One answer to a burning question

Discussion in 'Nikon' started by chulster, Jun 13, 2020.

  1. Have you ever wondered, when stacking a teleconverter and an extension tube, whether it is better to put the TC behind the ET or the ET behind the TC? Neither have I, and yet I set out this morning to get the answer.

    The photos below were both taken on a D810 with a 50mm f/1.2 Ai-s lens with a 14mm PK-12 extension tube and a Kenko TelePlus Pro 1.4x teleconverter. For the first photo, the equipment was arranged as Camera -> TC -> ET -> Lens; for the second, Camera ->ET -> TC -> Lens. The set aperture was f/5.6 (I have no idea what the effective aperture was.) All sharpening and corrections were disabled.

    View attachment DSC_2431.jpg
    View attachment DSC_2432.jpg

    As you can see, there is very little difference between the two images. Either image is very slightly sharper depending on where you look.

    I did notice that the second arrangement (Camera ->ET -> TC -> Lens) did not allow me to get quite as close (physically) as the first one. However, final magnification is the same, so that's only a difference in working distance.

    So, there's an answer! For this particular combination of gear, it makes virtually no difference how you arrange the pieces.

    You're welcome! :p
     
    Albin''s images and ericphelps like this.
  2. William Michael

    William Michael Moderator Staff Member

    Interesting field test.

    The physical arrangement matters when the the Tele-converter being used will not mount to the Lens because of the length of the rear section of the Lens: in this situation the Extension Tube serves a dual purpose - it also allows a physical space into which the rear of the Lens will sit.

    For example, in Canon DSLR gear, the (Canon) Tele-conveters will not (physically) mount to several Lenses because of the reason stated above: (typically) all which is required is a 12mm Extension Tube, placed between the Lens and the Tele-converter, to allow the combination Lens>Extension Tube>Tele-converter>Camera.

    This might be the case with (some) Nikon gear, I am not sure.

    Also (with Canon gear) employing a third party Tele-extender, may negate this issue: for one example the EF 85/1.8 will not mount to a Canon Tele-extender because of the Lens's rear section, however that Lens will mount to (some models) of Kenko Tele-extenders.

    WW
     
  3. I have the 3 models of the Kenko tele-extenders - purchased as they were much cheaper than Nikons - and found soon after, that I could attach any of my 10 Nikons lenses at the at time. win win situation.
     
  4. I have the Kenko 25mm tube. It's great to have a tube that provides pass-through communication and even screw-drive AF between lens and camera. I'm too much of a cheap bastard to buy the full set, though.
     
  5. i'd say "try it"but not on a totally "flat"subject, that is pretty useless in my view.
    See what it does to matter in front and behind the focal plane.

    Differences would become vissible in the corners and at the edges of the resulting picture.

    Also try a grey or white card so you can see the the "falloff" .
    Try a shot with like a wineglass backlighted, to show internal reflections between the TC and main lens.

    I would expect better results from the Tube first and then the TC, because tubes always have some "Internal reflection"which can cause a haze in the center of the picture, which would be enhanceed by the TC if it is at tha camera side of the contraption..
     
    Last edited: Jun 14, 2020
  6. how close can you get just using the extension tube, or a longer one, I don´t see the advantage in using a TC in this setup.
     
  7. There must be a reason why some TCs have a protruding 'nose' that gets their front glass closer to the rear of the matching lens. And whatever optical advantage that might give will obviously be destroyed by sticking an extension tube in there.

    But if the TC is just a generic 3rd party offering, then all bets are off.

    "A burning question"?
    Not something that ever kept me awake at night! But then I'd only use a TC as a last resort anyway.
     
    Last edited: Jun 14, 2020
  8. I should know better than to try irony on the internet.
     
    Tony Parsons likes this.
  9. Well that's another question—and one that people may actually ask. It's a given that adding a TC into the mix will result in higher magnification than using an extension tube alone. But which yields better results: an extension tube of length l in combination with a TC, or an extension tube of length l + a by itself, assuming both setups yield the same magnification? I think this question has been investigated, although I haven't searched for any findings in the internet.
     
  10. The best description of this topic I have ever read is in John Shaw's book, "Close Ups in Nature", page 110. Here is a quote "Only at infinity focus is multiplying the focal length the same as multiplying the magnification."
     
  11. I recently acquired a Vivitar 100mm macro lens with its 1:1 adaptor, AND two sets of three extension tubes, AND a 2x teleconverter, all bayoneted together, it was over a foot long. The seller said he used it to photograph a fly, focus stacking with a massive number of images. I can't remember what order they were assembled in.
     
    chulster likes this.
  12. As long as there is mechanical compatibility, if the TC is next to the camera, the extension tube adds to the focusing of the lens at its native focal length. For the same absolute magnification, the working distance will be less than if the TC is mounted to the lens. In the latter case, the extension tube augments the focusing relative to the magnified focal length.

    John Shaw, nature photographer, prefers one over the other. That I can't remember which speaks volumes. Like a previous responder, I use a TC only reluctantly, and never for closeups. I do prefer using longer lenses for closeups in nature, for the added working distance.

    Ed Ingold
     
  13. Camera-TC-ET-Lens - TC multiplies the magnification
    In this setup, the extension tube (ET) increases the magnification of the lens, and the TC then multiplies the resulting magnification.

    Camera-ET-TC-Lens - TC multiplies the focal length
    In this setup, the TC multiplies the focal length of the lens. The extension tube then increases the magnification of the resulting lens/TC.

    The magnification of a lens and extension tube is given by: extension / focal length.
    It should be plain that a given extension tube will increase the magnification less when attached to a longer lens. Therefore the first combination above will result in higher magnifications since the ET is applied to the native lens, not the longer lens/TC.

    Which of the two combinations will give better results will depend on the individual lens, TC and the amount of extension. Some combinations will work better in the first setup, others will work better the other way around, and for others it won't make much difference. I don't think it is possible to make any generalised rules about which is better, you need to try and see what works.
     
  14. yup, me too.

    I've been using the 200-500mm recently for butterflies. ~420mm and just under 2.20m doesn't scare them too much. Mine's a bit soft at 500mm.

    Works well with the TC14 II at close range. Haven't tried an ext. ring. It might snap!

    Did Nikon never make any 'custom' tubes for longer teles?

    EDIT. Just found the TC800 1.25 for AFS. Does it only work on the 800mm E? Seems a shame!
     
  15. Nikon made the TC 301 teleconverter, a 2x tc made for Nikon AF/AIS lenses 300mm or more. If attached to a AF lens, focus was done manually.
     
  16. The TC800 1.25 is made specifically for the AFS 800/5.6, but but I am fairly sure it would fit other super-telephotos. As far as I know there is nothing to physically stop it fitting. Adding it to a 400/2.8 would give a nice 500/3.5, and a 600/4 would become a 750/5. Although not optimised for other lenses, I guess that performance should be good as TCs designed for telephotos tend to work well across all telephotos, and low-power TCs tend to have less impact on image quality than stronger ones.

    Nikon never made AF extension tubes but there are third party options. Nikon's extension tubes (PK-11, PK-12, PK-13, PN-11) are from the 1970s and 80s, they are very well made but only support AI metering - no CPU contacts.
     
  17. However, there's nothing physically to stop you using a 200-500mm on the nifty J5.... so Nikon did it in software...:(

    Ah, the 400mm 2.8, the basis of many wonderful combos....:cool:
     
  18. How long would you expec such a "Custom"tube" to be, to show any effect on a "long tele"?
     
  19. I'm glad you asked because I was about to ask...!

    AFAIK, the old idea of adding the same as the focal length, ie 50mm extension for a normal 50mm lens got you to 1:1, so I guess you'd need 135mm to get the Sigma 135mm to a 1:1 macro (inf. not available!)

    So 300mm for a 300mm 2.8....?

    Humm, maybe not a good idea then!
     
  20. Xactly... :D
     

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