Camera size vs enlargement size.

Discussion in 'Darkroom Developing and Printing' started by Some Dude, Jun 24, 2004.

  1. Some Dude

    Some Dude Guest


    I need to copy (photograph) an 8x8' (yes, foot) charcoal drawing and
    then reduce the photo to something that will fit inside a door (e.g.
    around 4x6'). I am wondering what sort of camera I am going to need
    for this to print without having to enlarge the transparency. Is this
    impossible? 4x5? Bigger? gulp, 8x10 format?

    I am hoping to retain the exact original quality and then even have a
    sharper output when the image is reduced.

    Am I dreaming?

    Some Dude, Jun 24, 2004
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  2. Some Dude

    Hemi4268 Guest


    The math is kinda simple. The eye sees about 8 lines per millmeter at 10
    inches. So that is what you need to make a exact 8 ft by 8 ft original.

    Now all you have to figure is the reduction. 8 ft x 8 ft to a 1 ft by 1 ft
    image is a 1:8 reduction. The resolution will need to be 8 times as great or
    64 l/mm on the 1ft by 1 ft image This can be done with modern equipment and

    Hemi4268, Jun 24, 2004
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  3. Some Dude

    Mark A Guest

    I would consider doing something with digital printing. Should work fine for
    a charcoal drawing.
    Mark A, Jun 24, 2004
  4. Let's calculate how well it could be done with 35-mm equipment, just as a
    point of comparison.

    I presume this is color, so you'll be using something like Ektachrome 100 or
    Fuji Velvia film with a resolution of about 100 lines per mm.

    Your camera lens, assuming a very good one, will probably resolve at least
    half this; say 50 lines per mm.

    That's across 1 inch of film. Your original is 8 x 12 = 96 inches wide.

    So on the original, you will be resolving 0.5 lines per mm. That will *not*
    capture the details of the pencil strokes, or whatever, although it will
    look fine when viewed from a distance.

    I'd suggest 4x5-inch sheet film as a minimum; 35-mm is not up to the task,
    but something 4 times bigger (4x5) probably would be acceptable.

    Making the enlargement will be much harder.

    Have you considered using digital technology? Again, even the best digital
    SLRs right now aren't going to do any better than 35-mm film. But you could
    cheat by running a sharpening filter to bring out some detail that is partly
    lost. The results might be quite pleasing, and you could make the
    enlargement on a digital printer.
    Michael A. Covington, Jun 24, 2004
  5. I think 4x5 would do it, 35mm definitely would not. Use
    something like 100T-Max. The big problem is going to be
    printing it, the same problem as in photo-murals. Vibration
    is the enemy here. You will have a long throw and probably a
    long exposure time. Depending on what's available in your
    area having the negative scanned and printed electronically
    might result in better quality. Electronic printing will
    also give you the ability to modify the image if desired.
    Increasing edge sharpness is not possible for large
    negatives since "acutance" effects are of fixed scale.
    Using as long a lens as possible on the camera will help
    with uniformity of illumination of the negative. You may
    have to use polarizers on the lights and lens to eliminate
    surface reflections. It is certainly a practical project, I
    rather think the best technique is to use a photographic
    negative and electronic printing.
    Richard Knoppow, Jun 24, 2004
  6. Some Dude

    Hemi4268 Guest


    Actually you could do this in 35mm if you take enough pictures. Just figure
    where you would get about an 8:1 ratio reduction and snap away. Scan all the
    images and put them together with a good merge software.

    Hemi4268, Jun 25, 2004
  7. Some Dude

    Some Dude Guest

    Folks thanks for the info.

    I assumed 4x5 without really thinking about it and it seems the way to
    go. As cost is not a factor I am considering tmax 100 4x5 and then
    having it output onto a digital printer (lightjet/vutek?) ..Not sure
    what the client wants as far as material...

    Q: So why not just frame the original?

    A: How many houses do you know can fit 8'x8' framed drawings into
    their doors? :)

    Some Dude, Jun 25, 2004
  8. Some Dude

    Some Dude Guest

    I never considered doing this job with digitals but...

    I do have two digitals. A D1X and a D100. They are both right around
    6MP. I don't know too much about them technically but based on some
    preliminary tests on my inkjet (epson 2200) and a loupe seems to imply
    that a 6MP camera can't even get close to a blowup of the size I am
    requiring. (minimum 3-5' x and y). Maybe i'm wrong- I don't know the
    megapixel-to-print size ratio either..

    Some Dude, Jun 25, 2004
  9. Some Dude

    Digitalis Guest

    You can do it with the digitals if you are careful. Create a mosaic of
    shots, then stitch them together using Photoshop or stitching software.
    Use care in how you create the mosaic, you need to know where each shot

    As for megapixels you need keep in mind that most printers work in the 200
    to 300 dpi range. As a rough guide, take your final image size, say
    5 feet square, convert to inches (60 inches square) then multiply each
    final dimension by the resolution requirement of your printer. In this
    case, for a 300 dpi printer:

    total pixels = 300 dpi * 60 inches high * 300 dpi * 60 inches wide
    total pixels = 324,000,000 or about 324 megapixels.

    It is an exercise for the reader to figure out how to get a mosaic of this
    size and whether it is necessary for a satisfactory print. Note that
    viewing distance is not taken into account using this calculation, and you
    may be happier with a smaller mosaic.
    Digitalis, Jun 27, 2004
  10. Work backwards:

    sqrt (6,000,000) =~ 2,500 pix/side

    5ft = 1524 mm

    The smallest pix you can do is .6 pix/mm

    I will leave it to someone else to determine the minimum viewing
    Nicholas O. Lindan, Jun 27, 2004
  11. [5ft x 5ft print with 6Mpix camera - what happens]
    Eye resolves ~1 arc-minute = 1/60 degree = 3e-4 radians

    Using sin(a) ~= a in radians

    pixel size / distance = 3e-4 rad

    distance = 0.6 / 3e-4 = 2,000 mm = 2 m =~ 7 ft

    If you keep the audience kinda far away the
    print will look OK.

    In the general case a 6Mp picture will look
    OK if it subtends 40 degrees or less.
    Nicholas O. Lindan, Jun 28, 2004
  12. Some Dude

    Peter Zisson Guest

    Q: So why not just frame the original?
    Actually, a flat sheet 8' sq. is not that far from the opening of a standard
    36" door, which is about 85" corner to corner. If the backing is flexible
    it could be curved without kinking.
    Peter Zisson, Jun 28, 2004
  13. Some Dude

    Al Doyle Guest


    Trust your 2-1/4 camera to do good job. Use the slowest
    film you can obtain, with a really sharp developer like Rodinal
    diluted 1:100. When I had to do such work I used Agfa !FF,
    Panotomic X, or ADOX KB-14. Making the enlargement is
    just a matter of turning your enlarger around on its baseboard,
    so that it overhangs your desk, and projects the image to the
    floor. Raising the baseboard with boxes will get you still larger

    If that isn't enough, obtain a first surface mirror and place it
    under the enlarger lens at a 45 degree angle. This way you
    can project the image across the darkroom as far as you need.
    Use two-sided tape to hold the paper to the wall. Be mindful to
    take some of the tackiness out of the tape, or the paper will
    tear when you try to remove it the first time.

    With this method I've made murals from subminiature negatives as
    small as 10 x 14mm in area. So your 2-1/4 negative should be just fine.

    Best regards,

    Al Doyle

    (please remove the Z)
    Al Doyle, Jun 28, 2004
  14. Some Dude

    John Guest

    Shoot with the largest camera you have available. Preferably
    8X10 which is easily scanable on a Howtek 8000.


    John S. Douglas, Photographer -
    Please remove the "_" when replying via email
    John, Jun 29, 2004
  15. Some Dude

    John Guest

    Not only can I fit them through my doors, also through my
    windows. Try making that into a darkroom !


    John S. Douglas, Photographer -
    Please remove the "_" when replying via email
    John, Jun 29, 2004
  16. Some Dude

    John Guest

    Fageddabout digital ! It's about as good as color film from
    the early 60's.


    John S. Douglas, Photographer -
    Please remove the "_" when replying via email
    John, Jun 29, 2004
  17. Some Dude

    Some Dude Guest

    Forgive me for picking on you but, rodinal diulted 1:100 is not
    "harp". I am somewaht familiar with this stuff for its exact
    *opposite* properties. So maybe you're talking 1:25 but 1:100 you're
    on crack, man ;) (not flaming you).

    Tmax 100 is the perfect 4x5 film to use for this project, i'm
    convinced. Anything slower is probably not worth it and not

    You have some great *inventitive* ideas there but I'm shooting big -
    Sinar P2 with a Rodenstock 65/4.5 is what i'm planning to shoot with
    right now.

    The transparencies are going out to a lab to be printed on the same
    paper the charcoal was done on (charcoal paper? its like a rough
    yellowish constructon paper).

    I will keep this in mind for future thoughts.


    Some Dude, Jun 30, 2004
  18. Some Dude

    Some Dude Guest

    hear hear John! ;)

    Sorry I don't have enough time in the day to get the miniscule
    particulate that accumulates on my CCD after changing a lens in a
    walk-in autoclav.


    Some Dude, Jun 30, 2004
  19. Some Dude

    one_of_many Guest

    Charcoal images generally have a very compressed tonal range and are well
    suited to very fine, high-contrast film - or very fine film underexposed
    and over-developed. 4x5 will do just fine. Even 6cm will work.
    one_of_many, Jun 30, 2004
  20. Some Dude

    John Guest

    Tech Pan, 4X5, HC110 Dil. F, EI 16.


    John S. Douglas, Photographer -
    Please remove the "_" when replying via email
    John, Jul 2, 2004
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