Focusing my bloomin Pinkham & Smith

[George Kara]

Hi All

A few months ago I purchased a pinkhham and smith 18" 6 Semi Achromatic. I have been trying to gain some sort of knowledge base for accurately or semi accurately focusing this beast.

My theory has been to focus as good as possible and then do a series of shots in +/- 2mm increments to find where the chemical focus is on the lens. I believe that I have found this to after blowing through some instant film. It appears that in increase in in bellows extension of 2mm at approx 12ft works best. I have read somewhere that approx .25% adjustment for the focal length is the amount to use for this adjustment. For this lens that would equal approx 1.5mm so this seems OK.

I shot using my 4x5 back vs the 8x10 since I have some instant fuji available.

This lens is soooo hard to focus with all that spherical aberration. Trying to find the models eyes is similar to looking through murky water. Are there any techniques to assist with initial focus on this thing? My intent is to shoot the figure and portraits so any advice would be greatly appreciated.

[Steve Hamley]

George,

Sounds like your method of testing is sound and working.

As far as focusing goes, it can be difficult for a really diffuse lens. You might try increasing the lighting/contrast to focus, trying a higher or lower power loupe, or perhaps a different GG. Or perhaps a tiny bit of oil on the GG in a spot if a very fine surface would help versus a coarse one.

You might also stop down to focus although from reading various lenses instructions this might not always work.

Good luck, and please post your findings.

Cheers, Steve

[Don Hutton]

A laser pointer is very handy for these situations (IMO) - while it may be very diffused, you can get an idea of where the "best focus" occurs when the red dot is smallest...

[Glenn Thoreson]

Some nose oil on the ground side of the glass is an old trick for things like this. It works, too. Wipe some in a spot right in the middle, so it doesn't interfere with other things.

[Lynn Jones]

Hi George,

I've used just about all of the soft focus lenses. Since these lenses have huge shift of focus, what most of us use do is to focus at the aperture wanted for the photograph. Due to the nature of these things, the shift of focus is different for every focused distance so it isn't very efeective so simply add a mm or two. In addition, as the aperture changes so does the resolution (in addition to DOF), contrast, and color.

BTW, my old company, B&J, made P&S lenses for several decades, they are truly lovely portrait lenses (also for soft focus landscapes). They were originally from the Boston manufacturer but along about WWII B&J agreed to make them. What they would do was to accept pre paid orders for the P&S lenses and when they had ordered 25 or more of them, then B&J made them.

One of my favorites of this lens type was the Kodak Portrait lens. There is no way to describe it, you have to feel it, especially in color.

Lynn

[Jim Galli]

My method, fwiw, is to latch onto some detail that is important and roll through the very wide range of general focus until the thing I am looking at goes out of focus on the near side. I then just just roll it back until I see my detail come back in. Averaging leveraged the most for the very near edge counteracts the chemical thing and I seem to always get what I'm after.


http://tonopahpictures.0catch.com/Pinkham-Smith/12SAseries_I/DayvilleFireDept12SAf8s.jpg (http://tonopahpictures.0catch.com/Pinkham-Smith/12SAseries_I/DayvilleFireDept12SAf8.jpg)
dayville fire dept

The above done with a 12 inch P&S Semi Achromatic Series I lens. My focus point was the name on the door area. Admitedly the 12 inch is a little easier to tame than the 18 inch is. When you get weary of fighting with it, send it to me.

[Jason Greenberg Motamedi]

One thing which may help is using an orthochromatic film, as this would remove one of several variables. With color film you have way too many variables to learn much about the lens.

I am not completely clear about the timeline, but panchromatic film wasn't available commercially until about 1910 or so, and may or may not have been much used by the pictorialists. I assume that your lens is from the 1910s or 1920s, so perhaps it was designed for use with orthochromatic film. Anybody know?

[Ernest Purdum]

To my surprise, my 1908 George Murphy catalogue lists panchromatic plates (in fifteen sizes up to 20 X 24). I would have thought it later, since ortho was still so common in the 1930's when I was getting interested in all this.

[Jason Greenberg Motamedi]

Interesting Ernest.

I checked Wikipedia (add a big caveat here), and apparently panchromatic film was available commercially in 1906. Earlier than I would have guessed. Anyhow, I assume that orthochromatic (and blue sensitive?) films were available and still being used through the pictorial era.

Does anyone know what films were most commonly used by the pictorialists?

[Lynn Jones]

Hi all,

Miethe of Agfa invented panchromatic emulsions in 1903, shortly after that several film and plate maker manufactured the stuff. The Lumiere Brothers in Lyon, France created "Autochrome" positive RGB color plates in about 1907 and the first National Geo cover in color was from and Autochrome plate in that year. Red, green, and blue tiny particles were sprinkled on a panchromatic emulsion, was photographed through the RGB and processed in reversal b/w chemicals. This and Polachrome were the only RGB photo systems used directly without CMYK. Obviously digital shoots in RGB as soes conventional color emulsion, but they cant be printed without CMYK.

Lynn