help please!

Discussion in 'Photography Beginners' Forum' started by jonasr_jp, Jul 3, 2006.

  1. jonasr_jp

    jonasr_jp TPF Noob!

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    Hi recently i bought a tripod and then i got this extension macro tube as well, now i`m wondering what it actually do, as i am a newbie and dont understand english that well, maybe someone could explain it a little better, i have a pentax ist ds with an original 18 - 50mm lins, the only thing that happends when i put these things together is that its get blurry and dark, and the original lins is upside down.

    can someone enlight me?



    http://cgi.ebay.com/Macro-Extension-Tube-Set-for-Pentax-ist-D-Ds_W0QQitemZ220002212111QQihZ012QQcategoryZ79000QQrdZ1QQcmdZViewItem
     
  2. Torus34

    Torus34 No longer a newbie, moving up!

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    Extension tubes allow you to get close to a subject. You can even get close enough so that the image on the film is larger than the object you are photographing.

    You'll need quite a bit of information to use them at their best. As an example, as you get closer to a subject, you must increase the exposure. If your set did not come with instructions, try to locate a copy. A full explanation of extension tubes would take up too much space to put here in this thread.

    Perhaps someone knows of a web site for instructions.
     
  3. Digital Matt

    Digital Matt alter ego: Analog Matt

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    This is a decent explanation from the Kenko website:

    Kenko DG Teleplus Extension Tube Set

    Extension tubes are designed to enable a lens to focus closer than its normal set minimum focusing distance. Getting closer has the effect of magnifying your subject (making it appear larger in the viewfinder and in your pictures). They are exceptionally useful for macro photography, enabling you to convert almost any lens into a macro lens at a fraction of the cost while maintaining its original optical quality.

    The DG extension tubes have no optics. They are mounted in between the camera body and lens to create more distance between the lens and film plane. By moving the lens father away from the film or CCD sensor in the camera, the lens is forced to focus much closer than normal. The greater the length of the extension tube, the closer the lens can focus.

    The KENKO DG AUTO EXTENSION TUBE SET contains three tubes of different length, a 12 mm, 20 mm, and 36 mm, which can be used individually or in any combination to obtain the desired magnification. Kenko also makes a DG UNITUBE 12 mm or 25 mm which can be purchased individually.

    Kenko's Auto Focus extension tubes are designed with all the circuitry and mechanical coupling to maintain auto focus and TTL auto exposure with most Canon, Nikon, and Minolta lenses given there is enough light to activate the cameras AF system properly.
     
  4. jonasr_jp

    jonasr_jp TPF Noob!

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    i think i understand how it should work, the problem is that it dont, the picture just get darker the longer extension i do, and its all blurry, and the lens can only be put on upside down.
     
  5. Digital Matt

    Digital Matt alter ego: Analog Matt

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    The view through the viewfinder will get darker, yes, because you are losing lots of light. The lens should be mounted normally to the extension tubes. The reason you say it's all blurry, is because there is a very thin line of Depth of Field. Mostly likely, your focus point will only be an inch from the end of the lens, and the depth of field might only be a fraction of an inch. Try putting your finger in front of the lens, and you'll see how close you need to be. Use a tripod, and stop down your aperture from f8~f16, mirror lock if you have it, and a cable release. That will insure you get the sharpest picture you can get.

    Btw, what lens are you using, and how many mm of extension tube?
     
  6. Torus34

    Torus34 No longer a newbie, moving up!

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    I need two pieces of information:

    1. When you assemble all the parts so that they match the illustration from ebay, one end attaches to the camera and the lens goes on the other end backwards, yes?

    2. If you then take off the lens and remove the ring that the lens was screwed into, can you attach the lens so that it is pointed the normal [not backward] way?

    These two answers will help me a lot in helping you. There's still a lot of information that you will need, but at least I'll know what your set can do.

    Please note that you will do best at first if you go to manual mode, set your zoom lens to the 50mm setting and set the focus at infinity.
     
  7. jonasr_jp

    jonasr_jp TPF Noob!

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    Hi thanks everyone for the help,

    The lens i use is the original lens that comes with the ist ds camera its a 18 - 55mm lens.

    the lens will what ever way i try to put it on be upside down, and the viewfinder is dark allmost so you cant see anything, and the picture gets blurry and noisy and as dark as in the viewfinder.
     
  8. Torus34

    Torus34 No longer a newbie, moving up!

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    Thank you. Email sent.

    DM: I've sent you a PM of my email to Jonas. The set that Jonas bought is a simple one. Chances are good that the tubes use a 50mm thread for connection. The lens must be reversed. This means that the camera must be operated in a fully manual mode. I believe the *ist ds permits this. As a personal note, I have always had a deep and abiding distrust of any camera which does not have a full manual 'fall-back' mode. All but one of my rigs are operated battery-free.
     
  9. jonasr_jp

    jonasr_jp TPF Noob!

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    Thank you so much torus and matt for the explanations,,

    didnt really get it to work with the lens, but yesterday i did some impulse shopping, a 100-300mm pentax lens for 30$ and the extension tube worked perfectly with it, it didnt get dark at all, so it seems like it was the lens that was the problem.
     
  10. Torus34

    Torus34 No longer a newbie, moving up!

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    All's well that ends well. We did what we could.
     

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