Choosing filters

For those folks who are uncertain which filter to use, here are spectral graphs for various filters.

A filters effect on the photographic negative depends heavily on the type of film you're shooting.
In other words... the emulsion's spectral sensitivity should be taken into consideration when selecting a filter.
This is especially true when using non-panchromatic films (x-ray, Infrared, Ortho, collodion, etc.).

Consult your films data sheet for it's spectral response curve and compare it to each filters curve.

The heavy dark line is the filters transmission drawn on a 360-750nm colored background.
Panchromatic films are more sensitive in the central portion of the graph.
It's here where most contrast filters are used (Yellow-green/ Orange/Red).

If you're shooting paper negatives, the Blue/Green part of the graph is most important.
Single grade photo papers are mostly Blue sensitive.
VC papers have added green sensitivity.
Orange/Red filters are nothing more than safe lights in this case.

The dashed line represents the spectral response for Ilford's Ortho Plus film.
Ortho films can only see Blue/Green light... Yellow/Red filters are mostly useless.

The 380-520nm outlined area defines the spectral response for typical wet plate (collodion) emulsions.
A Blue filter may make focusing easier by blocking out the distracting Yellow/Red component.

Reinhold
www.re-inventedPhotoEquip.com

Thank you for posting this useful Info.

Kodak once publishrd an extremely useful book with all filter dataand by using that data in combination with the spectral sensitivity data of your film you could study the efect of any filterand light source with a simple spreadsheet.

Kodak once publishrd an extremely useful book with all filter dataand by using that data in combination with the spectral sensitivity data of your film you could study the efect of any filterand light source with a simple spreadsheet.(see above)

I believe the books is called "Using Filters" and was part of the Kodak Workshop series and was full of great info

That Kodak Wratten filter book is excellent. I consult it frequently, even though I mostly use glass filters. It has been out of print awhile, but you
can sometimes stumble onto things like this in used bookstores.