Last week I was developing a test roll of tri-x and was surprised to find that on several frames, 4 consecutive, there appeared a vignetting effect. Each of the four corners of the frame had a white area of overexposure/overdevelopment. The rest of the roll was fine except for the last two frames which showed the same effect. I am at a loss as to why this has happened, and in an apparently inconsistent manner. I was shooting with a Nikon Fe, never any trouble, Tri-x 400 at EI of 320 and developed in a single tank of T-max with a 20% more development time of 7min 15 seconds.

-- Justin Fullmer (provo.jfullmer@state.ut.us), April 30, 2001

Answers

Were the corners denser or thinner in the negs?

-- John Hicks (jbh@magicnet.net), April 30, 2001.

In response to the above; the corners were white on the negative. So when I printed I would get a little black triangle in each corner.

-- Justin Fullmer (provo.jfullmer@state.ut.us), April 30, 2001.

Justin:

I doubt very seriously that this problem has anything at all to do with the processing of the film. This was more than likely an optical problem. The vignetting could have been caused by a number of things. Did you use one or more filters on the lens? Did you use a lens hood (some call it a shade)? If so, did you use it along with the filter or filters? What was the focal length of the lens? Wide angle lenses have this kind of problem quite often if too many filters or the wrong hood are used. Was the lens a zoom? Some zooms can vignette, especially with filters and hoods attached. I'm sure that one or more of the things I've mentioned is the cause of your problem.

-- Ken Burns (kenburns@twave.net), April 30, 2001.

I was using a vivitar 28-90 with a light yellow filter. The lens was at the 28 setting and I was taking a shot of an interesting barn door that was just painted white. There was lots of direct sunlight from behind probably f16 at 500th of a sec.

-- Justin Fullmer (provo.jfullmer@state.ut.us), April 30, 2001.

Sounds like your filter was a bit to thick for the 28mm setting thereby causing vignetting... you can get "thin mounted" filters which are about 1/2 the thickness to cure this or buy a larger filter and use a step up ring.

-- Scott Walton (f64sw@hotmail.com), May 01, 2001.

I tend to agree with Scott. One of the things I was cautioned about when I went to buy a polarizer for my newly acuired wide angle lens for my Pentax645, was to use the "thin" type filters to prevent vignetting when using this lens. It's something to look at. Maybe shoot a roll without any filters when in the wide angle mode?

-- LaRoy Owen (TakeapicOwen@netscape.net), May 06, 2001.

Justin...I to believe it was the filter causing vignetting. To check this set the zoom on the widest (28mm) setting. Stop down the lens as far as it will go (f22 or so. Then look through your camera as it is pointed at the blue sky (not at the sun!). If it is your filter vignetting the corners of the viewfinder will appear to be cutoff or much darker then the center...jim

-- Jim Vanson (p645n@hotmail.com), May 06, 2001.