mystery lens of the day

[Dan Fromm]

This morning I squandered $10 on a Fotokopist Spezial Reproduktions Objektiv 1:6.8 f = 18 cm. It appears to be an uncoated dialyte.

A Google search for Fotokopist and Spezial or Reproduktions or Objektiv found a couple of expired eBay listings, nothing else relevant. There's no mention of fotokopist on usenet.

I realize that to find out what my new treasure is good for I'll have to ask it by burning some film. Can anyone tell me more about it than I already know?

TIA,

Dan

 

[Ole]

"Fotokopist" is German for photo copy machine, that could be a hint...

Uncoated dialyte is very probable. Most photocopier lenses are - and the rest are coated.

 

[Dan Fromm]

It seems that Fotokopist was a company. But no info about the lenses. And its definitely a dialyte, almost certainly uncoated. And a little light as paperweights go.

 

[Ole]

That's part of the attraction of dialytes as "users" - there's lots of air and not much glass in them! Some of the early ones were marketed as "convertible", my Podenstock plate camera (with 135mm Eurynar, yet another dialyte) has a second infinity mark labeled "Hintenlinze allein" - rear lens alone.

I shamefully confess I haven't tried this, but at least my 1910 book states that "stopping far down is essential" for this.

Hmmm... Maybe an idea for a cheaper casket set than Wisner's, and sharper than the Bush Vademecum aplanat set? And lightweight, too...

 

[Dan Fromm]

Ole, I took your hint and looked more closely at the thing.

It isn't quite symmetrical, the two cells have different focal lengths. Each can form an image, i.e., the lens is convertible if desired. I have the impression that at ~ 4m the lens forms a better image reversed than facing normally. By an odd coincidence the two cells have identical threading, so reversing the lens by swapping the cells from front to rear and rear to front is easy. Hmmm.

Thanks for the suggestions,

Dan