Ilfochrome exposure in large camera obscura

[Ken Allen]

Hi All,

I have a multi-part question regarding recording an image in a large Camera Obscura. Has anyone used 30x40 inch Ilfochrome paper in a camera obscura that will be recording a daylight scene? If so what ASA setting/ or what Lux value did you need to achieve for 90% white?
Does anyone know of a lab in New York City that still processes Ilfochrome?
Have people used other large format (30x40 inches to 50x60 inches) materials to record images (pos/neg, color/b&w) and how did they work for you?

Details: The camera obscura is room sized using a single element lens with a focal length of 144" at infinity. Currently the lens has an 8.5 in. aperture (f17), but I will be creating smaller apertures (2 in. [f72], 1 in. [f144], .5 in. [f288], .25 in. [f576]). I will use an 85B filter for color papers.

Any input on recording materials and experiences would be greatly appreciated.

Best,

[Donald Brewster]

http://www.glennview.com/ciba.htm

A good start here.

[bob carnie]

Ken

I have a ciba processor here in Toronto, We have indeed tried Ilfochrome Classic paper expose in an 8x10 enlarger.

We did this quite a few years ago so bear with my fading memory.

To colour balance you really need to know how to correct in front of the lens with filters . As well the ISO of this paper is quite slow so be prepared for long exposures , taking in account the filters , the paper speed, and as well your large camera lens diagphram I would imagine a static subject is required.

Testing is required and you will need to find a lab close by that will run your paper . You can buy 30x40 sheets from Ilford or through the Lab you chose.

I would suggest that shooting this way will require a couple of days of concentrated effort with as little lag time between exposure and process.

If this is a still life project , we do rent a studio in the same building as the processor, all you would need is to drag the equipment and yourself to Toronto .

good luck with your project