Pentax ZX-50: shutter to motor drive synchronization problem?

Discussion in 'Pentax' started by LEM, Oct 13, 2003.

  1. LEM

    LEM Guest

    Well, this is the most weired way for a camera to fail I can think of...
    I've looked all over google, and could not find a single encounter of the
    same problem, so I just curious if the camera in question is unique in
    that, or it is something heard of before?

    My father just returned from a vacation where he took photos with the
    following setup:
    - Pentax ZX-50 (about 9 yrs old, but with low milege, mostly vacation use)
    - Pentax 28-80mm f/3.5-5.6 lens (less than 1yr old)
    - Kodak 200 speed regular film you can get in a drugstore (don't know the
    exact name, but you get the idea).
    - Used mostly in automatic exposure mode.

    After developing the films, a big surprise. About a half of the pictures
    are as sharp as the above lens can get, well exposed and all, and the other
    half what initially looked like badly out of focus. All pictures went in
    blocks. E.g. the film would have 10 well exposed photos, then 14 blurred,
    there was no single appearence of a blurred image surrounded by well
    exposed and vice-versa.

    After a careful examination, my own conclusion was this:
    Somehow the shutter and the motor winding the film went out of sync. So the
    later started to wind film to the next frame during the exposition, with
    shutter still open! This was happening on and off, with no specific pattern
    (at least none we could figure out yet). So, if I guessed what the problem
    is correctly, one of the following could be the cause: A - faulty
    electronics, though I can hardly think of anything... B - physical obstacle
    that delayed shutter closing by just enough to have the film drive started
    (none revealed by visual inspection). The problem with this one -- I think
    it would have created some sort of overexposure, which was not obvious from
    the shots, unless of course it delayed opening by the same ammount of
    time....

    Here is a link to the examples of the spoiled shots and my thoughts about
    them:

    http://lem.freeshell.org/pentax_examples/

    Now if you have read this far, and visited the link above to see it for
    yourself, my word of appreciation to you, and a question or two:

    1. Do you think my diagnosis of the problem is correct?
    2. If answer to 1 is negative -- would you hazard your own guess based on
    my description and the examples above (I won't hold you liable for it)...
    3. In either case, have you ever heard of something similar happening to
    either the specific Pentax camera or to any other brand at all? Is it
    common? Is this a problem with ZX-50, or budget pentax bodies all around?
    4. Finally -- what would it be like to have it fixed, keeping in mind that
    a new Pentax ZX-60 body sells for $150 at B&H, therefore any price tag that
    goes into three digits will probably not be worth it...

    To be honest I think I already know the answer to #4, so maybe I will
    finally get a good excuse to pay a visit to B&H, and get a few things for
    my own (remember, I'm talking about my fathers camera now) ;-/

    Thank you in advance for all your help!

    LEM.
    (I'd rather get your answer in the NG, but if you have to e-mail me, remove
    all digits from the address before doing so).
     
    LEM, Oct 13, 2003
    #1
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  2. Get a tripod and run 2 or 3 rolls all from the tripod. Use Manual
    exposure mode and set the shutter speeds yourself.
    It's tough to tell without seeing the negatives. If things are as
    you describe, your negs should blur into each other and you shouldn't
    get a complete set from a 24 exposure roll.
    I had a ZX-50 as a backup to a PZ-1P and it didn't miss a shot. In
    fact there were times I preferred the smaller camera to the PZ-1P.
    ZX-50s are between $50 and $100 on ebay. I'd say get another one, or
    look for the sturdier ZX-5 or 5n.

    headscratcher
     
    headscratcher, Oct 13, 2003
    #2
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  3. LEM

    LEM Guest

    http://lem.freeshell.org/pentax_examples/
    This is something I will do one day unless I can tell for sure without it.
    For now... scroll down...
    This is a very good point. I should see if there are traces of previous
    frames on the consecutive ones. In the mean time, looking at negatives
    against a light reveals just about what you describe. The negatives look a
    bit overlapped, there are no clear unexposed spaces between them, instead,
    the spaces between negatives are somewhat dark, though there are 24
    exposures per film. The later I can explain by the fact that the film
    advance works correctly, except it starts off too early (before shutter is
    closed).

    I will try to scan a couple of negatives and/or a space between them. I
    don't have the good equipment for that, but do have a dome-shaped negative
    adapter for my scanner, hopefully it will provide enough detail to tell...
    I'll post them on the same page mentioned above later, and will follow up
    to the group when that's done.
    This is probably the next logical step. But in the mean time I want to get
    the best of my curiosity, as to what happened here. Is it worth to get
    another ZX-50 on eBay, even if for $50, or is it better to go with new ZX-
    60. I don't think the current budget will allow for anything more expensive
    than that.

    Your own experience with ZX-50 sounds encouraging though!

    LEM.
     
    LEM, Oct 13, 2003
    #3
  4. LEM

    jriegle Guest

    I think you nailed it. In your fist shot, it looks like the lens got grease
    or something similar on it wiped in one direction, but looking closer, I can
    see the light smear is one direction only. The second shot confirms it.

    Remove the batteries from the camera and turn it on (be sure the LCD goes
    blank). Turn the camera off and reinstall the battery (a new battery would
    be ideal). Put the camera on a tripod and shoot a roll. Have it processed to
    see if the problem persists.
    John
     
    jriegle, Oct 14, 2003
    #4
  5. LEM

    LEM Guest

    http://lem.freeshell.org/pentax_examples/
    Whew. One thing I learned for sure, is that the dome slide adapter is
    useless in scanning negatives on a flatbed... Anyway, I put them in a
    backlit magnifier and photographed with my digital camera. Far-far from the
    best, but better than scanned versions... So I added a few more pictures
    and corresponding comments to the same page:

    http://lem.freeshell.org/pentax_examples/

    Based on these I can be fairly sure, that my original version stands,
    unless someone can offer a better version that would cover all of the shown
    artifacts. Now, has this ever happened to anyone else? Any ideas as to the
    cause? Mechanical obstacle, electronics failure, a curse or an evil spell?

    I'd appreciate any ideas in this department.

    Thanks in advance,
    LEM.
    (to e-mail directly, remove all digits from address).
     
    LEM, Oct 14, 2003
    #5
  6. LEM

    LEM Guest

    Yes, my first thing to blame was the lens as well (it was releatively new
    too, only a couple of rolls shot with it prior to this vacation). Then I
    looked at more prints, and thought maybe a lab messed them up, like pulled
    through some tight slit while the emulsion was still wet. But that didn't
    stand either, becasue they developed 8 rolls for us. 4 From above named
    Pentax, and 4 from Olympus P&S they used on the same vacation... Problems
    only appeared on Pentax films...
    Sounds like you're suggesting to do a "cold reboot" on the camera, in
    computer terms... Does it have some sort of small lithium backup battery to
    worry about, or the two standard ones you put in are all there is? Not sure
    if the tripod test will give me anything. The last film that came from this
    camera was 100% fine, with no problems whatsoever. So looks like it comes
    and goes, and if I do a test and results are good, I still can't be sure if
    the problem is solved, unless I can pinpoint the cause and make sure it is
    eliminated completely!

    Thanks for your suggestion though, what I'm gonna try eventually, is a few
    shots, then "cold boot", and more shots... Will see if it will get us
    anywhere.

    I will have to check with my father, if he changed batteries before the
    last film though! Maybe that was the problem... Hm... another idea! Could
    the weak batteries in the camera have caused this? E.g. sluggish shutter
    performance or synchronization problems due to the lack of power?

    LEM
    (remove digits from address to write directly)
     
    LEM, Oct 14, 2003
    #6
  7. LEM

    Hickster0711 Guest

    Don't take this too seriously; just a wild guess, but on my ZX-30, most times
    it would auto- load fine, but a few times it would skip the sprocket holes, and
    the screen would not show #1. I was just wondering if yours loaded off center
    that one time, and on some frames created tension in the spool, then went
    "boing" forward, when the shutter was released. If the leader was wrinkled just
    a little while loading, I believe that might happen, especially if the bottom
    sprocket holes engaged and the top ones missed a little. I'd give it another
    shot before I condemned the whole thing. Bob Hickey
     
    Hickster0711, Oct 14, 2003
    #7
  8. LEM

    jriegle Guest

    I'm not positive, but I don't think the camera has a backup battery unless
    it has a databack. My ZX-5n did, but it is independent of the camera
    electronics.
    Normally, the camera is programmed to stop functioning when the battery
    voltage falls to a level where the camera could malfunction. It could be
    possible that a weak battery causes a malfunction.
    John
     
    jriegle, Oct 14, 2003
    #8
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