New Article on Heliar Lenses

[CCHarrison]

See


http://members.aol.com/dcolucci/heliar.htm


Dan

[Wimpler]

Nice collection of usefull ifnormation. Thank you.

[Ken Lee]

Excellent !

[Arne Croell]

Very nice overview. There is one error I see: it is true that Voigtländer showed the f/4.5 Heliar as the original Heliar design in their advertisements until the late 1960's, but this was not the reality. Both the post-WWII 4.5 Heliars and at least the ones from the 1920's and 30's (e.g. from the Bergheil) use the Dynar design. This can be checked by looking at the movements of reflections of a flashlight in the front element. Its easier to see if the center negative element is removed, which is usually quite easy to do as it unscrews or a retaining ring for it unscrews. The dim reflection from the cemented interface moves opposite to the reflection in the front surface when moving the flashlight, so it has the opposite curvature. The Universal-Heliar, on the other hand, always employed the original Heliar design and this can be seen in the reflections, too.
Arne

[CCHarrison]

Hello Arne

I do have some notes in my research that agrees with what you are saying, but I couldnt confirm it with advertisements. Did they just keep advertising the old layout ?

thanks
Dan

PS - I have taken out the one sentence you are referring to. Thanks

[Arne Croell]

Dan, yes they kept using the old layout in the ads, even into the 1960's. Its actually correct for the Universal-Heliar, and often they had that on the same page, so this may be a reason.
And I have checked several Heliars and a post-WWII Universal-Heliar that I own. In addition, the ads for the Apo-Lanthar show the Dynar design, and if you compare reflections the movements are nearly identical for a Heliar and the same focal length Apo-Lanthar, so they must be the same basic design.

[CCHarrison]

I did notice that about the Lanthar. In fact, is it only the low dispersion/radioactive glass type that differs b/t the color heliar and the apo lanthar ?

[Arne Croell]

Well the curvatures and distances of the lens elements are slightly different between the Heliar and the Apo-Lanthar, but not a lot. However, it was newly calculated by Albrecht W. Tronnier, not a reused design. If you want to compare, the US patent no. for the Apo.Lanthar is 2,645,154, and the German one 880,802.

I actually own a barrel prototype Voigtländer 21cm f/4.5 lens that is labeled "Color Heliar". It turned out that this is actually an Apo-Lanthar - I measured the lens curvatures with a spherometer and they are identical to the Apo-Lanthar, but different from a 21cm Heliar, and the front lens is radioactive. It appears that they originally intended to sell it as an improved Heliar, but then decided for a completely different name, and the other version for smaller format lenses (which was also developed by Tronnier) was called "Color-Heliar".

[CCHarrison]

Thanks for the insights & conversation. Have you read Prochnow's Voigtlander 3 book ? I am wondering if there is any new Heliar information contained.

Thanks
Dan

[Ole Tjugen]

Well done, Dan!

Comparing a Heliar (1934) and an Apo-Lanthar (1968), both 150mm f:4.5, shows that the curvatures and spacings are slightly different - as is to be expected since the lanthanum crown glass element has a very different refractive index and dispersion. But the basic design is Dynar in both cases.