Help me date a Lerebours & Secretan lens

[jumanji]

I got a Lerebours et Secretan petzval lens, serial number 24xx, focal length about 8". Anybody know when it was made?
Thank you.

[Steven Tribe]

Unfortunately, L & S did not engrave their address in Paris, which would have helped.

Corrado's recent book illustrates lots of Petzvals and other designs with numbers close to yours. He calls them "post 1845 and pre- 1856.
I enclose examples of the engraving. If you post a photo(s) I can reproduce the lens which is closest in serial number and appearance.

[CCHarrison]

I would estimate the lens to be 1850 +/- 1 year.

Dan

[jumanji]

Here is the picture of the name engraved:

[Steven Tribe]

This is the nearest serial no. I could find to yours - a landscape lens. I don't apologise for the reproduction quality as I don't have copyright on it!

The very earliest L & S lenses were without serial numbers.
I think CC is spot-on with the likely date!

[goamules]

Lerebours were known to engrave tiny serial numbers on the edge of the rear glass face. Not the rim as usual, but the actual face of the glass, with tiny print. I started calling this "rice writing" in another thread. See if yours has it, but it doesn't help date them. They are really nice lenses.

[jumanji]

Oh yes, now I see it. Interesting! Very tiny indeed.
1850 is fairly early. And I think it's a good lens. Have not taken any photo with it yet but I checked and it seems to be very sharp in the center.

[Steven Tribe]

Garret's thread is entitled, Lerebours Serial Number - Rice Writing.
Unfortunately, the illustrations have gone.

[goamules]

Here are some pictures of a Lerebours' with tiny engraved serial number on the glass:

https://farm6.staticflickr.com/5563/14846044279_0cdb65bd7d_b.jpg

https://farm4.staticflickr.com/3891/14846043939_66f8421d90_b.jpg