It suffers from internal reflection and it really washes out detail and reduce the contrast by much...
I've tilted it up slightly but as I can tell from the herschel wedge image, I know it's still well within the field of view. So, I guess that I'll have to tilt it further.
Maybe to build something like the mechanism of a Tmax... of course, to make it simpler so that the cost will be lower... Time to go to the drawing board again.
Just a random thought, maybe a small rubbish bin will do the trick... grin