Scanning and Film Latitude + Dynamic Range

[edo_t]

<p>Yes this is a short question that will probably lead to more and more question:<br>

When scanning film (eg with a Epson V700) do files always end up as just JPEGs or TIFFs? and if so does it maintain the same degree of dynamic range as the film? I'm asking because I am trying to move from DSLRs to Medium Format film (6x7) for fashion photography so i want to know if there is as much freedom as with 32bit raw files. I know its a different medium, but i find film so much nicer to look at from the get-go.</p>

<p>I guess it is also because retouching is of such prominent importance in fashion~</p>

 

[doug grosjean]

<p>I can't answer your question. </p>

<p>But for very special photos, I'll scan film at a normal setting, then another scan underexposed, and another overexposed, and combine them on 3 different layers. It's not really HDR, but a step in that direction. Film has a bit more exposure lattitude than digital, so it makes sense to me to do that (sometimes), to exploit that wider range.</p>

<p>I'm attaching a photo where I used that technique. Scanning and merging the 3 images allowed me to dodge / burn the shadows in the foreground, and get great color on the blue sky in the background. Location: Cumberland Pass, Colorado. August 2005.</p><div></div>

[sfcole]

<p>Edo,<br>

The files from any scanner end up as whatever you specify. It's up to you. Also, you can usually scan at higher bit depths, although some argue it won't matter, especially if exposure and contrast are good to begin with.<br>

My question is why dynamic range is so important, especially in what would probably be a highly-controlled lighting situation. Presumably you wouldn't be worried about digging the maximum detail out of shadow areas unless you made some serious lighting errors. I doubt HDR would be an issue for fashion photography.<br>

By retouching, do you mean portrait-retouching software like Portrait Professional?</p>

[Ed_Ingold]

<p>The dynamic range of Epson scanners exceeds that of the film. That's because the dynamic range of the subject is compressed in the process of capture. The range of density on color negative film is approximately 5 stops. That of reversal film and B&W film is approximately 7 stops. The scanner has a range of approximately 9 stops, comparable to a digital camera.</p>

<p>The big problem with flatbed scanners is practical resolution, which is only about 2000 lp/mm. This is much less than film, and only half that of a Nikon LS-8000 scanner. In lieu of a dedicated film scanner, you can use a flatbed for small enlargements or web use, or for proofing film to be sent out for drum scans.</p>

[edo_t]

<p>I don't use any retouch software, I do everything using photoshops native tools as i find them more intuitive and yielding of better results. The reason I am inquiring is because i am new to lighting and very new to film so i want to know if i can save myself if i do screw up. Plus on location shoots may benefit from having more dynamic range in high contrast daylight. Are any of you scanning with a v700? i have no scanner yet, and dont have a highbudget mind you.</p>

[sfcole]

<p>Edo, I don't mean to dissuade you, but if you intend to charge for your services, you may be asking the wrong question. What I'm hearing is that due to lack of lighting and film experience, can you rely on the scanner to save your butt if a client is on the line? I wouldn't count on it. It's tempting to see film use as a schtick to set yourself apart, but that doesn't mean it's the best medium....</p>

[Dave Luttmann]

<p>Edward, can you explain this a bit more. I've never heard anyone state that color neg materials have a lower DR than positives. As I routinely get over 10 stops with color neg film (Fuji Pro 400H), I'm not certain I'm understanding what you mean by having only 5 stops. </p>

<p>Case in point, according to you, color neg has less DR than Velvia. Or are you not accounting for latitude within this range?</p>

[steve m smith]

<blockquote>

<p>The range of density on color negative film is approximately 5 stops. That of reversal film and B&W film is approximately 7 stops. The scanner has a range of approximately 9 stops, comparable to a digital camera.</p>

</blockquote>

<p>I think you have the order reversed!</p>

[edo_t]

<p>All very interesting to hear. Right now I am not actually a full-time working photographer, though I intend to be. Anyway, for client work I will shoot all digital. My lighting isn't necessarily bad but there is much more for me to learn. The film work will be entirely personal for the time being (landscape, achitecture etc.). I shoot 35mm right now but I am ditching it for a Mamiya 6x7 system.</p>

<p>I wanted to shoot digital for client shoots and also shoot a roll of film or two throughout the shoot as I transition in that direction. Also, for drum scanning where would I send it off too that has a reasonable price? Everything I see is something like $40 a scan~</p>

<p>anyway, yes don't negatives always have more dynamic range? and so there is a scanning "raw" file that is similar to the one we get out of digital?</p>

[francisco_disilvestro]

<p>I think Edward is right. Don't confuse scene dynamic range with the dynamic range (or range of density) of the film.</p>

<p>Negative film can record a higher scene DR compared to reversal film, but it is compressed to about 5 stops in the film or lower than the resulting reversal film.</p>

<p>The DR of the scanner has to deal with the film dynamic range, not the original scene</p>

[AlanKlein]

<p>If the scanner DR is larger than the film DR, why are people obssessed with changing the black points, the white points, shofting hoistograms etc during the scan? It seems the scanner wouold pick up the full DR of the film with a staringht unadjusted scan.</p>

[john_a5]

<p>The best scanners--and there may be software available for the one you are mentioning--can scan what is essentially a raw scan--very high bit depth/dynamic range--which can be output at various densities to capture the full range of what is on the film. Otherwise, rescanning to a Tiff at 16 bit at different densities might be required, but any scan has a bit more available than what you initially see and can be compressed in PS--it just may not be enough at both ends. Rescanning can introduce geometry errors where images wont fit together perfectly and that is why the "raw" scan is very desirable.</p>

<p>This isn't a matter of saving anyone's butt, it is a matter of knowing your materials and taking advantage of the equipment you have at your disposal. When the light is controllable, the full dynamic range of any film might not be used, but when you leave the studio, you have to know your tools to tame the light and choice of film development and the ability of your scanner are all legitimate tools at your disposal.</p>

[randall_pukalo]

<p>Edward has it right, but here is what is confusing people. He refers to the dynamic range of the resultant image formed on the film, not the dynamic range of the scene at time of capture. For example, although negative film can handle a scene brightness range of say 9 stops, it captures and records this onto the film, compressing it in the process. The 9 stops in the scene are mapped onto the negative film. If one then takes a densitometer, or scanner, and measures the brightness range formed on the film, from the lightest to most dense parts of the negative, it is only say 5 stops. The dynamic range has been compressed.<br>

Negative film has greater scene capture dynamic range but it compresses it on the film, whereas slide film has a narrower capture range, but the resultant range on the film is expanded. That is why slides are both much more brilliant than negatives, but also more difficult to scan (higher dynamic range of the film image itself), and easier to blow out the highlights.<br>

Confusing, I know.</p>

[john_a5]

<p>I understand Randall's point here, but I don't agree with the conclusion. At least in my experience, transparencies scanning is pretty automatic, unless your scanner does not have a good profile for what you are scanning. The reasons are just the same as he mentions as creating the difficulty, blown highlights or plugged shadows can't be brought back. If it isn't properly exposed, then there really isn't much you can do about it.</p>

<p>Negatives compress the scale, as it were, but no one scan, except if your scanner does a raw scan, can capture the full range of the negative in a useful way--if its full usable range has been used. Negatives, in my experience, can range into 12 usable stops* and that can't print directly. You have to either compress the scan or make separate outputs. If you actually have all those stops/dynamic range, separate outputs will probably be required for different areas as adjustments to tame all of them will be too soft in most areas to ever produce a serviceable image--even with the power of Photoshop. You will just lose too much of the local contrast within the image to create an effective output in one scan.</p>

<p>Anyway, my experience (Imacon/Hasselblad Scanner) is that transparencies, because they already closely approximate a prints capabilities, are easily scanned. Negative require a much different set of skills because you do have to manage many more usable stops into usable output.</p>

<p>*the number of stops or the dynamic range is dependent on the film characteristics (toe and shoulder) and the developer used. The film can only record clear to its highest density, but the highest densities may happen (block up) quickly with some film/developer combinations and yet run smoothly with others for a longer period of time.</p>

[AlanKlein]

<p>If transparencies are easier to scan, why are the Kodak Portra negative films being pushed as the product for scanners which most film users who aren't printing chemically are going too? My experience with flat bed scanning with non-Portra negative and trasnparencies is not much difference in the final result.</p>

<p>John A: What is a raw scan?</p>

[robert lee]

<blockquote>

<p>Negatives compress the scale ... but no one scan ... can capture the full range of the negative in a useful way ...</p>

</blockquote>

<p>The maximum density of negative film, especially color material, just isn't all that wide. No reasonable scanner will have trouble punching through it. So by definition, the full range of the negative can be digitized. The less than ideal comes about if the scene is excessively flat. This is where more precision (more real bits per channel) from the better scanners is beneficial.</p>

<blockquote>

<p>If you actually have all those stops/dynamic range, separate outputs will probably be required for different areas as adjustments to tame all of them will be too soft in most areas to ever produce a serviceable image--even with the power of Photoshop.</p>

</blockquote>

<p>That's not the case. Even in the old days, local contrast manipulations were routine in the wet darkroom via selective dodging and burning. The same techniques work in digital post, and is in fact easier and far more precise. Creating contrast masks, for example, is but a couple minutes of work.</p>

<p>Color negatives provide even bigger envelope of opportunity. Each channel can be masked individually,and the print resulting from the ensemble.</p>

[paul_goutiere]

<p>I purchased a scanner to relieve myself of the burden and expense of building a full sized darkroom. I did not realize at the time I bought the scanner what a fantastic tool it can be.<br>

It seems that if the information is on the film, I can retrieve it. I have scanned some really bad negatives who's range exceed my abilities in the darkroom and created usable prints.<br>

For me, the scanner gives me more range than I had with what I had with the darkroom plus the added advantage of using film rather than switching to digital capture.</p>

<p> </p>

[Craig_Cooper11664875449]

<ol>

<li>Scanners don't produce RAW scans; at best some (ie Nikons) can produce a non inverted tiff of gamma equal to 1 - this is not RAW.</li>

<li>Reversal film has a higher <em>density</em> range than negative film</li>

<li>Negative film can capture a larger <em>brightness</em> range than reversal film</li>

<li>Negative films (B&W and colour) only deliver a dynamic range of around 2.0 so most scanners have no problem fully capturing the <em>entire</em> dynamic range (in a single pass)</li>

<li>Reversal film delivers densities between about 4.0 and 5.5, which really tests the limits of many scanners</li>

</ol>

[paul_goutiere]

<p>The Nikon CS9000 scanner creates a NEF file. Is this not a RAW file?</p>

[john_a5]

<p>Yes, scanners do output raw scans which to the negative are equivalent to a raw file from a scene before your digital camera. I don't know about others, but an Imacon/Hasselblad scanner will output a scan that contains everything that the scanner can see--you do not set anything (it is the 3f scan-which was also their raw capture format for awhile). Then, you set the controls to adjust the contrast and densities for the output you desire. You never need to scan the neg or transparency again to get the various output desired. (it does allow separate scans, but there is no point since the "raw" scan contains everything that can possibly be gotten out of the film)</p>

<p>First, I shoot all Portra films these days--and have for about 7-8 years now, but scanned many transparencies and cross processed films (both ways) since '96. Most negatives do scan pretty straight forward--especially when there was no sky, but there are times--shade or backlit in foreground and sky in back where you need to do separate output to get all of the information in the best form. Yes, the scanner output can compress all of this information into one output, but it will not be pretty. If you have a 9 or 10 stop range, with 5 in the sky and 5 in the foreground, the compression to get it all will make both areas look awful and efforts to resurrect those areas will not always go well--and at the least stress the file tremendously--major histogram gaps. You can't mask, burn and dodge in a scan, so putting out reasonable output for both areas is a much better solution to the problem. It might be like printing a b/w image with a grade 4 filter and then burning in the sky with a number 1--this yields a much better result than printing the whole thing with a number 1 filter and then using bleach to put contrast back into area that should have been printed with the #4 filter.</p>

<p>The background image on this page is probably a good example--backlit and shade in foreground and backlit clouds, blue sky and wisps in the upper portion--two scans were required to get the dynamic range in the film and maintain micro and local contrast. http://www.youtube.com/Amtrak</p>

<p>edit: Yes, I hear that Nikon's also put out the same sort of RAW scan I describe for the Imacon/Hasselblad.</p>

[john_a5]

<p>To Allen: The reason that photographers are using negative films is just because they do have a much wider dynamic range than transparency films. I think it is actually much wider than most realize in fact. The scanner can also dig out some pretty incredible results. I have a piece of film that look clear and yet the image I got off it has been sold as stock and in my portfolio for years. In the studio, you control the light and transparency film is a thing of beauty, but even there, negative film has its advantages because you don't really need to bracket it like you do TP film, a third of a stop on TP film can make a big difference but with neg film, not going to be seen.</p>

<p>The scanners also seem to like a bit thinner negative than what is optimal in the darkroom, this also gives you a little more headroom. I can shoot my film, for scanning, at the rated iso or even a bit faster, and know that I will get a good solid scan from it. Transparencies, scanned or not, have a limited dynamic range and the best results are when it is exposed properly--looks great on the light table.</p>

[Ed_Ingold]

<p><em>Edward, can you explain this a bit more. I've never heard anyone state that color neg materials have a lower DR than positives. As I routinely get over 10 stops with color neg film (Fuji Pro 400H), I'm not certain I'm understanding what you mean by having only 5 stops.</em></p>

<p>The answer is simple, Dave. You refer to the dynamic range of a subject which can be captured on film. I'm speaking of the image itself, as it exists on film. We are both correct once we read from the same page.</p>

<p>Film capture incurs a compression of results. With negative film, this compression is nearly 2:1, including portions of the rather long toe and shoulder regions. With color negative film, the density range is about 5 stops. The numbers come from characteristic curves published by Fuji, Kodak and others in their technical data sheets. The only thing of interest in scanning is the range of densities <strong>on film </strong>which represent useful image data.</p>

<p>Color reversal fim actually magnifies the contrast of a limited range of subject "data", by a factor of 1:2. An especially contrasty film like Velvia has a density range on film of nearly 10 stops, but uses this range to cover only about 5 stops of subject luminance.</p>

<p>A B&W negative can get even denser than Velvia, owing to the opacity of metallic silver in the emulsion. However, the practical density range is much smaller, as witnessed by the characteristic curves, keeping it in the range of modern scanners.</p>

[john_a5]

<p>Edward, I think the confusion as to what you are saying is that you are speaking in terms of equating the densities of neg film to the densities of Transparency film. I don't think that is a fair comparison although, using the same measure, accurate. Negative films, to get the increased dynamic range must compress the scene as the medium itself can only record black to clear, as is the case for a TP. The rub in your presentation is that it ignores that output modes for neg film are not using the same scale you are suggesting here, so they re-expand the compressed data back to the original contrast--or some facsimile based on the operators decisions.</p>

<p>Anyway, if one were to measure a negatives way of recording each full stop and apply it to a TP, we would all be confused because we know that a TP does not capture 10 stops of information. It is just a bit misleading to not apply proper measurements to the medium based on the medium's characteristics (how zones/stops are recorded on a given media)--not necessarily wrong information, just a bit misleading and confusing--and maybe somewhat irrelevant.</p>

[Ed_Ingold]

<p>For anyone interested in the techy parts, characteristic curves are presented in terms of logarithmic values. Optical density is log(A'/A), where A = the instrument reference point. In order to convert log differences to the f/stop equivalence, divide the numerical difference by log2 = 0.301.</p>

<p>DMax is the maximum density which can be measured by a scanner. This value is in the range of 3.8 to 4.8, depending on the make and model of the scanner. The Epson is said to have a DMax of 4.2. DMax is only indirectly related to the dynamic range of the scanner, since it represents only one end of that scale. B&W film can have a DMax in excess of 5. However, completely fogged film is better used to view solar eclipses* than for printing ;-)</p>

<p>* Velvia can't be used to view eclipses. It looks black but passes infrared freely, which can fry your retina. Silver blocks all wavelengths relatively well. Rather than risk my eyes, I would use a welder's mask.</p>

[Dave Luttmann]

<p>Thanks Edward, I understand where you're coming from now. I had scene and film range confused from your post.</p>

<p>Craig, scanners can indeed output to raw. I use viewscan and can save in Raw and DNG.</p>