Is that a criterion now? I thought we where off on a nice tangent?
I was obviously replying to S138s usual direct or indirect love letter to Epson.
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Is that a criterion now? I thought we where off on a nice tangent?Not sure what you intended to state here particularly as it applies to the original topic . . .
So as a semi-tangent to this article, let's say you want to scan 120 film? Is an Epson V800/850 going to give better results than a V700/750? I'm not trolling, but I need to "prepare" my "Chief Financial Officer" for a "purchase approval" for a scanner in the near future.
Is that a criterion now? I thought we where off on a nice tangent?
I was obviously replying to S138 usual direct or indirect love letter to Epson.
So, as members of this thread, what can we agree on? Where are the points of disagreement? Why? Is there any non-emotional way to resolve these disagreements?
Phil Burton
Epson V700 is able to get all IQ Portra 160 is able to record,
Even the best drum scanners cannot resolve all the details on the film. You have a significant loss.
The output i've see nfrom those scanners (yes, even the v850), even when using glass carriers, doesn't do justice to 120 film. It smears the image...
Obviously scanner performance at least in in terms of the ability to resolve detail is a known value.
But the basic fact is that people are getting quality scans from the Epson scanners. They can get better ones from a drum scan (very expensive, very fiddly, and equipment is getting scarce), or from a DSLR (I suspect the quality of the lens is a factor here-- but can be *very* fiddly if you want better resolution than the Epson, and the price is either comparable at the low end, or in the "how high is up" category at the X1 end). In theory, dedicated film scanners such as the PlusTek should deliver better results, but no unit since the discontinued Coolscan has received consistently good reviews-- so it's expensive *and* obsolete.
I realize the fundamental purpose of a scanner is take an analog image and turn it into a digital file-- and anytime you convert analog to digital or vice versa, things can get a little squirrely-- but I have difficulty believing that Epson could build a scanner, claim it's capable of 6400 PPI, and not get hit by the mother of all class-action lawsuits because it can barely manage 2400 PPI. If the scanner had come out last year, fine-- but the v700/v750 came out in 2006, at a time when film -> digital was all the rage.
But if the film contains more detail not achieved by the Epsons then obviously better (more expensive) scanners can further resolve it.
Is that a criterion now? I thought we where off on a nice tangent?
I was obviously replying to S138 usual direct or indirect love letter to Epson.
claim it's capable of 6400 PPI, and not get hit by the mother of all class-action lawsuits because it can barely manage 2400 PPI.
Ultimately, I think a new type of scanner is needed (well, would be useful, at any rate)-- a "flatbed" scanner that uses a square-ish imager with a quality lens, and creates a stitchable mosaic of whatever size film you put in up to 8x10 (or conceivably larger). I think one could be built for under $500 USD. Certainly for less than the cost of a v850.
Downsizing has nothing to do with the Rayleigh criterion. While the Shannon-Nyquist sampling theorem also applies to downsizing images, it does not necessarily suggest a margin for effective resolution. When I tested Photoshop’s Preserve Details resampling algorithm by downsizing USAF 1951 HiRes test target images it could retain the effective pixel resolution when the target was tilted slightly and exceed the effective pixel resolution when the target was tilted by 45°. Only when the target was oriented in parallel to the pixel grid a very small margin of 1-2% was required to avoid aliasing and resolve the target resolution.I did it...
But to conserve the 2600 effective you cannot downsize it to 2600, you have to add a safety margin related to rayleight/nyquist/shannon/etc criterion.
If you take the original crop and you make a super pixel peeping (of the clock) in Ps you will find that an edge takes around some 4 pixels to make the transition, this suggests that the actual effective performance is less than 1/2 of the scanned resolution, so 2600 or less, by no means it is 4000.
The 125 lp/mm value is line pairs per mm. You need at least two pixel rows per line pair. Therefore, the 6350 ppi minimum requirement to resolve 125 lp/mm is correct.You know, I'm not sure it is. Most of the efforts to determine scanner resolution are based around an analog test chart. Even some of the claims as the terrible MTF of the Epson appear to be based on a fairly tortured paper that attempted to use the USAF target in a totally different way than it was designed, to calculate the MTF.
I realize the fundamental purpose of a scanner is take an analog image and turn it into a digital file-- and anytime you convert analog to digital or vice versa, things can get a little squirrely-- but I have difficulty believing that Epson could build a scanner, claim it's capable of 6400 PPI, and not get hit by the mother of all class-action lawsuits because it can barely manage 2400 PPI. If the scanner had come out last year, fine-- but the v700/v750 came out in 2006, at a time when film -> digital was all the rage.
Something doesn't add up. Even the original discussion in this thread, produced a large debate as to what "125 lp/mm" actually meant. Silverfast, using their algorithm, suggests that that translates to 3175 PPI. I believe someone in this thread suggested that actually, 6350 PPI would be required, per Nyquist (while shaky on frequency sampling in general, I had the impression that the 125 lp/mm measurement was already taking Nyquist into account, and therefore 3175 would be sufficient).
Much of this feels like a great deal of hand-waving and armchair engineering-- the sort that suggested that you couldn't breathe in a car going 35 mph, or that bumblebees don't have enough lift to fly-- all great theories, but if empirical evidence contradicts the theory, a new theory is required. I'm not dismissing the information in this thread-- I think there's some really solid information, and I do appreciate all the contributions (and if I offended anyone by trying to steer away from hardware, that was not my intent. The thread on LF forums got pretty ugly at one point).
But the basic fact is that people are getting quality scans from the Epson scanners. They can get better ones from a drum scan (very expensive, very fiddly, and equipment is getting scarce), or from a DSLR (I suspect the quality of the lens is a factor here-- but can be *very* fiddly if you want better resolution than the Epson, and the price is either comparable at the low end, or in the "how high is up" category at the X1 end). In theory, dedicated film scanners such as the PlusTek should deliver better results, but no unit since the discontinued Coolscan has received consistently good reviews-- so it's expensive *and* obsolete.
This one using the V700 of the same frame of Fuji RVP. No improvement past 4800dpi.
...
But Epson's 4800dpi - or 6400dpi, does not resolve more then Coolscan's 4000dpi. It doesn't even match it.
While the Shannon-Nyquist sampling theorem also applies to downsizing images, it does not necessarily suggest a margin for effective resolution.
The other crop of the Minolta 5400ppi scan contains finer details and some higher contrast lines that spread just over a single line of pixels indicating that the effective resolution and level of real detail in that area is very close to the sampling resolution.
There are several things that are highly problematic with those articles.
.............
Clarke has a few examples from a drum scanner. But we know nothing of it’s calibration or other circumstances concerning the scanning.
With that out of the way, the articles themselves are technically and semantically dubious in a number of ways.
There is much weasel wording and handwaving, where the authors think they can get away with it.
There are no concise parts part about method, or any rigorous references to other works or sources to speak of.
These are not scientific or academic peer reviewable articles (and they don't purport to be), though I guess for many people they give off an academic air, that impresses and appears to have special authority, due to the authors clearly being used to writing academic papers.
Tim Vitales article while interesting in a number of ways, appears to be mostly a scrape of other papers and articles, with little work done by the author himself.
Tim Vitale is a conservator who specialises in photos. That does not tell us much about his technical authority.
Clarkes article has a number of gross inaccuracies, omissions, lack of clarity, forces conclusions and frankly seems biased (perhaps for the reasons I mentioned to begin with).
That wouldn’t be such a problem if the two articles weren’t among the first that pops up with a google search, and if they didn’t still get cited time and time again.
There have been several examples or hints at just how much resolution is in a square inch/mm of film in the intervening fifteen years.
Here is a two examples;
Tim Parkins tests are pretty famous.
The resolving power of most films is much higher than you think. Don’t trust the calculated resolution figures in Tim Vitale's document that you quoted. His calculations are fundamentally flawed. A much better source are the film resolution test results of Henning Serger. JP Buffington picked up some of Henning’s posts on photrio in his blog: http://jpbuffington.com/?p=167
Henning published additional results in other forums as well. Having personally checked a few of his test films under the microscope at 100x magnification I can confirm the credibility of his results. When I did my own tests in 2008 and 2009 the results were very similar. As these are real world tests of system resolution, Henning’s results can be taken as a reference on the potential resolving power of the emulsions he tested. While he used very good taking lenses (Zeiss Makro-Planar 2/50 and Nikkor 1.8/50 AI-S) for his tests these lenses are not the cutting edge by today’s standards. More recent introductions of new lens designs will probably yield even higher resolution from 35mm film.
That is absolutely wrong and has nothing to do with reality. The author of that
- has no knowledge at all of lens performance
- has never done resolution tests by himself.
Because the lens resolution is much much higher than that (and therefore also the resulting system resolution). For many decades now good prime lenses are either only diffraction limited, or are very close to that at their sweet spot.
We are seeing here again a typical internet problem: People, who have never done such tests by themselves, are quoting other people who have never done such tests by themselves.
And that results in wrong and misleading statements.
ADOX - Innovation in Analog Photography.
First of the Epsons can provide a good scan. This one from a WWII 4X5 taken by a colleagues dad who was a combat photographer in Europe. Laid directly on the glass. No post work done other then cleaning up some dust and scratches.
Full res 2400dpi file -> http://www.fototime.com/5DCEE0B3D75F78C/orig.jpg
Couldn't have done it with my Coolscans and my colleague liked it well enough to get his own V700 to scan his dad's films....
Full res file -> http://www.fototime.com/02BB797801DCA89/orig.jpg
It's unfortunate that there is no standard "real world test" frame of film we could all use. Individually we have to decide for ourselves what is good enough for our own real world results.
There's no evidence that T-Max 100 has the same structural layout as T-Max 400. Indeed, given that T-Max 100 was available as glass plates until quite late on, all the evidence points to a blended set of emulsions coated in a single layer.
Shanebrook pages 18 and 20 shows that both TMY and TX are made coated in two sensitive layers, nothing is said about TMX.
What evidence is there about TMX having single layer ? Look at page 18 (figure 16), cubic crystals blended in the T layer would destroy the perfect horizontal arrangement of the flat crystals, consider this, it would be painful destroying that.
Anyway this is not relevant for that reasoning, at TOC 1000:1 there is a 10 stops range, we see resolution from ultra slow speed crystals overexposed +7 stops at least, as we have some 3 stops from meter point to toe. Those crystals would be under "equivalent" ISO 1.
TMX is rated 200lp/mm in the datasheet, but this is at TOC 1000:1 contrast, by no means you will find a pictorial situation in what you project 1000:1at 200cy/mm on film, at 200lp/mm you project zero contrast.
In practice most of the image is at TOC 1.6:1 (65lp/mm before lens degradation), some edges may be 3 or 8:1, you may need an strong backlight silhouette in perfect focus and on tripod to get a ideal situation for high film performance, but this is a very particular situation. A contrasty very, very black line on a perfect white background is to deliver 8:1, and usually things are more or less gray than totally black or white.
I use Tmax 100 in MF and 4x5. What advantage do the extra tabular layers and other criteria of this film that make this film different? What practical effect would I see in my photography?If you'd read the segment on plate coating you'd know that you would not be able to coat a supercoating layer on the machine if T-Max 100 was multilayer. The gap between single and multilayer coated BW films often falls somewhere above 100 and below 200-250 as the problems of single layer blended coatings increase to where they are more problematic than the disadvantages of multilayer. As far as is known, T-Max 100 consists almost entirely of flat/ tabular crystal structures (of such great available surface area that the supercoat has to be unusually thick to moderate development times) - the two different layers seems to have been an innovation borrowed from colour neg technology for T-Max 400. Pretty much no 100 speed BW film on the market is multilayer as far as has been disclosed, though they almost all use some degree or other of emulsion blending. If you tried to use the structure shown in T-Max 400's cross section as a single layer, you would likely run into equilibration issues. There is often a significant coated thickness difference between 100 and 400 speed films & this is at least in part due to the multiple layers in the faster film. But this not surprising given the way that you start from the perspective that you believe that you are more knowledgeable than the entirety of Ilford/ Kodak/ Agfa/ Fuji/ Adox's R&D...
I use Tmax 100 in MF and 4x5. What advantage do the extra tabular layers and other criteria of this film that make this film different? What practical effect would I see in my photography?
How would these features show up in my photography? What would it look different to a person who didn't know what film I used?The thin single-layer, multiple emulsion type of construction allows for very high sharpness (less internal reflection between layers) with good latitude and the flat T-grains allow for a potentially much better speed / grain relationship with grains more tightly packed for better coverage - at the cost of a possible granularity character that some seem to spend a lot of time obsessing over. Not really an issue I've found. Faster films have to use more complex techniques to improve speed/ grain & combat internal reflections from consequent multi-layer approaches. The highly efficient dye sensitising techniques used by Kodak add a further chunk of speed & are almost as important as the grain structures.
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