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Photo Forum / Film Photography / Darkroom / November 2005Filter grades
Hi, Given the exposure times of a two-filter approach to printing, is there a way to derive the theoretical effective grade without doing print matching using all the available grades ? For example, for a given print on VC paper with condenser/tungsten projection, I need 12 seconds on grade 0 4 seconds on grade 5 If I was to replace that by a single filter grade, what would it be ? ps: I use Ilford multigrade filters and Ilford recoomends one extra stop of exposure for grades above 3 1/2 thanks in advance, waiming > Hi, > [quoted text clipped - 14 lines] > thanks in advance, > waiming Yes you can use a step wedge and measure the density of each wedge then you can calculate the grade the enlarger gave you at that height and at that filtration and development time and temp.  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 >>Hi, >> [quoted text clipped - 18 lines] > then you can calculate the grade the enlarger gave you at that height > and at that filtration and development time and temp. Before running out to order the step wedge, I like to know what is used to measure the wedge density. In case it needs a densitometer that I don't have. I have never used a step wedge but I guess that some wedges will "fuse" as one varies the contrast to either the low or high end. Doesn't the wedge give an indication by noting how many of them has been "fused" due to grade filtering ? Or perhaps I need to have a reference wedge output for each filter grade at the specified enlarger height, dev time and temp. I was thinking of spreading the "wear" of my filters instead of just using the 0 and 5. If the cost of the wedge outweighs changing a whole filter pack just for a new set of 0 and 5, I would stay with split filtering... > Before running out to order the step wedge, I like to know what is used > to measure the wedge density. In case it needs a densitometer that I > don't have. Initially you need to have a wedge that either comes with established densities (pre-read by the manufacturer)-calibrated Or you can get a local lab perhaps to read an uncalibrated one for you. Then once you know where the step value you wish to print for falls on the wedge you can print for that value and observe where other values fall thereby gaining the ability to determine relative contrast. > I have never used a step wedge but I guess that some wedges will "fuse" > as one varies the contrast to either the low or high end. Doesn't the > wedge give an indication by noting how many of them has been "fused" due > to grade filtering ? Or perhaps I need to have a reference wedge output > for each filter grade at the specified enlarger height, dev time and temp. A typical example some wedges come in increments of 1/2 stop and have 21 increments total, 21 steps are probably the most commonly used. > I was thinking of spreading the "wear" of my filters instead of just > using the 0 and 5. If the cost of the wedge outweighs changing a whole > filter pack just for a new set of 0 and 5, I would stay with split > filtering... Well, to me the most important consideration is wether you can get the contrast you desire, realizing that contrast adjustment is separate from exposure. If you had a Dichroic or adjustable "stepless"filter lamp house you could adjust the contrast anywhere you desire. The only way you can completely do that with a Condenser head is by using a base filtration and then adding yellow or magenta filters as needed. It sounds like you would need to buy strickly yellow or magenta filters -not the standard. 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 >>I was thinking of spreading the "wear" of my filters instead of just >>using the 0 and 5. If the cost of the wedge outweighs changing a whole [quoted text clipped - 4 lines] > the contrast you desire, realizing that contrast adjustment is separate > from exposure. Thanks for highlighting that. My prints have been staring back at me trying to tell me just that but I wasn't getting it then :-) waiming > Before running out to order the step wedge, I like to know what is used > to measure the wedge density. In case it needs a densitometer that I > don't have. The wedge is made in even density increments. The most common are 0.3 or 0.5 od. If you want to be really picky for extra $$ you can buy a wedge with a calibration slip and you can find that the 1.0od wedge is really 1.045 od - for photography this is overkill. > I have never used a step wedge ... Assumptions are dangerous then. > but I guess that some wedges will "fuse" > as one varies the contrast to either the low or high end. No. > Doesn't the > wedge give an indication by noting how many of them has been "fused" due > to grade filtering ? They don't fuse. Each density patch on the 'wedge' is numbered. > Or perhaps I need to have a reference wedge output > for each filter grade at the specified enlarger height, dev time and temp. Yes. A series of 12 exposures will do it. I do four 4x5" exposures on an 8x10 sheet, shift the sheet between exposures. Process all three 8x10 sheets together. You may want to find someone to measure the test print densities. It can be quite a revelation: the 'curves' aren't as shown in the books: lumps and bumps; and many filters make no difference from the filter next to them [2 1/2 == 2 is common]. > I was thinking of spreading the "wear" of my filters instead of just > using the 0 and 5. If the cost of the wedge outweighs changing a whole > filter pack just for a new set of 0 and 5, I would stay with split > filtering... If conserving money is the object photography is not the answer. SignatureNicholas O. Lindan, Cleveland, Ohio Consulting Engineer: Electronics; Informatics; Photonics. To reply, remove spaces: n o lindan at ix . netcom . com Fstop timer - http://www.nolindan.com/da/fstop/index.htm > If conserving money is the object photography is not the answer. That's for sure. 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 >>Or perhaps I need to have a reference wedge output >>for each filter grade at the specified enlarger height, dev time and temp. > [quoted text clipped - 6 lines] > books: lumps and bumps; and many filters make no difference from the > filter next to them [2 1/2 == 2 is common]. Thanks for the explanation. waiming > Before running out to order the step wedge, I like to know what is used > to measure the wedge density. In case it needs a densitometer that I > don't have. You might want to run out and get Anchell's book "The Variable Contrast Printing Manual". He has a chapter on calibrating grades. Basically stick the wedge in the enlarger. Make a print. Count the number of steps that are neither pure paper white or pure black. Compare that number to the chart and you get a grade. It's a bit more complicated then that but not much more. > I was thinking of spreading the "wear" of my filters instead of just > using the 0 and 5. If the cost of the wedge outweighs changing a whole > filter pack just for a new set of 0 and 5, I would stay with split > filtering... Just get a couple of sheets of lighting gels made by Rosco. 20"x24" they cost about $6 each and will work fine for spilt filtering. Need a green and a blue. Or put the money towards a colour head. Nick Signature--------------------------------------- "Digital the new ice fishing" --------------------------------------- It's nice to be able to compare to a graded paper, so that you can match the contrast as closely as possible toa graded paper. After all, graded papers are better. > > Before running out to order the step wedge, I like to know what is used > > to measure the wedge density. In case it needs a densitometer that I [quoted text clipped - 21 lines] > "Digital the new ice fishing" > --------------------------------------- It's nice to be able to compare to a graded paper, so that you can match the contrast as closely as possible to a graded paper. After all, graded papers are better. > > Before running out to order the step wedge, I like to know what is used > > to measure the wedge density. In case it needs a densitometer that I [quoted text clipped - 21 lines] > "Digital the new ice fishing" > --------------------------------------- > Need a green and a blue. Won't yellow and magenta do? I've checked a few Ilford MG paper characteristic curves. Over all the lines do not indicate grade untill densities above 1 to 1.5 have been reached. Below those densities grade lines merge. In effect, for half or more of their density range those MG papers are little more than a single grade paper. I was surprised at seeing that. No wonder split filtration is used so and to the extreme. Ilford's MG is in contrast with their Graded Galerie paper. Each Grade's curve is distinct from one another toe to shoulder. The grade is in the paper, no splits needed. Dan >> Need a green and a blue. > > Won't yellow and magenta do? Yup. I just don't know which ones-) You'd have to look at the curves on the Rosco website to see which ones would work best. Nick Signature--------------------------------------- "Digital the new ice fishing" --------------------------------------- > > Need a green and a blue. > [quoted text clipped - 9 lines] > Each Grade's curve is distinct from one another toe to shoulder. > The grade is in the paper, no splits needed. Dan Graded paper is not perfect, either. I do prefer to use graded paper for serious work. Very seldom do you need the great range that today's VC papers provide. Many photographers must either have horrible negatives or want grotesquely distorted tonality. I hardly ever change filtration, usually hovering around grade 3. Almost every so-called 'creative technique' used in photography is actually some form of image degradation. I want none of that. >>Before running out to order the step wedge, I like to know what is used >>to measure the wedge density. In case it needs a densitometer that I [quoted text clipped - 5 lines] > neither pure paper white or pure black. Compare that number to the chart and > you get a grade. It's a bit more complicated then that but not much more. Will definitely do that. Just need to move the book from the wait list into the order basket... >>I was thinking of spreading the "wear" of my filters instead of just >>using the 0 and 5. If the cost of the wedge outweighs changing a whole [quoted text clipped - 4 lines] > cost about $6 each and will work fine for spilt filtering. Need a green and > a blue. Or put the money towards a colour head. Thanks, will look into that. waiming > > ... I like to know what is used > > to measure the wedge density. In case it needs a [quoted text clipped - 3 lines] > Count the number of steps that are neither pure paper white > or pure black. Compare that number to the chart ... You can close your eyes and plung forward or you can slow down and take a look at Ilford's own curves for their own MG papers. As I've already mentioned and in general, any of the MG papers show little grade variation below densities of 1-1.5. The most dense areas do show MG characteristics. Much of the middle and all of the little dense areas show perhaps no more than a 2 grade variation twixt 0 and 5 filters. It's all there in B&W at Ilford's site. In contrast compare their graded, Galerie in particular, with the MG papers. I don't work with MG, VC, MC, PC or whatever papers. If those lousy characteristic curves weren't enough reason I was to drop them anyway in favor of the much higher level of darkroom lighting afforded by Graded papers. Dan >>>... I like to know what is used >>>to measure the wedge density. In case it needs a [quoted text clipped - 9 lines] > As I've already mentioned and in general, any of the MG > papers show little grade variation below densities of 1-1.5. I have a set of negatives (after a development accident) with densities below that. The filters and MG don't do much except in areas where the densities (window back light) are of a reasonable level. I couldn't believe it then, but now it makes sense. > The most dense areas do show MG characteristics. Much of > the middle and all of the little dense areas show perhaps [quoted text clipped - 5 lines] > I was to drop them anyway in favor of the much higher level > of darkroom lighting afforded by Graded papers. Dan I have started using some of the graded RC papers (0 and 3) that I got from exchanging my 405 polaroid back. Despite their age, the prints look pretty good from the few trials I have made. Your comments are giving me more reason to compare what I have in my MG stock(pile). > > As I've already mentioned and in general, any of the MG > > papers show little grade variation below densities of 1-1.5. [quoted text clipped - 14 lines] > pretty good from the few trials I have made. Your comments are giving me > more reason to compare what I have in my MG stock(pile). I in no way ment to imply that very good quality prints can not or are not made on MG papers. Ilford's curves were something of a surprise to me. They claim seven grades. From looking at their graphs I'd think three a streach. Safely they might be considered two grade papers below densities of one or a little more. With their good separation in the more dense areas of the print they may be the cure for some negatives. Ilford's Galerie though does show that separation top to bottom. For myself and Graded papers, MG developers, pre-exposure, water bath, and other whole print contrast control techniques are at ones disposal. I suppose those techniques could be used with MG papers. Graded paper's greatest appeal for me is the much higher level of darkroom lighting they afford. Dan >>I have started using some of the graded RC papers (0 and 3) that I got >>from exchanging my 405 polaroid back. Despite their age, the prints look [quoted text clipped - 3 lines] > I in no way ment to imply that very good quality prints can not > or are not made on MG papers. Ilford's curves were something of No, I don't doubt that either. I m just curious to run a comparison to see what the difference can be and probably exploit it if I ever come to need it. > a surprise to me. They claim seven grades. From looking at their > graphs I'd think three a streach. Safely they might be considered [quoted text clipped - 7 lines] > MG papers. Graded paper's greatest appeal for me is the much > higher level of darkroom lighting they afford. Dan Here where I live in France, in a provincial town far from Paris, getting graded papers means mail ordering from a specialized supplier. The pros have gone color or digital. B&W is like a specialty thing now. As I am in the early exploration phase, I am trying the different things available to see which one works best within the limits of availability. Thanks for sharing the experience. waiming > Here where I live in France, in a provincial town far from Paris, Not the Alsace-Lorraine area by any chance? I traveled that area quite a bit in 63 and 64 while with the Headquarter Company of a Combat Engineer Battalion stationed at Etain Air Base. I was THE photographer and lab man for that Battalion. Dan > > Here where I live in France, in a provincial town far from Paris, > > Not the Alsace-Lorraine area by any chance? I traveled that > area quite a bit in 63 and 64 while with the Headquarter Company > of a Combat Engineer Battalion stationed at Etain Air Base. > I was THE photographer and lab man for that Battalion. Dan Whoa: I always pictured you as 30 ish since I was born in 64 that makes you,..... :-) A lot older than thirty. 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 >>Here where I live in France, in a provincial town far from Paris, > > Not the Alsace-Lorraine area by any chance? I traveled that nope, all the way on the opposite side to the west - Brittany :-) My town is near to the Brittany-Normandy frontier. waiming > I in no way ment to imply that very good quality prints can not > or are not made on MG papers. Ilford's curves were something of > a surprise to me. They claim seven grades. From looking at their > graphs I'd think three a streach. Safely they might be considered > two grade papers below densities of one or a little more. I tested Afga paper. The low range was below 0. The high about 4.5. The test was done with my enlarger,len and developer so it's only valid with my setup. I also only tested the high and low range. Only way to know what you're getting is to test your setup. Nick Signature--------------------------------------- "Digital the new ice fishing" --------------------------------------- You first need to use some graded paper to find out what your VC grades actually are. The filter numbers are often quite different from the 'real' grades. > Hi, > [quoted text clipped - 14 lines] > thanks in advance, > waiming Thanks. for the tip. waiming > You first need to use some graded paper to find out what your VC grades > actually are. The filter numbers are often quite different from the [quoted text clipped - 18 lines] >>thanks in advance, >>waiming |
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