CanuckBassist
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This is a classic example of what happens when you don't agitate sufficiently.
Despite the commonly heard "wisdom" about gentle agitation, that advice can be taken too far. This is a classic example of what happens when you don't agitate sufficiently. Medium format film developed in small tanks is more prone to exhibiting these problems than 35 mm stocks. If you're using a SS tank, try to get at least 5 to 7 good snappy inversion in 5 seconds every 1/2 minute. If plastic tanks are your thing and you like to use the agitation stick instead of inversion, go for at least 5 to 7 complete back and forth motions in 5 seconds every 1/2 minute.
If it's a light leak problem, wouldn't the band be lighter than the rest of the frame?
I absolutely agree with this . These are road ruts that are minus density across nuetral areas that are not agitated or better put, the developer has not reached the film surface evenly and fast enough that produce dark bands in a positive image of the negative.
I developed my first roll of 120 a few days ago. I noticed a vertical "band" in 4 of the 12 exposures (exposures #4, 6, 9, and 10).
I can't be sure, but I don't think it's caused by the camera because the shots used different apertures and shutter speeds. On the other hand, I'm not convinced it's caused by the developer either because the exposures would either have this "band" or not have it entirely.
So could this have been caused by the developing process?
Let me make sure I understand what you're describing correctly. You have one hand on the lid and one the bottom. You turn the tank 180 degrees so it's upside down, and then back rightside up, repeating multiple times. I did this exactly for the first 30 seconds. I also tapped the bottom on my table to dislodge air bubbles.
I also wasn't trying to skimp on chem. I pushed the film to 1600, and 16minutes in B is the only way I found posted, so I figured I'd start from there.
I have the bronzed metal shutter curtains.
I plan to sacrifice a roll to experiment. I just don't know when I can get around to it.
******They don't cross over to the adjacent frames, which I brought up in the original post. There're only two affected frames that are next to each other, and now that I'm looking at the negatives, the "band" on the two adjacent affected frames don't line up perfectly, they're at a slight angle in each affected frame.
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So the areas of differing density do not carry into the clear area between frames. Thus, I would think, this is coming from the lens side of the camera only.
I was hoping this would be a developing problem because I don't see a pattern in aperture or shutter speed in the affected frames.
*****
Yes. That would be easy to fix.
It's also odd that the "bands" are darker rather than lighter.
******
Darker on the negative--meaning they are getting more light? That is, flare light in addition to the exposure.
Since the "bands" are not perfectly vertical, can we rule out a shutter curtain problem?
*****The bands are lighter on the negative, darker in the reversed picture.
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Being the dinosaur I am, I do not know if scanning works the same way as printing a neg would. Still, we've got differential density. That's either a problem with exposure or development (or heaven forefend, both) It does not carry into the clear film beyond the frame. That leads to rule out exposure outside of the camera--like a faulty tank. Development still remains; but it is on intermittens frame--so that tends to rule out faulty development. This leads to something happening in the camera. Since it does not go beyond the exposed area of the film, we discount faulty light seals. What remains is the shutter. And the varying density could conceivably be caused by an erratic shutter moving too quickly (crud in the retarding-escapement mechanism of the mechanical shutter) resulting in underexposure (neg too light) coupled with a shutter flare problem giving excess anomolous density in other areas (neg too dark.). What a conundrum.
At this point, I think I'll just have to wait until I go through an experimental roll to see if it happens again.
I'd bet on shutter. Looks just like the bands on a widelux when the shutter is sticky.
Wouldn't that affect every exposure though?
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Not necessarilly.
And there seems to be no relationship between shutter speed and the effect
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Erratic problems are the ones most difficult to solve.
And if a shutter is due for a CLA, it can be erratic. Works one time fine; not the next. Depends upon many, many variables; state of the lubrication; temperature. humidity; even the angle the camera is being held; how long between shots. I have seen it all.
What a vexation!
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