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Photo Forum / Film Photography / Darkroom / November 2004filter grades and time?
Hi guys, is there a direct relationship between b&w filter grades and exposure time? i would basically like to gauge exposuretime from filter to filter if i step up or down, even if its a general rule it would be ok, something more of a guess work... anything. k Yes there is a direct relationship... they wont let as much light through while they're on than while they're off. That being said it's best to ALWAYS start with a filter if you think you're going to need them... rather that using no filter and then applying a filter if you think you need it (in which case you now have to start all over with an exposure test strip). So instead start with a 2 or 2.5 and adjust higher or lower from there if you need to. This way you'll know how to adjust your exposure from you're starting filter. Most filter sets I've looked at are made to let the same ammount of light through, except #4 to #5 where you're letting half as much light through. The papers that came with the filter set should show you what exposure adjustments you should make. > Hi guys, > [quoted text clipped - 5 lines] > > k The Kodak and Ilford systems have uniform exposure with all the filters from )) through 3 1/2, then double for 4 through 5 or so. This only applies for a specific tone, normally around D0.60. This is of course is bugger-all use if you select your exposure based on highlights. Of course people who know the zone system will immediately be able to identify the Zone placement that corresponds to 0.6. Clearly Uranium Committee knows his Zone placement and must practice it regularly to be able to make such an obvious recommendation. Chris Woodhouse On 25/11/04 10:15 pm, in article 9c532379.0411251415.19372247@posting.google.com, "Uranium Committee" <uraniumcommittee@yahoo.com> wrote: >> Hi guys, >> [quoted text clipped - 8 lines] > The Kodak and Ilford systems have uniform exposure with all the > filters from )) through 3 1/2, then double for 4 through 5 or so. > This only applies for a specific tone, normally around D0.60. This is of > course is bugger-all use if you select your exposure based on highlights. [quoted text clipped - 5 lines] > > Chris Woodhouse Kodak and Ilford have different points of reference. > On 25/11/04 10:15 pm, in article > 9c532379.0411251415.19372247@posting.google.com, "Uranium Committee" [quoted text clipped - 12 lines] > > The Kodak and Ilford systems have uniform exposure with all the > > filters from )) through 3 1/2, then double for 4 through 5 or so. On 27/11/04 12:16 am, in article 9c532379.0411261616.1649147d@posting.google.com, "Uranium Committee" <uraniumcommittee@yahoo.com> wrote: <snipped> >>> The Kodak and Ilford systems have uniform exposure with all the >>> filters from )) through 3 1/2, then double for 4 through 5 or so.> >> This only applies for a specific tone, normally around D0.60. This is of >> course is bugger-all use if you select your exposure based on highlights. [quoted text clipped - 5 lines] >> >> Chris Woodhouse > Kodak and Ilford have different points of reference. Quite, which makes your recommendation all the more pointless. At the end of the day, if you want to use the photo chemical process, and work with it without endless trial and error, you have to understand the sensitometry - up to a point. This isn't a theoretical exercise. It makes practical sense. It enables one to go into a darkroom and make first-off quality prints that satisfy. Welcome to the pleasure Zone. > On 27/11/04 12:16 am, in article > 9c532379.0411261616.1649147d@posting.google.com, "Uranium Committee" [quoted text clipped - 19 lines] > > Quite, which makes your recommendation all the more pointless. HUH? Kodak and Ilford designed their systems so that you don't wase a lot of paper when you switch filters. Is that pointless? > The Kodak and Ilford systems have uniform exposure with all the > filters from )) through 3 1/2, then double for 4 through 5 or so. This should be true in theory. My experience through observation is that moving from filter to filter does change the highlight desnity, even with Ilford paper, Ilford filters, and Ilford developer (and a regulated power source). Stephen Anchell, The Variable Contrast Printing Manual, documents a process for calibrating exposure across filters. --Phil (Be gone with him) > This should be true in theory. My experience through observation is > that moving from filter to filter does change the highlight desnity, > even with Ilford paper, Ilford filters, and Ilford developer (and a > regulated power source). Stephen Anchell, The Variable Contrast > Printing Manual, documents a process for calibrating exposure across > filters. Your experience matches mine. In no way does a change from grade 2 filteration to grade three allow you the same exsposure. Just like camera work there's a filter factor. Now if had been stated that the respective manufactures provide a chart of those factors I could agree. Filters effect the speed of the paper as well as the contrast the two things in my experience are seperate entities although linked. Greg  SignatureLF Website @ http://members.verizon.net/~gregoryblank "To announce that there must be no criticism of the President, or that we are to stand by the President, right or wrong, is not only unpatriotic and servile, but is morally treasonable to the American public."--Theodore Roosevelt, May 7, 1918 > (Be gone with him) > [quoted text clipped - 14 lines] > > Greg They match at some mid-tone, not at the highlights. |
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