Digtal vs 8x10 film

Discussion in 'Film and Processing' started by stuartmoxham, Sep 22, 2011.

  1. Anybody take a look at this yet.
    http://www.luminous-landscape.com/reviews/cameras/iq180_vs_8x10.shtml
    Is this really correct. I remember that D30 test years ago.
     
  2. How many more Digital vs film threads will we have this week?
     
  3. When I first saw the subject of this post I thought the same thing as Larry Dressler but it really is an interesting article and was glad my attention was drawn to it.
     
  4. Well.......

    I have to say that I am a bit skeptical about those film scans. I scan 4x5 at a bit more than twice the dpi they mentioned for the 8x10--thus equivalent+ magnification--and my results are better than those--Imacon 848 scanner. I have also seen prints with larger magnification from 8x10 film--Richard Misrach Beach series--and you can count the grains of sand in those 8'x10' foot prints shot from his hotel balcony.

    That said, I am a long time 4x5 film shooter. I make various size prints up to 40x50 and comparing 4x5 images to those shot on my 1dsmkIII at that size will leave most impressed with the results of the smaller camera. Certainly, the digital shots don't have that organic feel that the nominal grain in these prints imparts, but that can be remedied if one were so inclined. i don't buy the articles conclusions totally, but I do think digital is now a viable alternative if that matches one's needs and intended use.
     
  5. The scans are less than 800ppi and show grain on Fuji acros 100. What did they develop the Acros in? Also the Ektar shots are really unsharp. Something seems so wrong to me.
     
  6. They are comparing 80MP to 8x10 film. That's 1 million pixels per square inch. That's the equivalent of claiming you only need 1.33 million pixels to equal 35mm film. Something which even the most pro-digital photographer would admit to being nonsense.
     
  7. Several years ago I was in San Francisco and saw a set of very large color photos. They were being exhibited somewhere near Fosherman's Wharf. The photos were taken on large format Velvia, which was then scanned. I contacted George Schaub at Camerashopper to see of he would be interested in an article about the photographer and his hybrid workflow. As things turned out I did not have time to work on the project. A year or two ago there was an article in the NY Times (I think) about a tinkerer who used large sheets of aerial film for enormous prints. The film was so large he had to build a camera for it. There was a lot of PP because the film was not made for regular shooting. As I understand it, very large b&w prints made by projection printing of large format negatives still look better than anything you can do with large digital files and digital printing but you need very expensive equipment. Comparing scans of film with original digital files has only so much validity. Projection printing of the negative compared with digital printing of the original digital file will give you a better idea of what each method is capable of.
     
  8. See I was right....
     
  9. Comparing scans of film with original digital files has only so much validity. Projection printing of the negative compared with digital printing of the original digital file will give you a better idea of what each method is capable of.​
    Exactly. If you want to compare one with the other (and I really couldn't care less now) you have to compare a fully digitally produced print with a fully optically produced print. Otherwise it's just a digital vs. scanner test and the scanner is usually the weakest link.
     
  10. I'll have one of those orange apples please.
     
  11. Larry...
    You printed that backwards.
    It's supposed to be apples to oranges, not oranges to apples. ;-p
    - Leigh
     
  12. Really you need to compare using the methods you would use for producing your prints. No point to even think about optical prints if that is not what you usually produce. There are a great number of people today that do not produce optical prints so it is perfectly valid for them to compare film scans to digital images. Personally I would more interested in optical prints myself but many packed up their darkrooms and went over to scanning film and producing digital prints. What I was concerned about was how a low resolution just under 800ppi scan could look so soft in the center of the image especially the Ektar scan. I would have expected a it to look tack sharp especially as it was from a drum scanner.
     
  13. LOL I am Appoled I made that mistake. :)
     
  14. I know that many find these threads boring but they are interesting to a few like me!
     
  15. Not to take anything away Starvy but I have to say if the archives were looked at all this has been said before and since there have been no improvements in Enlargers and the enlarging lenses or scanners in years all is just what one feels and feelings can't be explained. If they could there would be no wars in the world.
     
  16. Well, I'm not sure how he got so much grain in a 745 ppi scan for the Acros. Did he push the film 10 stops in Rodinal? That said, I'm sure the IQ from the digital back is superb. I've played enough with the P45 and know that despite the better resolution of 4x5 film, I can produce a 32x40 from the P45 that is superb. The IQ180 should be quite a bit better still.
    At the end of the day, a 40mp camera is sufficiently close to 4x5 that I'd be happy to go there. But take the LL site with a grain of salt. We all remember to well the Canon D30 vs Provia which became the laughingstock of the internet. As an owner of the D30, I can tell you the comparison is nothing but joke.
     
  17. LOL Dave. Contrast was not enough for that. Thing is they hit the spot then started to reduce sensor size... I used to be in the Air Force and we used LF film in a roller in SR-71s and other Aircraft. Thing is Digital cameras took a *X&$#**X&$#**X&$#**X&$#* load of Gama ray shielding in upper altitudes and space that though was quicker it weighed more. No more waiting for the film to be returned and processed.
     
  18. That test is to be disregarded. I emailed the L. Landscape to run the test against medium format and they declined. They toy with their readers.
    They are scanning at 745 dpi (laughable) and also indicating that they come up with grain and blurry images. It is silly but a long lived tradition for the L. Landscape.
    Well that is not what film looks like.
    Their medium format digital camera is easily outresolved by MF film.
     
  19. It is also very funny they scan the film at fewer megapixels than the digital camera to make sure they don't look bad.
     
  20. I use a V700 and I get better... with smaller... Ohh well this is a dead thread unless you ant to keep it alive with real truth and scans. I am too lazy to do it again..
     
  21. The L. Landscape does provide some amusement factor though with their silly articles.
    I wonder if it intentional just to entertain people with humor.
     
  22. Are the digital enlargements photoshopped or Straight out of the camera with no post production work?
     
  23. The L. Landscape does provide some amusement factor though with their silly articles.
    I wonder if it intentional just to entertain people with humor.
     
  24. Like A somewhat famous Nikon guy what is his name? Ken Rockwell or something..... :)
     
  25. That Phase One's sensor is smaller than a 645 frame. If you do the math it's at about 4900 PPI, so smaller pixels than my D7000. You do get to use Mamiya glass, which is nice, and 80MP is a lot, but an 8x10 frame has 23x as much area as this camera's sensor, and you can easily get Ektar, Portra, Velvia, Delta, etc. in 8x10.
    All they've done by running the scans at low res to match the pixel count of the digital, not using proper sharpening, and doing a sharpness comparison, is to show that bad scanning technique kills sharpness.
     
  26. An 8x10 contact print from Tri-X shows no grain... Or pixels or noise or whatever you want to call it even if you have to do digital on a V700... LORd... I want to quit.... even at 300 it will overload most computers if you want to tiff it.
     
  27. That whole test is unbelievably retarded. At least silly old K.R. comes out and says up front not to take him seriously
     
  28. I found the article in LL fascinating. Imagine comparing a poor scan to a Hi-Res. Digital. Methinks my Canon Super-shot S590 might indeed be better than 8 x 10. My printing needs are smaller. Mostly 4 x 6, occasional 8 x 10/12. If one was to "optically"print the large format..
    Ken Rockwell "tests" are great! Everything there is a fair comparison. Folks who bought into the Leica M8/M9 must really be mad when an ancient 1956 Leica M-3,60's Summicron 50mm, sails past the digital M9/M8 in terms of color and feel using Velvia. Film has this wonderful "organic" look. Digital is way more precise but cold..
    I use film and digital. Digital allows me to shoot till I drop. Film makes me question each exposure. This leads to poorer photos! I am only safe when I use Black and White film because there are no snotty nosed,fat fingered and least caring people in the chain of development and proofing. I am my own lab.
    The LL article proved absolutely NOTHING. What did you expect from a site that knew and concealed the major flaw of the Leica M8? The magenta color cast which I get on my really cheap old Kodak Easy Share.
     
  29. Maybe I should go dig up my old D30 vs 35mm Provia comparison. It'll show how they don't know how to scan or PP film at the LL. My favorite though was his 6x7 vs the 1Ds where he said the 1Ds had more resolution. Then a couple of years later, he posted the 645 vs 1Ds2 and said the 1Ds2 had almost as much rez as the 645. Huh? Let's see....11mp better than 6x7, but 17mp worse than 645. Oh well, I just keep laughing at their "tests."
    Ya Larry, I know, the contrast would be off the chart pushed that much. My point is that I don't get that much grain from 4x5 FP4 scanned at 3200ppi.....so how does he get that much grain from Acros at 745 ppi....or as he says, "DPI." I've yet to figure out how a scanner "dots" an image....or scans an image into "dots." I guess we have someone who doesn't know the difference between printing and scanning.
     
  30. I don't get that much grain from Neopan400 in Rodinal scanned a 800ppi.
    The writer posted a follow up article. Someone on rangefinder forum posted a link to this.
    http://www.markuszuber.com/8by10.html
     
  31. I like the comment he adds with TMAX 400 would should show even more grain but no more detail at 745dpi.

    The reason why I take the time to post these things is because unscrupulous test like theirs are posted for personal financial reasons at the expense of hurting an entire community of artists.
    So here is what film looks like:
    00ZNAL-400899584.jpg
     
  32. Thanks Mauro. This is something many of us have pointed out over the years. I recall posting my D30 vs Provia samples at DPReview about 9 or 10 years ago....where I was labelled a liar, biased, etc, because I simply showed the Provia to far outresolve the D30...and even my 10D. I had many people email me saying they found the same thing...but didn't want to get roasted by all the LL followers.
    I can tell you this much...I get better results from my Epson V700 for 4x5 than the LL did in this test with 8x10. That should about sum it up for everyone.
    Maybe I should set up something in my blog so it can be referrenced by people who beleive the LL nonsense.
     
  33. The two crops on top also represent the difference in resolving power between the 80MP MF digital and an 8x10 piece of fast film.
    The difference is so meaganormous that the LL's undertaking this project tops their history of embarrasements.
     
  34. FYI the shot above was shot with my Mamiya RZ67 and scaned at 97 megapixels (4,000 native dpi) with my Coolscan 9000.
     
  35. But Mauro.....how can that be? LL has already said there is no additional information other than grain beyond 745 ppi.... ;-)
    This one is easy. If LL is correct, then your 745ppi and 4000ppi images should look the same. If they don't look the same, then LL has some "Splainin" to do!
     
  36. Well, since they drank their own coolaid and have been shotting landscapes with 3mp to 20mp cameras for the last 10 years, the have no choice but to make up a story so people won't turn their 30x40 prints into torches and come to their doors.
    The funniest thing is that Michael R. himself emailed me saying he didn't want to do a side by side testing with me of his 80mp MF and my MF film.
    Actually even funnier is that people without experience will quote this test from the Luminous Landscape for years to come.
     
  37. This is even being questioned at the LL. Lenny Eiger is an expert in scanning and says:
    "It's just plain ridiculous and the article should be pulled. It's clearly misleading."
    I really wish they would stop posting the useless, misleading tests.
     
  38. Larry,
    If you are not interest in this topic then why don't just you stay away and leave the thread to those who are truly interested in a meaningful discussion on this topic. Just because you don't like the topic does not mean that everyone else needs to share your opinion. Your pejorative comments in this thread are not helpful in any way whatsoever.
     
  39. Alan I am following this with interest.
     
  40. There is no scanner in existence (that I know of) that can extract the available information from a high-quality 8x10 (or 4x5) image. This can be proven incontrovertibly by the numbers.
    Given that a high-quality film and lens combination can resolve 100 lp/mm (the actual number is irrelevant):
    A line pair is defined as a black line adjacent to a white line, so you have 200 lines per millimeter.
    Looking at this on a single scan line you have 200 dots per mm, alternating black and white.
    Standard sampling theory requires that you take at least two samples of each data element*, so a basic scan of that line would require 400 samples per mm.
    That equates to a scanner resolution of 10,160 dpi!
    Even that resolution won't provide a high-quality data set, only a marginal one. An accurate scan would require four to eight times that resolution.
    Numbers don't lie.
    - Leigh
    *Note: The 2x sampling criterion is universal in the electronic world. It applies to all types of data acquisition. It has nothing to do with photography.
     
  41. Leigh, no one questions that the film can capture at least 20 times the detail than the 80MP digital camera.
    Even with my Mamiya 6x7 cameras and Coolscan I can get almost 100 MP of detail. The limitations on my workflow (in order) are:
    1- the scanner at aprox 150 lpmm,
    2- followed by the film (Velvia or Ektar: 160 lpmm, Tmax-Xtol: 220 lpmm or TPan-Technidol: 300 lpmm),
    3- and lastly the lenses - I have tested my mamiya lenses aprox 400 lpmm (measured on microscope projection).
    The Luminous landscape is only showing the lowest common denominator of their lens, technique, focusing and laughable scanning resolution. It is worth noting that their results are so extremely poor that cannot be attributed to incompetence or equipment; they clearly show intention to mislead.
     
  42. By my previous crops you can appreciate the vast difference in resolving power between film and the 80mp MF camera. That's why the test is a joke.
    00ZNVG-401099584.jpg
     
  43. Now scan only at 745dpi and don't sharpen and you get the result they presented (assuming their technique for the shot was good).
    Luminous Landscapes 745 dpi with improper/no sharpening:
    00ZNVN-401103584.jpg
     
  44. Leigh,
    I agree with your analysis conceptually, but i believe there is in error by a factor of two. The Nyquist sampling theory says that the sampling rate needs to be at least 2X the frequency of the highest frequency component in the signal in order to reconstruct the signal without error. If we pretend that a white/black pair corresponds to one period of a sinusoidal signal (a slight simplification, but not too far from wrong) then the Nyquist limit is two sampling points per black/white line pair. This is a factor of two lower sampling than the estimate you provided.
    As a practical matter if you are close to the Nyquist limit you could end up with some kind of Moire pattern if the signal is an extended sinusoidal signal, so it is better to sample at a rate somewhat higher than the Nyquist limit.
     
  45. If we pretend that a white/black pair corresponds to one period of a sinusoidal signal...​
    Hi Alan,
    That's the error. Each line is a full cycle, not a half cycle.
    This is easily demonstrated by shifting the sample point relative to the data set.
    If you have a sensor with 200 elements/mm, corresponding to the 200 lines of the original data, and you align the sensor so each element lines up exactly with the center of each line, you can acquire the data as alternating black and white.
    However, if you shift the sensor by one half line width, you end up with a data set that is uniformly gray, each sensor element seeing one half white and one half black in the subject.
    Since the alignment of the sensor with the original is completely random, you must treat each line as a separate full cycle.
    Thus my original 400 sample value is correct.
    - Leigh
     
  46. It is worth noting that their results are so extremely poor that cannot be attributed to incompetence or equipment; they clearly show intention to mislead.​
    Hi Mauro,
    I agree completely. I have not read the original article, and don't intend to do so.
    It seems obvious from the comments here that LL has an agenda and is trying to fabricate some 'science' to back it up...
    unsuccessfully, but that won't prevent its propagation in internet history. ;-(
    - Leigh
     
  47. The way to be sure would be to have the best scan possible made from an 8x10 negative then downsize it to 80 megapixels. If there is any difference then there is clearly more detail in the film.... Or is that what Mauro did?
     
  48. Leigh,
    Consider a simplified example. Assume there is one line pair per inch. That would be 1/2 inch of black and 1/2 inch of white. The spatial frequency of this signal is 1.l (To be strictly correct and include the units the spatial frequency would be 1/inch.) The Nyquist limit is to sample at twice the spatial frequency, i.e. to sample the signal at a rate of two times per inch. Thus, there is one line pair per inch, and you must sample at two samples per inch. Everything scales linearly with frequency, whatever the spatial frequency is (in line pairs per inch), so the Nyquist limit is twice the number of line pairs per inch. According to the Nyquist sampling theory, if the signal is bandwidth limited such that the highest frequency in the signal is less than the Nyquist limit then you can mathematically reconstruct the original function without error if you sample at the Nyquist sampling frequency.

    Your comment about the strange results that you would get by a slight shift of the sampling grid (your comment about uniformly gray) is correct, i.e. you would get a uniformly gray result. That is a special case of the Moire pattern problem I mentioned, and it is a good reason for sampling at a rate that is much higher than the nominal Nyquist limit. It is a subtle and interesting point, but nevertheless the Nyquist limit is twice the spatial frequency.
    Looking at the Moire problem a little deeper, suppose you were sampling at a rate that is just a little higher than the Nyquist limit, such as 2.02 samples per inch if we had a signal with a spatial frequency of 1/inch (i.e. one line pair per inch.) You could start off being in phase with the signal, i.e. the sampling points being aligned with the light and dark parts of pattern. In that case you will capture the alternating light/dark pattern in that part of the image. However, after proceeding part way across the frame the sampling device (the image sensor) would get out of phase and it would sample the nodes in the pattern, i.e. the region right at the light/dark boundary. During this part of the image you would get a uniformly gray result rather than a light/dark pattern. (This is similar to the ) Proceeding still further across the frame, the sampling device would again be in phase with the image and reproduce the alternating light/dark pattern. Thus, sampling at close to the Nyquist is not actually good enough to do a good job of capturing an image, and in that sense I agree with your comment about sampling at a higher rate. In the specific example you cited you recommended sampling at twice the Nyquist limit, and I agree that it is a good idea.
    I think one of the implications of this discussion is that you need to sample at a rate substantially higher than the Nyquist frequency if you are going to produce a direct image. However, if you are going to mathematically process the sampled signal and then reconstruct the image then sampling at the Nyqist sampling rate (actually, just a slightly higher frequency than the nominal nyqist limit) would be enough to perfectly reconstruct the image.
    At least that's my analysis. It doesn't necessarily mean I am right, but I have been using Fourier transforms in my work for many nears, least some degree, and I have published several papers based on Fourier analysis of certain functions, and I am therefore pretty confident in my analysis.
     
  49. To elaborate on what I just wrote, I think there is a difference between direct capture of an image by sampling and reconstruction of a sampled image.
    To reconstruct the image you would calculate the entire frequency spectrum of the image (including the phase factors) and then add up all the wave forms to reconstruct the image.
    On the other hand, if you were directly capturing the image you would say that the image is taken straight off the sensor, without any further signal processing.
    Additional discussion is welcome. I am sure there is something we can all learn from this discussion.
    Oh, one more thing. I agree that there is no way that a 80 Mb sensor is going to capture all the detail of a good 4x5 image. I agree that there simply aren't enough sampling points in an 80 Mb image to do that. We disagree only in a numerical factor, and depending on how one frames the problem (taken a sampled image directly as the image itself vs. reconstruction of a sampled image using mathematical methods) we may not even be in disagreement with each other.
     
  50. Steve, I am easily showing the difference between 745 dpi and 4,000 dpi on TMAX 400.
    If the Luminous Landscape claims that they do not have any detail past 745 dpi.
    Also, 745dpi scan coincides with the resolution of the 80mp digital; so te crops above represent as well the difference in resolving capacity between the digital camera and the film.
     
  51. (To be strictly correct and include the units the spatial frequency would be 1/inch.)​
    Hi Alan,
    Your error derives from interpreting each line as a half cycle.
    It's not. It's a full cycle.
    Each line can have any tonal value from white to black. We're simply assigning discrete values to each for the purpose of discussion. You could just as easily have adjacent white lines, or black lines, or gray lines.
    - Leigh
     
  52. Leigh, the sampling rate to scan film losslessly is higher than 2x, this is because the grain structure is random. The simplest way to understand it is that if you are scanning a perfectly horizontal line pair, a 2x sampling rate will suffice to reproduce it. If the lines are diagonal and formed by components of random size and distribution, a 2x sampling rate will reproduce a jagged staircase in places where the original was more uniform.
    Another way to understand it is by drawing a line on the sand with a 1 millimeter toothpick and then scanning with a 0.5 millimeter sampling rate. You won't get anything like the original.
    For practical purposes though 6,000 - 7,000 dpi capture 99 percent of the detail that current film can record. Aside of some jaggies added.
    The Luminous Landscape 745 dpi is so ridiculous that can only cater to a brand new generation of novice photographers. Sadly, it will stay on the internet to confuse people for years to come.
     
  53. Hi Mauro,
    If you'll review my post from 4:51PM, you'll see my comment regarding the 2x factor, thus:
    "Even that resolution won't provide a high-quality data set, only a marginal one. An accurate scan would require four to eight times that resolution."
    I believe you and I agree on this.
    - Leigh
     
  54. I definitely agree.
     
  55. By the way, if anyone associated with the Luminous Landscape reads this post, my offer to shoot side by side to the 80mp digital with my 6x7 film cameras stands. MF film will show a clear resolution advantage over the 80mp digital (particularity with the same lenses as the crop factor of the digital camera will deteriorate microcontrast significantly).
     
  56. Leigh,
    A cycle is, by definition, when a periodic signal has returned to its original state without any additional repeats. If you have a pattern of black-white-black-white-black-white-black-white-... One cycle encompasses a single black-white pair, because that is the minimum amount of pattern that will come back to the original state, from which it can repeat with another black-white cycle, and so forth.
    If one tries to define it as half that, say a single black, then it is not a cycle because the next thing to come is white, which is not a repeat of what came just before. In a black-white... pattern a single black line corresponds to a half-cycle (assuming that the black and white lines are of equal width), and a single white line corresponds to a half-cycle.
    By the way, a repeating black-white pattern is the combination of a zero-frequency component (the average over one cycle, which is gray) and a pattern containing a fundamental frequency (the basic frequency of the cycle) upon which is superimposed a series of odd-order harmonics whose relative amplitudes are the inverse of the harmonic number. For example, the third order harmonic has a relative amplitude of 1/3, the fifth order harmonic has a relative amplitude of 1/5, etc. However, in a discussion such as we are having it is convenient to ignore the harmonics and pay attention only to the fundamental.
     
  57. Yes, Alan,
    I know that a square wave is the sum of a fundamental and all odd harmonics.
    I also know that the Nyquist limit is the anti-aliasing limit that defines the minimum sampling frequency (or maximum signal frequency) that can be used without introducing spurious responses.
    Now go back and re-read my 5:37 PM post regarding sensor/subject alignment and dispute it if you can.
    - Leigh
     
  58. Leigh, if you are talking about sampling at the nodes and the result coming out gray, I have already acknowledged that point and discussed it.
    Now, with respect to the definition of a cycle, here is the definition from that font of all knowledge, Wikidedia:
    A process that returns to its beginning and repeats itself in the same sequence...
    This is essentially a paraphrase of the definition of cycle I gave in my last post.
     
  59. Some additional information on the sampling theorem, again from Wikipedia:
    "More recent statements of the theorem are sometimes careful to exclude the equality condition; that is, the condition is if x(t) contains no frequencies higher than or equal to B; this condition is equivalent to Shannon's except when the function includes a steady sinusoidal component at exactly frequency B..."
    The condition you described, which is where the signal was sampled (only) at the nodes, resulting in a uniformly gray set of points, corresponds to the condition where the signal was sampled at exactly twice the signal frequency. According to the more correct version of the sampling theory (quoted above) that sampling rate does not satisfy the sampling theorem. The sampling theorem as usually (and incorrectly) quoted says that the sampling rate must equal or exceed twice signal frequency. However, the more correct version says that the sampling rate must exceed the twice the signal frequency. Sampling at a rate equal to twice the signal frequency is not quite enough.
     
  60. The reason why I take the time to post these things is because unscrupulous test like theirs are posted for personal financial reasons at the expense of hurting an entire community of artists.
    I am sure that everyone can remember how Luminous Landscape was of the opinion that the 3MP 1.6x crop Canon D30 was equal in quality to medium format film. The site hasn't changed all that much.
    Mauro's images are very telling. Thanks for posting them. :)
     
  61. Leigh,
    OK, I performed a numerical experiment on the computer. I started with a sinusoidal function with a frequency of 1 and an amplitude offset of 1 unit. (The function is sin(2*pi*f*t)+1, where f=1.) This is to simulate an offset sinusoidal function that varies from perfect dark (a value of 0) to perfect light (which in this simulation is arbitrarily defined to be a value of 2. The function has an average value of 1 (i.e. gray).


    I then sampled the function in two ways. The first was to at time points of multiples of 0.03125 seconds. This rate is well in excess of the Nyquist limit (0.50 seconds). The second was at time points of 0.46875 seconds, which is barely within Nyquist limit.


    Here is what happened. The first sampling scheme gave a fine grained representation of the original function, i.e. a smooth-looking sinusoidal function with a low of 0, an average of 1, and a maximum of 2. If we take the pattern on the sampling points (the sensor elements) to be a direct representation then the pattern is a visually true result.
    The second sampling scheme gave a modulated sinusoidal function. At one point it is gray. Then at later points it starts to modulate, alternating between slightly darker and slightly lighter gray. The modulation builds until it is alternates between full dark and full white. Then the modulation decreases until it is gray again. The pattern repeats itself. This corresponds to a condition I discussed in one of my previous posts. It also corresponds to a strategy where the pattern on the sensors (the sampling points) is taken as if it were a direct representation of the image. However, this pattern is not a visually true result because it does not represent an even and sinusoidally varying pattern of light and dark, but rather it presents a Moire-like pattern, with the sinusoidal pattern being modulated by a function of lower period. Although the sampling rate satisfies the Nyquist sampling criterion, taking the sensor element readings as if it were a direct representation of the pattern does not give a visually true result.
    However, In taking the Fourier transform of the two sampled results I get the following results. In the case of fast sampling (0.03125 seconds) I get a peak at zero frequency for the real part, and peaks at frequencies of 1 and -1 for the imaginary part of the function. (The Fourier transform uses complex numbers, which is why there is a real part and an imaginary part.) The two imaginary peaks have amplitudes of equal and opposite sign. The real-number peak at zero frequency corresponds to the average value of the function, which is 1 and which corresponds to gray. The imaginary-number peaks at frequencies of 1 and -1 corresponds to the sinusoidal part of the image, i.e. the alternating part of the function. From this information I can produce an error-free representation of the original offset-sinusoidal image by summing signals containing the three frequency components.
    What happens when I do a Fourier transform on the vector obtained by sampling at intervals of 0.46875 seconds? Remember, that sampling interval barely satisfies the Nyquist sampling theorem, and the results of the sampling, if taken as a direct representation of the image, did not produce a true image. Here is the result of the Fourier analysis. I get a peak at zero frequency for the real part, and peaks at frequencies of 1 and -1 for the imaginary part of the function. (The Fourier transform uses complex numbers, which is why there is a real part and an imaginary part.) The two imaginary peaks have amplitudes of equal and opposite sign. The real-number peak at zero frequency corresponds to the average value of the function, which is 1 and which corresponds to gray. The imaginary-number peaks at frequencies of 1 and -1 corresponds to the sinusoidal part of the image, i.e. the alternating part of the function. From this information I can produce an error-free representation of the original offset-sinusoidal image by summing signals containing the three frequency components. In other words, when I perform an appropriate set of mathematical operations I get exactly the same result as when I sampled at the faster sampling rate of 0.03125 seconds.
    Thus, the result is as I have previously discussed, namely that if you are sampling a repetitive pattern at a rate just slightly higher than the Nyquist cutoff, and if you take the resulting vector directly as a true representation of the image, you get a false result of a periodic image. However, if you do an appropriate mathematical transformation of the data you can reconstruct an error-free representation of the original image. Thus, sampling at the the Nyquist freequency (actually, to be stricture correct I should say slightly faster than the Nyquist frequency) does not give a true representation of the image if the numbers are taken as a direct representation of the original image, but the data has enough information in it to reconstruct the original image if one performs an appropriate set of mathematical operations.


    One result of this analysis is that if you want to take the sampled data as a direct representation of the image then you need to sample at a rate much higher than the Nyquist sampling rate. Your example of using four sampling points over the light-dark line pair is a reasonable approach. However, it is, nevertheless, almost twice the Nyquist rate and therefore is, from a signal processing perspective, somewhat in the realm of overkill. However, I do agree that your sampling rate does produce a good direct representation of the image, and I also agree sampling at the Nyquist rate (or, as just discussed, at slightly faster than the Nyquist rate) does not necessarily produce a good direct visual representation of the image.
    If you would like the table of numbers I generated in the simulation then send me a personal message.
     
  62. No need to go crazy with theory. Just draw a picture on a square patterned paper. Then try replicating it by randomly placing (position and angle) another square pattern paper on top (against a window) filling only those square that have more black than white. How much smaller the pattern on the second paper needs to be to reproduce the original fairly accurately.
    Now, even worse, try the original made of random elements (like grain) instead of squares.
    For printing purposes though, as long as you have 300+ dpi you are good.
     
  63. Hi Alan,
    First of all, a cycle is a time interval. It has nothing to do with amplitude.
    Your assertion that consecutive cycles must be amplitude-continuous is invalid. Ask anyone who has ever dealt with binary data. Of course, if there's a discontinuity at the cycle boundary that greatly increases the transmission bandwidth of the signal, but that's relevant to the current discussion.
    The white/black dataset constitutes a binary data stream, and must be sampled as such. The Nyquist limit does not relate to accurate reconstruction of a dataset.
    - Leigh
     
  64. There has been a lot of discussion about the scanning, I can't help but wonder if the samples (especially the Ektar sample) don't have some kind of focus problem or film flatness problem.
    Something I am curious about though, if one only wanted to make a 16x20 inch then a 600ppi scan from the 8x10 neg would be enough. Would there be any advantage of say going with a 1200ppi scan would any of the extra detail make it onto the 16x20inch and would we be able to see it looking at the print from about 2 feet away.
     
  65. Oversampling the scan and then reducing it, will ensure Nyquist is not limitting you.
    To your comment regarding the quality of the picture itself, their scan is so poor that it is impossible to determine whether the picture was also poor. Per their own comments about not finding detail pass 745 dpi you may infer the picture is bad too.
     
  66. Leigh,
    You said that the Nyquist theorem does not relate to the accurate reproduction of a dataset, and by the context of the discussion I presume you mean a data set composed of a series of light/dark lines. I am not sure exactly what you mean by that statement, but if we take it at face value (i.e. that "the Nyquist theorem does not relate tot he accurate reproduction of a dataset") in the context of the present discussion then your statement goes against all the well established principles of signal processing theory.
    Would you care to elaborate on what you mean by your statement?
    There is absolutely no question that a digital image is a function that has been sampled and digitized on an equally spaced grid, and there is absolutely no question that the Nyquist theorem applies to the ability of a sampled function to capture the information in the original function. Therefore, the Nyquist theorem has direct application to digital imaging, and in particular it determines the ability to which one can reconstruct the original image from the sampled data set.
     
  67. Leigh,
    One more thing. Contrary to your assertion, nowhere did I say that cycles must be amplitude-continuous. They must, however, be repetitive because repetitiveness is essentially the definition of cyclical.
     
  68. I don't know if anyone noticed but there is a link at the article page stating:
    "Update: Some people have been critical of this test, saying that the 8X10" scans were not done at a high enough resolution. Markus has responded to this and also posted higher resolution samples here."

    http://www.markuszuber.com/8by10.html
    But when you go at the "answer" page you read:
    "Of course you will say that the scanning resolution was not high enough. I have had a close look using a 20x loupe on the negatives and slides to see what I/we all have/had to see that the resolution of the 8x10" films does not have the same richness of details as we can see from the IQ180 shots. When I can see the grain, I know that there is nothing more behind. You can increase microcontrast but this will mainly lead to a more pronounced grain. This is also the reason why I did not go and look for other guys for doing a higher resolution scanning."
    What is 20X in comparison to 745dpi?
     
  69. Giovanni, there's a number of problems with the authors statements. For starters, I'm not sure how the B&W film was processed....but with a 745ppi scan, there should be no grain visible. Second, his images appear soft from the get go. I don't see such softness in my 4x5 scans even at 2400ppi. SO this points to simply another issue with the capture process.
    I think this will become nothing more than the old D30 vs 35mm Provia scans that have been laughed at by experienced photographers for the better part of a decade. All it appears that matters is that web traffic is up at the LL.
     
  70. Wow, is this getting extremely technical and I think I am actually understanding it is what is really bugging the crap out of me. However, I wish to ask a few points about scanning and printing. Please excuse my complete ignorance on printing anything above a 120 negative...
    One: How does a 8x10 negative get printed? I realize you could contact print, but if you wanted to make that wall sized print, how is that done? Are there enlargers really that big? Is it the same with 4x5?
    Two: Scanning. My cheap Epson v500 (I know I should have gotten the 700 or 750.....couldn't throw the money at it then) seems to do fine for the extremely limited 120 and 35mm scanning I have done with it. I will admit it appears that I can scan better than the photo lab I use to develop and scan my film currently (I use a Kodak 6850 to print mostly in 6x8 or smaller). Does a drum scanner simply scan the same point over and over again for better sampling? Is that why they are so much better?
    I really would love to see the direct comparison to digital camera to digital print versus film negative to paper print......how about a 4x6, 8x10, 16 x20 and then a couple of monster sized prints from 35mm, 120, 4x5 and 8x10......THAT would be an excellent article for a photography magazine. (yes I realize advertisers would not like that article printed, except for the photo paper divisions of Kodak and Illford.....)
    Bob E.
     
  71. Are there enlargers really that big?​
    Yes..... and bigger
    A lot of people just contact print their 8x10 negatives to make 8x10 prints though. Many of these use alternative techniques which need UV light which will not pass through an enlarger's lens to be effective..
     
  72. Enlargers that big used to be commonplace and required in custom labs. We had five of them and the best was a computerized Durst horizontal 10 x 10 complete with pin-registered anti-newton ring glass negative carriers, a 2,000 watt halogen light source, custom lenses and a 15 foot vacuum wall with a vertical paper dispenser. Except for a few parts I could sell, everything was thrown to the metal scrap heap in January. Such is life in the digital world.
    You asked about drum scanning, and it remains the gold standard for many reasons. The film is fluid mounted to the drum so it's clean and perfectly flat, therefore sharp and clear corner to corner. Each point is directly sampled in exactly the same way without having to go through a lens or complicated light path so flare is minimal. Since the film is sampled spot for spot by PMT rather than a CCD technology, the results are generally smoother with higher dynamic range.
    People think of using a drum scanner when they need large scans, but even small scans are better. It's the not the number of pixels but the quality of the pixels that makes it better. Of course, any scanner is only as good as the operator and his skill in post processing is just as important as the technology.
     
  73. Thanks John and Steve. I wish I would have had the opportunity to have seen one of those huge enlargers......must have been an amazing sight to have seen in operation. What a shame to have simply thrown it in the dumpster.....
    And now I know exactly how a drum scanner works too. Thanks so much for explaining exactly how it is done. So far, I have only had maybe two photos I would consider drum scanning. All the other "good" ones needed some sort of Photoshoping since I don't think my local lab does much if any real enlarging anymore. I really need to ask. Most of my work centers around close up people photography, not alot of landscape stuff yet....I can barely remember being able to "touch up" photos under the enlarger......that was a long time ago.
    Bob E.
     
  74. Right, that's it, I'm off to buy a D30. Anyone know where I can get one?
     
  75. David Rohrer , Sep 29, 2011; 01:17 p.m.
    Since it was mentioned earlier I thought I would link it for every ones viewing pleasure.
    LL D30 v film http://www.luminous-landscape.com/reviews/cameras/d30/d30_vs_film.shtml
    surprised this is still on the web after 11 years​
    I'm surprised as well. As a owner of the D30, and a previous owner of an Imacon 343, all I can say is it's a load of you know what. I've yet to find anyone who thinks at even 8x10 the D30 was better. I produced my own serious of sample prints at 8x10 and 11x14 using a Minolta Scan Dual IV a number of years back. Verdict....no one, and I mean not one person ever took the D30 over the Provia......so it's odd that he had people raving about 13x19 prints. Nice try.
     
  76. Love the Luminous Landscape!
    The D30 tested on DPRview showed less than 2 megapixels of detail. Yet he also left comments below the article as "The most approximated look to a D30 file is a 4x5 transparency drum scanned".
    Endless amusement.
     
  77. I have an old Nikon D1h does that mean that I get near the look of 4x5 film?
     
  78. Dave do you have any of the comparison files that you could upload to this thread.
     
  79. That was many years ago Stuart. But it seems like there is still some interest in this. I may fire up the old D30 and do another shot to show people. I don't use Provia any longer, but I could grab a roll for fun!
     
  80. I would be interested to see the results. Does not have to be Provia no point buying something that you don't use. I always feel that the most interesting test would be to use both as you would normally use them, rather than set something up specifically as a test just shoot subjects that you would normaly shoot.
     
  81. I'm 95% a film shooter, but I'm not a digital hater. I still think the test is flawed and works to digital's favor in this case. I don't think the issue is with the scan as much as there is a problem with focus or more specifically, DOF. Tim Parkin touches on this here: http://www.landscapegb.com/2011/10/the-perils-of-testing/. I'm pretty shocked with the Acros results as others have mentioned, but really that's the least of this "test's" problems.
    Also It should be mentioned that when we talk about the resolution that film can achieve, we also talk about diffraction. When we say that film reaches 100lp/mm plus, that this is at small apertures and with smaller formats, not the f32 and 8x10 that was used. Scanning the 8x10 at 4000 SPI would not really help in this situation, 2540SPI or so with the drum scanner would have been enough to get everything on the film. That's higher than the 7** whatever they used, but we should still keep in mind that largeformat is not medium format.
     

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