Digital camera shots of CRTs

Discussion in 'UK Photography' started by Tony, Oct 1, 2012.

  1. Tony

    Tony Guest

    I've bought an old portable TV to supplment my 8bit mid-life crisis (I'm
    buying old ZX Spectrums). The portable is much better than our main LCD
    TV in terms of the quality of the image (believe it or not), and since
    I'm going to be doing some shocking badly soldering, I don't want to
    ruin the main TV.

    However, taking digital photographs of a CRT screen is a nightmare.
    Does anyone have any advice?

    I've got a Panasonic Lumix DMC-FZ8 [1] and a Panasonic Lumix FS18 [2].


    [1] http://en.wikipedia.org/wiki/Panasonic_Lumix_DMC-FZ8
    [2] http://www.panasonic.co.uk/html/en_...ras/DMC-FS18/Specification/6826523/index.html


    --
    Tony Evans
    Saving trees and wasting electrons since 1993
    blog -> http://perceptionistruth.com/
    books -> http://www.bookthing.co.uk/
    [ anything below this line wasn't written by me ]
     
    Tony, Oct 1, 2012
    #1
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  2. Tony

    spacecadet Guest

    Just use a shutter speed of 1/15 or slower so you get a complete frame.
    1/30 will not quite capture the two 50Hz scans which make up a complete
    frame.
     
    spacecadet, Oct 1, 2012
    #2
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  3. Tripod. 1/25th or slower. 2-3m away and zoom in.

    Other things that help might be to darken the room, but not black -
    just to minimise any reflections, and clean the glass too!

    A friend of mine makes beer money by buying broken spectrums, fixing
    them and selling them again!

    Gordon
     
    Gordon Henderson, Oct 1, 2012
    #3
  4. Tony

    Davey Guest

    That sounds as though he repairs rainbows. <g>
    I have an old US-sold ZX81, does anybody want to buy it? Don't all shout
    at once.....
     
    Davey, Oct 1, 2012
    #4
  5. Tony

    Tony Guest

    Thanks. I'll shall give that a go.
    Yes, if you can get them from somewhere without postage, then it's
    probably worth a few quid every time you fix one, eBay on the other hand
    probably strips that profit in both directions with postage and
    charges.

    --
    Tony Evans
    Saving trees and wasting electrons since 1993
    blog -> http://perceptionistruth.com/
    books -> http://www.bookthing.co.uk/
    [ anything below this line wasn't written by me ]
     
    Tony, Oct 1, 2012
    #5
  6. Tony

    Tony Guest

    Alright, thanks, I'll give that a shot.

    --
    Tony Evans
    Saving trees and wasting electrons since 1993
    blog -> http://perceptionistruth.com/
    books -> http://www.bookthing.co.uk/
    [ anything below this line wasn't written by me ]
     
    Tony, Oct 1, 2012
    #6
  7. Tony

    Tony Guest

    On eBay, if it works? Yes, ~£40 depending on condition.


    --
    Tony Evans
    Saving trees and wasting electrons since 1993
    blog -> http://perceptionistruth.com/
    books -> http://www.bookthing.co.uk/
    [ anything below this line wasn't written by me ]
     
    Tony, Oct 1, 2012
    #7
  8. Tony

    Rob Morley Guest

    Possibly more effective or convenient to stick a TV card in a PC and do
    a screen capture?
     
    Rob Morley, Oct 1, 2012
    #8
  9. Tony

    Tony Guest

    Interesting idea, and I might do that for other reasons (and I hadn't
    thought of it, so thank you), but I really want to photograph the screen
    as part of photographing the Spectrums, to document the progress I'm
    making (for my own personal enjoyment) in terms of fixing them up.

    Sort of 'haha look how crazy this is, playing Manic Miner on an old
    portable TV with a real Spectrum' without having to go 'sorry you can
    only see a 1 inch strip of the picture'.

    --
    Tony Evans
    Saving trees and wasting electrons since 1993
    blog -> http://perceptionistruth.com/
    books -> http://www.bookthing.co.uk/
    [ anything below this line wasn't written by me ]
     
    Tony, Oct 1, 2012
    #9
  10. Tony

    D.M. Procida Guest

    If you have children, buy them Commodore 64s and whatnot for Christmas.
    They love them. Mine do anyway.
    Is this something to do with digital photograohy in itself, or just the
    cameras you're using?

    Daniele
     
    D.M. Procida, Oct 5, 2012
    #10
  11. Tony

    Woody Guest

    "D.M. Procida" <>
    wrote in message
    A TV picture is made up of 25 full pictures or 50 frames (half
    pictures) per second. Each frame is a full scan of the, say, odd
    numbered lines - 312 of them - followed by a full scan of the
    even numbered lines - the other 312. In practice you actually
    only see 576 lines the others being used for data, text, and
    other similar additions. This is called an interlaced picture.

    It this follows that to even come near to a complete picture of a
    CRT screen you will need to have an exposure of at least 1/25th
    second or longer. If you don't you will get a bright band of the
    part of the screen scanned whilst the shutter is open with the
    rest being darker as it decays.
     
    Woody, Oct 5, 2012
    #11
  12. Tony

    Geoff Berrow Guest

    I think you may still get a bright band as the scan is continuous.
    Long time since I've done it. As long as it's a still image on the
    screen, I'd go for as long an exposure as is possible to minimise
    this.

    Interestingly enough I've photographed our plasma screen several times
    and the results are always perfect. Perhaps that isn't retro enough
    for you though Tony. ;-)





    Geoff Berrow
    www.slipperyhill.co.uk
    New CD, 'Gathering Speed' out now! Available
    on our website or from iTunes/Amazon
     
    Geoff Berrow, Oct 21, 2012
    #12

  13. I've "successfully" photographed CRT screens using a similar camera
    as one of those available to OP - a Panasonic Lumix DMC-FZ7 -
    rather than a FZ8. The FZ8 is still in its box.

    This is one of the try-out shots without cropping.

    http://i47.tinypic.com/33mpmo2.jpg


    The image on the screen is a still from an off-air videotape
    of a film. which was used for a "now and then" film locations
    website. (Hanwell Library/Carry on Constable)

    The quality isn't up to much but banding has been avoided.
    Another problem was moire.

    Unfortunately I can't remeber exactly what I did, only that it
    only took around five minutes experimentation altering the
    the shutter speed and stop. One thing I do remeber doing is
    pre-focussing on the Phillips Logo on the bezel beneath the
    screen before each shot which may account for the tilt.



    michael adams

    ....
     
    michael adams, Oct 22, 2012
    #13
  14. Er....However looking at the EXIF information suggests
    it was 1/50 sec at F8

    Other details will be the same as for the OP's camera.



    only that it
     
    michael adams, Oct 22, 2012
    #14
  15. Tony

    Ian Jackson Guest

    I think I'm right in saying that with LCD (and probably also plasma)
    displays, a pixel remains in a constant level of brightness for a period
    of a whole field. It is only when the pixel is refreshed that its
    brightness can change. This is one of the things that causes flat screen
    pictures to move jerkily. However, an any instant, as nothing in the
    picture is changing, it has the advantage of being easier to photograph
    with a fast-ish shutter speed.

    On the other hand, with a CRT, once a pixel (or the equivalent thereof)
    is illuminated by the electron beam, its brightness then progressively
    decays until the next field, when beam hits it again. As a result, at
    any instant, part of the picture is always fading away, and you need a
    longer shutter speed in order to capture the whole 40ms picture.
     
    Ian Jackson, Oct 22, 2012
    #15

  16. Although I do have flat screens, which may or may not have given
    a better result - the VHS was already hooked up to a Philips CRT
    and I remebered having successfully done this before. In the distant
    past I also successfully photographed computer generated output on
    a CRT on film so as to get accurate colour matches - this was before
    the days of affordable and accurate colour printers

    And as is pointed out in my follow-up post, having belatedly thought to
    actually refer to the EXIF information nowadays thoughtfully
    provided gratis along with the snaps

    that particular shot was taken 1/50 sec at F8

    Allegedly



    michael adams

    ....



     
    michael adams, Oct 22, 2012
    #16
  17. Tony

    Rob Morley Guest

    Long ago I did some colour negative shots of a CRT TV, darkened room,
    think it would have been a normal lens, medium aperture and auto
    shutter with ISO 100 - I don't recall any problem with banding.
     
    Rob Morley, Oct 22, 2012
    #17
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