RH Designs Analyzer Pro Calibration data

[mmerig]

There are many combinations of enlargers, paper, developers etc. that affect image tonality. For those who use the RH Designs AP to help determine exposure and contrast settings, here are settings that could be helpful. If others contribute similar data, perhaps a pattern will emerge that will save people time, or at least what follows could be a starting point. RH Designs provides data on several papers, and I include one of them for comparison. RHD's calibration manual points out how starting values for a paper can be found in published tables. Ilford supplies these, but I don't know about others. It's probably better to do your own calibration, and it takes maybe 45 minutes to an hour to set-up and do it for one paper type. I can get all of the combinations of exposure and contrasts on one 5 by 7" paper. I can explain and show that if anyone is interested.

Most likely, the main factors for the settings will be the paper, enlarger type (condenser, diffusion), bulb (halogen, tungsten, cold light) filter brand, or color head settings, which can be set to match Ilford's filters.

So, a standardized format for data could be:

Paper brand and type, Enlarger type (condenser, diffusion, other) bulb type, and exposure off-sets and contrast numbers ordered by Ilford filter grade. RC = resin coated, FB = fiber based, WT = warmtone MG = multigrade

Here are some examples. the first is from the RHD manual, the others are mine. I used semi-colon and comma separators to make it easier to get the data into a spreadsheet, in case we want to look for overall patterns once there are several combinations available.

The bulb I use is a PH211. Its frosted and in an Omega D2, so not a true condenser set-up that would have a point light source.

Ilford MG IV Deluxe RC,diffusion,halogen;00,0,179;0,0,144;1,0,132;2,0,109;3,0,89;4,0,65;5,0,47

Ilford MG IV Deluxe RC,condenser,tungsten;00,-2,211;0,-4,196;1,-5,176; 2,-5,152;3,-6,123;4,-7,89;5,-9,51

Ilford MG Deluxe RC,condenser,tungsten;00,-6,165;0,-8,142;1,-8,128;2,-8,90;3,-8,75;4,-8,60;5,-11,60

Ilford MGIV WT RC,condenser,tungsten;00,8,222;0,7,189;1,7,159;2,6,133;3,6,110;4,6,90;5,0,73

Ilford MG Classic FB,condenser,tungsten;00,-5,220;0,-7,188;1,-9,160;2,-10,136;3,-13,116;4,-20,00;5,-29;86

 

[albada]

Thanks for this info. I'm surprised at the low maximum contrasts attained by Ilford MGIV WT RC and lford MG Classic FB. For these papers, grade 5 is more like grade 4.

 

[mmerig]

Thanks for the feed back. I see what you mean about the high contrast grades for the two papers you mention. I use the simple method in the RHD manual to get contrast grades. It is more difficult to get an accurate value at the higher grades because the density range is so compressed (as expected). Plus or minus 5 contrast values from the true value (or what someone else may pick) is as close as I can probably get. A difference of 1 step on the wedge is equal to 15 values on the meter, or half a stop.

I rarely use contrast grades > 3.5, especially for the warm tone, which I don't use as much anyway. So I may be in for surprise when I do. I can scan and post my step wedge exposures if anyone is interested. Same goes for the exposure set.

Even with the RHD AP, I often make minor tweaks in my head, especially if the image does not have highlights bright enough and large enough to meter (same for shadows). So it's not totally mind-less, as some people think.