Archived posting to the Leica Users Group, 2005/10/13
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]At 5:19 PM -0400 10/13/05, John Black wrote:
> > >
>>
>> Dunno how you do it...I can't make 400CN even with red filter. Beautiful.
>>
>> >
>
>I can't either. I gave up several years ago on (at that time T400CN) the
>C41 B&W films because I couldn't get any effect much at all with my colored
>filters. Looked much the same with as without. Went back to Tri-X and
>everything returned to normal with filters.
>
>Don't know what I did wrong.
>
>JB
>
The spectral sensitivity of the chromogenic films is much closer to
what our eyes see, and what colour film sees than what most B&W film
sees. Most B&W films have somewhat extended blue sensitivity and
often red as well, and are a bit deficient in the yellow-green
region. Therefore, Tri-X needs a light Y-G filter to bring it back to
'normal', whereas chromogenic film produces a fairly definite
'effect' with a Y-G filter.
A deep red, like a 25 or even more so 29 are strong enough to pretty
much overpower most intrinsic spectral inequalities so you should get
a similar result. Most filter effects are affected by relative
exposure, though, especially with standard B&W film and contrast
enhancing filters. Overexpose and filter effects are reduced.
--
* Henning J. Wulff
/|\ Wulff Photography & Design
/###\ mailto:henningw@archiphoto.com
|[ ]| http://www.archiphoto.com