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Ektar 100 versus Alpha 900, Velvia 100, Portra 160VC and TMax 100


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<p>Richard, thanks. Yeah I think I pretty much answered my own questions.</p>

<p>So, basically, a 'true' 8000ppi scanner would have resolved 6.2 & 6.3 as black & white lines (higher contrast) than the darker gray and lighter gray lines that the Nikon LS-5000/LS-9000 resolved them as.</p>

<p>Yes?</p>

<p>Not that this same effect couldn't be simulated by adding significant sharpening to the Nikon scans...</p>

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<p>At least 2x dpi are needed to resolve the same dpi (line pairs) because the lines (black) are getting close to each other at the utimate film resolving power. The space between 2 black lines must be resolved by 2 pixels. Otherwise, fuzzy scanning results will be obtained that do not reflect the true film resolving power. Too bad, the bottleneck is the resolving power of scanners (from film to digitalization).</p>

<p>Richard</p>

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<p>I guess I see this as an alignment problem (which Scott Turner has confirmed in personal communication)... basically if the pixels on a 4000ppi scanner were perfectly aligned with the line pairs of a resolution test chart, such that the black line fell perfectly on one pixel width, and the white space next to the black line perfectly projected into the immediately nearby pixel, then one could get, theoretically, nearly 100% response instead of darker gray/lighter gray lines (lowered contrast) for the lines on a chart corresponding to 4000ppi resolution.</p>

<p>But what are the chances of that always happening? Slim. Half the black line may fall on one pixel, while half the black line falls on the next pixel, creating 50% | 50% for two pixels that should've been 100% | 0%. Hence the drop in contrast for details on par with the resolution of the scanner.</p>

<p>But for 'real world' detail, which Fuji Velvia data sheets itself claims the film only records 5.5 MP of information (or 2000ppi, roughly), this probably really isn't an issue. Which is probably why 'in the real world', the Imacon scan doesn't make a whole lot of a difference compared to a <em>properly done</em> Nikon LS-9000 scan.</p>

<p>Still, it'll be very interesting when my scanning facility reopens and I plop Mauro's film shots of resolution test charts on the Imacon vs. the Nikon.</p>

<p>Cheers,<br>

Rishi</p>

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<p>Rishi, regarding the Coolscans resolution comparisons:</p>

<p>1) The difusser has certainly and impact and at least you should sharpen before assessing resolution.<br>

2) The Coolscans have better resolution across the steps of the motor than across the CCD arrangement.</p>

<p>In evaluating the resolution of my charts, my lines pph factor measured 890, If your calculations are close (+/- a few percentage points) to that number then you are measuring the correct distance.</p>

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<p>I still haven't posted my assessment, sorry.</p>

<p>But I need to correct a previous statement... I looked at the films on the microscope again using a different diffuser, and my estimation of TMX or Velvia didn't change, but I was able to see the Ektar more clearly (color negative film is hard to judge under the microscope given the orange mask and the inherently low contrast).</p>

<p>But the Ektar held up well against the Velvia on my second look...</p>

<p>My estimations are:</p>

<p>TMX: 26MP<br>

Velvia: 21MP<br>

Ektar: 21MP</p>

<p>This goes well with another site that claimed they could resolve 154 lines/mm on Ektar 100, right up against 160 lines/mm for Velvia.</p>

<p>I'd really like to test 'real world' contrast.</p>

<p>In the meantime, an interesting article by Norman Koren on 4000ppi vs 8000ppi scans:<br>

<a href="http://www.normankoren.com/Tutorials/Scan8000.html">http://www.normankoren.com/Tutorials/Scan8000.html</a></p>

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<p>Haha, yes Mauro... but don't get too excited... it was based off of the exact same test, literally, given you mailed me the results :)</p>

<p>But yes, in general I agree with your results.</p>

<p>HOWEVER, I realized you applied a, well, what <strong>I</strong> would call, ridiculous amount of sharpening to the film scan (unless your LS-9000 is magically 10 times superior to mine... and I checked focus many times plus held the film flat using AN glass).</p>

<p>So, I also applied what I felt would be a similar amount of sharpening to the Sony A900 image. In which case, barring aliasing, I think the Sony can resolve up to 3700 LPPH, which makes it a 20.5MP camera.</p>

<p>I'm really curious to see the Imacon scan because it's clear my LS-4000 can't resolve all the detail on the film. Perhaps one of the LS-5000 or LS-9000s in the lab can do better... I will post back results in January.</p>

<p>Regardless, though, let's keep in mind that digital's resolution (as far as I know) doesn't drop off as fast as film (20MP --> 5.5 MP), or does it?</p>

<p>Mauro, or anyone, can you comment? I haven't found digital SLR tests of 1.6:1 charts.</p>

<p>Cheers,<br>

Rishi</p>

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<p>"Regardless, though, let's keep in mind that digital's resolution (as far as I know) doesn't drop off as fast as film (20MP --> 5.5 MP), or does it?<br>

Mauro, or anyone, can you comment? I haven't found digital SLR tests of 1.6:1 charts."<br>

Partially true, but it doesn't work that way. </p>

<p>First, it is true resolution in film goes down as contrast goes down, same as the human eye. Digital drops off as a cliff. But scenes in real life are a blended result of low-high contrast and low-high frequency detail. Where high contrast-high-frequency intertwain low contrast-low-frequency.</p>

<p>Second, resolution itself in film is obviously a random array - same as nature - not a discrete array as in digital.</p>

<p>Third, a black and white chart in my opinion, favors digital - not film, as it hides the terrible color resolution of digital.<br>

"So, I also applied what I felt would be a similar amount of sharpening to the Sony A900 image. In which case, barring aliasing, I think the Sony can resolve up to 3700 LPPH, which makes it a 20.5MP camera."<br>

Sharpening does not invent detail. Can you post a side by side of the point where you consider the a900 still gives you individual lines at 3700?</p>

<p> </p>

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<blockquote>

<p>Can you post a side by side of the point where you consider the a900 still gives you individual lines at 3700?</p>

</blockquote>

<p>I already did, Mauro :) Look above. I do a comparison of a 3700 LPPH section of the Ektar scan next to a 3800 LPPH section of the Sony A900... and I assert, once again, that there's no way one can reasonably say the Ektar resolves the lines better than the Sony around this region of 3700 - 3800 LPPH.</p>

 

<blockquote>

<p>Second, resolution itself in film is obviously a random array - same as nature - not a discrete array as in digital.</p>

</blockquote>

<p>Very true. Which is why buildings and lines look so much better in digital (to me), whereas random detail (trees), to me, look better in my film shots [in side-by-side comparisons].</p>

 

<blockquote>

<p>First, it is true resolution in film goes down as contrast goes down, same as the human eye. Digital drops off as a cliff. But scenes in real life are a blended result of low-high contrast and low-high frequency detail. Where high contrast-high-frequency intertwain low contrast-low-frequency.</p>

</blockquote>

<p>Digital dropping off as a cliff is desirable to film dropping off gradually (assuming that the gradual drop-off begins at a higher contrast than the cliff drop-off, of course). In order to accurately represent low to high contrast (or <strong>any</strong> contrast range), you want the recording medium to have the its maximal response throughout the contrast range. This is the best way to accurately represent a signal: have a 100% response to it no matter the signal. This is very basic theory... So I'm not sure what you're trying to say. The lens already decreases the contrast its recording, the film decreases it more, and so what you get in the end is not the best representation of what was originally there. If you could up the response to 100% for either the lens or the recording medium, you'd do a better job for most of the contrast range... up until, of course, where the digital 'drops off like a cliff'. But this'd be much better than dropping off gradually.</p>

<p>Rishi</p>

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<p>And Mauro... why doesn't a film lover such as yourself do some 1.6:1 contrast resolution chart tests as well as red, green, & blue color resolution chart tests with digital SLRs??</p>

<p>:)</p>

<p>Has anyone performed these tests? I can't find them on Google.<br>

Thanks,<br /> Rishi</p>

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<p>It's fair to say Sony Alpha 900 resolves some lines at 3700 not all of them. It happened when the lines were aligned with the pixels. Otherwise, a blurred gap occurred. Mauro in his test includes some real life subjects to go beyond the contrast of 1000:1. If I understand correctly, it's easy for the software in the DSLR to guess straight lines, simple shapes, etc.<br>

Richard</p>

 

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<p>Agreed Richard. I'd also say that it's fair to say in the Ektar scan that 4/5 lines were resolved at 3700 LPPH... for the Sony, 7/9. That's 80% vs. 77.8%. They're on par with each other.</p>

<p>Under the microscope, though, all the lines can be resolved (in my observation)... so perhaps the film slightly outresolves the Sony A900.<br>

<br /> To me, that doesn't matter though. As I only deal with scanned film. Again, the Imacon results will be very interesting. Trying to enjoy the holidays despite the anticipation of being able to back to the scanning lab :)</p>

<p>-Rishi</p>

 

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<p>Mauro, you do agree that maintaining 100% response (or as close as you can get to it) and then sharply dropping off is better than the gradual drop-off of film's response, no?</p>

<p>In fact, Velvia boosts the response to >100% for lower frequency detail, which really makes it pop. And that's the best part of Velvia.</p>

<p>Also, Mauro, I forget -- do you fluid mount, or use glass carriers?<br>

Rishi</p>

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<p>"Mauro, you do agree that maintaining 100% response (or as close as you can get to it) and then sharply dropping off is better than the gradual drop-off of film's response, no?"<br>

Like you said, it depends. If you are shooting a building the former is better. If you are shooting nature, the latter. In every portionf of the picture you will have amix of finer detail of high contrast and lower detail on low contrast - same as the natural eye response.<br>

"Also, Mauro, I forget -- do you fluid mount, or use glass carriers?"<br>

Glass for 6x7 and bare for 35mm.</p>

<p> </p>

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