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Extension tube question

Discussion in 'General Technical Discussion' started by Beezle, Aug 28, 2005.

  1. I am using a manual focus lens (Nikon 55 AIS) with an extension tube (Nikon PK-13) on my D2X.

    What should I be entering as the focal length when the lens is on the tube? Can't seem to find anything in the lens or tube manual.
  2. Iliah


    Jan 29, 2005
    IMHO the focal length of a lens with extension tubes stays more or less the same, if the lems does not change its focal length with focusing without extension tubes.
  3. By enter, if you mean on an EXIF, it would be the same. You could specify the extension tube you were using. If you are talking about flash calculations each extension tube has some light loss based on the length of the tube. Look in the spec for the particular length you are using. For myself, I would just calculate it based on the focal length of the lens and then based on the historgram result, add an EV correction in your camera. Keep it consistant for that that particular extension tube.
  4. Thanks for the replies.

    I am talking about the value you enter into the D2X (or D2H I think). You indicate a lens' speed and focal length and the D2X will meter them.

    The exposures I have taken with the focal length unchanged seem fine, so I am would guess you are correct, Iliah.
  5. The focal length of the lens stays the same. All you are doing is altering the nearest focussing point and consequently the reproduction ratio.

    Best wishes. Bob F.
  6. Iliah


    Jan 29, 2005
    Of course. Extension tubes are just focusing aids, like focusing helicoid or bellows. When I mount a lens into Linhof bellows, it does not change the focal length whatever the extension is. Otherwize, would they state the focal length for the lenses that are meant to use only with bellows? :) 
  7. So maybe I ought to be finding myself a bellows to use with my Nikon cameras? :) 

    Or are they particularly expensive?
  8. So I see Nikon has the bellows PB-6. What lenses will work with it? I have plenty of AF D primes (50 1.4, 35 2, 86 1.4, 60, 105).

    What sort of rig does one use to mount the rail to a tripod? Hm, I also need a rack/table for moving subjects.
  9. Being a user of a PB6 - Extension Rings - Reversal Ring etc.etc.etc., what is it that you are wanting this equipment for? Without this information it is going to be very difficult to answer any of your questions. Also please note that I am in the UK and will not be answering any questions untill tomorrow.

    Best wishes. Bob F.
  10. Iliah


    Jan 29, 2005
    you can use PB4, it gives interesting possibilities, especially w/Bellows Nikkor 135 lens; or with F/M39 adaptor and longer enlarger lenses:) 
  11. Pretty simple really. I have two Nikon DSLRs, the D70 and D2X, some manual focus AIS and a fair number of modern Nikon lenses and I am curious about super close in photography.

    I have never used a bellows. Just this one PK-13 extension ring. I didn't even know for sure that I could use the PK-13 with modern Nikon lenses without ruining them. So far, it looks like I didn't break anything. :biggrin:

    You can see a few images done with the 55 AIS plus extension and the 105 micro with the same extension here:


    I'd be interested in what would give the best results at those sorts of magnifications and greater.
  12. I have looked at the photo of the Chinese Latern and the Reproduction Ratios seem to range from about 1:3 to a maximum of 3:1. All these are easily obtainable with the PK/PN extension tube set and a 24mm lens. In fact if you have one with a 52mm thread, then buy a BR-2A reversing ring and watch by experimenting with various combinations your R/R rise to about 8:1.

    As you are going to lose any coupling to metering etc. then it does not matter which of the older lenses you use, as long as they have click stops that allow you stop and lock down manually. You are going to have to experiment to find out what your f stop - flash output is going to be, but once you have found the combination then it generally remains stable for most R:Rs.

    To be honest I really think that you are trying to run before you can walk and would suggest you might like to try a close-up lens or close-up attachment lenses and learn the basics of micro/macro photography before trying to get to grips with the intracacies of Photomiography.

    Nikon produce an excellent free brochure called Nikon and The World of Close-up Photography. Get one from the Nikon offices in your country and read it. This will give a mass of useful information including what equipment you need to get the various Rep/Ratios.

    Hope this helps.
    BW. Bob F.
  13. Well, details help more. I'm a clever enough fellow to apply the possibilities once I know them. I've been using ordinary macro lenses for a few decades now. I just never tried to go beyond 1:1 with an SLR before.
    Last edited by a moderator: Aug 29, 2005
  14. JeffKohn


    Apr 21, 2005
    Houston, TX
    Kenko makes a set of extension tubes that maintain metering and AF. They can be stacked to give you quite a bit of extension.
  15. I noticed that set on BH. Not that they were in stock. :rolleyes: 

    I think I will try those and reversing next, and see if I can borrow a bellows from one of the pros I know to give that a go.

    I also realized it is better to move the camera and not the subject, if only because the wife doesn't always approve of my cutting the subject from it's place in the garden. :wink: So, I am obtaining a Novoflex rail.
  16. The Novoflex rail will be excellent for extension tubes, but will not be necessary with Nikon Bellows.

    Go to Ebay for the Kenko Tubes. They list more than you will ever need.

    BW. Bob F.
    Last edited by a moderator: Aug 29, 2005
  17. Thanks, ebay did the trick. I usually avoid ebay like the plague, but this time I used it.

    Actually a good friend of mine is one of the managers of their anti fraud people, then again that might have something to do with my reluctance. :wink:

  18. I use Ebay for almost 100% of my purchases in respect of Camera Equipment and virtually everything else. You just have to use your commonsense and once you become familiar with the procedure you can soon spot a scammer.
    Very pleased you have obtained some tubes. Good luck and keep in touch.

    BW. Bob F.
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