Is it common to see handwriting on lens element edges?

[Tom Keenan]

I admit that I have not disassembled many older brass lenses but recently I took an old petzval lens apart to clean. Both lens groups are "signed" on the unpolished edge of the glass. It is my understanding that many of these lenses were sold with no exterior markings so was it common to add an interior manufacturer "mark" or "signature" to these vintage lenses? Or is it more likely that an owner of the lens just wrote something there to keep the elements organized or something?
Thanks
Tom Keenan

[Steven Tribe]

This is a french speciality. Most Jamin Darlot - but yours is a Hermagis! Made by the finishing section by the maker in 18xx.

[CCHarrison]

It is not uncommon to see this....Darlot lenses seem to be most frequently mentioned as having markings... for some firms it may represent a "quality control" type of mark, while in other cases it could signal a repair, or even an inventory marking..

Dan

[Steven Tribe]

Your lens was probably not sold as a Hermagis. They were pretty good at engraving their objectives with very large letters! There are three possibilities:

- It is a clone, non-branded, version of one of their own 2 petzval portrait series lens.

- It is an order for a series of objectives, with some differences from their usual offerings, from a camera maker/retailer - most of these did put their own name on the lens, though.

- Hermagis just supplied the optics to another maker (perhaps, not even French) of objectives. There are a couple of names in French lenses who seen to have done nothing themselves but just bought-in the finished brassware and optics and were most interest in marketing.

The absence of exterior marks might indicate an earlier life as a projection lens. Photo?

[Tom Keenan]

I have always thought that the lens was a projection lens because it looks like it was removed from somewhere. It does have a slot on the opposite side for a stop.
Thanks
Tom Keenan

[Steven Tribe]

I would think this lens was sold as an Hermagis after all, as the outer casing with the tangential focussing drive was there - but has been lost. This casing, with flange thread, is where the distinctive Hermagis engraving would have been. Projection lenses don't have waterhouse stops unless made by a previous owner. The front doesn't look right for an early (portrait) photographic petzval - unless something is missing. The bigger it is - the more likely it is to be early.

[Tom Keenan]

Thanks for the info. I think the next step is to load up some film and see what the images look like. Does the "tangential drive" do anything except vary the distance of the entire unit from the film plane??
Thanks
Tom Keenan

[Gordon Moat]

Looks like the lens hood and the barrel would be missing, if this is a Petzval type design. The first image of the cemented elements would likely be the front group of a Petzval. If the rear group is two separate elements with a spacer between them, then even more likely. If you can get it mounted to a camera, then you could probably work without the radial drive. The important part is those lens elements.

Ciao!

Gordon Moat Photography

[Steven Tribe]

Tom - early cameras were pretty rudimentary as far as adjustment. Often basically interlocking boxes - or the adjustments on the base were loosening bolts and friction movement. So manufacturer's of lenses allowed for focussing through a turn screw which engaged in the toothed rail on the barrel to allow the barrel to move in and out of focus. The system became less important on cameras as they became more complex and better made. There were two types, the tangential (which is far commoner and the axis of the adjusting screw is at a tangent to the circumference of the barrel) and the radial ( uncommon - just a few makers- and where the turning axis points directly towards the centre of the barrel). Lenses in the 20th C used helicoil mounting threads to acheive the same movement.

[Steven Tribe]

You can see a few photos of a complete Hermagis at the following:

http://www.liveauctioneers.com/item/3633894

If you remove the "outsides" and the front, the remaining barrel will look like yours. The description for this completed auction is very faulty, though.