Mysterious behavior TC 1.7 and 300 f/2.8

Discussion in 'General Technical Discussion' started by snugelbune, Jul 23, 2007.

  1. snugelbune

    snugelbune

    313
    Mar 15, 2006
    NYC suburbs
    Hey guys,

    So, I'll try to keep this short (difficult for me, so remember I'm trying).

    About 3 times in the last 2 months I've had a weird situation with my 300 f/2.8 AF-S II and Nikon TC17. The camera (or lens as it may be) refuses to even try to auto focus. When I take the TC 17 off and mount the 300 f/2.8, it AF's just fine. Now, that would seem like an obvious TC problem...EXCEPT...when this is happening, if I mount the TC to my 70-200 it AF's just fine. Then, after a while it has always started to AF with the TC and 300 f/2.8. Yesterday, I tried for over an hour...the 300 f/2.8 would work just fine solo, but would not work at all with the TC...when I got home (extremely frustrated from missing a day of shooting the way I wanted to, I mounted the 70-200 with the TC 17 and it worked fine). After mounting the TC and 70-200, I gave one last try with the 300 and TC and voila it worked.

    I am confused as if this is a TC problem, why does it work with the 70-200?

    If this is a lens problem (the 300 f/2.8) why does the lens work perfectly on it's own?

    Any ideas? My biggest problem is that I purchased the TC 2 years ago before understanding the consequences of buying a gray market product from Nikon...so the TC is the ONLY thing in my bag that is not a US model. I guess my other fear is that the 300 f/2.8 is one I bought used and while it has been an exceptional lens for me, I'm not sure exactly how old it is and wouldn't have a clue as to what it might cost for me to get it repaired should it need it...but then again, it works fine on it's own.

    Ok, I'll stop writing now, any ideas, suggestions, etc. would REALLy be appreciated.
     
  2. Probably poor contact. Try cleaning all the contact points.
     
  3. snugelbune

    snugelbune

    313
    Mar 15, 2006
    NYC suburbs
    Hi Phil,

    thanks for the response...this was my first line of defense against this problem...cleaned both sides of the TC as well as the 300 f/2.8 and the camera mounting area and no change in immediate functionality. And, I'm not sure I was clear on this, I can go 2-3 weeks w/out having this problem at all.

    But, I will try again, in the meantime, what's your second guess?
     
  4. It's just a guess. Since it's intermittent, contact seems to be the problem. See if there is certain degree of play when the lens + TC is mounted. It may cause a slight misalignment of the contacts and thus the problem.
     
  5. snugelbune

    snugelbune

    313
    Mar 15, 2006
    NYC suburbs
    Aha,

    you might have hit on it. I've complained about the TC and the 300 feeling quite "loose" when mounted on the camera. I don't get that play with the 70-200 and I don't get it when the 300 is mounted without the TC...I've always wondered if this was a problem waiting to happen, and perhaps this is how it is showing itself.

    I guess my next question might be something like...is it bad if there is play, and is there anything I can really do about it/should do about it.

    Thanks Phil, I have been bothered by this in the past, but I didn't put these two things together. Perhaps I should have.
     
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