Urgent help requested, dark hexagons on SWC prints

Hello kind knowlegable people:

 

I am used to seeing highlighted hexagons on my SWC prints if I shoot

into the sun with the lens shade off, normal.

 

But shooting a couple of test rolls I find DARK hexagons (ie not

highlights), all in the same place about 7mm into the top of the frame,

centred, in some cases there is one more hexagon displaced downwards to

the left, frame after frame, and this is the big one: even with my back

to the sun, or with sidelighting, i.e independently of the direction of

the light.

 

It is not developing, the hexagons are in the same place on each frame,

its not the filmtype because it has occured on fuji and kodak

 

I wanted to take the camera to do a project tommorrow, but I don't know

what this problem is, I've never seen such a thing before, all my

pevious negas with this camera are fine, can anyone help please.

CORRECTION:

 

there in only one dark "hexagon" appearing in in eash frame, 4mm width.

 

thanks

Very closely inspect inside the camera and back for gobs of hair, dust, fuzz, something hanging into the back's film gate etc, anything that would cast a shadow on the film. The problem is most likely not in the lens/shutter.

Are you using a filter? Any possibility of an internal reflection?

No filter, it was a bit dusty inside the iside of the camera though, I cleaned it and run some tests, let's see...

i checked my swc last night: the aperature is a pentagon.

Put the rear focusing screen adapter on the SWC, and check it with the fixed magnifing hood. Set the camera on a tripod, shutter to B & lock shutter open. If you can see the hex image at all apertures, into and away from the sun, it's not the lens. if it apears only at some apertures at some angles then it is lens related.

 

Does the shutter fully close after each shot?

 

When was the camera last serviced?

 

Good luck!