Any infos about this very common proj Petzval?

[cyberjunkie]

I own a few of those very common projection Petzvals, with black hinged "shutter" cap, and with a front slot for some kind of magic lantern slid-in filter.
They are very easy to find on Ebay, here is an interesting auction, where the lens is shown attached to the original magic lantern:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=180769893553+

I have seen many examples of those lenses, either in person or in picture.
The focal length that are easier to find seem to be those between 6" to 8".
IIRC, those i have at home start at 7" and go up to 12", and all of them have the same diameter, so different FL can go on the same focusing "tube". It means that the speed of the lenses gets smaller with the increase of focal length.

I tried to find which maker built these lenses, but to no avail. I have a catalog in .pdf format where the entire(?) line of lenses is reported, as accessories of a magic lantern apparatus. No reference to the actual maker of the optics, though.
The engravings on the cap are not of much help: some have just the FL, some have a small brand mark, with the "London Made" line and the date 1816, another one had the word "OPTIMUS" in it.
The latter could be a clue, but i really don't know if the optics were made in London by Perken, Son and Rayment, or were just engraved as such, because sold together with a magic lantern made by that brand.

I must admit that i didn't make a single image with them, because the 12" is a recent acquisition, and the others are probably too short.
I am looking for a way to mount the front doublet in some kind of shutter, one of the lenses came with two front elements (one at the front and the other at the rear of the barrel!), both with "7 1/2 in." engraved on the cap. Any of them could be used alone, as a poor man's landscape lens, wide open, on 5x7". I am afraid the original barrel "tube" could prove too long to avoid vignetting.

I got very curious about these lenses. Any information about the maker, or any first hand impression, will make me a little happier :)

have fun

CJ

EDIT:
here is a picture of one the various cap styles

[Steven Tribe]

Oh dear, you raise many questions!!
Optimus is easy. Anything with Optimus on it was sold by Perken Son & Rayment.
Trademarks were taken very seriously within European countries (UK with Optimus) whilst trademarks were not respected across frontiers. (Euryscope is the best example).
Jim Galli and Renes have done most work with making makeshift landscape lenses (not so makeshift, either). I have made about 4. 3 of these involved mounting front achromats from surplus projection petzvals in old Landscape barrels which had lost their rear achromats (Swift, Marion and Grubb). I have bought a number of other lensless barrels with rotary stops with which I plan to repeat the exercise. Sometimes, threads and the desired focal length do match with barrel threads but I have done glue jobs as well.
I have done nothing with shutters as good reliable shutters having a reasonable opening are not an inexpensive item!
I think I remember the double 7 1/2" magic lantern lens. An owner of two of these has mixed up his front and rear sets.
My personal view about makers of projection lenses is that it is difficult enough to locate camera lens makers. All the parts of the magic lantern were sub-contracted out to many suppliers (russian iron, gas fitments cabinet makers, lens makers (objective and condenser)) making identification impossible.

Projection lenses on e**y can be a surprise! During the last week there was a projection lens made by T,T & H with a serial number that was probably pre-Cooke patent days. A very rare Petzval T,T & H.

[renes]

It's hard and in most cases impossible to find out who was the glasses maker of no-name projection/magic lanter lens with no engraving on it. Before I owned a few branded meniscus lenses (Darlot, Lancaster, Gundlach and recently Beck and Conley) I tried a few ones taken from the front of no-name projection peztvals. The images seen on the ground glass were not impressed, in my view - I think any achromat used by Kodak in dozens of its meniscus cameras gives much better sofftnes and more interesting look when are uncorced. But lots of no-name projection are worth lenses (used as petzvals), they can produce good to great quality images.