Film base and resolving power

JaZ99 · Feb 20, 2013

Hi,

I've just developed my very first Delta 400 film (120). I souped it together with TMY-2 in Thornton's 2-bath for 2*5.5 minutes. I've noticed something weird.
The base density of TMY-2 and Delta 400 looks the same to me, however, when I see through the clear part, the films look very different. The TMY-2 base is almost clear, but the Delta 400 base gives very soft looking objects. It is like looking at the trees in the mist. I didn't print it nor scan it yet, and I'm wondering: is it normal for Delta 400? Does it affect the resolving power? Or maybe my developer is not a good match for it?

JaZ

Gerald C Koch · Feb 20, 2013

Is the emulsion side of the film closest to your eye or are you looking through the base at the emulsion?

JaZ99 · Feb 20, 2013

It is the same both ways.

Mustafa Umut Sarac · Feb 20, 2013

I am sorry but I could not understand what you mean with soft looking objects ? I read that Delta have 4 density at black side of negative but Kodak have 3 or so. I suspect that increased density may be effect the clear part of the negative. May be you are lucky , if you have details at your clearest part of the negative , you have details. But I really dont know. Delta is extremelly interesting film and its creates degrades where we see ultra cleaned , tamed with photoshop , fashion pictures. Its ultra high contrast film to my eye. I want 100 or 200 asa , I could not remember now but I saw similar pictures only at PN55 Polaroid African American portraits. Excellent. Skin shines and its look like wet.

Gerald C Koch · Feb 20, 2013

When film is printed the light passes first through the base and then the emulsion. Therefore the base has no effect on resolution.

A developer can have no effect on the film base since it is just plastic. Some films have used a silver halide antihalation layer on the back of the film. With such films inadequate fixing might cause some perceived cloudiness. Howewver I doubt either of the films you mention use this technique.

250swb · Feb 20, 2013

JaZ99 said:
Does it affect the resolving power? Or maybe my developer is not a good match for it?

I suppose if you put the negative in the enlarger upside down (emulsion side up), the film base could affect the resolution. But as the emulsion is the last thing the light from the enlarger goes through (and the thing you focus on) the film base wouldn't normally affect resolution, only lower the contrast. So a 'heavier' film base would only diffuse the light but not make the image less sharp, assuming the distinction that contrast and sharpness are two different things.

Steve

Mustafa Umut Sarac · Feb 20, 2013

When film is printed the light passes first through the base and then the emulsion. Therefore the base has no effect on resolution.

I think even an clear base must have an effect on resolution. Basic check at optical resolution / wikipedia article, refractive index of clear base is important. I bet abbe number is important at more detailed analysis. Short answer , every clear base have an MTF graph and Phase graph for each material selection. And surface correctness and the internal morphology resulting from stretch or heat difference will effect the result also.

If Gerald , I follow your path , if the light passes the base first , base will create a aberration phase for the light. It will than meet with the emulsion and lens and to be needed to be summed.

Umut

Newt_on_Swings · Feb 20, 2013

A clear base just allows for faster printing times. Tmax 100 in 120 is practically clear. Colored bases such as with color neg films will act like a safe light. And staining developers will also give a bit of this safe light effect to some areas such as sky's. Also i you are printing on vs or graded would also make a difference. I think Barry's diaxtol is a type of staining developer. I'll have to check in his book the edge of darkness.

MattKing · Feb 20, 2013

The base cannot induce a reduction in resolution.

It might induce some minor distortion, if it is significantly flawed.

It can, however, change the appearance of the negative when it is viewed with the naked eye.

OzJohn · Feb 20, 2013

Newt_on_Swings said:
Colored bases such as with color neg films will act like a safe light.

Its a bit off topic and I have no intention to nit pick what the OP has said but could someone who knows please clarify for me once and for all if colour neg film base is in any way coloured? It is often claimed, in many different places, to be so but I've always understood the "base" colour to be residual couplers that are themselves coloured and therefore colour neg is coated on ordinary clear base. OzJohn

Prof_Pixel · Feb 20, 2013

Basically, the orange color is from the color couplers and is used for color masking color correction. See Bunny Hanson's 1950 article Color Correction with Colored Couplers at http://www.opticsinfobase.org/josa/abstract.cfm?uri=josa-40-3-166[/B]

Newt_on_Swings · Feb 20, 2013

Newt_on_Swings said:
A clear base just allows for faster printing times. Tmax 100 in 120 is practically clear. Colored bases such as with color neg films will act like a safe light. And staining developers will also give a bit of this safe light effect to some areas such as sky's. Also i you are printing on vs or graded would also make a difference. I think Barry's diaxtol is a type of staining developer. I'll have to check in his book the edge of darkness.

Gosh, the typos haha:

Also if you are printing on vc or graded would also make a difference.

To elaborate, graded would be more of the safe light effect, VC papers will decrease contrast and act as if you were printing at a lower grade.

JaZ99 · Feb 21, 2013

Please excuse me the quality of the attached pictures, but I hope it is clear now what I mean.

TMY-2 is on the left, Delta 400 is on the right. As you can see, the Delta's base
is much more "milky" than the other one.

The density of the base is more or less the same:

250swb · Feb 21, 2013

Yes, different densities, different colours, it doesn't matter, that has no bearing on resolution or degrading the resolution of the film. The 'resolution' information is contained in the emulsion layer, not the film base. The film base can only affect contrast or exposure time under the enlarger, and even then not by much.

Steve

John Wiegerink · Feb 21, 2013

250swb said:
Yes, different densities, different colours, it doesn't matter, that has no bearing on resolution or degrading the resolution of the film. The 'resolution' information is contained in the emulsion layer, not the film base. The film base can only affect contrast or exposure time under the enlarger, and even then not by much.

Steve

That sure seems hard to believe, but who am I to say. It would seem that a film with a real dense base would have something to do with reduced resolution. Of course I have seen no film with a base this dense either. JohnW

Gerald C Koch · Feb 21, 2013

Unless some one can produce examples of PRINTS (not scans which create various false artifacts) of each film that show a difference in resolution then people are overthinking a nonexistant problem.

John Wiegerink · Feb 21, 2013

Gerald C Koch said:
Unless some one can produce examples of PRINTS (not scans which create various false artifacts) of each film that show a difference in resolution then people are overthinking a nonexistant problem.

Not me Gerald! I follow the old line, "If it ain't broke, don't fix it". I have never seen a problem, but must admit that I like to see as clear a base as possible whether it makes a difference or not. I guess it's like water. If you have two glasses of water, one murky-muddy looking and the other crystal clear, which are you more likely to drink ? Now, most of us are going to be willing to drink the crystal clear glass and not the murky one. Of course what we don't see is all those little animals in the clear glass that are out to do us harm while the murky glass has been purged of those gritters. Looks can be deceiving? JohnW

Film base and resolving power

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