Video With Sun in the Frame

Discussion in 'Amateur Video Production' started by charles, Feb 16, 2014.

  1. charles

    charles Guest

    I want to try playing with time lapse of sunsets, both narrow (long
    lens) and the sky (wide lens setting)

    My Canon t2i book mentions several times not to let the sun in the
    frame when the mirror is up, the sun can cause damage to the camera. I
    have tried one shot using the Thousand Oaks Solar filter
    http://www.thousandoaksoptical.com/solar.html
    but it is too dark, too much attenuation. Noise in the video.

    Is there an appropriate ND filter that would protect the camera while
    permitting reasonable exposure?

    I want to try this with the t2i and also with a couple low end video
    cameras I have, only for personal fun at this time. I don't want to
    ruin the cameras.

    Thanks
     
    charles, Feb 16, 2014
    #1
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  2. charles

    Brian Guest

    For a time lapse you usually take a few frames of video every minute (or
    maybe less than a minute). The exposure for video would be about 1/30 sec
    at the slowest rate and any bright light can be reduced by the cameras
    aperture to avoid over exposure so I can't see any problem. If you had the
    shutter open for a longer period of time then it could cause damage to the
    camera but your recording would be too over exposed for this kind of
    exposure.

    I remember someone telling me that older video cameras had problems with
    the sun.

    Having said this it would be wise to double check with the manufacture of
    the camera to make certain there is no problem as I would not want you to
    ruin your camera.
     
    Brian, Feb 16, 2014
    #2
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  3. Remember that the viewing panel always shows the view through the lens;
    this implies that the image of the sun is always falling on the
    detector.

    For the OP:
    Astronomers use metal films (or occasionally ND plastic) with an
    optical density of 5, i.e., transmission ratio of 1/10,0000, for safe
    solar viewing.

    Look at a camera store for a screw-in filter of ND4 or more and you
    should be OK. ND3 might even be safe for the camera. I am being
    conservative, probably (hopefully, conservative enough!).
     
    Gene E. Bloch, Feb 17, 2014
    #3
  4. charles

    charles Guest


    Thanks for the info. I managed to confuse myself a bit more.
    http://en.wikipedia.org/wiki/Neutral_density_filter
    tells about ND filters and the optical density of /f stop reduction
    for different ones.

    One naming system gives ND3.9 as 13 stops, a different system gives
    ND4 as 3 stops.

    Are we using the system that gives 3 stops for ND4?

    Once upon a time I thought I understood the math behind the numbers,
    but that was long ago.

    Good ND filters seem a bit expensive, I ordered a couple sets of cheap
    ones to play with. I know stacking them will degrade the imiage, but
    it will give me some indication of the exposure needed.
     
    charles, Feb 17, 2014
    #4
  5. charles

    charles Guest


    2 stops for ND4, I can't remember from one page to another.
    <:)
     
    charles, Feb 17, 2014
    #5
  6. The only scheme I know of uses density = log base 10 (transmission),
    but usually the - sign is suppressed, i.e., the log is log (13) rather
    than log (1/13).

    So ND3.9 is 12.95551957 :)

    The other seems to be just taking the absorption directly, since 2
    stops is a factor of 4 (I saw the correction of your typo...).
     
    Gene E. Bloch, Feb 18, 2014
    #6
  7. charles

    charles Guest


    I received an answer from Canon. They don't know. :)
     
    charles, Feb 18, 2014
    #7
  8. charles

    Brian Guest

    Brian, Feb 18, 2014
    #8
  9. charles

    Brian Guest

    Also Try the Canon Forum as I have had a good response to my questions from
    this group.

    http://photography-on-the.net/forum/
     
    Brian, Feb 18, 2014
    #9
  10. charles

    charles Guest

    charles, Feb 18, 2014
    #10
  11. charles

    GaryT Guest

    If you are shooting a time lapse, maybe consider NOT shooting it AS video. I
    have always done time lapse as a series of still shots, using an
    intervalometer. I don't know the t2i specs but one can either purchase an
    intervalometer, use your watch and a remote shutter release and expose the
    frames manually (tedious), or be a little bit adventuresome and install the
    Magic Lantern firmware which has an intervalometer built in. Shooting stills
    with an automated setup on a sturdy tripod will have minimal mirror shake
    and does not involve using live view, so the sensor is not exposed to the
    sun more than a fraction of the time.

    Once you know the total number of shots needed based on the capture time,
    length of the final video desired, and number of frames per second you want,
    calculate the interval between shots and start capturing. Easy peasy.
     
    GaryT, Feb 22, 2014
    #11
  12. charles

    Brian Guest

    You should be aware that using the shutter a lot on a DSLR camera can wear
    out the shutter mechanism. It happened for a photographer using his DSLR
    camera for animation. At 30 fps, 1 minute of video will need 1,800 shutter
    operations. But if your sunset is going to last less than a minute then it
    won't require too many photos.
     
    Brian, Feb 22, 2014
    #12
  13. This is true, although the average animated "scene" is not likely to
    last longer than a few seconds - but if the total animated video is
    long, or if much more shooting is done to get enough good footage for
    even a fairly short video, the shutter-actuation numbers can increase
    to "disturbing" totals rather rapidly. Even the new Panasonic GH4 (with
    its rated likely mechanical actuation total before shutter failure of
    about 200,000 actuations) would be destroyed after shooting not much
    more than 100 minutes-worth of stills for video at 30p. Many mirrorless
    cameras now offer an alternative electronic shutter (it's quiet, has
    no "shake", and doesn't wear out), but using it with sun-shooting with
    no mechanical shutter cover over the sensor (or mirror protection for
    the mechanical shutter) returns us to the original problem (which
    doesn't appear to exist while shooting most normal stills and videos
    with these cameras with the sun included as long as the camera is in
    motion). Perhaps a solution would be to have some sort of flap cover
    for the lens (if needed by the camera and shutter-type used) to use
    between the exposures - but for cameras with mirrors and mechanical
    shutters (if one is willing to "spend" the shutter life doing the sun
    animations with it), doing this should not cause problems during the
    brief exposures used so long as the mirror is not locked up and the
    shutter is not locked open. But, I do remember that at least with the
    early Canon interchangeable Mini-DV camcorder, allowing the sun to
    hit the viewfinder could possibly damage that... (but that's likely
    irrelevant...;-).
    --DR
     
    David Ruether, Feb 22, 2014
    #13
  14. charles

    GaryT Guest

    What is not being taken into account is how those MTBF numbers are
    generated. As I understand it, samples of a particular model are mounted on
    stands, fired continuously until failure, then the results are averaged.
    Even in time lapse that is not how the camera is used in real life. In
    normal use there is a lot more time between actuations for the mechanism to
    rest and cool down compared to the testing process.

    However I am still trying to wrap my head around how using a ND filter
    solves the overall problem. Whether you are shooting in bright or dim
    conditions, at some point you need "X" amount of light for a certain period
    of time to get the desired exposure of each frame. If you can't limit the
    amount of light for the right exposure with a combination of shutter speed,
    aperature and ISO then you need the ND filter. If one is using the ND filter
    to block the light between frames, it is also blocking the light DURING the
    frame capture. So now (assuming you didn't otherwise need the ND) wouldn't
    you need to compensate by opening the aperature (and getting a DOF you may
    not want), slowing the shutter and perhaps getting blur, or raising the ISO
    and increasing the noise? I could easily be missing something obvious
    however. I agree that some kind of flap cover would do the trick, but that
    is basically just a supplemental "shutter" and would have it's own cost to
    create and possible downsides (like shake) to use.

    Depending on the value of the camera and the amount of time lapse one wants
    to shoot, it may be cost effective to just plan on the cost of shutter
    replacement as part of doing business.

    I am also not quite understanding how using a video camera is advantageous.
    You can extract frames and reconstruct them into the time lapse video, but
    *typically* for any given camera that can do both stills and video, won't
    the standard still shots be higher resolution than the video frames? When I
    look at video on a frame by frame basis, the frames never looks as sharp as
    a properly captured still image. That would indicate to me that the series
    of stills would be more likely to give the highest quality final result. But
    again, there is a lot I don't know and could be missing in my thinking
    process.
     
    GaryT, Feb 22, 2014
    #14
  15. Have you ever started a fire with a magnifying glass by focusing
    sunlight on a piece of flammable material?

    In this case the camera's detector is serving as the target.
     
    Gene E. Bloch, Feb 22, 2014
    #15
  16. charles

    charles Guest

    What I have so far, yesterday I got the ND filters to fit one of the
    video cameras, a JVC Everio. It has built in time lapse function, no
    mechanical shutter.

    The shot lasted 25 minutes in real time, I captured a frame once every
    10 seconds, and that is way too infrequent. After playing with the
    video on Premier Elements, it looks like one second intervals would be
    more appropriate.

    I used ND4 and ND8 stacked, which should have given me 5 stops of
    attenuation, and it looked to be about right for conditions yesterday,
    sunset over the ocean with some clouds.

    I don't know how to get EXIF from this camera, so I don't know what
    parameters the camera set up inself.
     
    charles, Feb 22, 2014
    #16
  17. I suspect that heating is not an issue unless the sequencing is
    done at nearly the highest possible firing rate, and even then,
    heat may not be an issue - but in real-world use, these shutters
    do wear out, although maybe not for the vast majority of users
    (ones NOT shooting massive amounts of stills, or doing animations).
    I don't think you are...!;-) I've shot the sun many a time, with
    lenses ranging from a 220-degree fisheye to 1400mm tele, on film
    without problems - and with a DSLR (with its "flappy" mirror and
    "bouncy" focal-plane shutter, the sensor is well-protected except
    during the (VERY brief) exposure, which should not cause a problem.
    I would use it only *between* exposures with cameras that do not
    protect the sensor from light...;-)
    C. $300 or so is not a "fun-accessory" cost, especially if done
    repeatedly...;-) But THIS may be one "plus" for having all those
    "old-fashioned" and "unnecessary" things moving around inside a
    digital camera (DSLR-type) before and during each exposure...;-)
    BTW, I just came back in from shooting 2,000mm and 4,000mm (35mm
    FF-equivalent) with my Panasonic G5 (sharp EVF, with magnification
    available for adjusting the VERY "touchy" focus - and I could use
    the "bounceless" electronic shutter option for shake-free exposures,
    fired with a $25 radio remote control...;-)
    The complete answer to this is complicated...;-) In general, what
    you pointed out is correct, but there are available a few still-
    cameras-that-shoot-video that are nearly as sharp with video frames
    as with still frames taken *with the same resolution*. Oh-oh! Here
    it comes...: those cameras are mostly made by Panasonic (and they
    are mostly inexpensive!). The Pan. GM1, G5, G6, GX7, GH3, and GH4
    all take very sharp video - with the GH4 able to shoot as high as
    4K resolution, all-I (real-frame) video, up to 96P, at data-rates
    up to 200Mbps, at up to 10-bit 4:2:2 (or derived 4:4:4) color,
    and the price is less than several current DSLR models! But, I
    rant...!;-) Recently I gave here the URLs for an amazing video
    on Wyoming that was shot with animated stills, and for some video
    output from the GH4, some of which is also astonishingly sharp
    (even with the slow data-rates required by streaming).
    --DR
     
    David Ruether, Feb 22, 2014
    #17
  18. Thaks for the info. Be sure to let us know how the higher frame rate
    looks!

    ISTM that you're having a bit of fun...
     
    Gene E. Bloch, Feb 22, 2014
    #18
  19. I think there is some confusion here...;-) Let's say you're
    trying to start that fire with the magnifying glass (which
    is maybe around f2...;-), but you are only permitting, say,
    the exposure of all that sun's intense fury focused on that
    dry tinder to pass only through a smaller part of the
    magnifying glass (say, through a center hole in a cover
    over the magnifying glass 1/4 of the original diameter of
    the glass, or 4-stops less, allowing 1/16th of the light's
    intensity through), and you permit it to fall on the tinder
    for only, say, 1/1000th of a second (the heat from which
    would be unnoticed even if it were focused on your hand
    instead of the tinder...;-). THIS is why this is generally
    OK to do with a camera type that redirects the light away
    from the shutter and sensor except during the brief time
    of exposure. Now with rangefinder (and mirrorless) cameras,
    there MAY be a different story! 8^)
    --DR
     
    David Ruether, Feb 22, 2014
    #19
  20. charles

    Brian Guest

    There must be a lot of people that have taken videos and photos with the
    sun in the background and caught the sun in their photos. Sometimes you
    can't avoid it when you move your camera to track a subject.
    I've also seem hollywood movies that shows the setting of the sun.

    Another possibility is to record the sun off a reflection such as a mirror
    or some reflective surface.
     
    Brian, Feb 23, 2014
    #20
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