Pushed Off Ladder, Lens Hit, How to Test?

Discussion in 'Canon EOS' started by picturesque, Jul 15, 2007.

  1. Last night I was photographing the chair dances at a Jewish wedding, for which
    I stand on my ladder, since I am short. I don't know how, but someone either
    pushed me off the ladder and/or upset the ladder somehow, and I fell off the
    ladder, in the process hitting my 16-35mm lens on a table or chair edge. I am
    generally OK, but when I continued shooting, I noticed the focus was slow. I'd
    press the shutter button to focus, and it would hesitate, and the focus was
    slow to be acquired. Then things got better and now it seems to be back to
    normal. I did re-seat the lens, but wonder if it is possible for it to
    be "stunned" somehow... Also anyone have any suggestions as to tests to
    determine if it is OK, or what to look for? Fortunately both the camera bodies
    (5D and 20D) on me at the time and even the normally fragile 50mm f1.4 are
    physically unscathed. Of course, as I was falling, I was clutching my camera
    to my chest...
     
  2. Sounds like maybe the hit very slightly distorted something in the lens mechanism, and was causing a slight bind or rubbing in the focus area. After a few passes the parts that were rubbing against each other finally smoothed out and function is now about normal.
     
  3. I suggest you take some test shots to ensure the lens is still focusig n the right place. Something like a line of fence posts going away from you. Focus on an dentifiable post and see if the shot looks right. If you use a wide aperture the plane of focus should be easily identifiable and where it was supposed to be.
     
  4. Short of putting it on an optical bench, here are a couple of easy tests:

    1) Point your camera (on tripod) at a mirror and align it so you see the reflection of your lens dead center through the viewfinder. Now tape something with lots of detail and contrast, like a sheet of newsprint or graph paper, to the mirror and shoot it. The corners will come out softer than the center, but sharpness should drop off equally in all directions (i.e., all corners should look equally soft).

    2) Shoot something like bright city lights at night from a long distance, or stars in a very dark sky (with a high ISO to get short exposure - no trailing allowed!). You should see no coma (smearing to one side) at all in the middle, and any you see at the edges should be equal in all corners and pointing away from the center.

    Good luck... even if it turns out your lens needs realignment you were very lucky so far!
     
  5. That lens is nice enough that it is probably worth a trip to a Canon service center for a checkup.

    Hope you are OK, and glad it wasn't worse!

    Keith
     
  6. Thanks for all the info so far. I will definitely do some tests. I just ran some practical tests--photographing people the way I normally would plus the test Colin suggested and everything seems to be OK so far, except that I am astonished anew at how badly the 20D backfocuses on high contrast backgrounds given less than half a chance. Keith--thanks, I am OK save for the fact my heels hurt (that's what absorbed the impact), and even though I did fall backwards to the floor, everything else seems to be fine. I will probably send the lens in at some point for re-calibration. Just have to figure out what lens to get as a replacement/backup in the meantime. All I have are primes otherwise and while I can photograph weddings with primes only, it sure does help to have a zoom in some situations.
     
  7. Nadine,

    Sorry to hear about your fall, but glad to hear that you are okay. Maybe wedding photographers should get hazardous duty pay.

    I let my camera swing on its strap and my mounted 16-35 hit the edge of a rock, I was shooting a landscape not a wedding. There was a very slight scratch in the lens barrel, but no visible dent - it was a light hit. After the hit, the lens didn't want to focus to infinity unless it was first focused to its closes distance. When the focus ring had a chance to move a long distance, and gain some speed, it would move pass the spot that was rubbing and focus to infinity. If it was prefocused to a distance just short of the rub spot the motor didn't have enough power to move the focus ring pass the rub spot.

    It apparently doesn't take much to knock this lens motor out of adjustment. I suspect you will need to send it to Canon for adjustment.

    I was going to send mine to Canon but it was stolen before I could send it.

    Good luck and watch out for those ladders.

    Cliff
     
  8. Once switched to manually focusing, turn the focusing-ring backwards/forwards and check if it goes smooth along everywhere.

    Last year I had a Nikon AF 35-70/3.3-4.5 from a friend, fallen down while she was moving out from a car; this lens has not built-in focusing motor. Its focusing ring is a crown-gear of plasic and I found a couple of broken teeth inside, once opened; before, my fingers turning the focusing-ring felt it clearly forcing and stumbling/clogging on a point.

    I think yours got no real damage, indeed.

    .
     
  9. Hi Nadaine, glad you are ok, sometimes these things bruise the ego more, myself I`d get the lens straight to canon, it may seem ok and may be ok But for peace of mind it will help, rent one if you need one in a hurry. Never like to hear `my lens failed half way down the aisle` Hope it turn out ok

    chris
     
  10. Well after more tests, I've determined that the lens is indeed malfunctioning. The focus is inconsistent, especially on far subjects, so Cliff--maybe the lens is reacting the same as yours. And it backfocuses on the 20D more than the 5D. Yesterday, I shot a wedding with primes only, and it took me back to the days when I used to do that with my medium format gear. Lots of lens changes to keep up with today's way of shooting weddings.

    Anyway--thanks all for the info. Looks like I'm sending it in today.
     

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