Uneven density near frame edges

Hello Apug,

So for a while now I have noticed that when scanning my negatives, some frames will have uneven density in a gradient from center to edge, but it is the reverse of a lens vignette, going from less dense in the center to denser at the top and bottom of the frame only, sometimes even only the bottom. The result is an image with a lighter edge becoming normal as it goes towards the center. It is only visible on certain frames. I have only noticed this when scanning. I wonder if it is due to the sensitivity of the scanner, or my attention being drawn to more during visible shifts in contrast of the image? It appears almost like bromide streaking or edge effects of non-agitation, where active developer from the very low density frame edges issues into the image causing a higher rate of development right at the border and less so moving inward on the image. I have used two different holders , one that is directly at the edge and another that shows much of the border to exclude it is from any reflectivity of the holder. I am becoming a little annoyed that there may be some issue with my developing, although as I've said it dosent seem to appear in prints and isn't readily visible on the negative itself. Any ideas?

Is it perhaps that I am using too much developer? I am using a two feel metal tank and I fill it until I notice it overflow and then dump only a little bit. It may be possible my agitations are ineffective with too much developer. Luckily I do quite forceful agitation and tank slamming

Nikanon, I assume you are developing 35mm. If the darker boarders run along the the sprocket holes edge of the negative (long side of frame) I would think that could be over agitation, if the sorter edges of the frame are darker it would seem to me some kind of flaring of light somewhere in the camera. Try posting some examples and let the rest of the forum have a look, I'm just "a-geussun" .

Mike

Nikanon said:

Is it perhaps that I am using too much developer? I am using a two feel metal tank and I fill it until I notice it overflow and then dump only a little bit. It may be possible my agitations are ineffective with too much developer. Luckily I do quite forceful agitation and tank slamming

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High developer velocity inside the tank is usually the reason for overdeveloped edges with 35mm.
Curiously, low velocity can cause similar problems, but it's more that the center is underdeveloped rather than the edges being overdeveloped.

With 120 film it's similar, but since you don't have the sprocket holes you don't get much of the surge marks from developer rushing through the sprocket holes. Just an even density increase.

Nikanon,

You are probably right about too much developer. See how much you need to just cover the reels, and then measure that amount every time you develop.
Agitations are a gentle inversion of the tank taking about 2 seconds per inversion. You will get more consistent agitation using this method. I use measuring cups for my developer, stop and fix because its easy to measure accurately, and easy to pour the tank back into. Good luck.

Chris

+1 to Thomas and Mike. If you're agitating by twirling a stick rather than inverting, that can do it, too. Make sure you agitate evenly, by inversion, and do it for the first 30 seconds then a few inversions every 30 seconds after that. Yup, ask me how I know this one. :rolleyes: