Good points all. Well I'm going to go ahead and try all three on the same subject with blue skies and clouds and bracket them as well and see what happens. Should I bracket +1 and -1 or +2 and -2?
This may be a fine way to learn. Make sure you take a shot without filter in place as we'll so you can see what's going on in the scene.
One test I did one time was take a gray card out on an overcast day and fill the frame mostly with it and take a shot, metering off the card (make sure there is no glare on it). Then put each filter on and start with the manufacturers filter factor, then bracket + - 1/2 stop in each direction. For the red filter maybe bracket up to +1 as a red usually needs more. Make sure you keep detailed notes. Then contact print your set of negatives and find the shot with each filter that best matches the unfiltered shot of the gray card. This test can be interesting but then again you're shooting under overcast light which is slightly bluish. Alternatively you could shoot this test on a sunny day but then you introduce color temperatures from different times of day. See how you can overthink this??
No wonder some I've my exposures always seemed off, I always thought filter factors were STOPS...
Kind of stupid, why make you do math instead of just putting the stops on the filter? I'm sure it "all goes back to xxxxxxx reason" it's still annoying and dumb.
Thanks for the info
It isn't as stupid as you say.
The filter factors work well with ASA/ISO/EI numbers.
They work well with flash guide numbers.
They work well when you use more than one filter.
They work well with films that have different daylight and tungsten speeds.
They work well with calculations concerning bellows extension.
They fit well within a system.
“Photography is a complex and fluid medium, and its many factors are not applied in simple sequence. Rather, the process may be likened to the art of the juggler in keeping many balls in the air at one time!”
Ansel Adams, from the introduction to The Negative - The New Ansel Adams Photography Series / Book 2
The dividing the filter factor into the ASA speed and setting the light meter with the resultant offfset seems like a good idea at first blush. Bt what do you do if you're shooting a snow scene, or adding a polarizer, working wih a ND filter, and have to adjust by different stops in addition to the contrast filter? Then for a second shot you take one filter off. Wouldn't it be easier to just leave the meter at box speed and adjust the stops on the camera after adding them all up?