Page 1 of 2 12 LastLast
Results 1 to 10 of 17

Thread: Why scan to compare?

  1. #1

    Join Date
    Dec 2001
    Location
    NJ
    Posts
    6,491

    Why scan to compare?

    In the thread " LF vs MF lens quality", Stewart Skelt reported on comparisons of scans of "a bunch of 35mm, 6x6, 6x12 and 6x17 shots." Michael Reichmann also scans film before comparing shots.

    Pardon my ignorance of digital photography, but would y'all take pity on me and please explain how and why more can be learned from examining scans of negatives/transparencies than from direct examination of the negs/trannies? I've never got it, I still don't get it, and the practice is so prevalent that I fear I'm missing something important.

    Thanks,

    Dan

  2. #2

    Re: Why scan to compare?

    Hey Dan,

    I think its likely because more people have scanners than microscopes. Otherwise the ability to change views and magnifications with a click, side by side comparisons of more than one sample on screen together and the ability to quickly crop out equal film or subject areas are pretty good reasons as well.

    Using scans for lens evaluation has its pitfalls since it requires proven and polished technique to compare across formats and maybe even scanners with confidence, but so does making prints to compare results from different lenses.

    And if you're all set up to scan and print digitally then what else would you use than the tools at hand?
    Last edited by Henry Ambrose; 30-Jun-2006 at 08:10.

  3. #3
    Sheldon N's Avatar
    Join Date
    May 2006
    Location
    Portland, OR
    Posts
    606

    Re: Why scan to compare?

    I think it's because most people want to see for themselves. If you posted a web article with no examples to view, then its a lot harder for people to trust the author's own private conclusions.

    The second reason is because most people are now printing their color film in some sort of digital process. Since the film is going to be scanned anyway, it's just an assumed step in evaluating the shot.

    I agree with you, though, that the most accurate way to evaluate the film is with a high powered loupe or microscope.

  4. #4

    Join Date
    Dec 2005
    Location
    Southern California
    Posts
    2,721

    Re: Why scan to compare?

    What Henry said.

    Even more people have computers than microscopes. The real appeal of Inernet is its immediacy and direcntess. It is one thing to read a verbal description of what some expert or the other saw under their microscope a couple of months before the magazine went to print and quite another to see it the same day on your monitor.

    It also allows instant comparison of different opinions and claims. Yes, it is not perfect, but neither is film exposure and development.

  5. #5

    Join Date
    Sep 2003
    Location
    God's Country
    Posts
    2,077

    Re: Why scan to compare?

    Quote Originally Posted by Sheldon N
    I think it's because most people want to see for themselves. If you posted a web article with no examples to view, then its a lot harder for people to trust the author's own private conclusions.
    I have to agree with you. People need to "see" with their own eyes before believing something... especially on the www.

    However, the funny thing is that it's often times really difficult to make any qualitative judgements based on images posted on the net because the quality isn't very well represented on a computer screen!

    Personally, I'm like Dan in that I prefer to look at a transparency or negative through a good loupe.

    But, in essence, I think Henry hit the nail on the head - More scanners around than microscopes and every person scanning is instantly an expert scanner!

    Cheers
    Last edited by Capocheny; 30-Jun-2006 at 10:12.
    Life in the fast lane!

  6. #6
    Moderator Ralph Barker's Avatar
    Join Date
    Sep 1998
    Location
    Rio Rancho, NM
    Posts
    4,719

    Re: Why scan to compare?

    Another point that is often (conveniently?) overlooked is that the scanning process inserts another set of optical variables into the comparison. That may or may not be misleading, even if the same scanner is used, theoretically applying the same level of degradation to both scans. But, as mentioned by Henry and others, some method of presentation is "demanded" by the Web-viewing public, even if scientifically inappropriate.

  7. #7

    Re: Why scan to compare?

    People have become very use to looking at images on their computer monitor. There is also the practical matter of sending transparencies around so people could look at them through a loupe or microscope. Anyway, though you might find this interesting:

    http://www.porteous.net/test/digi.html

    Basically, very simple, not very well done, and looks like crap on a monitor. However, I do find it interesting that this site tries to show what a portion of an image looks like through a microscope.

    The only (somewhat) respected author who has not posted resolution images is Erwin Puts. He claims near 90 lp/mm from Kodak E100G and Fuji Astia 100F, though interestingly bashes the higher claims from Zeiss for various films. Probably many people would respect what Zeiss publishes, but they rarely have images or illustrations indicating their results.

    I think a quantitative approach to imaging is a product of the internet in general, and somewhat influenced by a seemingly endless marketing approach of MegaPixels. The reality is when you investigate many of the big name photographers it is not always apparant what film, camera, scanner, or any other gear they might use. Their images can often stand above their technical merits, or lack of technical merits.

    Ciao!

    Gordon Moat

  8. #8

    Join Date
    Sep 2003
    Location
    South Carolina
    Posts
    5,169

    Re: Why scan to compare?

    Quote Originally Posted by Ralph Barker
    Another point that is often (conveniently?) overlooked is that the scanning process inserts another set of optical variables into the comparison. That may or may not be misleading, even if the same scanner is used, theoretically applying the same level of degradation to both scans. But, as mentioned by Henry and others, some method of presentation is "demanded" by the Web-viewing public, even if scientifically inappropriate.

    I use a microscope to examine resolution. However, one issue that may not be immediatley apparent is that observation through a microscope will not necessarily show you how the negative will print. For this you might need to view the magnified image through a filter of similar wavelength to the spectral sensitivity of the process.

    But on the issue of scanning, does anyone know of a standard protocol on scanning and presenting the results on the net that would be widely accepted as valid and that would be capable of illustrating actual differences in sharpness, and in resolution up to around 60-70 lppm?

    Sandy King

  9. #9
    Moderator Ralph Barker's Avatar
    Join Date
    Sep 1998
    Location
    Rio Rancho, NM
    Posts
    4,719

    Re: Why scan to compare?

    Quote Originally Posted by sanking
    . . . does anyone know of a standard protocol on scanning and presenting the results on the net that would be widely accepted as valid and that would be capable of illustrating actual differences in sharpness, and in resolution up to around 60-70 lppm?
    I haven't seen anything, but that doesn't mean much. Each of the Web-based reviewers seem to follow their own procedures. It would be nice, however, if those who run such tests could agree on a standard protocol, and invite public comment prior to finalization - much the same way as ISO committees work.

    We might be able to set up a private group sub-forum here for those discussions, if there's interest.
    Last edited by Ralph Barker; 30-Jun-2006 at 15:24.

  10. #10

    Re: Why scan to compare?

    I fear that I may have misrepresented myself in the post in which I was quoted. I am not scanning in order to compare. I am scanning in order to print. However, I am scanning a large number of pictures all taken with the same three cameras and with a limited number of lenses, on the same scanner, and looked at on the same monitor. Over time I have built up a good knowledge of which of my lenses are sharper than others.

Similar Threads

  1. How long does it take you to scan ?
    By QT Luong in forum Digital Hardware
    Replies: 14
    Last Post: 10-Dec-2012, 06:17
  2. How do you scan for web-publishing?
    By Patrik Roseen in forum Digital Processing
    Replies: 4
    Last Post: 21-May-2006, 14:10
  3. Aliasing and scanning resolutions
    By Ed Richards in forum Digital Hardware
    Replies: 31
    Last Post: 20-Oct-2005, 22:35
  4. Why scan 8x10 at all?
    By Frank Petronio in forum Digital Hardware
    Replies: 17
    Last Post: 27-Dec-2004, 20:26
  5. CannoScan 9900F... Preview Scan vs Final Scan
    By Scott Rosenberg in forum Digital Hardware
    Replies: 10
    Last Post: 30-Oct-2004, 04:19

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •