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Photo Forum / Film Photography / Darkroom / September 2004Best B&W Exposure Index and Contrast Index for Scanning
I've read that some people say they deliberately under-expose their B&W negatives (without adjusting development time) and in doing so they gain one or two stops of exposure. They claim the scanner is capable of doing a better job than the enlarger on these (thin) negs. Whether this is true or not, are there any "best practices" when shooting black and white with the intentions of scanning? ie. reducing development time in the tanks? or is it better to shoot with the recommended exposures and development times and let the scanner do its job and make your sacrifices in PhotoShop? Note: this was also posted in comp.periphs.scanners but I thought it might be better received in rec.photo.darkroom > I've read that some people say they deliberately under-expose their B&W > negatives (without adjusting development time) and in doing so they gain [quoted text clipped - 7 lines] > let > the scanner do its job and make your sacrifices in PhotoShop? IMHO underexposing is a very bad idea. Expose for the shadows and develop for the highlights. I will stop there lest this turn into a Zone System thread. People make compromises in B&W exposure and development for scanning because consumer-level scanners cannot accomodate 'dense' parts of the negative (DMAX issues.) By making such compromises they err in two regards: first, it is unlikely they are exposing properly in the first place, but most important the exposure compromises mean that they are SOL should they wish to do conventional (real) wet-darkroom printing AND they won't have a good negative should they decide to have a proper scan done professionally, OR when consumer scanners are up to the task. You put it well. Make your 'sacrifices' in Photoshop. Or, if the subject can be exposed twice, shoot once for the shadows, and again for the highlights and use the arithmetic functions in Photoshop to merge the images. (By arithmetic, I mean the apply-image, and blend modes.) I have under exposed by a stop by accident. I can tell you that the scans came out no better on these thin negatives than the prints did - maybe a bit worse. > I've read that some people say they deliberately under-expose their B&W > negatives (without adjusting development time) and in doing so they gain one [quoted text clipped - 7 lines] > Note: this was also posted in comp.periphs.scanners but I thought it might > be better received in rec.photo.darkroom > I've read that some people say they deliberately under-expose their B&W > negatives (without adjusting development time) and in doing so they gain one [quoted text clipped - 7 lines] > Note: this was also posted in comp.periphs.scanners but I thought it might > be better received in rec.photo.darkroom DON'T use conventional films with the intention of scanning. They're designed to be used to make OPTICAL prints in an enlarger by projection. > DON'T use conventional films with the intention of scanning. They're > designed to be used to make OPTICAL prints in an enlarger by > projection. So now you are a digital expert? What "films" should a person use, and how should those films be exposed and developed - from your first-hand experience, please. >> DON'T use conventional films with the intention of scanning. They're >> designed to be used to make OPTICAL prints in an enlarger by [quoted text clipped - 3 lines] >should those films be exposed and developed - from your first-hand >experience, please. For once, UC is mostly correct, conventional monochrome films, do not work with Digital ICE and similar technologies, because the grain confuses the software which thinks that the grain is dirt on the negative. The Chromogenic films, (C41 and E6 Process) films work better with Digital ICE. Kodachrome is also problematic for Digital ICE. W > For once, UC is mostly correct, conventional monochrome films, do not > work with Digital ICE and similar technologies, because the grain > confuses the software which thinks that the grain is dirt on the > negative. First, I remain skeptical but besides, loose the ICE and be happy. I believe it is premature to be compromising film exposures just so that digitizing works. >> For once, UC is mostly correct, conventional monochrome films, do not >> work with Digital ICE and similar technologies, because the grain [quoted text clipped - 5 lines] >I believe it is premature to be compromising film exposures just so that >digitizing works. I think that should be prefixed with IMNSHO, some people want negatives that will last 7 generations beyond them, other people want to make their own lives easier. For example, suppose you ran into a bunch of photos taken by your great, great, great uncle Mortimer, who was a rather lacklustre photographer, who took many frames of film, in a format where you would need a custom built $5,000 enlarger to make prints from. Would you try printing a few, or just toss the whole collection into the nearest rubbish bin. Heck most of the stuff I shot in the late 1970's when I was justing learning photography, I look at now, and think, that really deserves the rubbish bin. Heck some of the stuff I shoot now, belongs in the rubbish bin. Had an interesting experience today, I live in Canada's biggest city, Toronto (2.5 million). There is a park, G Ross Lord Park, which also has within it a reservour. It's near where I live, so occassionally I go there shooting, today I went to the reservour, what shows up, a female Great Blue Heron. I shot nearly an entire roll of this bird, I would expect one in the country, but in a major city? W Actually I would contact print them all first with a light bulb and save the 5,000 for beer. > I think that should be prefixed with IMNSHO, some people want > negatives that will last 7 generations beyond them, other people want [quoted text clipped - 4 lines] > prints from. Would you try printing a few, or just toss the whole > collection into the nearest rubbish bin.  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 >Actually I would contact print them all first with a light bulb >and save the 5,000 for beer. Actually beyond about 3 generations, most images will get tossed, or having sat in a mouldy old basement, will have the backing rotted out, what is interesting though, once I scan them, and burn them onto CD, do I really need the original negative? I will keep them, but will there a technical reason to actually use the negatives as negatives, in the near future. Will it be easier to simply email the digitized image to the lab, and pickup the print a few hours later, in just abouit any size. Even for a AgBr print, it will soon be easier to supply the image digitally, then to go hunting through a thick file of negatives. I want to soon start doing my own C41 processing, followed by a high resolution scan, which will be processed to a low resolution image for cataloging, the high-res image will be burned to CD, the low res image will be catalogued and retained on the computer. The largest print I would likely make is 11x14, which needs a scan of under 3200DPI from a 35mm negative. W > >Actually I would contact print them all first with a light bulb > >and save the 5,000 for beer. [quoted text clipped - 5 lines] > there a technical reason to actually use the negatives as negatives, > in the near future. This has been argued a lot in various NGs, If you value the images you should save the negatives. > Will it be easier to simply email the digitized image to the lab, and > pickup the print a few hours later, in just abouit any size. Even for > a AgBr print, it will soon be easier to supply the image digitally, > then to go hunting through a thick file of negatives. You can certainly email images now for printing I've rather easily sent files for 5x7's and eight by tens,...some do 16x20's on FTP sites. Finding imagery will always remain an issue regardless & since disk space is still a lot more expensive than holding onto already processed film, unless you plan on scanning at high resolution you would be wise to file the negatives. > I want to soon start doing my own C41 processing, followed by a high > resolution scan, which will be processed to a low resolution image for [quoted text clipped - 4 lines] > > W Question is do you want to waste time scanning every negative, I don't. 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 > Actually beyond about 3 generations, most images will get tossed, or > having sat in a mouldy old basement, will have the backing rotted out, > what is interesting though, once I scan them, and burn them onto CD, > do I really need the original negative? I will keep them, but will > there a technical reason to actually use the negatives as negatives, > in the near future. I just dumped a bunch of 3.5" diskettes in a recent move. The oldest of them was about ten years old, and completely unreadable, despite storage in comfortable room conditions, protected from dust and feather dusters. The same happens to CD-R and CD-RW media, seemingly over a similar span; the best CD-R media aren't that old yet, but CD-R disks burned less than ten years ago are already starting to come up unreadable due to deterioration of the media surface. A replica CD, like the ones sold with music on them, is somewhat more durable, because the reflective surface is actual metal, but don't forget, also, that a music player will play right through an error that might render a file unreadable. By contrast, glass plates from the Wild West and Civil War eras are still perfectly printable, even if they have to be sandwiched with new glass to hold broken fragments in position; some information is lost from the edges of the cracks, but the image as a whole is preserved. I'll trust computer media to replace my film originals when I can record in a holographic form with a high level of redundancy -- that is, make a record that loses only resolution if a portion is lost or damaged, and can be recorded with excess resolution (beyond the level of original film grain) to protect against such losses from aging or damage in storage -- and when such media have been around long enough to give confidence they won't be oboleted by the next generation of higher density media. When do I expect to do that? Likely not in my lifetime (likely to be the next thirty to fifty years). SignatureI may be a scwewy wabbit, but I'm not going to Alcatwaz! -- E. J. Fudd, 1954 Donald Qualls, aka The Silent Observer Lathe Building Pages http://silent1.home.netcom.com/HomebuiltLathe.htm Speedway 7x12 Lathe Pages http://silent1.home.netcom.com/my7x12.htm Opinions expressed are my own -- take them for what they're worth and don't expect them to be perfect. > > DON'T use conventional films with the intention of scanning. They're > > designed to be used to make OPTICAL prints in an enlarger by [quoted text clipped - 3 lines] > should those films be exposed and developed - from your first-hand > experience, please. C-41 B&W films are better for scanning. Conventional films are silver images. C-41 films are dyes. Scanners work far better with the latter. >C-41 B&W films are better for scanning. Conventional films are silver >images. C-41 films are dyes. Scanners work far better with the latter. Depends on how you define "far better." I'm perfectly happy with the results I get from scanning silver halide film. Your mileage may vary. If you're talking about using infrared light to detect and remove dust, the silver halide blocks the IR light, so the scanning software thinks conventional negatives are full of dust. Just won't work. The IR passes through the dye layers of chromogenic films. That's a feature of many scanners that can be turned off. -- Eric http://canid.com/ |
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