Clear negatives?

[yeknom02]

Hi everyone,

I was watching some old interview footage with Garry Winogrand, and I saw him trimming his 35mm film strips. I was blown away by how clear the platic base of the film was! I shoot HP5, Tri-X, and Agfa APX 400, and they're all a relatively dense gray. What gives? I am wondering why they're not clearer, since it would make sense for enlargements.

-dan

 

[brucemuir]

a dense gray?
sounds like excessive base fog.
are you processing your own film and if so, is the area you are loading your reels/tanks light tight?

 

[fschifano]

Old interview footage, eh? Well, what can you tell from that? You have no idea what kind of film was being handled. You don't know the spectral sensitivity the original cine camera film. Man, you're coming to conclusions about stuff that you can't know. And yes, some films have less base density, minus any fog, than others. TMax 100, when you get all the sensitizing dyes out, is remarkably clear. Foma 120 and sheet films are blue, and not faint blue either but a very distinct cyan. It means nothing, so what's the problem?

 

[yeknom02]

No, it's not fogging, I don't think. I use a changing bag for loading my reels and tanks and the density is pretty uniform. I also tested it by dropping the undeveloped leader in fixer for about 5 minutes. It's coming out with a purplish gray tint to it.

What's this "sensitizing dye" you mention? Is there another film developing step that I never read about that I should be doing to get rid of it?

It makes sense now that I think about it that some base density would only increase the exposure time for printing and probably wouldn't affect the contrast or dynamic range of the image. I've made some enlargements with my negatives and they turned out great! So, there's no problem, I'm just wondering if the base layer has become characteristically darker over the years for some reason or another.

 

[CBG]

There is a thread that deals in the issues of blue / pink / purple tint on bw negative stock and how to get rid of it. www.apug.org/forums/forum37/33868-p...ew-tri-x-other-films-not-blue-green-cast.html

Once you have rid your film of the dye tinting through using the right fixer for long enough, and hypo clearing agent / wash aid for long enough, you might find your film has an overall fogging or exposure through storage not cold enough, if the film is ummm, vintage stock. As you note, that is usually not a crisis as long as you can print through it.

 

[Thomas Bertilsson]

You shouldn't worry about having a tint to the base of the film. Like Frank says, some films have more than others, with Foma 120 film taking the lead with a blue film base.
Films that come out basically completely clear - Kodak Tmax 100/400 and Fuji Acros. Others, like Kodak Tri-X and Agfa APX 400 have a definite tint to the base, but print just as well.

Basically - don't worry about it, because it doesn't affect the print quality.

But, if you have either a milky quality to the negative or the base fog is very dense, you can suspect either poor processing where the film isn't fixed properly, or old film stock (or both). It could be a light leak also, but that usually doesn't show up as uniform fog.

Use fresh film and make sure you fix enough and use fresh fixer.

 

[Nicholas Lindan]

To tell 'base tint' from emulsion fogging you can just scrape away a bit of the emulsion on the sprocket rebate with your fingernail when you hang it up to dry. If the film is already dry a dip in Clorox or boiling water will remove the emulsion pretty quickly.

 

[fschifano]

Normally, silver halides are sensitive only to blue and ultraviolet. Sensitizing dyes are added during manufacture to make the film sensitive to the entire visible spectrum. In TMax films, this dye is a distinct magenta color to the human eye. This coloration has gained a certain notoriety over the years as being particularly difficult to handle They should wash out completely during fixation and final wash. There's nothing special you need to do.