Help With Fogging Problemgreenspun.com : LUSENET : Large format photography : One Thread
I am encountering a very frustrating problem, primarily with outdoor exposures. Dark splotches/shadows appear from the corners of the negative (usually lower left)extending towards the center. Sometimes these shadows obscure the negative altogether. I don't think it is related to processing (using a Jobo expert drum), because some negatives (even some outdoor exposures) in the same batch come out fine. I am using t-max 100. Is this flare? I have tried to shade the lens with the slide, and it doesn't seem to help. Camera is a new Toyo Field. I am pretty sure I am loading the holders OK, but I am at a loss to solve this problem. Do I need a compendium hood? Any suggestions would be appreciated. Thanks.
-- Jim Poehling (email@example.com), July 03, 1999
I experienced a similar problem when my Zone VI camera was new. At first I had no problems because I wasn't use to using the bale back, so I would insert the film holder in the "normal" way. Once I sarted using the bale back when inserting, many of my exposures had a light fog as you described. For me if I opened the back and put the film holder in place and then closed the back, the film holder would not seat itself properly. You might look to see if the film holder is in the correct position when it has been inserted.
-- Jeff White (firstname.lastname@example.org), July 03, 1999.
Jeff's answer sounds good to me. Pat
-- pat j. krentz (email@example.com), July 04, 1999.
The improperly seated holder theory souds very plausible, I have been there done that, and there are techniques that work well to be sure that the holder is seated correctly. With a bail, insert the holder and as you release the bail, wiggle the holder ever so slightly in and out. This will show you whee the proper position is for the holder, it will catch in the correct spot and be very snug. With a tradional back inseting all of the way and then pulling gently back out on the holder shows when it is seated.
How do you remove the dark slide? Be sure to pull straight out from the holder, and when replacing the slide push it straight in. If you pull back on the dark slide, towards yourself, it can unseat the holder form the back of the camera. You might also remember to place a thumb, your left, in the center of the ground glass while resting you fingers on the top of the camera. Apply a slight amount of pressure with the thumb while removing the dark slide, this helps to ensure that the holder remains in place.
It is not a bad idea to try and cover the back, even of a brand new camera, of the camera with you dark cloth in bright light, especially when removing and replacing the dark slide. I try to at hold the slide so that it casts a shadow on the light trap end during the time tht the dark slide is removed.
Lastly, have you checked the holders themselves? Are they all new or are some or all used? Mark the holders and make careful note of which negative is in which holder. Then when processing, if there are defects, you can trace it to the possible "bad" holder.
All in all these types of negative defects can be the most difficult to detect and correct, and can crop up at any time and for no apparent reason. Care and patience will make most of them go away!
-- Marv (firstname.lastname@example.org), July 04, 1999.
Also make sure that the bellows is attached properly to the front and back standards. It is so often overlooked and I have seen it more than once. That goes for the locking slides on the ground glass also. james
-- james (email@example.com), July 04, 1999.
You might also check when loading your holders that you have the film all the way up into the guides, so that it rests inside the slight raised area at the open end of the holder where the end flap seats. If it is down where the end of the film is between this raised area and the flap, it can keep the end of the holder open just a bit. That might be enough on a bright day. Try loading one with the lights on to see just how the film has to go.
-- Tony Brent (firstname.lastname@example.org), July 05, 1999.
It certainly sounds like a light leak. If the dark areas are at the bottom of the negative, this means that the light is coming in through the top of the holder since the image is reversed on the negative. The leak could be caused by any of the tings that others have suggested. I would just like to second the suggestion that you keep the holder covered by the darkcloth for the entire time it is in the camera. When I first got into large format I had similar problems. I was putting the holder in the camera and it sometimes would sit there for five or ten minutes while I went through all the other large format gyrations. Even with the dark slide in the holder, this can cause light leaks particularly if the camera is in sun light. I now cover the top of the holder with my dark cloth as soon as the holder is placed in the camera and I leave it there until the photograph has been made. When pulling and replacing the dark slide I keep the darkcloth in my hand and grasp the slide with the dark cloth over the holder. Since I started doing this I've had no light leaks.
-- Brian Ellis (email@example.com), July 06, 1999.
Jim, a cheap way to test your holders is to cut some enlarging paper and put that in your holders and set them under a bright light for 3 to 5 minutes and then develope, if their are leaks it will show and it is cheaper than using film to find the leaks, you can do the same when checking for leaks in the bellows. The other thing you can do with paper in the holders is make paper negs, a lot of fun. Pat
-- pat j. krentz (firstname.lastname@example.org), July 12, 1999.