Chan TranChan Tran said:Every 30cc or 0.30 density of all three color is equal to 1 stop. The magenta is more heavy and the yellow is a bit on the light side.
Bob Carnie said:Only use two filters at any given time on the enlarger. If you use three you are only adding nuetral density by the amount of the lower filter number.
srs5694 said:Color papers tend to be much faster than B&W papers. I once did a test of printing a properly exposed Kodak BW400CN (chromogenic B&W, with orange mask) negative on both conventional B&W and color papers. On my Philips PCS130 with PCS150 control unit, I exposed as follows to get similar results:
- Agfa MCP 310 RC B&W paper: Yellow filtration = 40, magenta filtration = 30, 30s exposure @ f/8.
- Konica A7 color paper: Yellow filtration = 165, magenta filtration = 120, cyan filtration = 55, 15s exposure @ f/8.
To get the B&W exposure time down to 15s, it would be necessary to adjust the filtration to 10/0 rather than 40/30. That'd make for an average of 137.5 cc difference on the yellow and magenta channels (cyan isn't normally used for B&W). At 30cc per stop, that's about a 4.5-stop difference in speed between the Konica A7 RA-4 paper and the Agfa MCP 310 RC paper -- and the Agfa's a pretty fast B&W paper. Looked at another way, with the color paper's filtration settings, you'd need an exposure of between 4 and 8 minutes to get the proper exposure with the Agfa B&W paper. (The contrast would be off, but that's another matter.)
No doubt this analysis wouldn't hold up to rigorous scientific scrutiny, but it should give you a ballpark idea of how fast color papers are compared to B&W papers. Note that the orange mask in color films helps boost exposure times. Nonetheless, I find that I've got to boost my filtration settings up to get at least 2-3 stops of ND filtration for most negatives in order to get reasonable exposure times when making 8x10 prints.
Photo Engineer said:Since your color exposure used 3 filters, which is a no-no under normal conditions, you had the equivalent of 110 Y, 65 M and 55 neutral density which cost you 0.55 log E or nearly 2 stops. (1 and 2/3 stops).
...
You should never use 3 filters for either color or B&W unless you want to use it as a neutral density to increase exposure time.
srs5694 said:That's precisely why I did use it. I prefer to have printing times in the 10-30s range, and in fact my enlarger's timer (built into the Philips PCS150 controller) has a minimum print time of 5s. Using the filtration I used, I got an exposure time of 15s. Removing all the cyan filtration would have gotten an exposure time of about 5s.
FWIW, with this enlarger I generally need to use more than the 55 cyan filtration I mentioned in this example, since removing it would result in sub-5s print times. When doing color ringarounds I usually start with around 100C (and higher values for M and Y) and adjust exposure time and filtration as necessary. Even if I can, I don't usually bother removing "unnecessary" filtration unless my print times get above 30s or so; mucking with the dials once I've got things set to give me a good print just introduces more room for error. I'd rather wait another few seconds during exposure than have to redo a print because I mis-set some value.
All of this just goes to illustrate my original point: Modern color papers are very fast.
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