RE: Converting paper ISO speed to film ISO speed...

Wow 8 seconds for paper. I have never used paper and had such a short exposure. I am usually stuck around 60 seconds or so to get a good exposure on the same size of paper, however I an in the haze of Seattle where the light seems to go to die.

Jason

-----Original Message-----
From: Tom Miller [mailto:tomwmiller@comcast.net]
Sent: Fri 10/8/2004 7:44 AM
To: pinhole-discussion@spitbite.org
Cc:
Subject: RE: [pinhole-discussion] Converting paper ISO speed to film ISO speed...

Hi Loris,

My recommendation is to test the type of paper you'll be using in order to
determine its exposure in bright sunlight. Then give the paper extras
exposure based on the ambient light you are "shooting" in. Contact me
off-list if you'd like a Word document that describes the process in more
detail. tomwmiller@comcast.net. You can cut one sheet of 11x14 into four
sheets of 5x7 to help keep the cost down for testing.

The testing recommendation results from the differences in papers' spectral
sensitivities. I've found that, using 5x7 sheets of paper in a 3.5 inch (90
mm) camera resulted in basic daylight exposures ranging from 8 seconds for
Kodak P-Max Art RC to 45 seconds for Calumet warm tone matt RC.

The other thing that testing does is demonstrate the spectral sensitivity or
tonal range of the paper you're considering. Most photographic papers are
senstitive to blue or blue and a little green light. Whites blow out (or
block up, depending on the term you want to use) readily. Papers vary
widely in their tonal range when used as negatives.

I haven't noticed major problems with reciprocity failure in paper in most
situations. The only time I corrected a calculated exposure was when a
22-hour indoor exposure was a little thin. Another exposure at 43 hours
worked great.

Tom Miller

> -----Original Message-----
> From: owner-pinhole-discussion@spitbite.org
> [mailto:owner-pinhole-discussion@spitbite.org]On Behalf Of Loris Medici
> Sent: Friday, October 08, 2004 9:04 AM
> To: pinhole-discussion@spitbite.org
> Subject: [pinhole-discussion] Converting paper ISO speed to film ISO
> speed...
>
>
>
> I plan to build a 11"x14" pinhole camera... I will use photographic
> paper (B&W) as negatives.
>
> 1. Is there a method for converting Paper ISO Speeds to Film ISO Speed?
> For instance, if the manufacturer rates the speed of a paper as ISO
> P300, what ISO whould I rate this paper when using it as a film?
>
> 2. I hope the reciprocity failure is less drastic in paper when compared
> to film... Is there any useful reciprocity failure tables online (for
> B&W papers)?
>
> Thanks in advance,
> Loris.
>
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