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sanchi heuser
30-Aug-2015, 14:48
In some of my recent scans I discovered bands in the sky.
They do not appear on the negative. I proved that by putting the negative in the opposite way in the holder,
with the sky in the other direction.

I use an Epson Perfection V700 and Vuescan.
The scans are from 6x7 Portra 160, scanned at 48 Bit RGB, with 3200 dpi, Number of samples 3, output as raw file.
Scanner moved from the left to the right.


Here's an example picture (bands appear on the top edge):

https://farm6.staticflickr.com/5621/20257078143_2b5b6a72c6_o.jpg (https://flic.kr/p/wS3PzZ)Verlassene Fabrik #33 (https://flic.kr/p/wS3PzZ) by andi_heuser (https://www.flickr.com/photos/58013730@N08/), auf Flickr


What could be the cause for such bands?
Though they are only slight I would prefer to avoid these.

Andi

towolf
30-Aug-2015, 15:33
Is there anything on the glass in the location of the narrow calibration strip at the top of the scanner glass platen? Take a close look (maybe use a flashlight).

sanchi heuser
30-Aug-2015, 16:49
A good idea. Where is that strip exactly located?


Is there anything on the glass in the location of the narrow calibration strip at the top of the scanner glass platen? Take a close look (maybe use a flashlight).

towolf
31-Aug-2015, 02:23
Just the upper 1-2cm of glass close to the hinge. This section needs to be clear and is spared out by the plastic film holders or the Film Area Guide.

Could also be that you have dirt on the mirrors or the sensor.

mijosc
31-Aug-2015, 07:33
I've noticed this as well with my V750, particularly on my medium format scans. It happens with the stock Epson holder as well as the BetterScanning holder. It occurs in the same place, near the edge of the image along the film edge. I think it may have something to do with reflections off the holder, or perhaps a ghosting effect from the edge of the holder.

sanchi heuser
31-Aug-2015, 07:55
OK, thanks. That could be a possbility.
I'll try to place the negative close to the inner edge of the holder, so that the transparent parts of the negative disappear behind the plastic holder.
In some hours I've time to do that, and then I'll tell about results.

I'm only wondering why that didn't happen with the hundreds of the other medium format negatives I scanned before ?
Were your bands in the same horizontal direction ?



I've noticed this as well with my V750, particularly on my medium format scans. It happens with the stock Epson holder as well as the BetterScanning holder. It occurs in the same place, near the edge of the image along the film edge. I think it may have something to do with reflections off the holder, or perhaps a ghosting effect from the edge of the holder.

mijosc
31-Aug-2015, 10:11
I'm only wondering why that didn't happen with the hundreds of the other medium format negatives I scanned before ?
That I can't answer. On mine, I noticed the issue almost right away. On some negatives it is more apparent than others. Also, the more editing I do (contrast, etc.), the more it shows up.


Were your bands in the same horizontal direction ?
Yes, along the outer edge of the film.

I've never found a proper solution to this. On some negatives it's not that bad, so I just leave it alone. Other times I crop out the problem area. If anyone here can properly explain what's going on and a good solution, I would be grateful.

sanchi heuser
31-Aug-2015, 11:57
I made several scans:

1. with the negative turned in other direction = bands disappear

2. with the negatives transparent edge almost covered by the holder frame (at the side of the sky area) = bands appearing

3. with the calibration strip cleaned, negative in same position as in 2. = bands appearing

mijosc
1-Sep-2015, 09:52
Check out this thread on photo.net: http://photo.net/digital-darkroom-forum/00PWGu

In particular read the posts by Mori Insinger and Andreas Carl.

sanchi heuser
5-Sep-2015, 16:23
Thanks for that link.

So not my scanner is broken or the software has bugs:)

Mori Insinger (in the photo.net thread):

".... if one rotates the film 180 or 90 degrees depending on where on the image the sky or dense area is,
then the streaks can be further minimized and sometime eliminated. When doing this, one needs to rotate the film
so that the sky is toward the center of the scanning bed, as opposed to the outer edge.
In sum, putting the film toward the center slots on the film holder and then rotating film so that the sky is
toward the center seems to give the best results. Not always perfect, but better......."


That's the same I did. The bands disappeared when I turned the negative 180.
The sky was in direction to the center.
Since the bands were only slight in the sky area,
I think they'll disappear in other parts of the negative where things like nature or urban stuff are pictured.
Not the most perfect solution but it seems to work.
Other solution might be the masking of the negative.
I don't like to mask every single negative with tape but I could imagine to use a Betterscanning holder like Andreas Carl said (in the photo.net thread):

"...here is what I do: I move the film strip as close to the inner edge of the film holder as possible,
to minimize light leaking from that side (this is just a precaution, again, I never saw reflections happening on that side)
and then I place a mask on top of the AN glass [Anti Newton Glass] to completely mask the clear base along the outer edge of the film....."


Another point is, here Andreas Carl again:

"....Note to previous poster Kenneth Dodds: You have identified another cause of black bands,
which happens when the calibration sensor on top of the film is covered or dirty.
These bands show as perfectly even vertical bands and can occur at any place of the film strip...."


I sum up:
the negative should be in the right position
OR the outer edge masked
AND the calibration area free.




Check out this thread on photo.net: http://photo.net/digital-darkroom-forum/00PWGu

In particular read the posts by Mori Insinger and Andreas Carl.

kleinbatavia
5-Nov-2015, 11:48
I have arch-shaped streaks on the sky when I scan velvia and provia... It does not affect any b/w negatives. Any ideas what causes this? Thanks.

Doug Fisher
6-Nov-2015, 11:05
Could they be Newton Rings caused by film sagging and touching the scanning bed? You need to give us more information and a picture would be very helpful too.

Doug