Dating 24" Darlot Pill Box and your thoughts about it

[Jon Wilson]

I acquired this Darlot Pill Box a while ago and recently took it apart.
Looking to learn more about it. Any clue when it was made and your thoughts. I believe it is a 24" lens which has had its rack and pinion removed and a waterhouse slot installed. Thanks.

[Jon Wilson]

More pictures

[Jon Wilson]

even more pictures

[Steven Tribe]

Dare I say Frankenstein?

There are features which suggest this is a (very useful!) made up piece from two barrels. The raised area on the wider barrel looks like it covers the focussing track section and there are traces of track inside. The WHS stop in the pillbox comes from a much small lens barrel, I think, that started its life as a smaller lens (after 1858).

The cap looks original and making this- and the threads - would require professional skills. French landscape lenses with sleeves do exist, but they are uncommon. Darlot made landscape lenses, but his main efforts (again it must be after around 1862) were with varieties of Petzvals. The other 1850s and 1860s makers made lots more large landscape lenses - often without their name on the brass.

Considering the skill which went into covering the focussing track, I think you might consider that this is a cut down old Petzval lens, where the real cell is lost/damaged and the front achromat has been mounted in the rear. The is nothing odious about this Petzval achromat is identical to the Landscape achromat. I have a Lerebours Petzval and a Landscape lens of the same period and the achromats used on these two are completely identical. In fact, the lens cells can also be swapped between the two lenses.

The fact that the covered track covers almost the full length of the barrel suggests a previous life as a Petzval. I think I can see solder around the cap inside where there is usually a cap thread?

[Jim Fitzgerald]

Here is mine. The focal length is about 12-13". The lens is engraved Darlot and has one washer stop and the original brass cap which is marked AD on the inside. The lens has the same Darlot markings and is about 2 3/8" in diameter.

[Steven Tribe]

Jon, what is the diameter of your lens - around 81mm perhaps? This is an almost standard diameter for a 10-12" French Petzval. I have a pill box landscape, in the sleeveless version which is also about 20". And the second is the early Hermagis convertible in landscape mode (The flange thread is at the base of the lens hood) which has a 30" focal length.

[Jon Wilson]

Hi Steve,
The lens is approximately 93.472 mm or 3.68 inches in diameter. The waterhouse slot has a "pocket" or "sleeve" the for the aperture stop to be held in place. So could use a post-it paper to construct a small aperture opening.

[Mark Sawyer]

Dare I say Frankenstein?

I tend to agree with Steven; I've never seen that barrel configuration before. The front is designed for washer stops, so cutting it for Waterhouse stops makes no sense. BTW, the longest Darlot Landscape Lense I've ever seen listed is a 20-inch. Here's mine, a 20-inch Jamin Darlot.

[Jon Wilson]

I agree it is a professional cobble. I may not have calculated its FL correctly. Need to get it on lensboard and try it out. Attached more pics for analysis....I appreciate everyone's input.

[Jon Wilson]

If the FL is measured from the Waterhouse slot to the image on the wall it would be 28 inches and 23 inches from rear of lens.

[Mark Sawyer]

If the FL is measured from the Waterhouse slot to the image on the wall it would be 28 inches and 23 inches from rear of lens.

If you're shooting wide open (with spherical aberration), measure from the lens. If measuring from a stop (blocking the spherical aberration), measure from the stop. That's how focus shift works, changing the focal length as you stop down. That's also how soft focus works, soft being one focal length, sharp being another focal length. And that's also how males and females work. Males and pixies, I'm not so sure...

[Steven Tribe]

This would have been a 95mm. Makers had the opportunity to view their lenses naked and always used their unmounted diameters in their catalogues!

95mm is a less than common size. I don't have Darlot's catalogues but the Lerebours et Secretan had a 95mm landscape which had a focal length of 90cm. They even had ones of 110mm (Two versions - 90 and 120cm efl) and 160mm.
The same lens was used as the front achromat in their 95mm lensed Petzval. But there were 3 versions of the 95mm Petzval - so the shorter/faster one may have an achromat which matches your focal length.

95mm diameter achromats were not that popular a size. Most makers went from 81mm to either 90mm or 100mm plus.
Hermagis is the only other maker I can find (only a quick check) who had a 95mm.

[Jon Wilson]

If you're shooting wide open (with spherical aberration), measure from the lens. If measuring from a stop (blocking the spherical aberration), measure from the stop. That's how focus shift works, changing the focal length as you stop down. That's also how soft focus works, soft being one focal length, sharp being another focal length. And that's also how males and females work. Males and pixies, I'm not so sure...
Thank you Mark. That is a very helpful description. It made my “light bulb” come on.

[Jon Wilson]

This would have been a 95mm. Makers had the opportunity to view their lenses naked and always used their unmounted diameters in their catalogues!

95mm is a less than common size. I don't have Darlot's catalogues but the Lerebours et Secretan had a 95mm landscape which had a focal length of 90cm. They even had ones of 110mm (Two versions - 90 and 120cm efl) and 160mm.
The same lens was used as the front achromat in their 95mm lensed Petzval. But there were 3 versions of the 95mm Petzval - so the shorter/faster one may have an achromat which matches your focal length.

95mm diameter achromats were not that popular a size. Most makers went from 81mm to either 90mm or 100mm plus.
Hermagis is the only other maker I can find (only a quick check) who had a 95mm.

So, any lens pencil writing or lens serial number scratching?
I truly appreciate the benefits of your knowledge. I know the edge of the lens has “Darlot” penciled. I will take a closer look this weekend and post better pictures of the lens edge.

[Steven Tribe]

Can the lid holding the pill box be screwed off the main barrel? If it is soldered, without any trace of an internal thread, then it (the main barrel and the lens) is from a very large Petzval.

[Jon Wilson]

Can the lid holding the pill box be screwed off the main barrel? If it is soldered, without any trace of an internal thread, then it (the main barrel and the lens) are from a very large Petzval.

Yes Steve, you hit the nail on the head....the lid is soldered on and there isn't any trace of a thread. It must have started as part of a large petzval or cobbled by someone who had various parts. The glass does have "Darlot" penciled on edge (I do promise to post more pics of the lens edge this weekend).

What are your thoughts on the waterhouse slot which has a "sleeve"? Thought a sheet of film could be shape smaller apertures.
Jon

[Jon Wilson]

here are more and hopefully clearer pictures of the lens edge. The "Darlot" is light in pencil on the edge. Next to Darlot is "Paris". Then a symbol or initials, not sure what, maybe some Steve, Mark or someone else can identify it. There appears to be a "1" and then "48" maybe the 1 refers to it being the first lens on the original petzval? 48?

Steve, if this meniscus is 95 mm lens, how large of a petzval would it have come from?
Thanks. Jon