Darlot Lens ID Help

[Chris7521]

I need help with the ID of this type of lens. It is a Darlot with 4 lens elements (2 front/2 rear), all air spaced. It's about a 19" (f4?) lens and covers 8x10 at least. Photos are as they came out left to right. There are spacers that were between the elements which are not shown. Image on the GG is pretty soft and glowing. Any help in identifying the type would be much appreciated.

Front: front2 by Chris Badessa, on Flickr
Front #2 front by Chris Badessa, on Flickr

Rear: rear by Chris Badessa, on Flickr

IMG_1294 by Chris Badessa, on Flickr

[Chris7521]

IMG_1295 by Chris Badessa, on Flickr

[Steven Tribe]

Se II is a series 2 projection Petzval marketed directly by Darlot, rather than through an agent (forexample, B.French of Boston) or a magic lantern maker.

If the lenses and spacers are a complete match, then I would suggest that you have a set of two rear elements! Threads are the same and if someone had a pair of these, an error could have made after cleaning. If one of the spacers is quite thin, then it may be an air achromat in place of the usual cemented achromat.

Or it could be that the cemented achromat is present in disguise! Achromats breakdown and after cleaning the owner opted to introduce a spacer to escape messy re-cementing!
You can test, with a thin paper spacer, whether there is match between a concave and convex surface.

[seven]

a 19" f4 Petzval lens is at least 2-3 times bigger than that, so this can't be.
to me it looks like you've got a lens with two rear elements (just as Steven noticed already). this explains the soft and glowing image.
lens configuration for a Petzval should look like this :

[Chris7521]

Thanks guys. You are a big help and a great resource for everyone.

[jaytral]

[Chris7521]

Thanks for that jaytral. In all my searching I never stumble across it.

[Chris7521]

a 19" f4 Petzval lens is at least 2-3 times bigger than that, so this can't be.
to me it looks like you've got a lens with two rear elements (just as Steven noticed already). this explains the soft and glowing image.
lens configuration for a Petzval should look like this :

Yes of course it can't be a 19" f4. I wasn't thinking. What ever it used to be..looks like it was an f4 or close to that. Now it focus at 19" which I liked, but obviously no longer so fast.