Thanks Paul. The lens was the Schneider Linhof Super Angulon 90mm f5.6 panoramic.
The images are all 6x17 panos, I just took quick crops off the slides with my iphone. I was thinking about a hood, but I need one that will work for panoramic images without cropping.
Does the Lee wide angle hood work on the 617? Could the magenta spots be cause by something else besides lens flare?
Yes, but it's best for you to test(and test again, just to make sure) that you know EXACTLY where the maximum amount of coverage(without cropping into the image area itself) is.
On cameras such as the 617/sII/sIII and similar "point and shoot" style cameras with no actual viewfinder(ala SLR style), you have to either guess(usually inaccurate) or TEST(using a ground glass on the film rails(where the film sits when loaded). Linhof offers a ground-glass attachment from the factory, which is great for this purpose, alone(amongst other things too).
Of course flare is something that can, at times, NOT be avoided at all. Simple backlighting of a subject from a hard/point specular light source(such as the sun, or a small yet bright reflection(sun off of water).
In your case, I believe that the cause here was light from above(seeing that it is coming from the top edge of the frame, and that's the direction of light in the photographs primarily). Simply holding your hand(or better yet, a black card, say 9x11" or so) to block that light from directly hitting the lens is crucial towards removing/reducing the chance of flare potential.
Has anyone here used a Lee Wide Angle filter holder on a Panoramic camera?
I use a LEE wide angle hood on my 5X7" camera(same long dimension essentially as 6x17), and it works fine for my 90mm-->450mm Fujinon lenses.
Of course, having a ground-glass does aid in proper positioning of the hood.
I do my best to use the hood whenever I make a photograph, as I've had issues with flare myself(even bounced up from the ground(like white sand) into the lens.
On another note, I've found that Nikkor and Fujinon lenses(especially the later EBC-coated ones) are the most flare-resistant LF lenses I've used. Schneiders have been the most problematic w/ flare, then Rodenstocks. Nikkor's and Fuji's have had almost no issues. But the 90XL(assuming that's the one you have, since it's an SIII model?) is a FINE lens, and VERY, VERY sharp. Even when stopped down to F45
cheers,
Dan