Some Soft Focus Lens Sales Information

[Amedeus]

I wish there was a more definitive answer. If you read the old catalogs from Pinkham, I get the feeling the original Series I II and III were done this way but not the Series IV and later. Anyone know? I'm guessing. One guess is enough. The Cooke is a copy of Series IV but their advertising dept. had "poetic license" like ALL advertising depts have.

I'm adding one more somewhat educated guess here after measuring quite a few SF lenses.

I don't own a P&S I or III but my II (#1024) is hand adjusted. The rear element of my P&S out-of-series (#902) is "hand adjusted". My series IV 2b is not hand adjusted. I didn't measure my eidoscopes or PS945 yet but will do so when access to equipment allows.

[Petzval Paul]

Rudi, Is it possible to determine if a lens is 'hand-adjusted'? I've got a pre-series 'Smith lens' and had a series VI but never could notice any difference by looking at the glass. Like Jim, I suspect that the series IV and later were produced by more automated methods but have no way of backing that up.

[Amedeus]

I've never been able to tell by naked eye but only by measuring curvature and how the curvature changes over the surface of the lens. We're talking changes measured in microns. Quite possible that once the profile was established, one could do this using a series of lapping processes on mechanized lapping equipment.

I've note measured the Series VI yet either ;-)

[Petzval Paul]

I didn't realize that you bought that series II....sorry for bumping up the price BTW, what model is the #902 that has a rear element? An early doublet?

[Mark Sawyer]

Just a thanks to Rudi for the info, the first I've ever heard of someone actually finding evidence of the hand-worked surfaces. I've wondered about hand-working an element on some of my scratched up beated lenses just for fun, (I did some lapidary work in my younger days...) So it's the rear element that was worked? Do you know if it was worked at the edges or center?

The Cooke is a copy of Series IV but their advertising dept. had "poetic license" like ALL advertising depts have.

Yup, I noticed that Cooke's claimed that they "reproduced the unique performance of these hand aspherized lenses" without actually saying they hand aspherized the PS945...

[8x10 user]

You want the outside of the lens to be a shorter focal length then the center.

[goamules]

I don't think anyone posted (but surely you noticed) a rare (really!) soft focus lens that recently ended:

14" Beach Multi-Focal Series A - 160962806327 - $790

[Amedeus]

You want the outside of the lens to be a shorter focal length then the center.

Correct ... and that is from a practical lapping perspective also easiest to do

So it's the rear element that was worked? Do you know if it was worked at the edges or cent

In the cases of the #902 and #1024 I was able to detect aspherical surfaces on the rear element and at the edge.

BTW, what model is the #902 that has a rear element? An early doublet?

The #902 is an early doublet as far as I can tell. Research in the details is ongoing.

[Mark Sawyer]

Thank you, Rudi!

[Colin D]

I recently bought from fleabay a Ross Xpres 12in. f4.5 brass lens with flange for Aus. $414. It hasn't arrived yet but the glass looks to be in good to vg condition, wait and see on this when it arrives. Not sure how that price sounds but I notice a 300mm f5.6 Homocentric sold this week for $100 more so I don't think I paid above the odds but not sure.

Is the 12in. a soft focus lens? The only info I can find on it is from Jim who has/had one without iris and based on his shots it appears to be soft wide open at least. I also read where it was suggested to unscrew the front element to increase diffusion. Sounds interesting.

For your interest I bought last year a Voigtlander Dynar 180mm f6 barrel lens with flange for Aus. $60. The barrel is in poor condition but the glass and aperture blades are in good condition, some very fine cleaning marks on the front element, back element perfect, I don't think this is considered soft focus although when I get my Sinar lens I'll get to try it wide open.