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Photo Forum / Film Photography / Darkroom / November 2004Help Understanding Densitometer Readings+
Hi. I'm trying to figure out if my development times, agitation, etc., are correct, so I did the following. Any help will be greatly appreciated: I shot two sheets of Tri-X (TXP) at EI 250 developed in HC110 (from stock, diluted 1+10 for 8 min). One sheet was clear (no image) and the other had a gray card (18%) with a black and white card on either side. When I placed the gray card on Zone V, the black was at Zone IV (lower part of it) and the white on Zone VII/VIII. After I set the densitometer (Eseco Speedmaster) to 0 (using the clear sheet), I get these values: the gray read 0.74; the black 0.35 and the white 1.34. If each zone is 0.30 density (??), then this sort of makes sense to me but I'm unsure. Do these numbers make sense? Again, any help is greatly appreciated. RON _________________________________________________________________ B&W Landscape and Still Photography: http://www.ronaldgansphotography.com > Hi. I'm trying to figure out if my development times, agitation, etc., are > correct, so I did the following. Any help will be greatly appreciated: [quoted text clipped - 14 lines] > If each zone is 0.30 density (??), then this sort of makes sense to me but > I'm unsure. "zones" are measured along the Log exposure scale (X axis of a film curve graph.) These are 0.30 linear "stops." Density is a non-linear measure. If density were an equal linear measure of the exposure scale (zone I to VIII) a Zone VIII density would be 2.1 (0.3 x 7.) Way to high. Does that makes sense? Thus film densities reflect the nonlinear response of the film to exposure. So, in order for you to count zones you should either draw a graph or use a step wedge, but the density spread isn't going to reflect equal "zones." Again this is because while your meter measures light in equal stops, film doesn't respond this way; it _compresses_ tonal/density values. > Do these numbers make sense? Again, any help is greatly appreciated. Gray card is 0.74 net and zone VIII is 1.34 net (i.e., minus your film base?) These seem fairly average (correct) densities. However, you don't say what the black and white cards were metered at, and that's what matters. What counts is whether zone VIII density matches your metered zone VIII, and whether you get good shadow detail (i.e., zone III desnity matches metered zone III.) Ansel Adams in The Negative has a useful, basic method for determining effective film speed and proper zone placements as they relate to developed densities. > > Hi. I'm trying to figure out if my development times, agitation, etc., are > > correct, so I did the following. Any help will be greatly appreciated: [quoted text clipped - 7 lines] > > When I placed the gray card on Zone V, the black was at Zone IV (lower part > > of it) and the white on Zone VII/VIII. On second reading, it sounds like you did meter the black and white cards? Try metering for zone III on a gray card, nad zone VIII on a gray card and adjust accordingly. 0.35 seems a little low to me for a zone IV density and you may want to give a little more exposure (lower effective ISO speed.) > > After I set the densitometer (Eseco Speedmaster) to 0 (using the clear > > sheet), I get these values: the gray read 0.74; the black 0.35 and the white [quoted text clipped - 29 lines] > for determining effective film speed and proper zone > placements as they relate to developed densities. First, thanks for your help. I did meter the black and white cards. If 0.35 is low for Zone III, should I increase the development time? >> > Hi. I'm trying to figure out if my development times, agitation, etc., >> > are [quoted text clipped - 54 lines] >> for determining effective film speed and proper zone >> placements as they relate to developed densities. > First, thanks for your help. > > I did meter the black and white cards. > > If 0.35 is low for Zone III, should I increase the development time? 0.35 isn't low for III. I thought you said it was what you got at IV. 0.35 should give adequate shadow density for III. If you had a low density for III but a good density for VIII you should increase exposure (a lower ISO) and reduce development a little. Normally to determine your effective film speed you meter a gray card at zone I and vary the ISO exposure in 1/3 to 1/2 stops. Whichever exposure gives a 0.10 net density above fb+f is your effective film speed for that film, developer and time. This method of calculating your effective speed usually gives adequate shadow/zone III exposure. > >> > Hi. I'm trying to figure out if my development times, agitation, etc., > >> > are [quoted text clipped - 54 lines] > >> for determining effective film speed and proper zone > >> placements as they relate to developed densities. I shot a gray card (Tri-X TXP at 250) and placed it on Zone VIII and again on Zone III. Developed both together in HC110 (1+10) for 8 1/4 min. My meter was the Pentax Spotmeter (Calumet modified). Zone VIII has a density of 1.53 and Zone III of 0.43. This gives me an average of 0.22 per zone. But isn't Zone VIII with a density of 1.53 too high? I know some photographers look for a much lower target density. If so, I'm thinking I should decrease the development time, trying, say, 7 1/2 min. Again, does this make any sense? RON >> First, thanks for your help. >> [quoted text clipped - 82 lines] >> >> for determining effective film speed and proper zone >> >> placements as they relate to developed densities. > I shot a gray card (Tri-X TXP at 250) and placed it on Zone VIII and again > on Zone III. Developed both together in HC110 (1+10) for 8 1/4 min. My meter [quoted text clipped - 3 lines] > > This gives me an average of 0.22 per zone. This sort of calculation (density equally divided into "zones") is meaningless, as I previously wrote... > But isn't Zone VIII with a > density of 1.53 too high? I know some photographers look for a much lower > target density. If so, I'm thinking I should decrease the development time, > trying, say, 7 1/2 min. > > Again, does this make any sense? The results should have been similar, though not exact, to your previous test if either this test or your previous test was consistent. Then again, you said the previous black card test was 0.35 at zone IV, not zone III, so something doesn't sound right. If you go by the gray card tests, 0.43 (net?) is a bit on high side for zone III. So you might first try a higher speed rating by 1/3 stop (decrease exposure.) > RON > [quoted text clipped - 84 lines] > >> >> for determining effective film speed and proper zone > >> >> placements as they relate to developed densities. > So you might first try a higher speed rating by 1/3 stop (decrease > exposure.) Oh so precise grass hopper, thats only .07 density increment can we not just say .15 is good enough for B&W :-D Any more controlled and its not the touchy feely art I love,...LOL I can see E6 needing that kind of control but negatives? BTW have you ever looked into how much a 1/3 stop ND glass or resin filter runs they ain't cheap :-)  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 > > So you might first try a higher speed rating by 1/3 stop (decrease > > exposure.) > > Oh so precise grass hopper, thats only .07 density increment can we not just say > .15 is good enough for B&W :-D > Any more controlled and its not the touchy feely art I love,...LOL Sure, but ISO settings don't go in half stops. I save touchy feely stuff for printing, when I'm alone in the dark and no one can see... > I can see E6 needing that kind of control but negatives? Didn't I tell you? I process my negs in e6 ;) > BTW have you ever looked into how much a 1/3 stop ND > glass or resin filter runs they ain't cheap :-) [quoted text clipped - 5 lines] > is not only unpatriotic and servile, but is morally treasonable > to the American public."--Theodore Roosevelt, May 7, 1918 One other thing: I do have a copy of Basic Techniques in Photography, the book edited by John Schaefer (based on Adams's series). Adams mentions the Stouffer step wedge. Could this be used for creating negs? I know it is supposed to be used in an enlarger, but it seems ideal for negs. >> > Hi. I'm trying to figure out if my development times, agitation, etc., >> > are [quoted text clipped - 54 lines] >> for determining effective film speed and proper zone >> placements as they relate to developed densities. > One other thing: I do have a copy of Basic Techniques in Photography, the > book edited by John Schaefer (based on Adams's series). Adams mentions the > Stouffer step wedge. Could this be used for creating negs? I know it is > supposed to be used in an enlarger, but it seems ideal for negs. Yes, I use a step wedge exposed on film with a tungsten enlarger to determine my development times. With a 21 step wedge you can count the density range (zone I to VIII) in stepped increments of about 0.15 (half stop.) You can then read the steps on your speedmaster and plot film curves for N, N+, N-, etc. Film speed is then tested using a gray card exposed at zone I density (0.10.) A good text for this is Phil Davis Beyond the Zone System. > >> > Hi. I'm trying to figure out if my development times, agitation, etc., > >> > are [quoted text clipped - 54 lines] > >> for determining effective film speed and proper zone > >> placements as they relate to developed densities. > After I set the densitometer (Eseco Speedmaster) to 0 (using the clear > sheet), I get these values: the gray read 0.74; the black 0.35 and the white > 1.34. > > If each zone is 0.30 density (??), then this sort of makes sense to me but > I'm unsure. Exactly correct. 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 Thanks!! I know that after I get it all down pat, I won't understand how it wasn't always obvious. But for now, it isn't. RON >> After I set the densitometer (Eseco Speedmaster) to 0 (using the clear >> sheet), I get these values: the gray read 0.74; the black 0.35 and the [quoted text clipped - 6 lines] > > Exactly correct. >Hi. I'm trying to figure out if my development times, agitation, etc., are >correct, so I did the following. Any help will be greatly appreciated: [quoted text clipped - 20 lines] >_________________________________________________________________ >B&W Landscape and Still Photography: http://www.ronaldgansphotography.com One more thing-- I have a Eseco Compumaster (newer version). You should be calibrating the "0" of the meter with a completely empty stage and measuring gross density. Subtract your film base + fog reading from your gross density readings when doing your zone calibration. Setting your "0" point with the unexposed film could be distorting the shape of your curves. Presumably, you have some known density reference for adjusting the DMax calibration. I've found that Eseco's tech support is very helpful. Contact them through www.eseco-speedmaster.com, especially if you don't have a manual for it. I hope this helps a bit-- Greg -------------------------------------------------------------- Greg Mikol This email address is registered with the Washington State Attorney General's office and WAISP. Unsolicited Commercial Email sent to this address in violation of RCW 19.190.020 is subject to civil penalties of $500 per offense. First, thanks for your comments. What do you mean by an empty stage? You mean with no film at all? I have set my '0' point with unexposed film (but fixed) RON >>Hi. I'm trying to figure out if my development times, agitation, etc., are >>correct, so I did the following. Any help will be greatly appreciated: [quoted text clipped - 52 lines] > of RCW 19.190.020 is subject to civil penalties of $500 per > offense. > I have set my '0' point with unexposed film (but fixed) Then you have factored out fb+f. You've the wrong number. Step wedge steps are .15 or .10. There are 21 and 31 step wedges. Also, a gamma of .5 or a little more is normal. So each zone which is one full stop or .30 is to be reduced by half. Zone VIIII should fall at about 1.30. Zone III about .40; 0.1 plus 2 x .15. All thats above fb+f. BTW, would you like another Speedmaster. I've one that needs a bulb. Shipping + $10 and it's yours. It has a foot switch and the dial moves. I've now a Tobias. Dan > > I have set my '0' point with unexposed film (but fixed) > [quoted text clipped - 7 lines] > a bulb. Shipping + $10 and it's yours. It has a foot switch and > the dial moves. I've now a Tobias. Dan I'll Take it if its still available. How difficult are the bulbs to replace? Are they still available? greg(Remove)@gregblankphoto.com 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'll Take it if its still available. How difficult are the bulbs > to replace? Are they still available? > It's still. Could'nt say about the bulb. I searched Google for, eseco speedmaster repair . Their are quite a few. This unit is heavy and large; 1+ by 2+ feet and around 25lbs. Likely it was used for x-ray reading. The foot peddle leaves both hands free; good for handling large sheets. I'll check for a model number. If not you, back to eBay with it. Dan > Hi. I'm trying to figure out if my development times, agitation, etc., are > correct, so I did the following. If they print perfectly, they are correct. Nothing else matters. Foget zones. That is all bullshit. > Foget zones. That is all bullshit. YES "FOGET" ALL THAT YUR-ANUS SAYS AS MS IS FULL OF BS. SignatureLOL!!! |
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