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  1. #1
    Join Date
    Nov 2004
    Location
    Charlestown, MA
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    28

    1-4 Hour Exposures with FZ20?

    I am a soon-to-be FZ20 owner and wanted to know if any current Panasonic users have tried long exposures (over 15 minutes). I am interested in taking photos of star-trails at night like I was able to on my old film SLR. However, reading the FZ20 specs I am not sure if this is possible.

    Can anyone shed some light (no pun intended) on this for me please?

    Thanks!
    Pete

  2. #2
    Join Date
    Sep 2004
    Location
    western pa
    Posts
    2,334
    There is no bulb exposure so I do not think it would be possible.
    8 seconds is the longest exposure.
    .






    Gene
    http://grc225.zenfolio.com/
    http://imageevent.com/grc6
    one of these days I'll understand!

    Panasonic FZ20 & FZ30,FZ18
    D50 -- D80

  3. #3
    Join Date
    Nov 2004
    Posts
    22
    I was wondering about this, too. I have access to an observatory and take astronomy photos, and I thought it would be fun to hook up my new FZ20 to one of the telescopes to take some nice shots (haven't done it yet). The 8 second exposure time is more than enough for most heavenly things (most planets, moon, many stars and galaxies, comets, etc) but a longer exposure would be helpful. Too bad there isn't a firmware upgrade or something we could do to force the shutter to remain open while the CCD gathers.

    Oh well. Still a good camera.

  4. #4
    Join Date
    Nov 2004
    Location
    Charlestown, MA
    Posts
    28
    Thanks for the info. Do either of you know of any similar digicams in the $500 range that offer a B (bulb) exposure option?

  5. #5
    Join Date
    Dec 2004
    Location
    Goffstown, NH
    Posts
    47
    my guess is that you'll never see any ccd-based camera with >1minute exposure times using pure optical methods; even if the software would let you, it wouldn't work. (I am not an expert in astrophotography or CCD sensors, but do have a lot of digital signal processing experience) One of the big differences between film and CCDs (or any electronic sensor) is that film does a wonderful job of accumulating photons and nothing else. Electronic sensors have noise & drift which generally make them very poor at accumulating signals (adding them up over time) over a long timescale.

    However -- the right way to do this (and my guess is that this is how real astronomers work with images from CCDs) is to use the sensor to make the best use of its dynamic range and noise characteristics, and then take lots of pictures and combine them digitally by just adding up or averaging the light levels on a pixel-by-pixel basis. (you would need software to do this, and would probably want to use a lossless format like TIFF rather than JPEG) For example if you wanted a 1-minute exposure equivalent, take 60 1-second exposures or 30 2-second exposures, with the camera in the same spot, and process them digitally. If you take exposures that are too short, the signals are too small for the camera to convert the CCD's analog levels to digital. If you take exposures that are too long, you run into the noise/drift issue.

    I tried searching on google for "ccd long exposure minute OR minutes" and found lots of sites, one that looks informative is http://www.starizona.com/ccd/index.htm. "Regular" consumer cameras aren't really great, an acquaintance of mine is big into astrophotography and he has a special chilled CCD (cold generally lowers electronic noise) with an adapter for his telescope.

    good luck...
    --Jason

  6. #6
    Join Date
    Jul 2004
    Location
    Los Altos, CA
    Posts
    2,635

    Digital "Film" does have its limitations...

    Quote Originally Posted by freshlightphotographer
    Thanks for the info. Do either of you know of any similar digicams in the $500 range that offer a B (bulb) exposure option?
    Those little potential wells that hold the electronic charge corresponding to the light collected at each photo site on the CCD imager, can only hold their charge for so long without losing it to natural leakage that happens in any semiconductor chip. I'm afraid it would take some other technology to allow for extremely long exposure times. Your best bet would be to use an "intervalometer" technique with cameras that are compatible (the FZ20's remote input may make this possible) to periodically sample the image, i.e., take multiple shots of the sky or whatever you're shooting.
    Let a be your umbrella!

  7. #7
    Join Date
    Sep 2004
    Location
    western pa
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    2,334
    Quote Originally Posted by John_Reed
    Those little potential wells that hold the electronic charge corresponding to the light collected at each photo site on the CCD imager, can only hold their charge for so long without losing it to natural leakage that happens in any semiconductor chip. I'm afraid it would take some other technology to allow for extremely long exposure times. Your best bet would be to use an "intervalometer" technique with cameras that are compatible (the FZ20's remote input may make this possible) to periodically sample the image, i.e., take multiple shots of the sky or whatever you're shooting.
    I have no knowledge about that but it seeems correct as Fuji and Minolta cameras( may be others) seem to have a bulb setting but it seems to be limited to 30 seconds.
    .






    Gene
    http://grc225.zenfolio.com/
    http://imageevent.com/grc6
    one of these days I'll understand!

    Panasonic FZ20 & FZ30,FZ18
    D50 -- D80

  8. #8
    Join Date
    Nov 2004
    Location
    Charlestown, MA
    Posts
    28
    Jason, John (and Gene),

    Thanks for the extremely well-researched input. I guess I can't have any more reservations about the FZ20 then, might as well dive in since I won't be able to get exactly what I want from a digicam anyway.

    Regarding the image processing software, I think that is a fantastic workaround and I'll research it further.

    Incidentally, do you know if it is possible to control the camera through a computer software interface? If so, I would be able to take my laptop out into the field and have it tell the camera to take a precisely timed series of 240 shots at 30 second intervals to simulate a 2 hour exposure. This, if it is possible, would be very cool.

    Pete

  9. #9
    Join Date
    Jul 2004
    Location
    Los Altos, CA
    Posts
    2,635
    Quote Originally Posted by freshlightphotographer
    Incidentally, do you know if it is possible to control the camera through a computer software interface? If so, I would be able to take my laptop out into the field and have it tell the camera to take a precisely timed series of 240 shots at 30 second intervals to simulate a 2 hour exposure. This, if it is possible, would be very cool.

    Pete
    Well, for the FZ20, you'll never get a 30 second shutter open time, only 8 seconds max, but you should be able to get a 30 second interval, i.e., firing the shutter for 8 seconds every 30 seconds. It has a remote control input, which seems to be just a pair of terminals that get externally switched. If that is so, said "external switch" function could conceivably be controlled by your laptop to create an intervalometer. I don't know enough about the details of the FZ20's remote interface to say this for a fact, but it's likely that it's possible. Some assembly required!
    Let a be your umbrella!

  10. #10
    Join Date
    Dec 2004
    Location
    Titusville, NJ
    Posts
    21

    Thumbs up Image Stacker

    Quote Originally Posted by freshlightphotographer
    I am a soon-to-be FZ20 owner and wanted to know if any current Panasonic users have tried long exposures (over 15 minutes). I am interested in taking photos of star-trails at night like I was able to on my old film SLR. However, reading the FZ20 specs I am not sure if this is possible.

    Can anyone shed some light (no pun intended) on this for me please?

    Thanks!
    Pete
    Pete, Check this site out. I believe this is what you are after. A form of time lapse for digital photography. John Reed was on the right track with this.

    http://www.tawbaware.com/imgstack.htm

    Hope this helps.
    Larry

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