philippleser
Hi everyone,
I’ve almost used up my first 100-sheet pack of Easy Print 311 in 13x18 and I’m really impressed so far. My workflow in the darkroom has mainly involved a bit of trial and error, but it’s certainly produced some lovely prints.
I’ve recently become the owner of an RHD Zonemaster and have calibrated it for the EP 311. What surprises me is that the calculated exposure range is quite narrow:
Gradient, ISO R
0.85
1.70
2.60
3.55
4.30
5.25
In other words, at gradient 5 I’m already below one stop’s range. I can’t find a table like this in the datasheet; however, the Kentmere VC datasheet (it’s the same design, isn’t it?) lists values per gradient that are about 30 ISO R higher.
What could be the reason for this?
I use a Durst M601 enlarger with a colour mixing head, ADOX filters for gradation control, and I keep to the times quite precisely thanks to an electronic timer (which also switches off the Duka lighting during measurement).
As a developer, I use Paterson Acugrade with a constant development time of one minute at around 21 degrees.
I don’t have a reflected-light densitometer available for calibration, so I have to compare it visually with the grey scale.
Many thanks for any tips and insights,
Philipp
stoeckel
Hi Philipp,
I can’t really help you with this, but take comfort in the fact that I’m having a similar problem.
See my post ‘ADOX MCP – Meopta Color 3’ in this forum.
I’m also getting quite low ISO values with AnalyserPro. I’ve contacted RH Designs directly as well. However, I’m still waiting for a reply.
Best regards,
Johannes
cfb_de
Hello Philipp,
Please don’t assume that, for example, 30Y corresponds to a gradient of 2. It could just as easily be 80; this depends on the emulsion and is subject to increasingly greater variations as the batch sizes become smaller.
It would be better to calibrate based on “filter value vs. ISO-R” and then derive “ISO-R to gradient” from that.
But even in the past, the gradation specification was a definition chosen by the paper manufacturer within broad limits. See the discussions about Ilford Multigrade vs. Agfa MCP. It’s like ordering a medium pizza at Pizza Hut in Germany and the USA respectively. That’s left quite a few people scratching their heads :-)
BTW: Does your M601 also have this additional yellow filter at the back of the colour head (if I recall correctly, it doesn’t, but apparently every M605 colour head has one – except mine, I suppose)?
Best regards,
Franz
philippleser
Hi Franz,
The issue you mentioned had already crossed my mind when I was putting together my kit about a year ago. I eventually came to the conclusion that I’d probably be better off with a fixed set of filters for the drawer, so I’m using the ADOX filter set, which is supposed to be compatible with Ilford filters.
So it shouldn’t be down to the colour mixing head (which reminds me of something else odd: my colour controls cover a scale from 0 to 100, whereas in all the data sheets that mention reference values for the Durst colour heads, the scale goes up to 130 or 170. Strange. But as I said, I don’t use the colour mixing head like that)
My hope was that by choosing fixed filters, I would have one less parameter to calibrate.
Basically, my problem is also somewhat academic, perhaps superfluous, as I am currently managing to produce good prints and the value distribution shown by the measuring device also appears on the paper, at least to the naked eye.
(As a scientist, I simply can’t resist when there’s an opportunity to do something with meticulous precision or to calibrate it)
Best regards,
Philipp
cfb_de
Hello Philipp,
I’m also a scientist, and that’s precisely why I decided to take a critical look at the manufacturers’ specifications. It was purely empirical; I started doing this when I found that identical filter values from MCP and Foma produced different results. As a social sciences graduate, I’d probably have come to this realisation by reading the specialist literature :-)
With the sheet filters, you actually gain a whole host of additional degrees of freedom. Firstly, they tend to be calibrated to ‘specifications’; secondly, they fade over time. Thirdly, it would be interesting to know which paper and which lighting system were used to determine compatibility with Ilford filters (and there too: paper? lighting?).
Take the interference filters from your colour head and measure the ISO-R of the respective paper in 20-stop increments using a grey wedge. Once for M and once for Y. This is the only way to get facts for the respective paper batch.
The scale on the colour head is similar to that of a thermometer. Celsius ran from 0 to 100, Réaumur only went up to 80 at the top end (couldn’t he count any further?), and Fahrenheit set the reference point completely differently (why?).
It’s still the same with colour filters today: every manufacturer can do their own thing. And when it comes to photometric filter densities, 95% of all lab technicians are completely overwhelmed anyway. Having to calculate first and then perform exposure every single time is also more effort than manual calibration. At the same time, this opens up the market for ‘click-and-be-happy’ devices in the split-grade category (I’ll come back to that at some point).
Best regards,
Franz
philippleser
Hello Franz,
You’re absolutely right, of course. I think I was quite precise when measuring the ISO R values; in my case, the values refer to the gradient provided by the corresponding ADOX filter (which is, of course, useless if you want to compare values with other people). With that in mind, it would probably actually be better to align it directly with the colour mixing head and leave the filter drawer empty (which would also have the advantage of allowing you to use intermediate values).
I think I’ll start by re-measuring the negative process (using the Zonemaster, which I also use for print exposure measurement. Then at least I’ll have the same systematic deviations across the board), after which it will make more sense to discuss how best to print ‘normal’ negatives.
Many thanks for the tips so far!
Best regards,
Philipp
