( ((

 

[Frank R]

Have you ever tried? It isn't difficult.

Yes, I have. But I have never been confident that I was correct. That is where a reference would be handy to confirm my guesses.

 

[matti]

Thanks for trying to explain but I'm sorry I simply can not see the shape of the elements this way. This is the first time I am looking at reflections.

But when I compare the reflections of this lens to a tessar it is a bit different. In the tessar, when i change the angle of the light two reflections move one way and two reflections the other way. This makes sence as the front cell of the tessar would be () )(.

But in my lens three reflections move in one direction and one reflection move in the other direction.

Both the front and back element looks this way.

So, is this ennough info to identify the type?

/matti

You can see the shape of the elements (or cemented group).

Picture 1. is a dialyte. A Tessar or simple triplet would also look like that:

() )(

Picture 2. is a Dagor. It has three cemented elements in front of the shutter, and the group in one piece looks like this:

( (

A gauss design looks similar as the Dagor, but on them you would see two reflections bowing outwards.

(( ((

 

[patrickjames]

This is what a Dialyte Rodenstock Doppel Anastigmat Eurynar 135mm f/3.5 looks like wide open on a polaroid. The bokeh would be even sweeter on a full frame 4x5. This thread made me test this lens that I have had for the past year. I picked it up attached to a folder on the bay for $100. The focus was on the leftmost lilly.

 

[matti]

... so I tested it.

Nice! I had to try myself today and went to the unknown mashlands of Stockholm for some tests myself.
This is what came out from me playing with dof. The first one at largest aperture and the second one at about f22. Printed on Bergger Prestige. Sorry about my bad scanning. My scanner totally kills the dark tones...

/matti

 

[patrickjames]

I like the Eurynar so much wide open I doubt I will ever use it any other way. Looks like yours is a peach wide open as well.

Patrick