Pinhole winding and TMYII - Reciprocity
I havea used zero 6x9 deluxe pinhole that has given me fits when using Fuji ACROS 100 as the film take up spool never winds tightly enough to stop the film from unwraveling on the spool when the film is exposed. So I am going to try it with some thicker film stock to see if that will make enough difference. I tried adding in some gaffer tape to the opposite side under the spools, and it worked for a while. However it's intermittent in the success. If too tight, I get scratches on the emulsion. I tried Ilford HP5+ in the camera, and it works fine, but I have a really hard time seeing the numbers on the back through the holes. So I want to try TMY-II as it has a fairly thick film base. So to that end, what are people doing for reciprocity with this film in Pinhole cameras? Some of my exposures are way longer than the 100 seconds that the TMY-II data sheet mentions, and I want to be in the right ballpark. Anyone have any firm data on this?
Use a changing bag when unloading film that doesn't wind up tightly.
I've never had consistent results calculating reciprocity from the manufacturer's literature. I always have to make tests for each film type I use. You'd be better off making your own tests before photographing something important.
I don't have this problem with my Zero 6x9 using Acros. Put a piece of foam between the supply roll and the camera body. The tension should make the film wind more tightly.
[FONT=Comic Sans MS]Films NOT Dead - Just getting fixed![/FONT]
Andrew, some stray thoughts. I have a Zero 6x9 as well. Haven't had problems with the film unravelling on the spools when making exposures, but I did have problems with the film being loose overall inside the camera. This little bit of warp in the film would make straight lines look wavy, which can mess up a photo where you want straight lines. I did a couple of things after checking with Zernike Au of Zero Image. One is to bend the metal tangs that put a little pressure on the film as it winds off of the supply spool and onto the take-up spool. I also tore off the end flaps from the little carboard box that single rolls of 120 come in and put them under each spool to add more tension. I also cut a piece of four-ply museum board down to size so it would fit just inside the back cover of the Zero 6x9. This takes up most of the space between the actual film plane, when the film is tight, and the back of the camera. If you do this, you need to cut a window so you can read the exposure numbers through the red window. These three things helped A LOT.
One more quick thought from using Pinhole Blender cameras. Chris from Pinhole Blender recommends taping the paper leader on the 120 roll to the take-up spool. I'm not sure if this will help with the problems you're having; but it is a handy trick to know.
Maybe we'll run into each other pinholin' in MN sometime!
Look up Pinholedesigner. All one word. Down load the program and it gives the times for Tri-x, T-max as well as many others. Fuji acros is probably he best B&W film for pinhole. It has no reciprocity until 2 minutes any times after add 1/2 stop. My longest times with this film with an f/160 camera is if I get a meter reading of 8sec. at f/22 my time with resiprocity would only be 10:30 minutes. In normal daylight my times are 1/2 to 13sec. long.
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Thanks for the ideas... I've added in some extra gaffer tape and the last roll of ACROS came out fine. I will look at the pinhole designer site also.
As an extra idea to throw out there, I also noticed that when using the 6x9 configuration, the gaps between the negs is so small. As a work around, I use a piece of card from a film pack and slid it into the OUTSIDE part of the adjustable film gate. In mine, the little movable pieces of wood had some free play, now they don't. The card makes the film gate ever so slightly smaller, and helps out a lot!! This obviously is not an issue for the smaller formats.
I worked it out. Lemme see here. (rummage, rummage) It's in here somewhere . . . THERE IT IS.
With some helpful advice from MurrayMinchin I came up with this for my matchbox pinholes and my modified 6x6 folder using TMY. I would imaging the times would be comparable to TMY-2 but it might give you a starting place.
Suggested exposure/ adjusted time
1 sec/1 sec
2 sec/3 sec
4 sec/6 sec
8 sec/12 sec
15 sec/26 sec
30 sec/55 sec
60 sec/2 min
2 min/4.2 min
4 min/9 min
8 min/20 min
Normal processing (HC110 Dil 'B' at 68 degreesF for six minutes) leaves the negs a little thin so I think my next round of negs I'll add 10% developing time and see where that goes.
This thought just struck me. You have a used Zero. There is a ratchet mechanism built into the winding knob that should prevent the unraveling. Is it working on your camera? Can you wind the take-up knob in both directions? If it is broken you could contact Zernike Au at Zero Image to see about getting a replacement.
Originally Posted by Andrew Moxom
Well, I must say I don't spend a lot of time reading through forums, but this thread is impressive with the collective knowledge being shared. I too am a pinhole image maker and really appreciate all the advice.
I guess I'm not the only one dealing with loose winding 120 film rolls.
Tom, the ratchet is working fine. I think the main problem is that the film must be wandering somewhat from the lips of the film spool. It's like it isn't winding tightly from the get go. Tension is there when you load the spool and close the camera up. As you wind the film it does not lay neatly on the spool and could be caused by the winding side or free spool side where the film goes on crooked. Not sure if I am explaining this cleary though.