is anyody using a 605/670/m70 condensor enlarger for 6x6?
I got a problem with my 670 bw when enlarging 6x6:
Attached is a 40-50% crop from print, upper right corner, left normal, right with increased contrast.
There a brighter spot in the corner, caused by the numbers printed onto the Ilford Multigrade filters. they become more apparent when going to larger magnification ratios and/or stopping down the lens. (at about 40x40 cm and f/22 i can clearly read the number). Focus is exactly on the Film plane.
Rotation the filter by 90° just changes the corner the number appears in.
So I wonder, if I'm doing anything wrong, or is my enlarger needs adjustment, or maybe it's the lens' fault? (Rodagon 80/5.6 zebra)
If someone of you got a Durst 605/670/m70 condensor head (I think they all use the same Siriocon 80 for 6x6) could you please check if this happens to you, too?