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RH Designs Analyser/Zonemaster calibration - tile not useable

olk

Member
Joined
Jul 28, 2020
Messages
107
Location
Germany
Format
Medium Format
Hi,
the RH Analyser/Zonemaster comes with a tile which you have to match against the exposed test strip.
I also own a densitometer (calibrated, correctness tested against other calibration gray scale) and I measured that the pure white part of the tile is 0.01 logD (paper base)and the part labled '0.04' is 0.07 logD.
But my paper (Fomaspeed Variant 331) hat a fog+base of 0.07. After reading 'Way beyond Monochrome' I guess that I should not use the tile that comes with RH Anaylser/Zonemaster. Instead I should use my densitometer and measure the test strip to find the exposure for 0.07 (base+fog) + 0.04 = 0.11 (== Dmin) as the correct exposure for the highlights. Right?
(same applies for Dmax).
best regards, Oliver
 
I'd stick to the Zonemaster instructions or contact RHdesigns directly for advise.
 
In the book chapter 'Measuring Paper Contrast', p 303, describes that IDmin is defined as 0.04 above base+fog.
I guess that's what RH Design tries to achieve with its test tile which contains a rectangle wit label pure white == base+fog (0.01). The 0.04 log rectangle is used to match against the '0.04 + base+fog'.
So if I apply this to the Fomatone paper the '0.04 + base+fog' of the test tile is not correct because I've a much higher base+fog (0.07) on Fomatone. So I should use the densitometer an search the section on the test strip that matches 0.11 (0.04 + 0.07).
Right?
 

Yes, that is the way I do it as well.

The RH meter assumes paper white to be 0.00 and just off white to be 0.04. Of course it depends on the paper what your densitometer will give you. If I measure the tile it gives me 0.07 for the 'pure white' patch and 0.11 of the off white patch. In my case the tile is accurate (.11 - .07 = .04).

For the blacks it is a little bit different as you do not use absolute numbers, but relative ones. The meter assumes just off black to be 90% of the pure black value. Again, it depends on the paper you are using what the actual numbers are.

Good luck!
 
MrclSchprs said:
For the blacks it is a little bit different as you do not use absolute numbers, but relative ones. The meter assumes just off black to be 90% of the pure black value. Again, it depends on the paper you are using what the actual numbers are.
Click to expand...
The suggestion I got was to search for 1.89 logD.
 
olk said:
The suggestion I got was to search for 1.89 logD.
Click to expand...

I'm inclined to say it depends on the paper you're using as some papers never reach those densities. Fomabrom Variant 112 for example reaches only 1.38. Or at least that is the highest density I got from it.
 
I also own a densitometer (calibrated, correctness tested against other calibration gray scale)
Click to expand...
the part [of the tile] labled '0.04' is 0.07 logD
Click to expand...
contact RHdesigns directly for advise
Click to expand...
In my case the tile is accurate (.11 - .07 = .04).
Click to expand...

I don't think RHdesign will solve your problem by indicating they sent the wrong tile.

Reads as if there is a calibration issue with your reflection densitometer. Can you be more specific as to how you calibrated it.
 
I think my densitometer is correct because I've calibrated it with the calibration step wedge and the calibration description in the manual.
I verified the densitometer against another paper gray scale and the densitometer shows the correct density for each step on the scale.

The base is different between several papers. Additionally the fog depends on my process/the paper developer. So the base+fog will not the same between the tile and the paper used for calibration.
The Dmin is defined by the ISO standard as 0.04 above base+fog therefore the RH tile is not likely to correctly match the used paper.
 
For the price paid for these units, they should arrive ready calibrated for the full range of Ilford and Kentmere papers.
P.I.T.A having to go through the rigmarole of calibrating each type of paper yourself.
 

Hi there may I ask you a question. I am new to darkroom and have just purchased the stopclock pro and zonemaster. I am awaiting some paper developer to arrive before I do any calibrations and printing. When I look at the rh design website relaying to the greyscale. It says it ranges from zone 2 through to zone 8 in half stop increments. To my calculations that is only 13 squares not 15. So is it actually zones 2 through to 9. Helpp on this would be appreciated, because obviously it would impact on placement.
 
Beestonite said:
Helpp on this would be appreciated, because obviously it would impact on placement.
Click to expand...

That is a sharp observation! I think the devil is in the details. From the RH Designs website: In Zone System terms, the scale can be considered to cover Zones 2 – 8 in half zone steps approximately.

From my own experience, the ZMII is not a foolproof tool. You will need, or at least I needed, some time to get comfortable using it. You probably will notice that placing the spot readings on the scale will become more accurate after using the ZMII for a while. Even my calibrations improved over time.

Good luck to you and if I can help .... do not hesitate to ask!
 

Thank you very much for your reply, I have a negative in the enlarger what will prove a good test for the highlights in particular. I had ordered some paper developer, which unfortunately hasn't turned up as yet. I have a few sheets of mg 1V gloss. For these yesterday evening I installed the settings from the rh website. For the rest of the paper's which are mg v pearl fb classic matt and fb warmtone I will do full calibrations. There is also a few sheets of foma variant 123. I am away for a week on Friday so it may well be the Christmas period before I really get to play it it. Thank you very much for your kind offer of help. I am well need to take you up on that.
 


Hi pal, when I asked you the question about the zonemaster, I also asked the same question to RH Design. I got a reply today. The answer was to disregard the 2 very end segments
 
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