Table of lines per mm for common films?

I use a film camera for some prime focus wide-field images. Although I
understand that film generally has a resolution of 100-150 lines per
mm, where can I find a table that summarizes the line pairs per mm for
common films? North's _Advanced Amateur Astronomy_ has a table at p.
83, but it is from 1996. - Canopus56

P.S. - I assume I can convert film lp/mm into an equivalent square
detector size via:

Detector_size_mm = 1 / ( 2 * line pairs per mm * 2 )
Detector_size_microns = Detector_size_mm / (10 ^ -3)

On 28 Jan 2006 17:27:22 -0800, "canopus56" wrote:

I use a film camera for some prime focus wide-field images. Although I
understand that film generally has a resolution of 100-150 lines per
mm, where can I find a table that summarizes the line pairs per mm for
common films? North's _Advanced Amateur Astronomy_ has a table at p.
83, but it is from 1996. - Canopus56

P.S. - I assume I can convert film lp/mm into an equivalent square
detector size via:

Detector_size_mm = 1 / ( 2 * line pairs per mm * 2 )
Detector_size_microns = Detector_size_mm / (10 ^ -3)

Converting between film lp/mm and pixel size is very complex. Basically
lp/mm is an almost useless spec, especially for astroimaging. You need
to consider the MTF, which with film is not at all flat. lp/mm is
specified at zero contrast. Depending on actual contrast in an area,
common color films can have a resolution as low as 3 lp/mm!

In comparison, the MTF for CCDs is quite flat, not falling off until the
frequency data is about twice the pixel spacing.

Kodak data sheets generally show the MTF, but I haven't always been able
to find it for Japanese emulsions.

A CCD with 9um pixels has a higher spatial resolution than all but the
highest resolution films.

_________________________________________________

Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

Chris L Peterson wrote:
On 28 Jan 2006 17:27:22 -0800, "canopus56" wrote:
snip
Chris wrote:
Converting between film lp/mm and pixel size is very complex. Basically
lp/mm is an almost useless spec, especially for astroimaging. You need
to consider the MTF, which with film is not at all flat. lp/mm is
specified at zero contrast. Depending on actual contrast in an area,
common color films can have a resolution as low as 3 lp/mm!
snip

Thanks, Chris, all important considerations and probably in part why
North gives lines/mm for film resolution in a range, e.g. Kodak Gold
Ultra 400: 50-125 lp/mm. The lower figure is using a low contrast
grid and the second using a high contrast grid. Although image
contrast and film can't be matched precisely in the field, one can
still at least attempt match resolution of the film to scope's focal
length - as a step in empirically optimizing a series of exposures.

Sounds like I have to go my local camera shop and get the data sheets,
assuming they are not available online.

- Thanks again, Canopus56

On 28 Jan 2006 18:06:32 -0800, "canopus56" wrote:

Sounds like I have to go my local camera shop and get the data sheets,
assuming they are not available online.

I've always found Kodak data online, although it's been a couple of
years since I last needed it. Not so much luck with Fuji, however.

_________________________________________________

Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

"canopus56" wrote in message
ups.com...
I use a film camera for some prime focus wide-field images. Although I
understand that film generally has a resolution of 100-150 lines per
mm, where can I find a table that summarizes the line pairs per mm for
common films? North's _Advanced Amateur Astronomy_ has a table at p.
83, but it is from 1996. - Canopus56

P.S. - I assume I can convert film lp/mm into an equivalent square
detector size via:

Detector_size_mm = 1 / ( 2 * line pairs per mm * 2 )
Detector_size_microns = Detector_size_mm / (10 ^ -3)


And just where do you think this is all going to get you? just what do you
expect
to do that you haven't done already with film?