Black spots on negative?

R

RisenBeforeDawn

Newbie
Local time
9:29 PM
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Jul 23, 2019
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Hello everyone, New to the forum and 6 months into film. This is my second roll home developed so I’m very new but, I attempted my first star images at Lake George NY and I can’t seem to find any info on what is wrong with the negative

FujiGW690II
T-Max 400
30 minute exposure

Developed in D-76 1:1
9:00 at 68
Fixed for 10-15 min

Agitation for first minute and inversions for 10 seconds every minute

The rest of the images on the roll came out with beautiful contrast and fine grain. Decently sharp. This is the only image with the black spots. I was thinking it was an exposure issue. No clue though (also was the first frame of the roll if that may matter)

I didn’t read any forum rules for uploading images yet so I’ll post a google link to the image as well as three others from the roll.

Thanks and excited to be here!!!

https://drive.google.com/drive/folders/1SdMgZ11bPF8ykuk8tfyqd05zDq7xR3Vf
 
How was it scanned? Is that negative very low contrast by any chance, so contrast had to be boosted a lot in post? I suspect it may be that, perhaps grain aliasing from scanning that was boosted a lot. What happens if you boost the contrast on one of the other images?
Or it could be one of the infamous backing paper related mottling problems, amplified in this image by boosting the contrast... people who have had them will chime in.


Please show a phone snap of the negative, including borders.
 
The other shots look great, doubtful that the grainy star-trail shot is a development problem. I agree with Retinax that is most likely a post-processing issue.

Is the negative “thin,” and underexposed? Looks to me that you tried to rescued a thin negative in post. Seeing that strip of negatives would help us.
 
Ok awesome thanks! So I forgot to mention. Those images are edited (maybe it’s obvious) but yes I can post up the unedited scan as well. I believe it also had the blotches. As for exposure can 30 minutes be too long? I was reading about fog density but I didn’t quite understand it.

Another thing. Clouds covered a lot of the image about 20 minutes into the exposure so most of the area was exposing ambient light on the clouds for the last 10 minutes
 
Agreed, looks like a scanning/processing issue. Although most likely some of the mottling and comes from both the original scene and possible fog or such from the long exposure. Remember that the scanner is an imaging system in its own right, adding its own noise and such to the mix. The way your black areas seem to all be oriented in the same direction, and most likely the direction that the scanner was traveling, points to it as a major factor. Which is to be expected- most scanners have problems in shadow areas.



I'm sure someone familiar with astrophotography would know more exactly where all the various types of noise are coming from. You might search for a forum or two- very knowledgeable and obsessed people.


Welcome to the forum. Great camera and fun way to throw yourself into medium format and developing. The other three shots are all very nicely seen (which isn't a backhanded stab at the star shot, which is also nice but has some technical issues of course).
 
Wow. That mottling thing looks exactly like it lol. I’m still unclear on the exact definitions of thin and dense but the negatives exposure seems along the lines of what it should look like for a night image of the sky. The scan was decently flat/linear or whatever but nothing crazy. I’ll get the negative up when I get home. Sorry for all the posts just bored and excited to be back in a forum once again ��
 
Dan Daniel said:
Agreed, looks like a scanning/processing issue. Although most likely some of the mottling and comes from both the original scene and possible fog or such from the long exposure. Remember that the scanner is an imaging system in its own right, adding its own noise and such to the mix. The way your black areas seem to all be oriented in the same direction, and most likely the direction that the scanner was traveling, points to it as a major factor. Which is to be expected- most scanners have problems in shadow areas.



I'm sure someone familiar with astrophotography would know more exactly where all the various types of noise are coming from. You might search for a forum or two- very knowledgeable and obsessed people.


Welcome to the forum. Great camera and fun way to throw yourself into medium format and developing. The other three shots are all very nicely seen (which isn't a backhanded stab at the star shot, which is also nice but has some technical issues of course).
Click to expand...

Yeah I think it may a the scanning even though it does look a lot like that mottling thing. I’ll post up the negative and also try a rescan (V600) and not mess with the histogram much to see how it renders a second time. I’m not too bummed about the shot as it was a first attempt and I had my digital there as well lol. But I wanted to nail down the problem for future endeavors.

Also thanks for the welcome and kind words, by everyone. Really nice to be able to talk with people again versus just watching YouTube videos and reading haha
 
I have only messed a bit with night photography so here I am only thinking while typing: could it be "reciprocity" failure? Some films have it (long exposure toleration) and some don't.
 
Maybe I'm blind, but I don't see any spots on the photos on your first post. Just grain on the night shot, which is hard to avoid in low light. You will find Tri-X to be much more forgiving and flexible in those conditions. I always develop it full strength in D76 for the better tonality.
 
RisenBeforeDawn said:
... I’ll post up the negative and also try a rescan (V600) and not mess with the histogram much to see how it renders a second time. ...
Click to expand...


Be sure to scan at the scanner's maximum resolution even if you don't need that large a file. You are vastly better off downsampling in an image editor (e.g. Ps, ...) afterword.


There is a scanning issue that involves interference between the scanning resolution and the spatial frequency of the noise/grain that can produce what appears a mottling or noise. It doesn't happen with films that have varying size grain, but will happen with films that have very regular grain. Making a slight change in the scanning resolution can improve the results when this happens. It is essentially the same as tuning a musical instrument where the combined sound from a tuning fork and the instrument being tuned seems the "throb" when the instrument is out of tune and the throbbing slows and then ceases as the instrument is accurately turned or is massively out of tune.
 
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