Ha ha, thanks for the compliment. No, I'm not a teacher; I'm just a lifelong photo enthusiast who never lost his interest in it. Although I work in some aspect of the photo industry (end user, not manufacurer), I'm here on APUG just as a hobbyist. By the way, you are quite welcome for any help I've given. And I appreciate your feedback, often it's not clear if anyone has benefitted from advice.You would make a fantastic teacher (if you aren't one already)!
It might seem so, but if you work through the numbers, like before, the result turns out to be effectively the same as having used a cyan filter. I say effectively, because the cyan does not throw away so much of the light, so less exposure correction is needed.Though we are trying to "block" red with the use of green and blue filters, each one, nevertheless, still allows enough red light to pass through to effectively neutralize at least a percentage of the cyan that would appear in the final print.
Here's roughly how it goes, comparing a 30cc cyan filter vs the combination of 30cc green plus 30cc blue: Note that the 30cc designation means these filters will pass virtually all of their own color, but block about 50% of everything else.
For 30 cc Cyan: this will block 50% of the red light, and pass 100% of both green and blue light. Result, compared to original 100% of each color: red = 50%, green = 100%, and blue = 100%. So the relative result is that green and blue have equal strength, and the red is reduced to 1/2 of theirs.
For 30 cc green plus 30cc blue: green will block 50% each of the red and blue light, passing 100% of green light. Applied to this light is a blue filter which will block 50% each of the red and green light, passing 100% of blue light. The combined result is: red = 50% x 50% = 25%, green = 100% x 50% = 50%, and blue = 50% x 100% = 50%. So the relative color result is the same as the previous example, where green and blue light have equal strength, and the red light is 1/2 of that strength. However, in this case, all of the actual light transmission percentages are only 1/2 of the previous example, consequently we have to double the exposure time.
Nah! You have to develop some comfort, or confidence, that these ideas DO work properly, whether by doing it repetitively, or figuring it out, or perhaps someone you trust says that it is so. Otherwise, whenever something goes wrong, you'll always be wondering if the method is wrong, or if you simply made a mistake.Am I confusing things too much?