Pinkham & Smith 18" 6 - The beast

[George Kara]

Check out this spherical aberration. Wide open last night. Polaroid 51 with a voodoo incantation.

Even at f11 this puppy is throwing off all kinds of crazy diffusion. It is truly a one of a kind lens that Ill never be getting rid of.

The PS 945 is very easy to use compared to this lens.

[Petzval Paul]

Which series is this? I have a series VI which is very easy to use and has a great look but I've never used it closed down. This one is really wild, though!

[Jim Galli]

I seem to recall this was a series I. Yes, they are in a world and a class all their own. What exactly are we looking at here?

[George Kara]

Hi Guys. It is a series II. The engraving is P&S Semi-Achromatic 18in.1282.

I dont have a clue as to what 1282 is perhaps a serial number?

The image is of some wonderful drums and a Zambian mask I picked up in Africa. This lens seems to have a whole lot of voodoo going on. Im thinking of contacting Mark Sawyer down in Tucson for a little shoot. Perhaps we could set up some models and shoot away with a few soft focus lenses. I have a Cooke PS945 which is quite easy to work with - unlike the arcane and hidden skills needed for the P&S :). This weekend Ill fire up the AS 8x10 and see what happens over the labor day weekend.

[Mark Sawyer]

Im thinking of contacting Mark Sawyer down in Tucson for a little shoot. Perhaps we could set up some models and shoot away with a few soft focus lenses.

By all means, you should contact him! He's pretty hospitable, but to be honest, he doesn't know what he's doing...

[Nathan Potter]

Whew! George I'm glad you have confirmed the subject matter. I had thought it might be a perverse view of the adolescent groin. :D This seems to be a pretty interesting lens. The radially graded diffusion is hard to access though due to the obscure subject. Would be great to examine the treatment of a more recognizable subject. :)

Nate Potter, Austin TX.

[George Kara]

Actually nathan I was poring over anything and everything re: using this lens and came across a great book digitized by google written in 1917.

It looks like the reason the diffusion is so great is because of chemical focus - once again. I focused on the violet ( the authors term) rays which are easiest for us to see. The part that the film will see are the "green rays" .

The author suggests focusing as good as possible and then moving the film plane towards the lens until just begins to be out of focus. I must try this on the weekend.

He also suggests using a ray filter to assist. I have never seen nor heard of this kind of filter. Anyone ideas?

[Nathan Potter]

George, I have a vague recollection that a "ray filter" refers to a notch or bandpass filter or at least a sharp cutoff somewhere in the visible spectrum. In your instance it would be a filter that would pass mostly green "rays" or green wavelengths. A sharp bandpass will suck up a lot of intensity and make it difficult to focus though. If you're referring to the 1917 book it may be that the author is dealing with film which is less panchromatic than todays emulsions. And given that the P&S probably suffers from pretty serious chromatic abberation the 1917 book might make sense.

Nate Potter, Austin TX.

[cowanw]

Actually nathan I was poring over anything and everything re: using this lens and came across a great book digitized by google written in 1917.

It looks like the reason the diffusion is so great is because of chemical focus - once again. I focused on the violet ( the authors term) rays which are easiest for us to see. The part that the film will see are the "green rays" .

The author suggests focusing as good as possible and then moving the film plane towards the lens until just begins to be out of focus. I must try this on the weekend.

He also suggests using a ray filter to assist. I have never seen nor heard of this kind of filter. Anyone ideas?

According to Jones, 1911; a ray filter is really any colour filter just as we use now. The most used was yellow for the same reason we do now.
Anderson, 1939 says the same thing.
In your case, the use of a filter is to reduce the chromatic aberrations of the lens by limiting the variety of wavelengths passing through it. Yellow or red filters are said to sharpen the image.
Chemical focus is one of the explanations of Julia Margaret Cameron's "fuzzy pictures". It is said she failed to correct for visible vs UV/blue focus.
I have a hard time understanding this. I realize that chemical focus effect may result in the plane you thought you were focussed on not being in focus, but there must be some other distance where you were actually although mistakenly precisely in focus.
In your picture and in Cameron's picture, I don't think you have missed the plane of focus.
Regards
Bill

[Mark Sawyer]

I suspect the chemical focus may be less of an issue with today's films as compared to those of near a century ago. I suspect there may be some chromatic aberration going on that has the same effect though, focusing some colors here and others there. The "semi-" in "semi-achromat" may be more operative than we first suspect!

And as P$S... um, I mean P&S lenses get their effect from being hand-aspherized, that part may be better termed "aspherical aberration". :)