Help with a Darlot lens

[ScottPhotoCo]

Good afternoon! I was hoping I could enlist the help of the knowledgable members here to help identify and hopefully put to use a lens I recently picked up (cheap). :)

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I picked this up completely apart as seen. It is missing the fine focus knob/gearing. Basically I have no idea what FL it is or even how to correctly put it back together. Can anyone tell me more about this lens and what kind of fun I can have with it?

Thanks.

[ScottPhotoCo]

One more photo:

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One more note: There is an engraving on the barrel that says B.F. & Co.

[Steven Tribe]

It has lost the brass hood (quite common).
Photographic Petzval lens, imported by B.French of Boston. Data on petzval structure is on a section in CCHarrison's website and he has another section (catogue) which shows the range of these Darlots imported by French.

This is his most simple type of engraving with Italic script and without serial numbers.

[alex from holland]

Here you go Tim: http://collodion-art.blogspot.nl/2013/06/inside-petzval-lens.html

[Mark Sawyer]

Here's the Benjamin French & Co. catalog that has a description of your lens in it, (pages 15 and 20):

http://www.motamedi.info/text/French%201890.pdf

[ScottPhotoCo]

Thanks everyone for the help!

This doesn't appear to me to be a Petzval design (at least with what is currently here) as it only has two elements. I don't even know if the elements I have are correct.

If I had to hazard a guess I would say that the Darlot Portrait Lens that Mark posted the pdf for. I know nothing about this so I could be completely wrong.

Do any of you have anything similar that might be of assistance in how this lens properly goes together? I have a single element that is not attached and I have no idea how it might fit properly in the barrel or even if it is the correct element.

Also, is there any chance that I might find a rack and pinion element that would fit this?

Thanks again!

[Mark Sawyer]

The lens is almost certainly a Petzval, or at least, most of one. The cut-away lens photos in Alex's link shows the assembly. Note there's a cemented doublet at the front and two individual elements air-spaced at the rear. It appears your lens may be missing an element, or (hopefully) there may be two elements held together in the rear cell housing. It's not very likely you'll find the parts you need, but you never know... at least it was cheap! And you can use the front element as a landscape lens.

[alex from holland]

Don´t forget darlot made "objectif d`artiste". They only had 2 thin lens elements. But most likely yours is a petzval. Try to open the back lens part.
That part will have two glass lenses in it. (as shown in the picture)

[Jim C.]

You don't show a side view of the lens part in picture # 3, that looks to me to be
the front of the lens and the lens hood flange that's missing the hood, the hood flange
should unscrew and there should be another two threaded rings that hold the front element.

If you know a machinist they may be able to make you a new pinion, or at least measure the rack
on the lens tube to see if it's a currently used gear pitch. I believe the gear pitch on your Darlot
is obsolete, so finding something current and off the shelf isn't going to happen.

One more thing is that it looks like your lens has a waterhouse slot, use the slot to orient
which way the tube is to go into the sleeve, my Darlot also has felt O rings that damps
the lens movement, look for the grooves at both the inside ends of the engraved part ( main body ? ) of the lens.