If the developer level is too low, maybe the developer can ripple across the film while it's out of the developer - perhaps be a little trapped while it's out of the developer. None of that would explain the correspondence with sprocket holes, though - unless the developer could bead between two layers of film between two sprocket holes (it would drain through the holes).
It looks to me like you may be working J-24 capacity numbers for tray processing . The J-24 numbers for development in tanks work out instead to twice the capacity, meaning half the minimum amount of concentrate - 6.25 ml per 8"x10" or equivalent.
I hadn't noticed that, but you're right. Wouldn't tray processing be closer to the situation of a Jobo, rather than a tank? I might be wrong, but I'm thinking the Kodak tank capacities are for a large tank, not a small volume? Under 500ml is closer to a tray situation than a deep tank.
Worth an experiment anyway, just to eliminate a variable.
Just curious, logan but why not use just a 1510 tank as you used when you started the thread or a 1520 if its 120 ? Less developer and the amount is marked on the side of the tanks so easier to ensure you have the right amount
The Kodak documents use "small tank" and "large tank" when there is a need to differentiate between the types of tanks.
And I've always thought that when it comes to issues of developer exhaustion, the environment in an inversion tank is much closer to the environment in a Jobo than a tray would be.
I was using only a 1520 tank when I was using inversion processing (if I said 1510 earlier that was a typo) . But the 1520 tank will not sit level on the Jobo roller, even when the Roller is adjusted for the smallest tank size. I added the 1530 extension so that the body of the tank would fit between the rollers and, therefore, sit level.
My incredibly stupid mistake was taking the rotary processing number from the 1530 and thinking that was the minimum amount of chemistry necessary for the combined 1520+1530. I had forgotten that the 1530 was not just a 1520 extension but could be used with any other Jobo tank. So the number on the 1530 needs to be added to the number on the tank that it's extending Since I was using 500ml of chemistry, I figured I was significantly over the minimum. But it turns out my gaff meant I was using slightly less than the minimum, which is 330ml (the extension) plus 240ml (for the 1520) for a total of 570ml. Luckily, it hasn't seemed to adversely affect the rolls I've developed using the Roller up to this point, but I'll definitely be upping the amount of chemistry going forward. How embarrassing...
Ah, thanks I understand why now. Just a pity that the much more economical tanks such as the 1510 for 35mm and 1520 for 120 are not usable
A tiny amount of light hitting the edge of the film could make more density in the already-exposed parts of the film out of line with the sprocket holes, which would interrupt the travel of the light - even if it was not enough light to fog the edge of the film itself. You would not notice that amount of increased density in anything other than a very even tone - like the cloudless sky.
There is no possible manufacturers defect in the emulsion that can correspond to the location of sprocket holes, since those are added long after the emulsion is dry. (Are holes added or subtracted?)
I added a clarification to my earlier post that I cross-posted with yours.
The 1520 will sit level on the Roller, but its weight will not be distributed evenly and I was concerned it would tip off the roller during processing. There is no such problem with the larger tanks. I haven't tried the 1510 but I assume it would have a similar problem.
It works, but I thought the 1520 felt less than perfectly stable when rotating so I've been using the larger tank when doing rotary processing. Also, it seemed easier for me to maintain a constant rate of rotation when rotating from the body of the tank. But, if I hold both ends of the smaller tank and rotate from there then the tank is pretty stable. I might give the smaller tank another try.With both sets of rollers and one set close to lid are you sure that with the reduced amount of liquid needed for Jobo rotary processing you cannot keep the tank stable and level?
Frankly I am at at a loss anyway to work out what rotary processing achieves in relation to your problem that normal inversion doesn't
It works, but I thought the 1520 felt less than perfectly stable when rotating so I've been using the larger tank when doing rotary processing. Also, it seemed easier for me to maintain a constant rate of rotation when rotating from the body of the tank. But, if I hold both ends of the smaller tank and rotate from there then the tank is pretty stable. I might give the smaller tank another try.
It isn't a solution to the streaking problem I had earlier, but I felt that large areas of blank sky had more even development when using rotary processing so I've been sticking with it. It's also even more mindless than inversion processing since you don't have to keep track of the next inversion time - you just roll, roll, roll until the timer goes off It's also good exercise when using a dilute developer like Rodinal 1:50 and the development time is 10+ mins. Couple that with a stop bath time of 1 min, a fix time of 5 mins and the whole thing being preceded by a 3 min pre-soak, and that's nearly 20 minutes of continuous rotation. I should be ripped by the New Year
This is precisely why I switched to rotary processing. It's not just skies, it is also frame edges, which used to drive me nuts. I have routinely gotten the most evenly developed negatives with rotary agitation.It isn't a solution to the streaking problem I had earlier, but I felt that large areas of blank sky had more even development when using rotary processing so I've been sticking with it.
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