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Thread: Best Film For Scanner Comparisons...

  1. #1
    Scott Rosenberg's Avatar
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    Best Film For Scanner Comparisons...

    a friend of mine and i are laying out the test methodology we will employ in a study whereby we compare several scanners to determine which will hold up to enlargment better - smaller formats on dedicated film scanners or larger formats on flat beds. we are currently disscussing film choice and hoped to solicit some opinions from our friends on the forum.

    to make color comparison back to the original easier, we want to use positive film. ideally, we'd like to use the sharpest film possible, so thought initially velvia. however, we're also going to be assessing each scanners range, so wanted a film with a little more latitude, which pointed us to Astia. however, i've read that Astia isn't as sharp as Velvia, so that made Provia seem like a good choice, as it's something of a comprimise on both ends... sharper than Astia, but wider that Velvia.

    do you guys have any suggestions for film choice? is our reasoning thus far off-base?

    any inputs would be greatly appreciated.

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    Re: Best Film For Scanner Comparisons...

    I've never heard that Astia wasn't as sharp as any other film. Astia is a great film with neutral color and it scans very well.

    You have some beautiful images on your website...keep up the great work!

  3. #3

    Re: Best Film For Scanner Comparisons...

    Velvia.

    The density range of the Velvia film will tax the capabilities of any consumer scanner, and it will make the differences in DMAX capabilities the scanners the most readily apparent.

    This is one issue that is not scalable. Even if you do very little (or no) enlargement, the limitation on DMAX will have an impact on the scanner performance. Many people focus on sharpness, and it is important, but I generall argue that for chromes, DMAX is in some ways equally important.

    On the other end, I would recommend Astia (or maybe EPN) as possible the easiest film to scan. A person scanning small source materials may be able to produce a better result with Astia than a larger format scanned on Velvia. It depends on how small and how large.


    ---Michael
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    and photogravure printing

  4. #4
    Michael E. Gordon
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    Re: Best Film For Scanner Comparisons...

    Scott: Astia has a lower RMS granularity rating than any of the Velvia's and greater resolving power, too. Take a look at Fuji's spec sheets for each.

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    Ted Harris's Avatar
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    Re: Best Film For Scanner Comparisons...

    I agree with Michael .... Velvia. We have been using a Velvia transparency in the ever continuing scan around and the decision was initiall made, in part, for exactly the reasons Michael stated.

    Scott ... one suggestion ... you might also want to have a "reference scan" made on a high end scanner as a point of comparison. Be careful when you do this thoughand make sure you have it made at solid high resolution ... at least 2400 for 4x5 and appripriately higher for smaller formats. If you take it to a lab/service bureau you are likely to get a scan measured in megabytes rather than SPI.

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    Re: Best Film For Scanner Comparisons...

    Quote Originally Posted by Scott Rosenberg View Post
    a friend of mine and i are laying out the test methodology we will employ in a study whereby we compare several scanners to determine which will hold up to enlargment better - smaller formats on dedicated film scanners or larger formats on flat beds. we are currently disscussing film choice and hoped to solicit some opinions from our friends on the forum.

    to make color comparison back to the original easier, we want to use positive film. ideally, we'd like to use the sharpest film possible, so thought initially velvia. however, we're also going to be assessing each scanners range, so wanted a film with a little more latitude, which pointed us to Astia. however, i've read that Astia isn't as sharp as Velvia, so that made Provia seem like a good choice, as it's something of a comprimise on both ends... sharper than Astia, but wider that Velvia.

    do you guys have any suggestions for film choice? is our reasoning thus far off-base?

    any inputs would be greatly appreciated.
    It sort of depends on what your purpose is. If you want to write up your results for general consumption you might want to use a tranny film like Velvia, a color negative film like 160Portra, and a B&W negative film like FP4+. The scanners will likely do some films better than others.

    Else, if you are doing the study for your own consumption to help you decide what scanner to buy, you might get more meaningful results testing with the film(s) you plan to use the most.

    Also, I suggest comparing the color of a scan to the original is a difficult and perhaps not terribly meaningful task. Unless your exposures are going to be made only in a studio where you control 100% of the light so that it has exactly the qualities that the film is balanced for, you are always going to have to make some color corrections post scanning. This means that no matter how accurate the scanner, you are still going to do some color correction. The only question left is how much.

    If in fact your film will only be shot in the studio with lighting matched to the needs of the film, then you might want to consider profiling the scanners first. The profile should zero out the scanner as it were and give you a more accurate idea of how well the scan file can match the original. IIRC however, profiling only works with tranny films. There's too much variability of density with negatives films to make a good profile. It's been awhile for me, you might want to check and see if that is still true.

    Bruce Watson

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    Moderator Ralph Barker's Avatar
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    Re: Best Film For Scanner Comparisons...

    Rather than selecting just one film to "tax the Max" of the scanners, how about using a series of representative films? That might be more directly applicable to various readers' situations. You might also compare the scanned results to densitometer readings from the selected films, so as to more precisely quantify where the scanners fall short. If you also include spot meter readings from the original scene (of the same points chosen for densitometer readings?), that would complete the picture, so to speak, for the comparisons.

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    Scott Rosenberg's Avatar
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    Re: Best Film For Scanner Comparisons...

    thanks for the inputs, fellas.

    PV, thanks for the kind words about my work - that's always appreciated!

    To the question of films and DMAX, we reasoned that a film with more DMAX would be the better test vehicle to see subtle differences in the capabilities of the test scanners. if the film is the limiting reagent in terms of DMAX, then we wouldn't be able to make any relevant conclusions about the relative performance of the scanners. it was initially our assumption that the best test of the scanners ability to resolve shadow and highlight detail would be a film that could record the widest range of values, thus enabling us to better determine even slight differences between the scanners.

    here's an extreme example... if i want to determine which scanner can resolve more levels of grey, would not the most appropriate test target be the one with the most levels available? a target with two values, absolute black and absolute white, would not yield a lot of granularity in the results. however, a target with 256 levels of grey would bring into sharp relief the differences, even fine differences, between the scanners. more to the case in question, if the test shot is set up with a full range of values, from absolute white to absolute black, would Asita, which presumably will have a more subtle transition to total black, not make for a better test vehicle than Velvia, which will goto to detail-less black much more abruptly? if I’m hearing you guys right, this is faulty logic.

    Ted, we’ve discussed including a reference scan and will likely do so. There’s no doubt that the highest quality will be attained from the largest film scanned on the best drum scanner. As a data point, that would be interesting to represent the pinnacle of what is possible.

    Bruce, we originally were doing this to answer a couple questions that we’ve been wondering about for some time, however, once we started to flesh out the experiment, we saw that the results might interest a broader circle. So, we decided to cast a wider net and incorporate some things that would add validity to the study, but weren’t exactly germane to our specific situation – such as including scanners that we didn’t have as part of our workflow and using the most appropriate film to the study, instead of the emulsions that we most commonly use.

    The test shots will be made in a studio setting under very controlled lightening. Every precaution is being taken to eliminate as many sources of variation as possible.

    Thanks for the commentary thus far, this has all been very helpful.

  9. #9
    Ted Harris's Avatar
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    Re: Best Film For Scanner Comparisons...

    Scott,

    A couple more things to consider:

    1) If your purpose is to deterine if you can get better results from scanning a 6x7 or 6x9 transparency on a Nikon 9000 scanner than you can get from scanning a 4x5 transparency on a 'prosumer' flatbed scanner the answer without doing a huge amount of testing is very likely .... but at about three times the price of the most expensive of the currently available 'prosumer' flatbeds.

    2) If you are thinking in terms of assisting others you might want to take a look at http://www.largeformatphotography.info/scan-comparison/ on this Forum's Home Page ... that is the 'scan aroound or Collaborative Scanning Exrcise' that I mentioned in my earlier post. There are many, many scanners currently in the comparison with more being added ... I will be sending the results of the Screen Cezanne to Leigh Perry soon and then the transparency off to get yet another scanner added.

    3) If your decision relates strictly to scanning (e.g. you would shoot 6x9 with a roll film back in a Field or Rail camera) then this could be a worthwhile exercise for you. OTOH, I find using a rollfilm back a PITA and much perfer the larger image size of 4x5 ... although I do like the 6x9 aspect ratio and that is the reason I shoot more 5x7 than 4x5. If there are other aspets of the larger film size that appeal to you then remember that, while you will definitely see differences between the Microtek i800 on the probable low end the the Epson v750 on the probable high end, these differences will be incremental, small and subtle and nothing will be equal from scnner to scanner ... that is that while I am sure the v750 will give you the best reolution I am lmost s sure that it will not give you the best dMax or density range, that you will likely get from the i900. If you enjoy this sort of testing for the sake of testing and have the retail outlets near you that will allow you to do such testing (another iffy proposition) then go for it ..... if not, count your pennies and buy a scanner and start scanning ....

    Just some more thoughts and not to discourage you but to give you some more info to chew on.

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    Re: Best Film For Scanner Comparisons...

    Quote Originally Posted by Scott Rosenberg View Post
    here's an extreme example... if i want to determine which scanner can resolve more levels of grey, would not the most appropriate test target be the one with the most levels available? a target with two values, absolute black and absolute white, would not yield a lot of granularity in the results. however, a target with 256 levels of grey would bring into sharp relief the differences, even fine differences, between the scanners. more to the case in question, if the test shot is set up with a full range of values, from absolute white to absolute black, would Asita, which presumably will have a more subtle transition to total black, not make for a better test vehicle than Velvia, which will goto to detail-less black much more abruptly? if Iím hearing you guys right, this is faulty logic.
    It... depends. I know, I hate that too. Still...

    If your scanner has the capability to set the limits on the log amp circuit (most drum scanners do this -- setting the black and white points for scanning directs the software to set the upper and lower limits for the log amp circuits), then your logic might indeed be faulty. Basically, such a scanner will translate whatever density range you present to it, be it 0.3 or 3.0, and convert that into a range of digital values (for an 8 bit scan, 256 levels, 12 bits -> 4096, etc.). That is, an 8 bit scan would result in 256 levels for a target with density range 0.3, 1.0, 2.0, or 3.0. All have 256 levels in the scan file.

    If your scanner doesn't have adjustable limits on the log amp circuits (it would read from 0 - Dmax regardless of the density range of the film it's scanning) than your method makes more sense. In this case, the scanner would give maximum levels for a full range target and fewer levels for a restricted density range target. That is, an 8 bit scan might result in 8 levels for a target with a density range of 0.3, 50 levels for the 1.0 target, 125 levels for the 2.0 target, and 240 levels for the 3.0 target. (I'm just pulling numbers out of the air, I haven't done any of the math. I'm thinking it's likely to be non-linear).

    So, rather than test with a high density range target, it might be more informative to test with targets of high, medium, and low density ranges. Then you might see differences in how many levels you get for a given density range.

    Bruce Watson

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