another unmarked brass Cone lens

[dbendo]

This lens was with the Whole Plate Sears Poco camera I bought,it came in a box of extra's that came with it.

I saw the thread about the Cone Centralisateur lens that was not. This seems to be a Magic Lantern Petzval. It has no markings and It has no waterhouse slot. I am wondering if

the cone was from another lens, or did some Projection Petzvals have a Cone Lens. Focal length is 10" f5. The lens is 6" long. Does anyone have any other

info on a lens like this? Here is a test image, It looks like a really nice portrait lens.

137504 137505

[seven]

The cone looks like an original Darlot part, maybe someone just put it on a no-name projection lens.
You could post more pictures of it ?

[Mark Sawyer]

The cone looks very Darlot-esque, but the focusing knob does not look Darlot-ish at all. :confused:

Have you disassembled the lens to check for inscriptions on the sides of the elements?

[Steven Tribe]

There are really no alternatives. There were others with larger rear lenses but nothing that looked like this.

Sometimes the pencil/ink writing can be seen without removing the glass. Writing can be faint on the front achromat if the balsam has been changed during the last 150 years.

[Mark Sawyer]

It has no markings and It has no waterhouse slot. I am wondering if the cone was from another lens, or did some Projection Petzvals have a Cone Lens. Focal length is 10" f5.


There are really no alternatives. There were others with larger rear lenses but nothing that looked like this.

I agree with Steven; that has to be a Jamin-Darlot rear cone. But given it's an f/5, and the Cone Centralisateurs of that size were f/4, and that the knob doesn't look like any Darlot knob I've ever seen (especially of that era), I'm leaning towards a Frankenstein lens assembled from different parts. But it looks like it performs nicely!

[alex from holland]

cone lenses never had a waterhouse slot in it.
The apartures with cones lenses are inside the lens.
You had access to it by puling of the front part of the lens.
Just tried to combine the back of a cone lens with a "standard"darlot lens and that doesn't match.
BUT, if I look lclosely to the total lenght of your lens it looks like a standard Darlot Petzval with a attached cone.
And in that case the total lenght of the lens will be about 25% longer than a normal cone lens.
Could you post some dimensions of the lens?

[dbendo]

There are no pencil markings on the sides of the elements I had the lens completely apart. The body is 3 1/4 inch's without the Cone and hood. The cone is 1 3/4 inch's, Hood 1inch. Six inch's when put back together.

On an 8x10 camera I taped a clear ruler to a window, another ruler on the GG to get to 1:1 then measured 40 3/4" from window to GG divided by 4, a little over 10inch focal length. At arms length looking thru the front of the lens I measured a 2" opening inside the body divided 10" focal length by 2 to get F 5. Please correct me if this is not correct this is all new to me. thanks Dave

137551 137552 137553 137554

[dbendo]

The outside diameter of the front of the lens with out the hood is 2 3/8 " outside dia. of the cone is 3 1/2" the hood is 3"
Looking thru the cone the lens dia. is 2 1/2"

137555 137556 137557