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Questions about Extension Tubes

Discussion in 'Lens Lust' started by turtile, Aug 1, 2008.

  1. turtile

    turtile

    416
    May 12, 2008
    Delaware
    I can't seem to find an article anyone on what extension tubes actually do when in use.

    Do extension tubes just magnify the image on the senor by moving it the lens further away - will it decrease the amount of light hitting the sensor because of this fact? How does the length (mm) affect the focus and extra focus distance (is there a formula)?

    I'm thinking about either getting a 200mm F4 micro or a 300mm F4 w/ the PN-11 (can it still meter in Aperture Priority) so I can use it seperately for more reach since I already have the 70-200mm.

    Thanks
     
    Last edited by a moderator: Aug 2, 2008
  2. johnmh

    johnmh

    771
    Nov 21, 2007
    Greater NYC
    You're adding more glass between he sensor and what you're shooting - magnifying the image produced by the original lens. You lose light - 1 f/stop with the Nikon 1.4, 1 1/2 with the 1.7 and 2 full stops with the 2.0. The current gen Nikon TC's will only mount up to certain lenses and are physically 'keyed' to prevent their use in cases where they might damage the lens (you have physical interference in some cases with he TC elements projecting beyond the mounting surface into space where some lenses have moving elements).

    BTW - there's no functional difference between TC E and TC E-II convertors - only the finish is different. There's a whole bunch of older convertors for manual focus lenses with specific applications (TC-14A, TC-14B, TC-200, TC-201, TC-300.....) and various third party TC's that you can use on current lenses but I can't speak on those from any first hand knowledge.

    You can lose AF capability when using TC's on 'slow' lenses. As a rule if the lens was an f/2.8 or faster you're fine but on an f/4 the 2.0 TC cuts the light enough to prevent AF from working and he 1.7 is iffy in all but excellent light.

    The 70-200 works fine with all three TC's - no real effect at all with the 1.4, minimal with the 1.7. Some find that IQ is unacceptable with the 2.0 but IMO, it's as good as many of the cheaper third party 400 lenses. Some people say that the 300 f/4 works fine with TC's but my experience with the 200-400 f/4 backs up Nikon's stated limitations.
     
  3. Randy

    Randy

    May 11, 2006

    in your opinion only, many of us here will not use a TC on any zoom, even the 70-200
     
  4. Carole

    Carole

    Jun 15, 2008
    Bellingham, WA
    I've also been considering a teleconverter. I love my 70-300mm lens and find that I use it more than any other lens I have. But I'd like to get closer on my whale photos. Would a t/c work for me? Will I lose clarity and sharpness in my photos? Or is it just a question of losing f-stops?

    I've also been looking at the Sigma 80-400mm lens. Does anyone have this lens and do you like it?

    Carole
     
  5. The OP asked about a PN-11, which is not a teleconverter at all. It is an extension tube and will allow closer focusing, will not autofocus, and may allow spot or center-weighted metering, depending on the body. It will not give more reach, and will likely not focus on infinity.

    All of the Nikon TCs (TC-14E, TC-17E, TC20E) will "function" with the 70-200, although the quality of the image and level of AF function is in question.
     
  6. Randy

    Randy

    May 11, 2006
    IMO def no for a TC on the 70-300
    the sigma 80-400 is very good but may not focus fast enough for sports or birds in flight
     
  7. Carole

    Carole

    Jun 15, 2008
    Bellingham, WA
    Hmm, then what lens should I consider if I want to get closer shots of the whales than I'm getting with my 70-300? I'd prefer a zoom as we never know how close they will come to the boat.

    Thanks,
    Carole
     
  8. Randy

    Randy

    May 11, 2006
    if it must be a zoom then there is only 1 choice in my opinion, the 200-400. a superb lens but large, heavy and expensive.
    I think the 300/4 + 1.4 TC would be a better solution for the money and you could hand hold it.
    Sigma has alot of 400 & 500mm zooms but I wouldn't spend the money on one after having the sigma 50-500.
    Maybe borrow or rent one a 500mm sigma zoom
     
  9. Carole

    Carole

    Jun 15, 2008
    Bellingham, WA
    Well, I can't do large, heavy or expensive. I have CHF and the 70-300 that I have now is about my limit weight wise. I can't take a tripod on the whale watch boats as it's not permitted. So it has to be handheld.

    Is the 200-400 a Nikon lens, or other? I've also been looking at Tamron's, and others. I'd love to have what the whale researchers have, but I know that's out of the question :)  I've been checking around for a used one hoping that someone has one that's collecting dust :) 

    Carole
     
  10. Randy

    Randy

    May 11, 2006

    the 200-400 is a Nikon
    the 300/4 + TC is not to heavy
    I have a bad right arm and find it ok to hold and even better in a mono. IQ for the 300/4 even with the 1.4 tc is outstanding but you are only getting another 120mm over the 70-300. A used 300/4 is approx 900 and the tc is 400 so it's not a cheap solution
     
  11. Carole

    Carole

    Jun 15, 2008
    Bellingham, WA
    I looked at the 20-400 and that is totally out of the question unless I happen to have the winning lottery ticket :) 

    I think I'll just stick with my 70-300 and hope the whales come close to the boat :) 

    Carole
     
  12. turtile

    turtile

    416
    May 12, 2008
    Delaware
    I meant extension tubes! I don't know why I wrote TC.

    Sorry, my post must have been really confusing. I edited the first post. Thanks for all you help!
     
  13. Carole

    Carole

    Jun 15, 2008
    Bellingham, WA
    Forgot to ask - why the no on the TC for the 70-300? I tried a friend's this afternoon, and it was pretty cool. Not as sharp as I'd like, that's for sure. But definitely got me closer. I'm going whale watching tomorrow so I might try it out and see what I get. . . depends on how close they come to the boat :) 

    Carole
     
  14. arela

    arela

    480
    Jan 15, 2008
    Norway
    I use a Kenko 300 Pro 1.4 teleconverter with my 70-300 VR.
    Trouble is autofokusing as the aperture is to small (not enough light for AF to work well, it hunts). In the area 70 to about 200mm the AF works well under sunny cond.
    And you can "correct the focus" with the focus ring.

    If the Nikon TC's works as well, i dont know.
     
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