Looking for some info on assembling a casket lens

[csant]

Hello,
Since not so long I have a Hermagis casket lens - and am now looking for information on how to assemble it Besides my empirical approach of just checking which elements and which element combinations produce nice images - are there any rules I should know about?

The lens consists of a brass barrel, 6 elements and 8 Waterhouse stops. The elements are as follows:
3 elements with a brass shade of 6mm, marked as follows:
* Apl N° 5 bis
* G.A. N°5
* G.A. N° 6
and 3 elements all black without shade:
* Apl N° 5 bis (identical to the other one, except for the missing shade)
* Apl N° 7
* G.A. N° 7

The Waterhouse stops are marked as follows:
1, 1⅓, 4, 8, 16, 32, 64, 256

Now: I guess that "Apl" means Aplanat - but what does "G.A." stand for? Which elements are (likely) to be mounted in the front, which ones in the back? Which ones are (likely/unlikely) to be mounted in pairs? And which ones are (likely/unlikely) to be used alone?

Thanks!
/c

[CP Goerz]

GA is Grands Angulaires, you have a set for 24x30cm though the two #5 elements can be used to cover 40x50cm at F20. If I get a chance I'll scan the catalogue copy I have for yah.

[csant]

CP, that would be greatly appreciated. Any further input would also be great (it's a nice lens, BTW!)

[Ole Tjugen]

There is a picture of a Trousse Aplanatique #2 on my website http://www.casket-set.com/sets.html - complete with instructions. That might be a help.

[csant]

Ole, yes I have seen it - that explains some of my doubts. When mounting a single element, is it supposed to be mounted in front of, or behind the aperture? From what I have read, the old Aplanat had the aperture in front of the element?

[Sven Schroder]

Here is some info (see attachment) its from an E Francis set which appears to be made by hermagis and was interchangable with the hermagis set I sold (to Hollis).
Regards
Sven

[csant]

Sven, cool! Thank you very much (and I think that set is the one that is with me now)... There is a distinction made between front, and rear elements - should I imagine that the ones with (brass) shade are the front elements, the completely black ones without are the rear elements? Or does that not matter?

[CP Goerz]

Some of the cells may be sharper than others in the identical focal lengths so have a quick check to see which ones are the best and pop a tiny Sharpie dot on it. I use single cells behind the shutter as I think less stray light/flare will be flying around, also use a yellow filter to help with sharpness and contrast as per usual single cell use.


Try to use two elements together as often as possible as you'll see the results with the single cell aren't quite as good even when stopped down more. The set you have is a nice one, when you get bored with it let me know ;-)



I think you've already come up with the answer regarding the black cells for the rear and the shaded ones for the front. It doesn't really matter though, just use the best cell for the job :-)

[CP Goerz]

I can't seem to figure out how to add an attachment, just drop me your E and I'll send it to yah.

[csant]

CP, thank you very much - I sent you my e-mail address.