Jamin/Darlot cone centralisateur

[andrewch59]

I have purchased this lens recently and trying work out the speed of it139386If I remember correctly with my other lenses it is focal length divided by lens diameter or waterhouse stop diameter. In this case it is not a petzval, only a meniscus with a single lens in the cone. The focal length is a respectable 22 inches or so, is the focal length in this case divided by the front aperture diameter or the rear lens??

[Steven Tribe]

I still have this in my ebay watch list.

My understanding is that there is just the +ve of the original 2 rear lenses remaining in the cone. The -ve rear lens and the front achromat are gone. The engraved front ring is unusual to say the least.

In this case, with a single rear lens cell, your reasoning about F value is correct.

[andrewch59]

Thanks Steven, yes when first listed I thought it to be complete, I stopped watching and waited the end of the auction to bid. Unfortunately he had changed the description and added a pic showing only one glass lens, which I missed. He did compensate me with another very nice 14 inch Busch's portrait Aplanat. As far as the book goes I believe they actually came out in this configuration for landscape??

[andrewch59]

Measured at f26, a very good pic on the gg and glass is in excellent shape

[Steven Tribe]

I was actually the first bidder on this back in August!

9" Darlot/Jamin cones are not common.

The locking screw was popular in a couple of Darlot models from the mid 1860's. I doubt you will be able to supplement up to a complete original set, but it may be possible to find an achromat (magic lantern) which fits in the front for a more usual landscape use. The lens mounting ring might well be still present.

[andrewch59]

I was actually the first bidder on this back in August!

9" Darlot/Jamin cones are not common.

The locking screw was popular in a couple of Darlot models from the mid 1860's. I doubt you will be able to supplement up to a complete original set, but it may be possible to find an achromat (magic lantern) which fits in the front for a more usual landscape use. The lens mounting ring might well be still present.
No the ring is not present and the front lens thread is warped, as it is just a threaded band fixed to the barrel. I checked my other Jamin/Darlot petzval, which seems to be about the same size glass, also looked at a couple of my magic lanterns, but alas the thread is unusable I think.
I am making a mounting bracket to mount it on my focal plane shutter, will see what it produces.

[Steven Tribe]

"Alex from Holland" has a whole range of these Darlot cones, so he may have advice about repair, etc.

[andrewch59]

"Alex from Holland" has a whole range of these Darlot cones, so he may have advice about repair, etc.Tks for your help Steven, I might look in to that

[jesse]

I was actually the first bidder on this back in August!

9" Darlot/Jamin cones are not common.

The locking screw was popular in a couple of Darlot models from the mid 1860's. I doubt you will be able to supplement up to a complete original set, but it may be possible to find an achromat (magic lantern) which fits in the front for a more usual landscape use. The lens mounting ring might well be still present.

9" Darlot/Jamin cones are not common.

Really, my Jamin cone is around 9" :)

[Steven Tribe]

I guessed the 9" meant physical length as the lens set was not complete. I think the shorter cones are more frequently encountered as they were used for C de V's.