Emil Busch Aplanat coverage

[Jerevan]

Okay, this is one of those "how long is a piece of string questions"...

I have an old brass lens, an Emil Busch Aplanat no 2, 200 mm, marked with ROJA on the flange. I know this is supposed to cover 13x18, but by how much? Is there a way to mathematically get an idea of the coverage?

 

[Steve Hamley]

Shoot 2 pieces of film with it, with zero and maximum movements and look at the corners with a magnifying glass?

Cheers,

Steve

 

[Ole]

Which "Serie" is it? There's a big difference between Serie B and Serie C, although if it's "Serie A" it's a more "normal" one.

Specified coverage for the "Serie A" which may not be marked is identical to the focal length - for a given definition of "coverage".

 

[Jerevan]

I looked at it now. It is a "Rapid Aplanat, ser. D. F:7 No 2 F=200mm" It also says "Emil Busch A.-G. Rathenow." I'll just have to test it to the limits and see what's what, I guess.

 

[Ole]

OK - that's enough to go on. wide open they cover about 30 degrees or 1/2 focal length, increasing to 60 degrees, 1.15 focal lengths, at f:22 and down. So my guess is that it was made for "Postkartengrösse", 10x15cm, and not 13x18cm. Or maybe for portraits on 9x12cm (or Kabinettkarte?).

 

[Jerevan]

Thanks a lot, Ole. That'll mean it would work, in a way, with 13x18 if I stop it down to f:22 or smaller. I think I'll sell it and find something that covers a bit better.

 

[Barry S]

I have both the Emil Busch Aplanat No. 2 and a No. 5. The No. 5 is an 18" (457mm) lens and I'm not really using it, so feel free to PM me if you have any interest.

 

[Jerevan]

Thanks Barry for the offer, but then I'll have to get another camera, too... My bellows maxes out at ~270 mm.