Does 35mm have higher base + fog than 120 ?

I primarily shoot medium format. Tmax 100, Tmax 400, HP5 and Panf 50.
I had a bulk roll of 35 mm PanF Plus, a Nikon F100 with a 35 to 70 2.8 Nikon lens and decided to shoot it up.
I developed a couple of rolls in Xtol and thought the base + fog to be high. Thinking that maybe my bulk roll
was aged I bought another. Same issue. Shot a roll of 35mm FP125, same issue. Shot a roll of HP5, same issue.
Delta 100 same issue, base + fog is high.

To rule out the camera and lens I pulled a couple of feet off of the bulk roll of PanF in the dark, loaded a reel and developed same in Xtol.
My densitometer gave me a reading of 0.36.

I developed a roll of HP5, Tmax 100 and Delta 100 in Xtol, base + fog for all 0.08 to 0.1.

Does 35mm have a higher base + fog than 120 ?

Yes, generally speaking it does.

I guess I did'nt get the memo.

So, does 35mm have a lower contrast than 120 ?

I think it may have more so as to attenuate light passing through the film's plastic lengthwise, such as from the leader, inward. 120 is usually wrapped in black paper from end to end, and LF is only one sheet at a time always in the dark.

What you are seeing is the antihalation dye in the 35mm base.

bascom49 said:

I primarily shoot medium format. Tmax 100, Tmax 400, HP5 and Panf 50.
I had a bulk roll of 35 mm PanF Plus, a Nikon F100 with a 35 to 70 2.8 Nikon lens and decided to shoot it up.
I developed a couple of rolls in Xtol and thought the base + fog to be high. Thinking that maybe my bulk roll
was aged I bought another. Same issue. Shot a roll of 35mm FP125, same issue. Shot a roll of HP5, same issue.
Delta 100 same issue, base + fog is high.

To rule out the camera and lens I pulled a couple of feet off of the bulk roll of PanF in the dark, loaded a reel and developed same in Xtol.
My densitometer gave me a reading of 0.36.

I developed a roll of HP5, Tmax 100 and Delta 100 in Xtol, base + fog for all 0.08 to 0.1.

Does 35mm have a higher base + fog than 120 ?

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Hardly a definitive test since you mention nothing about the age and storage conditions of the films. What is needed is rigorous testing under lab conditions using sound statisitical methods. At a very minimum you must test 3 samples of each film under exactly the same confitions.

erikg said:

Yes, generally speaking it does.

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On what do you base this statement?

bascom49 said:

Does 35mm have a higher base + fog than 120 ?

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Apparently your does.

Light piping is really not a problem with the acetate base used in still films. Even if light piping were present it would only effect the first few frames of a 35 mm roll.

bascom49 said:

Does 35mm have a higher base + fog than 120 ?

Click to expand...

Yours does.

Prof_Pixel said:

What you are seeing is the antihalation dye in the 35mm base.

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someone on another forum asked why their film was purple and I said the same thing -- it's the dye. Let your 35mm film rinse for an hour, or even just let it sit in still water for an hour after rinsing for 10 in running water.

You will be amazed how much purple runs out with that final rinse, and how much clearer the base is.

if this were light piping it would be on the first couple of inches and nowhere else, and that is something I've never seen and I always leave the leader of my film out after I rewind.

ctrentelman

The film base used for 135 film usually contains a dye which is part of the plastic and not soluble in water or any processing solutions. Other formats usually do not have a similar film base. In any measurement of base fog the presence of this dye must be taken into account since the density it contributes is not fog. For many years the film base used for Kodak Plus-X 135 had a very dark blue color. No amount of washing could remove this dye.

Gerald C Koch said:

The film base used for 135 film usually contains a dye which is part of the plastic and not soluble in water or any processing solutions. Other formats usually do not have a similar film base. In any measurement of base fog the presence of this dye must be taken into account since the density it contributes is not fog. For many years the film base used for Kodak Plus-X 135 had a very dark blue color. No amount of washing could remove this dye.

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I was surprised no-one mentioned this before. It's quite noticeable with some films and is why Foma's reversal film is on a clearer base thantheir other films, and theur 120 films were on a very blue base this makes no difference to printing.

Ian

For clarification as there arose some confusion:

There are two kinds of AH-dyes:

-) those in a special AH-layer (typically volatile whilst processing, though sometimes not dyes in the proper sense)

-) those embedded in the base (fixed, but not used in all types of film)


When speaking of AH-dyes here at Apug typically the former are referred to, Prof_Pixel obviously referred to the latter.

bascom49 said:

I developed a roll of HP5, Tmax 100 and Delta 100 in Xtol, base + fog for all 0.08 to 0.1.

Does 35mm have a higher base + fog than 120 ?

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I should have clarified that these rolls giving me a lower base + fog densitometer reading were 120 medium format.

While not to laboratory standards I do think that my comparative testing between the two formats is accurate.

All films were washed for two minutes after fixing in running water, followed by two minutes in Kodak Hypo and then washed for ten minutes in running water.

I'm fairly sure that my washing procedure is adequate. If anyone else has an opinion please share.
The film base color is grey, not purple but very clear, not fogged.

I found a set of negatives that I had processed and printed from 135 Tmax 100 last year of a water fall. The film base is lower than Panf, HP5 and FP4 but markedly higher than Tmax 100 in medium format.

One could see it as a classic concept to give types 120/222 just an AH-layer on a colourless base and type 135 an AH-layer on a dyed base (plus even different base thiknesses).

(As other concepts in converting one could challenge this.)


If one needs a figure for base+fog, one should meter a sample from the very lot of film and processing in question.

I asked Simon at Ilford and he was gracious enough to send me a reply.
I'll certainly continue my support of Ilford and Ilford products.
I encourage everyone else to as well.


Dear Charles,

The base density on 35mm ( miniature ) film is higher than on 120 ( different substrate ), dyes in the emulsion and the film has a buffer to prevent light piping.

Thank you for using and valuing ILFORD Photo products :

Simon. ILFORD Photo / HARMAN technology Limited :

AgX said:

For clarification as there arose some confusion:

There are two kinds of AH-dyes:

-) those in a special AH-layer (typically volatile whilst processing, though sometimes not dyes in the proper sense)

-) those embedded in the base (fixed, but not used in all types of film)


When speaking of AH-dyes here at Apug typically the former are referred to, Prof_Pixel obviously referred to the latter.

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Yes. That's why I said "What you are seeing is the antihalation dye in the 35mm base." and NOT "on the 35mm base"

Prof_Pixel said:

Yes. That's why I said "What you are seeing is the antihalation dye in the 35mm base." and NOT "on the 35mm base"

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I took your info as fact and I appreciate your comment. I had already pm'ed Simon and just thought to share his response.

Ian Grant said:

I was surprised no-one mentioned this before. It's quite noticeable with some films and is why Foma's reversal film is on a clearer base thantheir other films, and theur 120 films were on a very blue base this makes no difference to printing.

Ian

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I think why no one mentioned this initially (and I include myself) is that we assumed that the OP and others had made this very important correction.

Jerry

I have a Kodak publication which gives typical b+f densities for their films;
T-max100 in 35=0.24 in120=0.11
T-max400 in 35=0.27 in 120=0.11
Sheet film for both speeds is 0.08
The book is called Advanced Black-and-White Photography from the Kodak Workshop Series

35mm B&W negative film IN GENERAL has a Grey (sometimes Blue) tinted base for anti-halo purposes. 120 and other roll film sometimes has a tint, but sometimes does not. (folks have complained about the Blue tint on Some Foma Made 120 film here in the past) If you are used to 120, SOME 35mm will have a darker base.

Light pipe effects are Quite strong with Polyester base film. I play with movies and if you hold up a reel of Polyester 16mm Movie film to a light you can see the light strongly, while a roll of Acetate film will look dark.. Film which gets fogged from Light Piping will look dark around the perforations. I have seldom seen fog on acetate film that can be attributed to light pipe effects., although I have seen fog from worn or damaged cassettes. I use a twin check tap on my reusable casettes and junk any that correspond to rolls of film with light trap related fog, to try to keep them for getting bad enough to ruin shots.

Dye that washes out in processing is not part of the film base, but may be part of an anti-halo treatment or part of the dyes used to make it panchromatic. The strongest Dye is on the EFKE films which have a purple dye that is visible on the back before processing. The most famous Anti-Halo is the REM-JET used on Motion Picture Negative Stocks ( and Kodachrome) which is a black coating that is removed by a special step in processing.