Optimal resolution for digitizing slides

[r_david]

<blockquote>

<p>is this statement just based on a casual observation from your own personal results</p>

</blockquote>

<p>Yep. And I'm not ashamed of it either.<br /> At - it looks like - 3,200dpi you're just scanning irrelevant information - unless you want to know the silver grain structure of the negative. But for better resolution, I suggest a scanner that can scan the molecular state of the emulsion - what? 1,000,000,000 dpi? Or better yet, the quantum state of the silver in the emulsion. But then, Schrödinger's cat may die and I don't want that.</p>

<p> </p>

[kivivuori]

<p>I think it depends what you`re trying get out from your negatives or slides. If you want to have an excellent scan from carefully exposed and developed TMAX 100 negative and really want to get out everything there might be, you`ll need a 8000 ppi drum scan.<br /><br />Having said that...<br /><br /> I also believe that in 99% of cases 4000 ppi is definitely high enough. But much more important than extra high dpi is the dynamics of the scanner - especially when you`re scanning Kodachromes.<br /><br />Nowadays I like Nikon D5200 body, reversed EL-Nikkor 50 mm f/2.8 N + Heliopan 216 set-up ring (52/40,5mm) with Nikon BR-2A Lens Reversing Ring. Small, sturdy & fast combo with > 4000 ppi resolution. No moving parts like bellows between the body and the lens.<br /><br />Esa Kivivuori<br />Finland<br /><br />https://www.flickr.com/photos/esakivivuori/<br /><br /></p>

[Ed_Ingold]

<p>The attached photos were taken using a Leica M3 and Ektar 100 film with a Summicron 50/2 lens, and a Leica M9-P, using a Zeiss Biogon 35/2.8 lens. The purpose was to compare the relative quality of the image using the same camera and same subject, within seconds of each other. The film was scanned on a Nikon LS-4000 at 4000 ppi. The camera has an 18 MP CCD, without an anti-aliasing filter.</p>

<p>The film scan clearly resolves the dye clouds. As you can also see, the digital image has more resolution, less noise, and a better depiction of the textures in the subject. Scanning at an higher resolution would serve no useful purpose. I was not diligent about using the same lens, but if anything, the 50 mm (film) lens has greater magnification and should show more detail. The lens is not the limiting factor in either image.</p>

<p>The first two are film and 1:1 detail. The second two are digital and 1:1 detail.</p>

<p><img src="http://d6d2h4gfvy8t8.cloudfront.net/18058060-lg.jpg" alt="" width="407" height="600" /></p>

<p><img src="http://d6d2h4gfvy8t8.cloudfront.net/18058059-lg.jpg" alt="" width="600" height="400" /></p>

<p><img src="http://d6d2h4gfvy8t8.cloudfront.net/18058058-lg.jpg" alt="" width="399" height="600" /></p>

<p><img src="http://d6d2h4gfvy8t8.cloudfront.net/18058057-lg.jpg" alt="" width="600" height="400" /></p>

[Ed_Ingold]

<p>Kodachrome is a relatively contrasty film with very dense blacks. Don't confuse the dynamic range of the slide with it's ability to capture the dynamic range of the subject. There is almost no detail in the dense areas of Kodachrome, and none at all at the other extreme (white or clear). It is the intermediate areas that count, consequently most scanners are more than capable of dealing with Kodachrome. Furthermore, Kodachrome is treated with an UV/IR absorbing lacquer on the emulsion side to better preserve the image against abrasion and time. It is this lacquer which renders ICE ineffective.</p>

[AlanKlein]

<p>Ed: What sharpening did you apply to the film scans? Why are the film pictures so green? (foam is green)</p>

[Ed_Ingold]

<p>No sharpening was applied to any of these images. The color balance is pretty much as it came from the scanner. It can be adjusted, the need for which is par for the course with negative film. If I adjust the foam to a more neutral hue, the water takes on a magenta hue. Pick your poison.</p>

<p>In any case, color balance was not my primary reason for this comparison. Any attempt to make the film scan match the digital image is probably beyond hope. In general, I find I can match one primary color fairly well, and sometimes two, but something always falls out of bounds. Every process distorts something. You have to pick something that distorts in a pleasing way and move on.</p>

<p>In terms of sharpness and contrast, using a rangefinder (or mirrorless) camera is about as good as it gets. No DSLR lens comes close to the performance of a Leica, Zeiss, or even Fuji lens. This serves to highlight differences in the medium and process of producing an image rather than the optics.</p>

[jamie_robertson2]

<blockquote>

<p>No DSLR lens comes close to the performance of a Leica, Zeiss, or even Fuji lens.</p>

 

</blockquote>

<p>As Les would say... "Do you have supporting data for this or is this statement just based on a casual observation from your own personal results or third party reference?"<br>

<br>

:-)</p>

[Ed_Ingold]

<p>Crayon pictures aren't casual? MTF data would show something, but there is no standardization for MTF data either. Nikon, Leica and Zeiss publish curves based on measurement taken from production lenses, whereas Canon (admittedly) generates it's curves using ray-tracing software form the theoretical design. One method includes manufacturing tolerances, the other doesn't. DXO data is derived from the sensor with which the lens is used, and not all sensors are the same either.</p>

<p>To make a long story short, I most definitely use my personal experience to reach the conclusion that lenses designed without the need to clear a swinging mirror are, in general, superior to SLR lenses. The differences narrow in the center of the field, as the lenses are stopped down (e.g., f5.6), and for focal lengths beyond 135 mm (there's nothing to compare). However I can use practically any lens on a Sony A7 with the right mount. I don't have "all" lenses at my disposal, but I can compare the ones I do have, namely Leica, Zeiss and Nikon, on a common platform.</p>

<p>Here I compare a Nikon 50/1.4 at f/1.4 and f/2.0 with a Zeiss Loxia 50/2 at f/2.0 at the right edge of the field, starting with an overview of the source. It was a flat day, so there's no "pop" to compare, which is perhaps the strongest hand of Zeiss. The overview is using the Loxia, showing a hint of Zeiss "pop". There is no sharpening or other adjustments beyond Lightroom defaults.</p>

<p><img src="http://d6d2h4gfvy8t8.cloudfront.net/18058266-lg.jpg" alt="" width="600" height="400" /></p>

<p>Nikon 50/1.4 @ f/1.4<br>

<img src="http://d6d2h4gfvy8t8.cloudfront.net/18058267-lg.jpg" alt="" /></p>

<p>Nikon 50/1.4 @ f/2.0<br>

<img src="http://d6d2h4gfvy8t8.cloudfront.net/18058264-lg.jpg" alt="" width="600" height="400" /></p>

<p>Zeiss Loxia 50/2 @ f/2<br>

<img src="http://d6d2h4gfvy8t8.cloudfront.net/18058268-lg.jpg" alt="" width="600" height="400" /></p>

<p> </p>

[glen_h]

<p>For Ektachrome 100:</p>

<p>http://www.kodak.com/global/en/professional/support/techPubs/e27/e27.pdf</p>

<p>Kodak claims 50 cycle/mm, or about 2500dpi at 30% response. <br>

That should be most of the size of the dye clouds.</p>

[rory_clague]

<p>If you can scan at 4000 ppi or higher, that is preferable in my experience. Scanning at lower frequencies may capture all of the image details, but there is more to a film image than simply the image details. The texture and granularity of film looks more pleasing when scanned at higher resolutions. A lot of what people have come to expect from film over the last 15 years, in my opinion, is due to nothing more than grain aliasing artifacts aggressively sharpened in post-processing. At lower frequencies, grain aliasing becomes harsher. If you scan at high resolutions, it becomes less visible. The result is that you end up scanning at a resolution that is higher than the spatial resolution of the film, but the grain becomes more pleasing - even finer, in my experience. Tri-X is rated to 50-100 lp/mm. I scan routinely at 116 lp/mm (about 5900 ppi), and find the grain looks better and the fine details look *fine* as they should, compared to when I scan at 80 lp/mm (4000 ppi). At 4000 ppi, the finest details are visible, but they look thicker and blockier than they do when scanned at higher resolutions. I imagine 8000 ppi scans are even better in these regards, but I don't have the means yet to sample at those frequencies.</p>

<p>So, the bottom line is, oversampling a negative produces better results, even if you aren't necessarily getting more information about the scene. You *are* getting more information about the medium, and this seems to reduce artifacts.<br>

<img src="https://farm1.staticflickr.com/528/20337538611_abc8cb0e6f_k_d.jpg" alt="" /></p>

[rory_clague]

<p>Here is a crop of the above image:<br>

<img src="https://farm1.staticflickr.com/279/19762456094_1ecd69805e_o_d.jpg" alt="" /></p>

[Ed_Ingold]

<p>Rory,<br>

How was this scanned?</p>