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Photo Forum / Film Photography / Medium format / October 2003Dynamic Range of films vs prints
The recent thread about transparencies vs negatives highlighted the different perceptions that people have about this subject. Lately I've done some scanning of color images with the new Minolta 5400 and have revised by opinion about the need for transparencies. If you look at my tips section you will see several on capturing the full range of densities and then scaling them to a suitable print. The factor that seems to have been missed in the dynamic range discussion is that it is not necessary to scale the densities uniformly. As another of my tips shows it is also possible to adjust different areas of the scene using different curves. So, I've revised my opinion and I now think that color negative film is probably easier to use and presents less restrictions when coupled with a modern scanner having good Dmax and 16 bit processing.  SignatureRobert D Feinman robertdfeinman@netscape.net Landscapes, Cityscapes, Panoramas and Photoshop Tips http://robertdfeinman.com > So, I've revised my opinion and I now think that color negative film is > probably easier to use and presents less restrictions when coupled with > a modern scanner having good Dmax and 16 bit processing. But how about color accuracy? I've always had FAR more problems getting the colours right (or even getting them to look nice) when scanning from negatives, when compared to scanning prints or slides. I think when shooting negative, flatbed-scanning a good 8x10" print will be the easiest by far, and probably also give the best quality. (because negatives are meant to be printed instead of scanned, and the main -necessary- correction will then be made when printing.) just my $0.02. Lourens Recently, Lourens Smak <smak@wanadoo.nl> posted: >> So, I've revised my opinion and I now think that color negative film >> is probably easier to use and presents less restrictions when [quoted text clipped - 8 lines] > (because negatives are meant to be printed instead of scanned, and > the main -necessary- correction will then be made when printing.) This is largely dependent on the scanner and its software. Pro-level scanners / software come with profiles for film (negative and positive) that will get you into the ballpark of color balance and dynamic range. You can then make adjustments to many variables... white & black points; d-range; color balance; hue, saturation, brightness; to name a few. You can then save those adjustments to a custom profile. If you shoot a standard target (e.g. the Kodak targets) with your film of choice, you can easily establish a profile that will render the correct balance for that film and lighting combination. Then, scanning the negatives will give better results than scanning a print, because you don't have the generation loss and compromises of dynamic range of the print. Regards, Neil > > I think when shooting negative, flatbed-scanning a good 8x10" print > > will be the easiest by far, and probably also give the best quality. [quoted text clipped - 7 lines] > d-range; color balance; hue, saturation, brightness; to name a few. You > can then save those adjustments to a custom profile. I know all that... that's why I said it would be much *easier* to scan a print. Not necessarily better, depending on the effort the scan-operator is willing to make, and the scanner- and software- quality to start with, as you also suggest. But esp. amateur negative-film has too much colour in it, and is extremely difficult to scan right. (even for a professional with a good drumscanner.) After printing it, it becomes a piece of cake even for an amateur. ;-) Lourens >> So, I've revised my opinion and I now think that color negative film is >> probably easier to use and presents less restrictions when coupled with [quoted text clipped - 8 lines] >negatives are meant to be printed instead of scanned, and the main >-necessary- correction will then be made when printing.) I strongly disagree. Scanning negatives is actually easier than scanning chromes, in terms of Dmax issues. Inversion of BW is absolutely trivial; inversion of color negs somewhat less so, but supported in every film scanner sold. Furthermore, when scanning a print, you are absolutely constrained by the tonality and sharpness of the print, and have suffered an extra optical generation that is completely superflous. Negative film is inherently ambiguous with regard to color, that is true. It is quite impossible to say from a negative what the "original" colors might have been. Neil Gould's suggestion of shooting an IT-8 target in one frame of each film might help. What film and film scanner were you using, Lourens? Is your statement based on long experience or just a few attempts? rafe b. http://www.terrapinphoto.com > I strongly disagree. Scanning negatives is actually > easier than scanning chromes, in terms of Dmax > issues. I was talking about colour... > Inversion of BW is absolutely trivial; inversion > of color negs somewhat less so, but supported in > every film scanner sold. Inversion isn't good enough; the (orange) mask layer has a varying density too... > Furthermore, when scanning a print, you are absolutely > constrained by the tonality and sharpness of the print, > and have suffered an extra optical generation that is > completely superflous. Yes, but a color-negative is *designed* to be printed on color (negative) paper, not to be scanned and simply inverted. What you have then is simply not a good starting-point. The optical extra generation should be no real problem, that's more a theoretical thing in my opinion. (unless the print is made at home with amateur equipment or so, or if the print is very small.) > What film and film scanner were you using, Lourens? > Is your statement based on long experience or just > a few attempts? I scan 35mm slides using a Canon FS4000. I don't have a lot of negatives to work with, but a few tries show getting a decent scan is really difficult. (I am impressed btw with the low amount of noise in shadow-areas with this scanner; it captures an amazing amount of shadow detail too. Don't know the Dmax value Canon says it has.) I scan in 14 bit of course, make basic corrections in the scanner software, and level the image to "perfection" (ahem) in Photoshop; only then I convert to 8bit. This takes some time as the basic files are about 110Mb, but it's the only way to do it right. I also shoot MF a lot (obvious as this is the MF group) but I don't scan that myself. usually these transparencies end up on a Crosfield or Imacon. I hardly use negative film. (both 35mm and 6x6) Also, I own a cheap-ish flatbed (Canon D2400U) and a >50Mb scan of a good print is quite easy. I don't do that a lot, but I know a few people who prefer working this way. Mainly these are photographers who have to use a lot of mixed lighting, like architecture- and interior- photographers... scanning a negative for them is often a true nightmare. Most of those have a high-end flatbed of course, not a $250 machine like mine. Another point is that grain looks different with scanned negatives, and usually it's a lot uglier, and a lot more, than with scanned transparencies. (But if you see that depends on final size, how close you inspect the final print, sharpening, etc. On screen it is obvious however.) ;-) Lourens > > I strongly disagree. Scanning negatives is actually > > easier than scanning chromes, in terms of Dmax [quoted text clipped - 8 lines] > Inversion isn't good enough; the (orange) mask layer has a varying > density too... Indeed it does, and it's never the same "orange", or orange at all! Agfa used to make a very good flatbed scanner which did decent transparencies, but the most excellent thing about the scanner was the huge library of film type corrections They are _complex_, in particular I found the curves to be hard to recreate when I had to go to a different scanner. >Indeed it does, and it's never the same "orange", or orange at all! Agfa >used to make a very good flatbed scanner which did decent transparencies, >but the most excellent thing about the scanner was the huge library of >film type corrections They are _complex_, in particular I found the curves >to be hard to recreate when I had to go to a different scanner. My Polaroid SprintScan Plus had these film-type profiles. As does the very popular scanner driver called VueScan. (This is a "universal" scanner driver that works on nearly every brand and model of flatbed or film scanner made.) Strangely, my Nikon does not use film-type profiles and yet IMHO does a better job inverting negatives than any other filmscanner / driver combination I've used. I simply don't understand what all the fuss is about -- unless one is expecting the look of Velvia from Supra with one click a button. I'd call that a bit unreasonable, myself. rafe b. http://www.terrapinphoto.com >> I strongly disagree. Scanning negatives is actually >> easier than scanning chromes, in terms of Dmax [quoted text clipped - 17 lines] >(negative) paper, not to be scanned and simply inverted. What you have >then is simply not a good starting-point. Well, if you don't shoot a lot of negatives, it's understandable that you'd not need or bother to take the trouble to learn to scan them -- or why you and I have very different assessments of the difficulty involved. As with most things -- practice makes perfect. The notion that negatives weren't "designed" or "intended" to be scanned is simply irrelevant. Oxygen wasn't "intended" to be mixed with gasoline, but it does so quite readily and it's a process that we absolutely depend on. Classic novels weren't "intended" to be archived for free on the internet, but they are and I'm happy for it. Further, your dismissal of that extra optical step as "no real problem... a theoretical thing" is critical and IMHO, entirely incorrect. Well, anyway, I've said my piece. I scan negatives all the time, and find the process to be rather straightforward and rewarding. It was a bit trickier with the crappy film scanner that started with five years ago, but with each new scanner I've used it gets better and easier. To make an "interprint" for color negatives is IMHO to miss the point and most of the advantages of the digital darkroom. rafe b. http://www.terrapinphoto.com SNIP > Inversion isn't good enough; the (orange) mask layer has a varying > density too... The mask is designed to have a density+secondary absorptions that are a constant. Since secondary absorptions increase with the exposure time, the mask density reduces with exposure time. Subtract this constant and the mask and complementary secondary absorptions are gone. The best way of removing this constant mask color while scanning, is by increasing the green/blue exposure versus the red exposure. SNIP > Yes, but a color-negative is *designed* to be printed on color > (negative) paper, not to be scanned and simply inverted. That's usually true, but not very important after digitization. After mask subtraction (actually a multiplication or division in this linear gamma domain) from the raw scanner data, the highest relevant densities in the negative need alignment. After this, only small non-linearities in the film curves remain. > What you have then is simply not a good starting-point. Slides also have built in characteristics that are not helpful in scanning. Remember they were designed to be projected with a low color temperature lightsource in a slightly illuminated environment, thus the exaggerated film contrast. D-max has an aweful color cast because the D-max of the color layers differs a lot. Also the filmbase is not neutral, but because a mask can't be used in projection, the secondary absorptions are still there so the saturation must be artificially boosted. This can only be correct at one exposure level, so it's a compromise. > The optical extra generation should be no real problem, that's more a > theoretical thing in my opinion. (unless the print is made at home with > amateur equipment or so, or if the print is very small.) You have just witnessed a reduction of the dynamic range captured in the film, by several orders of magnitude. Not theory, but very hard to recover from. Also the surface structure of the paper has been introduced as detail, and glossy paper is far from smooth if you look at it from up close. Bart >SNIP >> Inversion isn't good enough; the (orange) mask layer has a varying [quoted text clipped - 6 lines] >are gone. The best way of removing this constant mask color while scanning, >is by increasing the green/blue exposure versus the red exposure. Bingo. A fellow named Dane Kosaka noted that NikonScan's built in negative-inversion software was somewhat less than optimal. He devised a nifty workaround. The simple variant that I use goes like this: 1. Scan negatives as positives. 2. In the levels/histogram tool, click the auto-levels button. 3. Now invert each color channel individually. In step 2, you'll see that the red channel always defines the high end of the tonal range, and has the widest histogram, while the green and blue are capturing a much narrower and generally lower range of input codes. Setting the green exposure to +.6 units and the blue exposure to +1.2 units is a good starting point for normalizing the green and blue histograms. In any case, following steps 2 and 3, one generally ends up with a nicely inverted image, with no clipping and the best possible distribution of input values. Dane's detailed notes on the treatment of color negatives in NikonScan can be viewed at <http://www.marginalsoftware.com/LS8000Notes/LS8000Notes.htm> and <http://www.marginalsoftware.com/LS8000Notes/three_easy_ways.htm> rafe b. http://www.terrapinphoto.com > SNIP > > Inversion isn't good enough; the (orange) mask layer has a varying [quoted text clipped - 6 lines] > are gone. The best way of removing this constant mask color while scanning, > is by increasing the green/blue exposure versus the red exposure. could very well be; i'm no scientist but I certainly know inverting doesn't work. Also, when I read the above part it doesn't seem very consistent. There's a "constant" that has 2 parts that vary with exposure time... that doesn't sound very constant to me. What I know of a mask is that it also contains the image, so that just changing the colour of the scan does NOT remove the mask. different parts of the image need to have more or less of that colour removed. > > Yes, but a color-negative is *designed* to be printed on color > > (negative) paper, not to be scanned and simply inverted. > > That's usually true, but not very important after digitization. Not if you want a digital negative. Most people like positive images a lot better though. > Slides also have built in characteristics that are not helpful in scanning. > Remember they were designed to be projected with a low color temperature > lightsource in a slightly illuminated environment, thus the exaggerated film > contrast. D-max has an aweful color cast because the D-max of the color > layers differs a lot. That would be the same with negative film I guess. Also, you probably want Dmax to be 0.0.0 (RGB) after scanning a slide, so a cast won't matter much. If it should be lighter, 20.20.20 or so, it wouldn't be a Dmax area in the slide. >Also the filmbase is not neutral, That would be even worse with negative film I guess... > but because a mask > can't be used in projection, the secondary absorptions are still there so > the saturation must be artificially boosted. This can only be correct at one > exposure level, so it's a compromise. I'm sure you must be right. Don't know what you mean though. secondary absorptions?? saturation that must be boosted artificially?? I'm clueless. I know how to make a perfect transparency though, with over 10 years of professional advertising-photography behind me. And a transparency that looks good, can produce a good scan. It's quite simple. > You have just witnessed a reduction of the dynamic range captured in the > film, by several orders of magnitude. Not theory, but very hard to recover > from. You would need a print that shows the detail you want in your scan, of course... (duh...) > Also the surface structure of the paper has been introduced as detail, > and glossy paper is far from smooth if you look at it from up close. What makes you think a negative is smooth, looking at it with 4000dpi? In some holders it's even difficult to get the negative/slide to stay flat... Don't get me wrong, I'm not saying everyone should scan prints instead of negatives; I was just saying it can make color correction a lot easier. In my experience it's very well possible to get a good scan of a negative, (with a lot of fuss and tweaking usually), but generally speaking a (good) slide will produce the best possible result. With difficult lighting conditions when you definitely want to shoot negatives, or with difficult (pastel for example) colors, scanning a decent print instead of the negative *can* make life a lot easier. Don't let me stop you if you want to scan a negative... ;-) Lourens. >could very well be; i'm no scientist but I certainly know inverting >doesn't work. Actually, the procedure detailed by Dane Kosaka in my recent post shows that it does -- if the mask itself (ie., an unexposed segment of the negative) is used as the black reference for the image. >Not if you want a digital negative. Most people like positive images a >lot better though. Depends on your target market and audience, I would think. As you said you worked in advertising, I can see where working with chromes would make sense. OTOH, nearly everything I shoot is intended ultimately to make prints. >What makes you think a negative is smooth, looking at it with 4000dpi? >In some holders it's even difficult to get the negative/slide to stay >flat... But the same applies to an optical enlarger as well, doesn't it -- ie., the need to keep the film absolutely flat. You'd still have to deal with that issue even while making your "interprint." >Don't get me wrong, I'm not saying everyone should scan prints instead >of negatives; I was just saying it can make color correction a lot >easier. In my experience it's very well possible to get a good scan of a >negative, (with a lot of fuss and tweaking usually), but generally >speaking a (good) slide will produce the best possible result. If the slide's Dmax is comfortably below that of the scanner, it should be easy to scan - that is true. IMO, scanning negatives isn't much more difficult. >With difficult lighting conditions when you definitely want to shoot >negatives, or with difficult (pastel for example) colors, scanning a >decent print instead of the negative *can* make life a lot easier. Don't >let me stop you if you want to scan a negative... I'm not sure how adding an extra step makes the process easier. rafe b. http://www.terrapinphoto.com > I'm not sure how adding an extra step makes the process easier. Well, you posted a "nifty workaround" in another message, for a problem that you wouldn't have. ;-) I actually tried this nifty workaround, and it is far from ideal. Basically you scan a lot of the wrong information, which is tossed away immediately after scanning...you then spread out the remaining bit of data over the desired wider range. You end up with a reasonably good-looking image, but with a gamut that is a lot smaller than desired. (the histogram also clearly shows this...) A scan made that way will not be suitable for very common post-processing tasks, with banding very likely to happen for example; a bit of extra color-correction (or cmyk-conversion...) for montage or layout purposes could also become ugly quickly. But for just a straight digital print the method would probably be acceptable, if the workflow is kept 16-bit/channel for as long as possible. But then, why not just print the negative? Lourens >> I'm not sure how adding an extra step makes the process easier. > [quoted text clipped - 15 lines] >acceptable, if the workflow is kept 16-bit/channel for as long as >possible. But then, why not just print the negative? Do what you've got to do, Lourens. I've explained what I know on this matter, and why I work the way I do. It doesn't work for you. Who knows why. You have a workaround that works for you, even if it seems a bit silly to me. It all works out anyway: I shoot negs and am happy scanning them. You don't, for the most part, so it's no great loss for you, either. rafe b. http://www.terrapinphoto.com > It all works out anyway: I shoot negs and am happy > scanning them. You have a nice site by the way! (sorry, mine is closed for renovation at the moment) > You don't, for the most part, so it's > no great loss for you, either. exactly. and maybe my view of negative scanning is a bit distorted because I only use negative film with very difficult lighting conditions... ;-) Lourens >The recent thread about transparencies vs negatives highlighted the >different perceptions that people have about this subject. [quoted text clipped - 10 lines] >probably easier to use and presents less restrictions when coupled with >a modern scanner having good Dmax and 16 bit processing. For scanning, there are (at least) two major considerations here. First is the issue of "reversing" a negative and doing it right. Negatives are inherently ambiguous as to color, so "right" is always subjective. IMHO, most scanners do a pretty good job at it nowadays, but not everyone agrees. Second is the issue of Dmax, and this is where a fully- saturated chrome can get dicey. The quoted 4.8 Dmax of most CCD scanners is rather a joke. From what I've seen, most of them can be seriously challenged by a really contrasty chrome. This then becomes an advantage for negatives, because of their inherently lower Dmax. Best results will come from a chrome that has enough contrast to snap, but not so much as to swamp the scanner's dynamic range. Negs invariably need and use less range than the scanner can provide. rafe b. http://www.terrapinphoto.com |
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