On 5/26/2012 1:26 PM, anorton wrote:

I do not think the apparent multiple images are reflections. I think it
is just due to the waviness of the filter across the aperture. Each
image is formed by a different area of the filter that has a slightly
different wedge angle. The film works because even though it is wavy,
the front and back surfaces remain very parallel and do not deviate the
light.

What I hadn't noticed, being behind the camera, was that things got warm
enough for the little bits of duct tape to start slipping. By the end of
my shoot, the welding lens was a couple degrees out, far exceeding any
possible waviness in the filter itself.
In any case, a proper machined holder for the Baader filter is still a
nice thing to have and beats the rolled and glued paper tube the
instructions show...


Jon