A picture to thank the group

[Philippe Gauthier]

http://www.photo.net/photodb/image-display?photo_id=2304335&size=lg

I just wanted to thank the group for the help I got when looking for 8x10 film holders and information on my old rapid rectilinear lens. This is a cyanotype made from my first 8x10 negative (these huge neg are totally cool), using a 100+ year old Seneca View and a Conley 12.5 inches, f/8 rapid rectilinear lens of the same vintage (the f/stops on the Wollensak brass shutter are using the old pre-1900 american system, where 4 = f/8 and 256 = f/64.

[David A. Goldfarb]

Great, Philippe!

[Larry Gebhardt]

Nice picture Philippe. It looks like it was taken 100 years ago.

Do you have a reference for the American sytem you mentioned. I have a Conely 5x7 camera with a Conely 8", 14", 18" convertible lens. It is marked from 4 to 256 for the 8", which I was having a hard time believing given the size of the lens. I have not yet had a chance to shoot with it, partly because I wasn't sure about the stops. The camera has a patent date of Aug 13, 07 on one part so it is not older than that.

Larry

[Philippe Gauthier]

Larry, no need to look very far. I found the conversion table on this site (great reference, if you didn't know already!), under the "shutter" title:

http://www.largeformatphotography.info/shutters.html

The two systems have exactly the same value at f/16; the US system value then doubles for each complete f/stop if you close the lens, or is cut in half if you open the lens. So, US system 4, 8, 16, 32, 64, 128, 256... is equal to f/8, f/11, f/16, f/22, f/32 f/45, f/64.

[Philippe Gauthier]

Or, to make this even easier:
http://www.largeformatphotography.info/Apertures.gif

[Sidney Cammeresi]

How permanent is the cyanotype process? I couldn't find any definitive information on this via Google.

[Don Bryant]

Cyanotype printing is very archival if processed properly and printed on good quality paper or fabric.

Some of the oldest photographs are cyanotypes.

Non-buffered (non alkaline buffered) papers should be used to avoid fading.

Preservation may be enhanced by toning in a 20% solution of zinc chloride, nickel sulphate, or nickel nitrate. These chemicals are hazardous and should be handled with care as you would with selenium salts (this is per Dr. Mike Ware research, the world’s pre-eminent modern expert on cyanotype printing).

[Philippe Gauthier]

Alternatively, tea toning will turn the print violet or brown, while making it more resistant to alkalis. A strong tea is not as dangerous as the previously mentioned chemicals. I'm not sure about the archival characteristics of tea toned cyanotypes, however.

[Ole Tjugen]

Tea stains seem to be pretty permanent, so a toned cyanotype will probably outlast the maker - just like the tea stains on a white linen shirt ;)