Halation, film and pressure plates (35mm)

snusmumriken

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I've been trying out Kodak Double-X lately. On-line reviews have suggested it is not great in bright contrasty conditions because the highlights tend to run away. So of course I was curious to try it in such conditions. October sunshine in Paris provided the opportunity. The film coped very well, far better than I expected. But I re-discovered what I should have anticipated: why most modern films have an anti-halation layer.


So then I wondered why the pressure plate isn't somehow coated to reduce the light reflected back through the film backing. This photo was taken on an (old) Leica M6, in which the pressure plate is a plain smooth sheet. I remembered that my old Nikon FE had a textured pressure plate. I never wondered why. Is there in fact anything that the camera manufacturer can do to reduce halation, and if so, why don't all manufacturers do it?
 
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koraks

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snusmumriken said:
why most modern films have an anti-halation layer.
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But...do they? How many 35mm films actually have an anti-halation layer? Many/most films shed a very apparent anti-halo dye upon processing in 120 and sheet film formats, but not in 35mm!

snusmumriken said:
Is there in fact anything that the camera manufacturer can do to reduce halation
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Well, obviously, blackening the pressure plate, which indeed is being done consistently.

Are you sure what you're looking at is in fact halation? It looks too sharply defined for this. Furthermore, halation tends to make highlights bloom; in your case it seems a sharp duplication of shadow areas. Are you sure the effect is present in the physical negative?
 

bernard_L

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What camera? As stated by koraks, one sees a slightly offset ghost image. Shutter rebound? I've had this with a Compur shutter, and have not found the cure so far.
Did you look closely at pictures taken with other films but same camera, at shutter speeds equal or close to the picture shown?
 
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snusmumriken

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koraks said:
How many 35mm films actually have an anti-halation layer? Many/most films shed a very apparent anti-halo dye upon processing in 120 and sheet film formats, but not in 35mm!
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Apologies, my loose terminology. From my personal experience of different makes in 35mm, Kodak T-Max films have a strong anti-halation dye which can be a pain to wash out completely. I never noticed anything in Tri-X. My usual choices, Ilford FP4+ and HP5+, have a less pronounced purplish tint in the film which easily washes clear after fixing.
Now there's a very interesting thought. It is difficult to look for the duplication in the negative because being the highlights those parts are the densest. Just in case it's the scanner, II will try scanning the negative rotated 180 deg (but still emulsion down) and see what happens.

250swb said:
A ghost image posted on Halloween, but not halation. I don't think it's the camera to blame, are you sure the negative hasn't moved when it's being scanned?
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Leica M6. These are interesting thoughts, friends. I admit I didn't think of any alternative explanations. I will report back after further investigation.
 

koraks

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That's odd. I use HP5+ a lot in 35mm and I never noticed any anti-halation dye washing out of it. It's been ages since I used any TMAX100 or 400, so can't really comment on those.

Well, be all that as it may, in any case I would expect this issue to be unrelated to halation as such. I'm curious what the scanning experiment will tell. I understand it's difficult, but I'd still try to make something out on the negative itself with a decent loupe and some kind of light box / diffuse light source.
 
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snusmumriken

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koraks said:
That's odd. I use HP5+ a lot in 35mm and I never noticed any anti-halation dye washing out of it. It's been ages since I used any TMAX100 or 400, so can't really comment on those.
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My TMax days were long ago too. There was a strong purplish dye that coloured the initial wash water. The negatives look purplish to this day.
I don't see the same with Ilford films, but the film changes colour as you wash it, from a faintly purplish tint to an almost clear base. Interestingly, Double-X is as clear as it is possible to be, so that the negatives look starkly black-and-white. Hence me jumping to conclusions.
 
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snusmumriken

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This has been really instructive. Thanks to everyone for your suggestions.

First, I could make out nothing on the negatives. They aren't stupidly dense, but sufficient to make me unsure whether there was/wasn't a ghost image.

Second, adjacent frames shot at the same (pre-set) shutter speed did indeed show similar ghosting. Like this one:


However, I've just tried re-scanning exactly as before, and the new scans have no ghost images.



So I don't know what was going on with my scanner, but evidently it was having a bad day. It isn't credible that I knocked it during scanning for each of half-a-dozen consecutive frames. On the other hand, not every frame scanned on that day and from the same sequence of shots had ghost images.

Anyway, mystery solved: it was neither the film nor the camera. My apologies to both of them, and thanks again for your help.
 

AgX

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koraks said:
How many 35mm films actually have an anti-halation layer? Many/most films shed a very apparent anti-halo dye upon processing in 120 and sheet film formats, but not in 35mm!
Click to expand...

Anti-halation means are standard for camera films since generations. AH-means exist for more than 100 years!

Do not overlook that such means can be various, you do not have to see a colouring of baths, and if so it can have a different origin.
 

Helge

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Halation is the reflections from the phase change going from backing to air. And since that is some fraction of a millimetre away from the emulsion, its going to lead to the characteristic halos or auras around highlights.
What is less talked about is that, that reflection is actually speeding the film up a lot. Both by direct retro reflection, but also by "simu-flashing" with a slightly diffused backlight, in the shadows.
HIE and I believe D3200 didn't and doesn't employ antihalation backing for that reason.
What is interesting is washing off the anti halation die and actually using the pressure plate to reflect by putting tinfoil on it.
It leads to violent halation and a lot of extra speed. At least a stop and a half. If not two.
 

koraks

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AgX said:
Do not overlook that such means can be various, you do not have to see a colouring of baths, and if so it can have a different origin.
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Oh, I don't overlook these facts. But neither do I overlook the common practice in lower-end films such as Fomapan where antihalation measures are taken on 120 and sheet film that are either lacking or fundamentally different in 35mm. Personally, I think they're mostly lacking there. Of course that doesn't say anything about other, higher end film stocks. My question was genuine in that the question what kind of halation is present on any given 35mm film stock usually remains unanswered and at best culminates into more generic (still useful) answers such as yours.
 

ic-racer

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Can we see the negatives? All I see are prints.
 

AgX

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Basically Rollfilm and 35mm camera film tradionally have a different layer design. As result of this for coating economics applied AH means may differ in these two at same emulsion proper.
Also the requirements for the various film formats vary.
 

reddesert

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FWIW, these tints may be from sensitizing dyes, not anti-halation layers. They usually come out more thoroughly in the fixer or wash aid, depending on chemistry. T-max turns my Perma-Wash purple but the tint is removed from the film.
 

Helge

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TMax needs to fix for ten minutes at least, whereas “normal” film only needs four to five.
Good news is that a lot of that fixing can be done in semi “stand”.
Initial 4 minutes of regular continuous agitation, and then some agitation once in a while for the next 6.
 

mshchem

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reddesert said:
FWIW, these tints may be from sensitizing dyes, not anti-halation layers. They usually come out more thoroughly in the fixer or wash aid, depending on chemistry. T-max turns my Perma-Wash purple but the tint is removed from the film.
Click to expand...

I have the same experience. I use Kodak Hypo Clearing Agent, same principle as Perma-Wash. I love TMY. For years all I would shoot was TMX and TMY. I always assumed (right or wrong) that the purple was a sensitization dye???

The purple doesn't effect optical printing (IIRC according to EK) . I bought a 400' roll of Eastman Double X, just because I wanted to see what it was all about. I think it's better as a cine film than still film. MHOFWIW
 

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This is the first time I've seen a ghost image like the op got. Thank goodness it appears to be just an odd scanner problem. Like mshchem, Double X film images never did it for me though, it probably does work best as movie film.

But developer choices can make a big difference too. I liked Tri-X in D-76, so that's what I used for years. It was quite a nice surprise when I discovered that different developers could give a wide variety of looks to the shots.
 
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AgX

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The error is that gross that to the benefit of other readers who may just glancing over this thread I find my directness apt.


Anti-Halation means or rather their lacking are a pet topic at our forum, whereas at the industry it hardly is a topic since gnerations, other than some finetuning.
 
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