The streaking pattern here is not sharply defined and the emulsion-side of the film looks pristine when viewed under high magnification and oblique light - apart from the lower image density which of course shows up, subtly, due to the tanning action of the developer used in this case.
... The streaking pattern here is not sharply defined and the emulsion-side of the film looks pristine when viewed under high magnification and oblique light - ...
If the emulsion has same thickness
What if the quality of the gelatin was not even
That's not possible. There's no 'silver' in an unprocessed film. They start with silver nitrate, which is a soluble compound, and grow insoluble crystals of AgBr, AgCl and AgI. These are inherently photosensitive. Even if they somehow managed to get the stoichiometry wrong (which would be a bit like a chef cooking a 50lb steak by accident), any free Ag+ ions would bind somewhere along the road to Cl- that's inevitably present at some stage (e.g. in the gelatin in trace amounts), and the unintended crystal distribution would not end up in very specific spots on the film, because the emulsification happens in kettles, so will be homogeneous. If the latter fails, you may see density variations from one square foot of the film to another, not from one millimeter to the next.Or maybe the silver wasn`t sensitized even - if that is possible.
Or the silver grains were not evenly distributed in the gelatin.
Not applicable here; this strip of film was hung to dry in the same room I process all my film in. Temperature around 18C at most. Another roll of film (different brand) hung right next to it and dried fine, as do all rolls of film.too hot a dryer for your RH %
Runaway dye formation would have been visible AND it's doubtful it would show up in such an isolated way; neither is present here, plus I've processed truckloads of all kinds of fomapan film in Pyrocat, as have hordes of other photographers, with no problem whatsoever. So again a far-fetched, unlikely idea.If you used a staining developer, some of them have known problems with Foma films (runaway dye formation in one case).
This particular roll was affected on its entire length. The other example I posted occurred at the end of a roll and for all I know can very well extend past its end, but I don't happen to have the roll that was cut right next to it (can you imagine that). On the bulk roll I mentioned before, the coating defect started at maybe 1/3 of the roll and extended several meters and AFAIK right to the end of the roll (and likely beyond). Also, sub-mm bubbles seem like a perfectly likely cause; see earlier comment above.If it was a coating defect other than sub-mm bubbles, it would be much longer than 'a few 35mm frames' (more like metres)
On what scientific base do you say that?it's a coating defect
I don't get the endless chicaning to try and shift attention in other directions.
On what scientific base do you say that?
Haven't you checked the transport path on the camera?
I've had similar defects and base my speculation about iffy Foma QC based on this:
- No other film in existence has provided a variety of "fun defects" for me. Foma products have. Lines, pinholes, some "pepper grain"... Fomapan 200 and R 100 - went through numerous cassettes and Bulk rolls. R 100 in my case is the worst offender - beginning with erroneous reversal bleach times by Foma itself, ruining all my 10 films purchased directly from their webstore.
- No other film in my use has been affected by film transport and my handling of it in-camera. Transport problems would produce scratches on every fucking film and would look very well defined and with sharp edges. Alas - this defect looks completely different and other films via same camera, same gear, same projector, same handling - pristine!
So all that remains given these facts - something's up at the production end. And given the price - acceptable. And I too have a low tolerance towards baseless speculation when defect is very well captured for all to see, speaking for itself.
is incomprehensible.
It's about one's evaluation of time. And about picking one's fights.
I don't want to engage with manufacturer that offers cheapest film and has very low profit margin on their products, don't want to prepare samples and pay for shipping, waste my time on that. I want to shoot some film not pretend to be an investigator. And there's another quality cheap option - Kentmere! It produces no "fun defects" whatsoever, is very flexible, has neat latitude and its rated ISO is true.
See my arguments above - there's literally nothing at my end that could produce such lines, therefore it indicates manufacturing problems. No engineers needed to see that.
What can I say Ivo...
Since Foma hasn't give me any problem whatsoever, I will continue to use their products.
As you said, it's a matter of personal preference and evaluation of one's own time...
The refusal to send the offending film to Foma is incomprehensible.
The negatives are my niece's holiday photos. And apart from it not being my call to make on what to do with this film, I'm not going to send them to Foma only to get confirmation of something I already know.
Also, the defects are not scratches. Scratches are sharply delineated, virtually always penetrate all image layers and are visible on the emulsion layer. None of these characteristics are the case here.
They're also not the cause of an overly tight fitting felt trap in the cassette as this would create plus density pressure marks and/or scratches (mostly the latter). Again, neither applies here.
And for the record, none of this is an attempt to take a pi$$ on the manufacturer, so anyone who is happy shooting their foma film (including me, coincidentally) and suffers from cognitive dissonance now, you can untwist your panties now. It's all cool, just an intermittent QA problem, which many people know this manufacturer sometimes struggles with.
Sorry, you will have the cognitive dissonance because you can't understand that you can't replace a Foma engineer...
But speaking of the Foma engineers. A few years ago when I ran into the well-known coating defects on Foma 200 120, I sent samples to Foma. A couple of weeks later, I got a friendly email confirming that the problem was on their side. I also received some replacement rolls in the mail a few weeks after that. Which suffered from the same defects, but hey, the gesture was nice and I appreciated the fact that they were willing to confirm what I had already figured out by a process of systematic exclusion.
Very similar experiences here: Foma has been mostly very honest and humble in their behaviour and concerning assessments of their products. They have been always present at Photokina in Cologne
- they see these "budget products" for beginners, students, budget restricted photographers, lower-income markets (emerging markets) as their target markets
which lacks the sharp edges you'd expect of water spot damage
Photographic emulsion is around 10um thick. A coating defect consisting of a partially missing bit of image layer (out of several coating layers) will be all but invisible when looking at the actual emulsion side of the film, as is the case here. It's not like you get to see a hole in the layer with the base shining through or something.
if the emulsion on the lower density areas was a bit thinner than the rest, it still may be visible to the eye.
elastic deformation
If other users pre-soak their Fomas, they may not run into problems like these.
...
I really can't see a 3um thickness difference - it's on this order of magnitude we're talking. You'd be able to see if it it was sharply featured, but as you can see, this isn't. In practice, you really can't see the kind of small valley that we're talking about here. If I use my imagination and hold the emulsion to the light in just the right angle, I think I miiiiiighht just see a variation in the surface, dipping slightly where the stripes are, but really, it might just as well be the effect of the optical density just as well. I've tried to capture it on the shots I've shown above and as you can see, it's basically invisible.
...
It would either have had to deform the base along with the emulsion, which would show up as a very nasty set of bumps along the whole length of the roll, or the emulsion would have had to locally spall off the base to accommodate for the dimensional changes. Neither is evidently the case. I'm sorry, I don't see much merit to the hypothesis of a deformation that was there at the start of development and then magically disappeared. It doesn't make sense from a physical or a chemical perspective. And once more - pressure marks tend to result in plus density. You try it yourself; take an unexposed bit of film (in the dark) and scratch your nail across the surface. Works with paper, too. Then develop it. You'll get density. Only if you scratch hard enough to physically remove the emulsion, you can get minus density this way - but that also leaves physical density.
Fact is that I don't know what aspect of the manufacturing process caused this, only that it must have happened before the film was ever loaded into the camera, and that no other factor related to logistics, storage, xrays etc. etc. fits the damage pattern.
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