VLS 501 Head Durst

[Giovanni Da Ronch]

I' d like to know some onfo to VLS 501 head of Durst .
Which is the minimun step of VC paper 0,5 or 0,1 ?
When I change the contrast , I must setting the time or the haed have the automatic correction ?
Bye Bye , Giovanni .

[robc]

A setting of 2.5 should give you white light (no filtration). Turning it down to towards 0 dials in yellow and softens print contrast. Turning it up from 2.5 towards 5 dials in magenta filtration which increases contrast.

There is automatic exposure compensation on the VLS501 head. As you dial in yellow or magenta the amount of light reaching the paper reduces. To compensate, the compensation filter, which is fully closed at setting 2.5, opens up to let more light through as yellow or magenta filtration is added. It closes down as you move back towards the 2.5 setting.
There is a lever on the left of the head which switches the compensation filter on or off.
If that lever is switched on then the exposure should remain relatively constant across different fitration numbers. If it is switched off or its not working, then exposure will not remain constant across contrast settings.

A filtration of setting of 0,1 will be the softest contrast. A setting of 5 will be hardest contrast. You should start print exposure tests at a setting of 2.5.

N.B. Durst enlargers are well matched to Ilford papers. For other makes of paper a setting of 2.5 may be very different from a grade 2. Infact for VC papers you should just think in terms of soft to hard contrast and not worry about actual ISO Contrast Grades.

Also note that even though some enlargers have so called constant exposure controls they are not always very good so some manual exposure compensation is usually required.