Aristo VCL 8100, Kentmere FP VC FB, low contrast problem

[jeroldharter]

I have an Aristo vCL 8100 light source which I use on a Beseler 8x10 conversion. I use TMY2 developed in Xtol which I tested via BTZS to get my film speeds and development times based on a standard grade 2 paper ES. I use Kentmere FP VC FB paper which has worked well for me up until now on this setup as well as for my 4x5 setup for which I use a Beseler Dichro 45S light source.

Now I am having problems on the 8x10 setup. I messed up some negatives after forgetting to dilute the Xtol 1:1, so the are quite contrasty compared to what I am used to. I figured I might have to flash the paper or take other measures to reduce the contrast to printable levels. However I found myself printing them at Grade 4 on the VCL 8100.

That prompted me to do a BTZS paper test which revealed the problem. My real contrast range is more like Grade 0-3, with the VCL setting of "3" corresponding to a paper grade 1.5!

I use the light source in the "normal" mode rather than the split filter mode. In the normal mode, even the grade 5 light looks mostly green whereas in the split grade "blue" mode the light is a deep blue/purple. I did not think to do a paper test of the blue light, of course. But even if that works in increasing contrast I don't want to have to mess around that much.

Any ideas as to what I should do? Also, I don't know why this changed on me. The bulbs each seem to be working, the paper and chemistry are fresh, etc.

[jeroldharter]

I should mention that I ran a side by side paper test with Adox Vario Classic VC FB paper and it was even worse in terms of low contrast.

[jeroldharter]

Well... I scratched my ass long enough that I seem to have fixed the problem. My paper tests are in the wash and not yet through the densitometer, but visually they look right.

I did a test with blue light only and the step wedge print was very contrasty. I did another test with green only and it was very low contrast.

So I fiddled more with the (unlabeled) toggle switches. I guess that one was inadvertently nudged into an intermediate position or there was some mechanical issue with the contrast dial. In any case, after moving the toggles back and forth through a few cycles of the various combinations, I found the right setting so that the contrast knob produced a more robust color shift. So I re-tested the Kentmere paper and it looks great.

I post this hoping that someone else might be just as stupid and save some time in the future!

[ic-racer]

Perhaps analogous to the little unmarked seven position switch on the back of the Ilford MG500 controller. It controls the overall ratio of blue to green intensity. If it is set to 1 or 6 all your pictures will be either too contrasty or not contrasty enough even though you have set the proper grade on the front of the controller.