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How many ppi is enough for scanning 35mm?


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<p>I have often read comments in forums such as photo.net to the effect that scanning at numbers close 4000 ppi extracts all the image detail available in a 35mm image. I have long been skeptical of such comments. Here is a link to a scanner test that shows that scanning at higher numbers actually does extract more image detail.</p>

<p>http://www.filmscanner.info/en/HasselbladFlextightX5.html</p>

<p>The authors of the test compared results from a high end Nikon Super Coolscan 9000 ED scanner with an even higher end Hasselblad Flextight X5 scanner. The Nikon has a nominal resolution of 4000 ppi with an actual resolution of 3900 ppi, and the Hasselblad had a nominal resolution of 8000 ppi with an actual resolution of between 6150 and 6900 ppi, depending on the film orientation. The test scans showed that the 6000+ bit scanner clearly provided more image detail than the 3900 bit scanner, and it wasn't just the ability to resolve grain, but actual image detail. It was not even a case of the two being so closely matched as to require careful comparison. The difference was clearly seen by casual observation of blowups of a small part of an architectural image.</p>

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<p>What are your requirements? For the absolute best results, you need to have your images scanned with a drum scanner. That's not an inexpensive proposition, but the results are second to none. Of course moving up to a larger film format also provides better detail, and scanning it with a drum scanner is better yet! How good do you need it to be? </p>
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<p>This has nothing to do with spi. The Hasselblad is better because it has better lenses, film carriers, etc. The question you ask would be answered by comparing scans made at (say) 3000, 4000, and 6000 spi by the SAME scanner.</p>

<p>Edit: From the site you linked:<br>

The respective maximum resolution of both scanners is only available in the 35-mm image format, and the Flextight X5 "only" achieves an effective value of about 6900 ppi in a scan resolution of 8000ppi. Thus, the difference in the effective resolution that is possible to achieve between the X5 and the X1 is of 6900ppi against 6150ppi.<em> Both of these values are so extremely high that they exceed the resolution limit (grain boundary) of a 35-mm film.</em><br>

Thus, the difference in the resolution is rather nominal, as in case of the medium and the large formats, there is no difference in the resolution of both devices. <em>Therewith, the resolution criteria can be omitted as a real differential factor and should not have any influence in the purchase decision. </em>[emphasis mine]</p>

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<p>I've scanned 35mm at 4000 PPI (Nikon Coolscan V) and 5400 PPI (Minolta Scan Elite 5400). 4000 PPI will get most everything, in<em> most</em> cases. But occasionally, fine detail will become indistinct at 4000. One instance I noticed was vent holes on my wife's shoes, when she is about 10' distant, shot with a 50mm lens. The 5400 DPI picks up the vent hole detail clearly. At 4000 DPI it's indistinct.</p>
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<p>Les,</p>

<p>The comparison of interest to me was between 3900 ppi and 6000+ ppi, not between 6150 and 6900. Those numbers (3900 vs. 6000+) were based on shots of test targets, which means that any effects of lenses, carriers, etc. are already folded into the result. (By the way, the Nikon scanner reaches 97.5% of its theoretical maximum resolution, which shows that lenses, carriers, etc. are not significantly limiting on that instrument.)</p>

<p>You are right that maximum resolution on the Hasselblad scanner is available only for 35mm. I didn't bring up tests on the other formats in order to avoid complicating the discussion. However, the results on medium format do not contradict the fact that scanning in the range close to 4000ppi is not quite enough to pull out the full resolution possible from film. In that case it was the Nikon that resolves slightly more than the Hasselblad, in accord with the difference in rating (3900 vs. 3200).</p>

<p>Note added in editing. Mendel's results is consistent with the point that there is, at least in some cases, more resolution to be had from some film shots than can be captured using 4000ppi.</p>

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<p>I would like to be able scan without leaving any image quality on the table. If one can achieve that then the question of "what are you going to do with the image" is moot because if you have all the image quality in your scanned file you can always back off for a specific application (posting web images for example), or use all the quality if you want to make very large enlargements, but if you haven't scanned to achieve all the image quality available then you can never get it back without starting over and making a better scan, something which may not actually be possible if the available hardware doesn't support it.</p>

<p>The next best thing would of course be to scan without leaving much image quality on the table. It seems that this is where we are with currently available somewhat affordable 4000ppi scanners, and given the current market conditions in photography it seems unlikely to ever get any better. In that case we must be satisfied with "very good" rather than "best" results.</p>

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<p><em>I would like to be able scan without leaving any image quality on the table.</em></p>

<p>Then you have to scan with a drum scanner. An Imacon won't cut it, neither will the Nikon. The best of the drum scanners is the Aztek Premier. Find a shop with a Premier and a good experienced operator who makes an effort, and you'll pull all the image information it's possible to get from the film, short of a contact print.</p>

<p>That said, just about any drum scanner with a decent operator will do noticeably better then either the Nikon or the Imacon/Hasselblad with an equally qualified operator.</p>

<p>Finally, there's a lot (a huge amount) more to a scan than simple resolution.<br>

<em><br /></em></p>

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<p>Beware of simplistic values like “4000ppi is enough for this or that”. I can assure you a 2000ppi scan off a good PMT drum scanner from a gel mounted original will prove a vastly superior scan to a 4000ppi off a CCD Nikon or similar scanner. Put a crap lens on a 4x5 camera, its not going to provide the same level of quality as a superb lens on a medium format system. There is far more to all this than size (or max number of scanned pixels)!</p>

Author “Color Management for Photographers" & "Photoshop CC Color Management" (pluralsight.com)

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Of course you can get it back. A negative doesn't self destruct on scan. Scan it again with a drum scanner if you like it

enough to print large. Simple. There's no table.

 

Simple experiment: Go through the archives of images here and pick out a scan from a $200 flatbed then pick one

from a $10,000 Hasselblad or $4,000 Nikon scanner. If you can do that, only then is my question moot.

 

Do what you like, it's your time and money.

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<blockquote>

<p>Simple experiment: Go through the archives of images here and pick out a scan from a $200 flatbed then pick one from a $10,000 Hasselblad or $4,000 Nikon scanner. If you can do that, only then is my question moot.</p>

</blockquote>

<p>Why would I look at 60kb thumbnails to judge quality I want on print. Look at a 16x20 from a PMT and a cheap flatbed and tell me if the difference doesn't matter. Looking on screen here has nothing to do with anything.</p>

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I agree with just about eveyones comments so far. Yes, you can get more detail than 4000 ppi. But, your original

photo technique needs to have been very good to get that kind of detail. I found that a very high percentage of my

photos were covered by 4000. And, that the quality of the Nikon 9000's lens, light source and film holders was

sufficient. More routine photos could go to print with almost no post processing. Of course I have no illusion that the

higher dollar systems could get more detail, more ppi, more local contrast, have better lenses and so on. But,

unfortunately my technique, film choice, and cameras of the film era were not up to the task most of the time to

require much more than 4000ppi. I used a minolta 5400 II and it did get more detail, but the files needed more work

than the ones from the Nikon and the difference was kind of small in the final print.

 

It is a compromise. Some are ok with Epson flat beds, some are good with the Nikons, and some can't do less than

drum scans. It is up to your personal standards and budget.

 

Me, I'm really looking at MF digital in the hopefully not too distance future. I'm personally over trying to use film, I may even send out what is left of my film library to a lo cost scan service.

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<p>I do exactly the opposite of what you intend. Unless I know that I'm going to print a particular image, or have it accepted by a stock agency, I'll scan it quickly and cheaply on a flatbed. That equips me to handle my requirements from at least 90% of my legacy film images. If I need to get a larger better quality scan then I'll get an Imacon scan made which costs me maybe $11 a time. So I don't need to own an expensive scanner that is going to consume a heap of time. It slows me down by about 2 weeks when the need to use or print becomes apparent, is all- and in return for that I save a heap of time behind a scanner , a lot of time on a computer since my Imacon scans come to me hand cleaned in Photoshop, and I don't need money tied up in expensive scanners.</p>

<p>And indeed I'm with those who prefer scans from scanners I could never justify. My Imacon scans are 3200ppi from medium format against 4000ppi from a Nikon Coolscan but I still tend to prefer them for larger prints. As a 35mm user that compromise doesn't apply.</p>

<p>Also of course we can't realistically talk about how much detail there is in a 35mm photograph in generic terms. To make it worth scanning at more than 4000 ppi has a subject variable and a photographer variable. You need the quality in the photograph and the detail in the subject to make it worthwhile. </p>

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<blockquote>

<p>Why would I look at 60kb thumbnails to judge quality I want on print.</p>

</blockquote>

<p>I dunno. Why would you? I wouldn't.</p>

<blockquote>

<p>Looking on screen here has nothing to do with anything.</p>

</blockquote>

<p><br />For you perhaps. I would take a reasonable guess that the vast majority of scanned negatives never get printed at any size at all let alone 16x20, and at best are destined for web use. Just because you print every negative you scan at 16x20 has nothing to do with anything, when everyone else is just posting them on the web.</p>

<p> </p>

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<p>"The difference was clearly seen by casual observation of blowups of a small part of an architectural image."</p>

<p>Sounds to me like the printed equivalent of pixel peeping on-screen images at 100%. How large would the entire image be if blown up to the same level as these "small parts" of the image? And how closely would you actually view that image.</p>

<p>No one I know views 40x60 prints (as an example) at arm's length. Would the difference in detail really be visible at normal viewing distances?</p>

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<p>Pixel peeping? I assume you are using that in a good way and not as an insult.</p>

<p>By the way, I am a scientist by profession, and one of the things I seek in life is truth. That is a second reason why I am addressing this topic, to reverse some of the incorrect technical information that is circulating about how much scanner resolution is sufficient to capture all the detail in the best 35mm film shots, best in a technical sense, not necessarily in an aesthetic sense.</p>

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<p>Trouble is where do you draw the Alan and move up to a larger format. If 8000ppi is better than 4000ppi then 16000ppi could well have even more detail than 8000ppi. In the end though 35mm does not look that great compared to 6x7 even at an 11x14 inch print size assuming we are using similar film and decent lenses. I think I would move up to a larger film format than try to extract every last detail out of 35mm.</p>
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<p>For those like Alan who are interested in the scientific aspects of photography, here is a more technical explanation of why "it never ends". <br>

The underlying assumption in many of these discussions is that the film image has some fixed resolution and if it is scanned with that much resolution all of the information will be captured. In fact, when multiple processes, each with limited resolution, are applied to an image (or other signal), the "blurriness" of the individual processes are added together. The fancy term is convolution. The mathematics of the convolution is not always easy to define for real situations, but a commonly used approximation is:<br>

b_total = b1^2 + b2^2<br>

where b1 and b2 are the blurriness of the individual steps, and b_total is the total effective blurriness. We can think of blurriness as the reciprocal of the resolution.<br>

The significance of this relationship is shown in the graph below. The three curves are drawn assuming that the effective resolution of the camera and film are 2000, 4000 and 8000 dpi. In the units that are more often used for optical resolution these correspond to 40, 80 and 160 line-pairs per mm (lppm). The horizontal axis represents the scanner resolution and the vertical axis the resolution of the final scanned image. Notice that a scan resolution of about 6000 dpi is required before the 2,000 dpi image is recorded with nearly all of its resolution, but 4000 dpi comes pretty close. For more resolution in the film image, correspondingly higher scan resolution is required. <br>

What is the resolution of a typical 35mm film image? This can vary greatly, of course. With a very good lens and fine-grained film, 125 lppm (6000 dpi) might be possible, but it probably doesn't happen very often. The same convolution effect applies to the lens and film resolutions, and resolution will also be reduced by focusing errors, camera shake and other factors.<br>

It's worth mentioning that the same thing happens when a negative is printed optically or a slide is projected. Some enlarging lenses have very high resolution, but there are plenty of other degradations to the image. I think that the common experience is that a 4000 dpi scan and inkjet printing can be just about as good as the best optical prints.<br>

I hope this helps,<br>

David</p><div>00ZNmi-401405584.jpg.30e7225d2f16cbf4aa43f432998b3caf.jpg</div>

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