File Size vs. Printed Photo Size

Discussion in 'Digital Cameras' started by Richard Belthoff, Mar 19, 2005.

  1. I finally bought the Lumix FZ20k. It includes a variety of photo size
    options, from TIF to JPG, from 2560 to 640, from find to now to fine.
    Are there general recommendations about file size vs. the type of photos
    one might want to print? For example, if I will never exceed 5x7, can I
    reduce from, say, 2560 to 1280, and not worry about it?

    Thx.

    -Rich
     
    Richard Belthoff, Mar 19, 2005
    #1
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  2. Richard Belthoff

    rafe bustin Guest


    See the vast thread about "Big Megapixels."

    Bottom line... yes, of course you can make you
    file size smaller, but that limits your options
    in the future.

    *Why* do you want smaller files? More pictures
    per memory card? OK, but cards are cheap.

    It's up to you... that's why there are choices.
    That instruction manual may explain some of
    the tradeoffs, if they're not obvious.


    rafe b.
    http://www.terrapinphoto.com
     
    rafe bustin, Mar 19, 2005
    #2
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  3. A general recommendation is to print at 300ppi or thereabouts.
    Following the general recommendation, 2560 allows to print 8.5 inches,
    and 1280 allows 4.3 inches. Printing larger will result in visible
    loss of sharpness, but some people tolerate that.

    Bart
     
    Bart van der Wolf, Mar 19, 2005
    #3
  4. It's a commonly made recommendation. That doesn't mean one has to follow
    it.

    (As an aside: I find it comic that people discussing the latest and
    greatest technology persist in using inches. It's like measuring the
    cargo capacity of the Space Shuttle in bushels.)

    I suggest you run a few tests and determine for yourself what you need.
    I can't see the difference between 120 pixels per cm (300 pixels per
    inch) and 100 without a magnifying glass. I suspect that if you took a
    dozen photographs of a dozen different subjects and printed some after
    resampling to 120 and some to 100, practically no-one could tell you
    which was which on naked-eye inspection.

    At 80 ppc you still have to look closely to see any unsharpness - you
    can get very good prints at 80 ppc. Even 60 ppc is in my experience good
    enough for large prints of most subjects (though pixellation is visible
    if you have *very* high-contrast lines.)

    So 1280 will give very good results on a 16cm photograph (approx 7
    inches).

    Having said that, I would recommend taking most photographs at maximum
    resolution. It gives you room for cropping, for example. Once you've got
    them on the computer you can decide to leave the best ones in original
    form and trim down the so-so photos to a smaller size if you wish to
    economise on disk space or make backing-up easier. (There are a few
    people around here with money coming out of their ears who say you
    should just go off and buy a few more hard disks, but that isn't
    practical for everyone.)

    As for TIFF/JPG, I'd suggest that medium-compression JPG is likely to be
    good enough for almost all purposes. You might need finest JPG if you
    are cropping very heavily (i.e. printing a small area out of the photo)
    or are doing a lot of post-processing. I wouldn't bother with TIFF at
    all unless and until you know precisely why you need it.
     
    Stephen Poley, Mar 20, 2005
    #4
  5. Richard Belthoff

    Bob Williams Guest

    You paid extra bucks to get 5MP. Why not use all those MP?
    You may THINK you won't print larger than 5 x 7 but as you gain
    experience you will be making more and more 8 x 100s
    The only reason to shoot smaller is to conserve memory card space.
    That was a valid concern a few years back when a 1GB card cost $300.
    But today you can find a 1GB card for $75. Get one and don't look back.
    Shoot at highest resolution and lowest compression.
    That is what you paid for .....use it.
    Bob Williams
     
    Bob Williams, Mar 20, 2005
    #5
  6. I finally bought the Lumix FZ20k. It includes a variety of photo size
    As a general rule, you want 300dpi in a final print. (400dpi looks
    better, but beyond that you don't get much improvement. A 200dpi
    print doesn't look all that bad, either). So for a 5x7, you want
    1500x2100, or about 3.1Mpix. With JPEG encoding, you can get the file
    size down, but you're really better off using compressed TIFF. Some
    pictures look fine after they've been JPEG encoded; some look
    terrible.

    -Joel
     
    Dr. Joel M. Hoffman, Mar 21, 2005
    #6

  7. I don't believe that you (or anyone else) can tell the difference
    between a 300 dpi print and a 400 dpi print.
     
    Stephen Poley, Mar 21, 2005
    #7
  8. Richard Belthoff

    Bubbabob Guest

    If you have fine vertical lines or parallel diagonal lines, you'll see
    the difference. You need to pick a print resolution that has a
    relationship to the actual pitch of the nozzles. For all Epson and Canon
    printers it's 360 ppi. 720 works but there's not much point in it. Other
    values will cause moires.
     
    Bubbabob, Mar 21, 2005
    #8
  9. Richard Belthoff

    Bubbabob Guest

    If you want to find out what the appropriate rez for your printer is, go to
    this site, download the PDF files and print them. It will be obvious. A
    little empirical science beats a whole lot of anecdotal rot.

    <http://www.inkjetart.com/tips/ppi/>
     
    Bubbabob, Mar 21, 2005
    #9
  10. OK, we may be talking at cross-purposes. If we're talking about the
    actual printing process, I agree with your comments. There can be
    reasons for having a printing pitch finer than the resolution of the
    image being printed. But the OP was talking about photo image size.

    It's also true that my statement required some qualifications - but I
    decided to get a reaction first and then add them. ;-)

    See my other post.
     
    Stephen Poley, Mar 22, 2005
    #10
  11. Having made a sweeping statement, I guess I'd better add the
    qualifications.

    Firstly: I have frequently seen it said that the major commercial labs
    do no better than 300 pixels per inch, and I have seen no evidence to
    the contrary. And based on the evidence of what I have seen friends and
    acquaintances producing, one isn't going to improve on the quality of
    commercial labs with the run-of-the-mill printers that most people have.
    One is going to have to expend considerable money and effort. In that
    context the bald statement to an apparent newbie that 400 dpi (I gather
    pixels per inch was intended) looks better than 300, with no further
    qualification, is simply silly. Hence my rather sweeping reaction.

    Having said that, I remain rather skeptical about the claims of the
    megapixelphiles as far as real photographic situations are concerned.
    Yes, in testcard-like situations there may well be a visible difference.
    But no-one I know wants to look at photographs of testcards. Yes, if one
    is photographing fine black and white print, there may be a difference.
    I use a scanner/photocopier, not a camera. The line resolution tests you
    refer to apply only to pure black / pure white line pairs. Replace them
    with medium brown / medium green line pairs and you won't get even
    approximately the same results.

    In any case, for 80% of the camera users I have met (note that I didn't
    use the word photographer) striving for anything over 300 ppi would
    certainly be a complete waste of time.
     
    Stephen Poley, Mar 22, 2005
    #11
  12. Rubbish. The pack of paper lying in front of me now announces its
    dimensions as 210x297mm. Nothing about inches. My local processing
    service offers 13cm photos, 20cm photos etc. Nothing about inches.
    Who said anything about 100 dpi? I didn't.
     
    Stephen Poley, Mar 22, 2005
    #12
  13. Richard Belthoff

    Bubbabob Guest

    Noritsu 3101 processors, pretty much the top of the line, use 320 ppi.
    Fuji Frontiers operate at 400 ppi.
     
    Bubbabob, Mar 23, 2005
    #13
  14. Richard Belthoff

    Bubbabob Guest

    The accomodation for metric papers is in the printer driver software. The
    ink nozzles are laid out in inches.
     
    Bubbabob, Mar 23, 2005
    #14
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