Grade change time

[bwrules]

Hi.

I am wondering if there is a rule of thumb for time to step between grades. Roughly how much time do I need to go between grade 2 and 3 for example when printing? I am guessing 1/3 of established time, but not sure.

Thanks.

[polyglot]

With the Ilford paper+filters, the exposure times are meant to be approximately the same (for a constant midtone I think) for all grades except #5. Or if you're talking about split-grade printing, you would typically use #1 and #4, the ratio thereof depending on what actual contrast you wanted.

[2F/2F]

Are you talking about graded paper or VC paper?

With VC paper there is usually a big increase in exposure time when jumping up to grade 4. I am not sure if it can be boiled down into a more specific rule of thumb than that, but maybe. It will be different for each individual paper. In the little paper that comes in the box, there should be some info about this.

[Nicholas Lindan]

It depends on what tone you want to remain constant. Look at the family of HD curves for MGIV RC.



If you want to hold a ~0.6 od tone (a wee bit lighter than 18% gray / ZV) then there is no change required. If you want to hold a ZII 1.6 OD tone then you need to increase exposure by around 0.6 stops.

Darkroom Automation supplies HD graphs and speed charts for common Ilford papers. See the support files page http://www.darkroomautomation.com/support/index.htm

[David Brown]

I am wondering if there is a rule of thumb for time to step between grades.

Yes. Make a new test strip. Because ...

It depends ...

[bwrules]

Arista.edu FB VC Paper. It really does look like there is no way around a test strip, is there? So far it looks like 1/3 of time to go to 3 from 2. Thanks.

[hoffy]

Yes. Make a new test strip. Because ...

What he said!

[Jeff Kubach]

I agree use a test strip!

Jeff

[phelger]

I recently bought some equipment which solves the problem once and for all : A 'StopClock Professional' and a 'ZoneMaster II', both from RH Designs. here's the link :
http://www.rhdesigns.co.uk/darkroom/index.html
True, it comes at a price but the time and the photographic paper saved by using it is convince me it is worthwile
peter

[R gould]

As a rule of thumb with ilford filters it is the same time for filters 00 to 3 1/2 and double the time for filters 4 to 5, It always worked for me in my pre analyser/pro days,
Richard