maurits
10-Aug-2011, 05:09
I have two brass barrel Hermagis Eidoscopes. One is from the early 1920's, the other one from the end of that decade. Both being No. 3 Eidoscopes, they should have an equal focal length of 275 mm and cover 5x7" max without vignetting. But they are not equal...
The early lens (in the images on the right) behaves like an Eidoscope No. 2. Its focal length is 375 mm and it covers 8x10" with some room for movements.
Both barrels are virtually identical. The older barrel is about 3 mm less tall than the newer one. Their diameters are equal. The lens elements are interchangeable on each lens. As they should, since Eidoscope front and rear lenses are supposed to be equal. But the lens groups from the newer lens do not fit the older one and vice versa. Neither is the hood exchangeable. The flanges fit both lenses.
The only significant difference I can find is in the rear lens assembly of the older lens. Its glass diameter is smaller (53 mm instead of 60 mm) and on top of that it is throttled by a fixed metal ring, further shrinking the lens' diameter to 40 mm).
I doubt that someone just dropped an alien lens group into the rear. Like from an aplanat or so. I am pretty convinced that the rear assembly is original to this lens. It fits like a glove and is made of exactly the same material, style, finish and colour as the the front lens assembly. There is nothing either that suggests that the original rear assembly was somehow altered later to accept a strange element. Neither does it look like something is missing. I get the same number and type of reflections from all elements.
Best, the Weirdoscope renders a beautiful -soft and yet clear- image on the ground glass. Just like the 275 mm one, only larger. Like a compact No. 2...
I know Alex has (or had) an Eidoscope No. 1 that behaved like a No. 0. But his lens was physically constructed like a No. 0 and therefore probably only mis-engraved.
So what is mine? Has anyone ever seen an Eidoscope assembled like this before?
Cheers, Maurits
.
The early lens (in the images on the right) behaves like an Eidoscope No. 2. Its focal length is 375 mm and it covers 8x10" with some room for movements.
Both barrels are virtually identical. The older barrel is about 3 mm less tall than the newer one. Their diameters are equal. The lens elements are interchangeable on each lens. As they should, since Eidoscope front and rear lenses are supposed to be equal. But the lens groups from the newer lens do not fit the older one and vice versa. Neither is the hood exchangeable. The flanges fit both lenses.
The only significant difference I can find is in the rear lens assembly of the older lens. Its glass diameter is smaller (53 mm instead of 60 mm) and on top of that it is throttled by a fixed metal ring, further shrinking the lens' diameter to 40 mm).
I doubt that someone just dropped an alien lens group into the rear. Like from an aplanat or so. I am pretty convinced that the rear assembly is original to this lens. It fits like a glove and is made of exactly the same material, style, finish and colour as the the front lens assembly. There is nothing either that suggests that the original rear assembly was somehow altered later to accept a strange element. Neither does it look like something is missing. I get the same number and type of reflections from all elements.
Best, the Weirdoscope renders a beautiful -soft and yet clear- image on the ground glass. Just like the 275 mm one, only larger. Like a compact No. 2...
I know Alex has (or had) an Eidoscope No. 1 that behaved like a No. 0. But his lens was physically constructed like a No. 0 and therefore probably only mis-engraved.
So what is mine? Has anyone ever seen an Eidoscope assembled like this before?
Cheers, Maurits
.