Just confused...

[dietcookie]

After scouring through a ton a links and old discussions, for some reason I can't figure out the solution. I am going to the Sierras this weekend for four days to shoot photos, I 50 sheets of Efke 25, 4x5 to go through. From what I can gather, it being a Orthopanchromatic film, it has a reduced red sensitivity compared to a "panchromatic" film such as TMX. So what i'm getting at is, how do I add contrast to a plain ol blue sky? Should I only use a Yellow 15 filter? From what I understand, the compensation for a Red 25 is 8 stops, and does nothing to the sky? I will be using a polarizer, what filter should give me the darkest skies with nice cloud contrast? I pretty much learned that this is not the film to use for dramatic skies, but i'll make do.

[Ron Marshall]

The second link is to spectral transmission charts for various filters. A wratten #25 cuts off most light below 600nm, which is about where the sensitivity for your film ends (http://www.jandcphoto.com/JandC/AdoxTech.htm), so it would not be useful.

A #15 as you suggest would be a good choice, or a #12.

The #25 has a filter factor of 8, or three stops. 8 is two raised to the power of three: three stops is eight times less light.

http://www.photo.net/photo/edscott/cf000010.htm

[dietcookie]

Thanks for the links. So in the end, a Red 25 will not do anything for me correct?

[Ron Marshall]

Thanks for the links. So in the end, a Red 25 will not do anything for me correct?

It will just act as a three stop neutral density filter.

[Ted Harris]

Going back to the original question .... there are published data sheets for all of the Adox/efke films but first we need to know exactly what it says on your box of film. I ask because Adox/efke have two ISO 25 emulsions, one is orthopanchromatic and the other is a straighforward panchromatic film. If your box doesn't say 'ortho' on it chances are it is the straight panchromatic film but check and let us know.

[dietcookie]

Going back to the original question .... there are published data sheets for all of the Adox/efke films but first we need to know exactly what it says on your box of film. I ask because Adox/efke have two ISO 25 emulsions, one is orthopanchromatic and the other is a straighforward panchromatic film. If your box doesn't say 'ortho' on it chances are it is the straight panchromatic film but check and let us know.

I just checked, no where on the box does it say ortho or chromatic this...prety much only EFKE PL 25 M...whaddya think?

[Geary Lyons]

I've been using efke films for several years. I'm not aware that efke produces a panchromatic film in ASA25 (PL, R, or KB25) or ASA50 (PL, R, or KB50), just orthopanchromatic emulsions. They do produce an ASA 100, (PL100 et al) that is panchromatic.

The orthopan will produce a darker sky, without filtration, than the pan, without filtration, My experience is the differenence is about the same as a Yellow #12.

Cheers,
Geary

[dietcookie]

I've been using efke films for several years. I'm not aware that efke produces a panchromatic film in ASA25 (PL, R, or KB25) or ASA50 (PL, R, or KB50), just orthopanchromatic emulsions. They do produce an ASA 100, (PL100 et al) that is panchromatic.

The orthopan will produce a darker sky, without filtration, than the pan, without filtration, My experience is the differenence is about the same as a Yellow #12.

Cheers,
Geary

From what I have read, I am positive that the Efke 25 is Orthopanchromatic, red sensitivity is less than panchromatic(TMX/Delta Etc..).. I head out this weekend, I know I should be using a film I know well but I wanted to try something new, I won't have time to test it but by doing the math, hopefully sticking a yellow 15 on it will do the job.

[Geary Lyons]

From what I have read, I am positive that the Efke 25 is Orthopanchromatic, red sensitivity is less than panchromatic(TMX/Delta Etc..).. I head out this weekend, I know I should be using a film I know well but I wanted to try something new, I won't have time to test it but by doing the math, hopefully sticking a yellow 15 on it will do the job.

Shoot some without the filter, if for no other reason than a reference! Have fun! great film!

Cheers,
Geary