Godfrey
somewhat colored
... This is why you must always test and calibrate when planning to use B&W filtration.. 😉
G
G
This post sounds like what the OP really wants to know (or how I'm understanding them) is how many stops it takes to darken the image when using a given filter. So maybe this is what they are looking for:Thanks, but I'm at bit more confused than when started. What I'm asking for is The number of stops I need to reduce my speed for the following:
Yellow filter ____
Orange filter ____
Red filter ____-
Green filter ____
Thanks,
Bill
I mean you normally would use colour filters for the creative effect of colour filtration rather than the loss of light. If you just want loss of light use NDs, or close down the aperture to bring down shutter speed since they are proportional. A same level of exposure can be obtained through a variety of speed and aperture combinations established by the light value you choose.
I'm fascinated by the Kodak entries. When I was just barely old enough to notice such things as film speed, I was aware of Kodak Panatomic-X; Plus-X; and double-X. My dad switched from Double-X to Tri-X when Tri-X came out. At age 8 I was shooting Verichrome. Here I see Kodak "Super Sensitive" and "Super X." I have no memory of these. I'm having no luck with Google; but I'm guessing "Super Sensitive" might be a forerunner of Plus-X, and "Super X" could be the early Double X? Does anyone know?Correct... kinda.
Technically it depends on the film stock you're using and the time of day. Leitz New York published this table in the 1930s showing how filter factors can vary from film to film. All the "Filter No. 0, Filter No. 1" in the daylight sections are various grades of yellow filter; I also find it interesting that UV filters supposedly necessitate a 1-stop change in exposure on some films!
View attachment 4835717
And here's a chart from Wikipedia to help convert filter factors into "stops":
View attachment 4835718
Modern films are (mostly) a lot different to the film stocks being used back then with regards to colour sensitivity and the like - but it's still going to vary wildly from film to film, so it's worth testing with your most commonly-used films. I seem to remember the original Acros having an unusual response to certain colours compared to, for instance, HP5+.... and, of course, Ortho films are a totally different kettle of fish from the "regular" panchromatic stocks.
I had one particularly derpy moment where I tried to use an orange filter on Ortho film with a standard two-stop exposure adjustment, only to get a blank frame for my trouble. Felt like a right idiot when I realised what I'd done!
I'm not sure how you deduce that. Darkening the image = underexposure, non?This post sounds like what the OP really wants to know (or how I'm understanding them) is how many stops it takes to darken the image when using a given filter. So maybe this is what they are looking for:
If a yellow or green filter has a 1 stop published factor, and you want to reduce density by 1 stop, then do nothing; leave the aperture and shutter speed the same as you would have them without the filter;
If an orange filter has a 2 stop factor, and you want a 1 stop density reduction, open up 1 stop;
If a red filter has a 3 stop factor and you want a 3 stop density reduction, do nothing; if you want a 1 stop reduction, open up 2 stops; etc.
wrs, is this what you needed; if not, let's try again.
Yes, typically we are. But as I read the OP's last post, they asked to reduce their speed, which I took to mean sensitivity to exposure. Maybe they meant the shutter speed in order to increase their exposure owing to the density reduction of their filter, in which case I read them wrong. I believe then the answer they wanted would be to open up by an amount equal to the filter factors they already know and cited in post #1, for the filters mentioned. However, this point had already been answered before I responded, so I thought they must have meant something else. I'm sure now that I misunderstood.I'm not sure how you deduce that. Darkening the image = underexposure, non?
Typically we're trying to change the tonal relationships....
I think the first post in the thread provided necessary context: "I gave seen the standard rules for filters: 1 stop for yellow; 2 stops for orange; 3 stops for red; 1 stop for green. But there are corresponding rules for shutter speed lowering for the same purpose."Yes, typically we are. But as I read the OP's last post, they asked to reduce their speed, which I took to mean sensitivity to exposure. Maybe they meant the shutter speed in order to increase their exposure owing to the density reduction of their filter, in which case I read them wrong.