Anybody uses a Durst 605BW / 670BW? / Modular 70 BW for 6x6? (Marks in corners)

[spoilerhead]

Hey there,

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?

thanks

 

[ac12]

Are all 4 corners white like that?
I would have thought vignetting, but hard to tell with the white spot "coming out" of the corner.
What do the other corners look like?

As for the numbers on the filter, it sounds like the enlarger is using the entire filter, rather than just the center portion.
If so, I think you need to get another set of Ilford filters and when you cut it to size, REMOVE the numbers.

 

[spoilerhead]

just the corner with the number in it is brighter, so it clearly the imprint on the filter.

Guess i really have to buy a new set of filters.

 

[grahamp]

It happened with my M605. It is because the filter drawer is the same size as the 6x6 condenser and too close the the plane of focus of the lens. Under the right conditions I have actually printed the number! I started to use the filters (ordinary ones) below the lens. Tests did not show any visible loss of sharpness, and it was better than cropping out part of the frame.