C41 Issue: banding on negative (see image)

tnabbott · Jan 20, 2013

I shot a roll of 400 iso Portra VC yesterday and developed it at home in a Jobo machine using Flexicolor chemicals. There is a banding that appears on the negative. What may have caused this? My negatives are usually fine.

CatLABS · Jan 20, 2013

This looks a bit like scanner issues - can you see this abberation on the negative it self?
Does this go through all the way to the perforation?
Is it apparent on the entire roll?

Photo Engineer · Jan 20, 2013

Did you use a prewet? Is the Jobo level?

PE

tnabbott · Jan 20, 2013

Thanks for the replies.

The issue appears in the frames that are underexposed. So there are some frames from the roll that do not show this pattern, but the distinguishing factor appears to be the exposure. It could be a scanner issue, but my setup is well tested and has not produced issues like this before. So, I thought it might be development.

I prewet by 4 30 sec. washes. As far as I know, the Jobo was level.

AgX · Jan 20, 2013

How could an unlevelled Jobo-processor produce such effect?
If at all, I would rather think of a too low rotational speed leading to too low stirring of the processing baths. The major problem with this processing technique is laminar flow on part of the film.

Photo Engineer · Jan 20, 2013

Well, it looks like an unwetted film, using a non-level Jobo and with too slow a rotation speed. Thus you get streaks like that. OTOH, it might be that you need a stop after development.

Hard to diagnose not seeing all of the film and being so far away.

Sorry.

PE

CatLABS · Jan 20, 2013

It looks mostly like scanner abberations.
When you scan low density films much more light is passing through and hitting the sensor thus bringing out any abnormalities that would not be visible with a "normal" negative. You have not said if this is visible to the naked eye or not. If not - i would say this is a scanner issue.
This happens on Imacons when dust settles on the bulbs thus creating similar "banding". this is much more pronounced when the negatives are out of range, and can be seen in any scan (even the cleanest most calibrated imacon or other scanner) when the range and threshold are pushed to the limit in photoshop.

Photo Engineer · Jan 20, 2013

If the scanner brings out abnormalities, then the problem is in the film. Does that make sense to anyone?

PE

tnabbott · Jan 20, 2013

Thanks everyone! I do not think it's a scanner issue because of other scans I am getting from the same unit. I think its the film.

Quick question: should I be using the higher speed rotation on my Jobo? I have always used the low speed thinking it would help the motor last longer...

mts · Jan 21, 2013

Are the bands aligned (approximately) with sprocket holes? If so, then the effect is likely to have an origin in agitation during development.

tnabbott · Jan 21, 2013

mts said:
Are the bands aligned (approximately) with sprocket holes? If so, then the effect is likely to have an origin in agitation during development.

Thanks, but this was medium format film - no sprockets.

tnabbott · Jan 21, 2013

I've just run a second 220 roll (taken in the same outing) through the Jobo. I checked orientation of the processor (level) and used the higher speed rotation throughout. The chemicals are from the same batch as the prior roll (one shot, but Kodak's developer is designed for 2L mix). So, sometime tomorrow I will scan and post the results. Thanks!

CatLABS · Jan 21, 2013

Photo Engineer said:
If the scanner brings out abnormalities, then the problem is in the film. Does that make sense to anyone?

PE

No. The negative can be flawless, but if the bulb or sensor have even the slightest abnormality, it will affect the scan, just like a scratch on the condenser bottom glass.

Once again OP - can you see this issue on the negative with your own eyes?

What scanner are you using?
Is the scan you uploaded earlier modified in any way?

Try scanning any other underexposed negative you have which has previously seemed to be OK to you, and see what you get.

tnabbott · Jan 21, 2013

tnabbott said:
I've just run a second 220 roll (taken in the same outing) through the Jobo. I checked orientation of the processor (level) and used the higher speed rotation throughout. The chemicals are from the same batch as the prior roll (one shot, but Kodak's developer is designed for 2L mix). So, sometime tomorrow I will scan and post the results. Thanks!

Attached is a scan from this morning of a frame from the second 220 roll. I used the higher speed rotation throughout.

Photo Engineer · Jan 21, 2013

Looks good on my monitor.

PE

C41 Issue: banding on negative (see image)

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