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Blue Spots?

Jason Fox , Oct 08, 2010; 11:43 p.m.

Recently, I started processing my own C-41 film. Tonight I was scanning my latest roll and I have noticed a few frames have these blue spots. They are probably there in my previous few rolls too, but they had enough other problems that I never noticed. The film is some kind of Kodak consumer 400 (code is GC 400-8), it was processed in Jobo Press Kit chemistry according to the instructions and scanned on my Nikon Coolscan IV. I'd guess this is a simple thing but I have no idea what it is. I did have some trouble loading the film into the reel and I'm wondering if that is part of the problem. This color film seems much flimsier than B&W... Thanks for any help in pointing out how to avoid this. Also, what would the green spots next to it be? Below is a tiny part cropped out of the full frame.
Jason


Sample of Blue Spot

Responses


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Larry Dressler , Oct 09, 2010; 01:02 a.m.

Chinese UFO call the FAA. :-) We need more than just the crop we need the crop and the whole picture.... Also do they appear in the same area on the frame and was it the same film and the same batch? All imformation you have will help. Camera Lens or Lenses and what ever else you can think of.
Lighting may also help if you remember it.

Thanks Larry

James Dainis , Oct 09, 2010; 10:02 a.m.

On a print these would be yellow and red. I would suspect a pinhole light leak somewhere. If it is on the same place on every frame then it would be the camera. On different places on the frames then it would be the processor tank.

Jason Fox , Oct 09, 2010; 08:03 p.m.

Here is the full frame straight from VueScan. This was shot with my Pentax ME-F (seals replaced about 2 years ago), lens is Pentax-M f2.8 40-80 Zoom. Processing was done in my Jobo tank bought back about 1980 or so. The spots have only shown up on this one roll. (The problems in my previous rolls were crap on the film which turned out to be from our water and my home made rinse. The solution was to ditch the rinse and use Photo-Flo.) These spots are not on every frame and not in the same places when they do appear. But they are always towards the left side of the film with none on the right. Maybe a light leak due to the tank lid not seating properly? Might be time for a new tank?
Jason

Charles Monday , Oct 10, 2010; 12:00 a.m.

I see several blue spots on the image and only one with the flair around it. I believe the problem to be contaminates in the chemicals or dirt that stuck on the film during processing which prevented the chemicals from reaching the emulsion during processing.

James Dainis , Oct 10, 2010; 12:12 a.m.

So you are not showing the negative film frame but a positive of the film frame. On the negative the spot would be red, orange or yellow so that rules out a light leak. I assume you have actually looked at the negative and see a spot on it. It is not just something that shows up on the scan?

Take a loupe or magnifying glass and look at the spot on the negative itself. Does it look to be the same color as the orange film base, the color you see in the areas between frames? If so, it may be air bubbles, water impurities or dirt that prevents developer from getting to that spot. Air bubbles are usually much sharper and distinct though.

Jason Fox , Oct 10, 2010; 08:29 p.m.

Thank you, everyone, for your help. Seems this isn't so simple as I might have thought! Attached is a scan of just the area with the spots using VueScan. Each frame that has spots has a few. The green/yellow spots (next to the large blue one) are purple on the negative. The blue one is "brownish-black: in the center and ringed with an orange flare. The other smaller one to the lower left is just a small, orange fuzzy spot against the field of magenta grass.. I haven't had a problem with air bubbles so I don't think it's that. This looks more like something "exposed" on the film. Up and to the right of the group of spots there is another brown one which shows as white on the positive. That seems to be another artifact. I had not noticed that one till I looked at the negative scan.

Alan Marcus , Oct 11, 2010; 10:17 a.m.

It is difficult to make a diagnosis, not having the film in my hands. However, it is my opinion that these are pressure marks. Film is not only sensitive to light and heat, it is sensitive to pressure. This is called a pressure effect. This is the result of excessive pressure, usually caused when loading the film onto a reel for developing.

Pressure applied to the film will trip off the silver salts and renders them developable. Because color film consists of multiple emulsion layers, some are more susceptible to pressure than others thus the colors seen are in relation to which emulsion is most affected. Since the blue emulsion is on top, it is the most suitable. Sometimes the mark will have surface damage such as an abrasion, scuff, or scratch. I advise examine the surface, at the location of the spot, using a 10x magnifier. Best is the type used by jeweler and coin collectors. A 10x Hastings Triplet should be in the gadget bag of every serious photographer.

Examine the film by both transmitted light and reflected light looking for a surface deformity. Do not rule out a pressure effect even if you cannot see a surface blemish.

A pressure effect can yield both a positive and a negative effect. Pressure applied to film prior to developing is generally positive meaning plus density on negative film and minus density on slide film. Conversely, pressure applied while the film is immersed in the developer tends to retard development producing a negative density. On color negative film, the top blue layers shows yellow if the effect is positive. If the pressure retards development the yellow dye will not blossom and mark shows up as blue.

James Dainis , Oct 11, 2010; 11:29 a.m.

I bow to Mr. Marcus superior knowledge of manufacturing and processing of film. He was in that business for over a half century. But to me the spots look too small to be the result of pressure points. It just looks like crud on the film as the result of dirt in the developer or dirt on the film before it was put in the developer.

Alan Marcus , Oct 11, 2010; 08:52 p.m.

James, no need to bow to my 50+ years in the business. Many would say that Alan has 1 years experience 50 times.

Anyway, it is impossible for me to determine if this is due to a pressure effect or foreign substance adhering to the emulsion. Blue can also means exposure to yellow light either in the camera or during camera loading or in the darkroom. We cannot rule out that the film was somehow defective to begin with.


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