Avoiding circles caused by teleconverter lens

Discussion in 'Beyond the Basics' started by shuss, Dec 23, 2008.

  1. shuss

    shuss TPF Noob!

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    Just got a new 0.45x wide-angle teleconverter lens for my 14-40mm Olympus lens. I am seeing black edges on the sides when the lens is totally zoomed out. Is there a way to avoid this?
     
  2. AlexColeman

    AlexColeman TPF Noob!

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    No, it is just Vignetting. With those adaptors, you have to crop to eliminate, because DXo probably can't fix.
     
  3. JerryPH

    JerryPH No longer a newbie, moving up!

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    Thats called vignetting. You can address this in post process. Some cameras like the D3 or D700 can correct for vignetting in camera.
     
  4. benhasajeep

    benhasajeep TPF Noob!

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    You have just found the limitations of an adapter that is not designed for your lens. It fits but not designed for it. Basically it was made to fit the filter ring but it does not allow a large enough immage circle for wide angle. There is no way around it except to crop it out. Which is basically taking away some of the whole reason you bought a wide angle adapter! The attachment is thick enough it is actually blocking the view of the lens. With wide angle lenses even a filter can block some of the view. With these fairly thick lens adapters they block even more light. Even though it is a .45x effect. Deppending on how much you can zoom out, it may be only allowing you a .6x advantage.

    Example. Say you can see good light down to 20mm on your lens with the attachment on. Below that you can start seeing the edges getting darker (look in the corners). .45 x 20mm = 9mm. Since your lens goes down to 14 normally without the attachment with no problems. That attachment is only giving you a .64x wider view. .64 x 14mm = 8.94mm

    This is the reason most people stay from these attachments on SLR lenses. They are just not made for specific lenses. They are made to fit a filter ring size. On telephoto that is not so bad. But wide angle they are just about useless. Or at least in your case, not as useable as it could or should be.

    One last example. I have a nikon 8700 prosumer camera. Point and shoot that looks like SLR. I have a wide angle converter lens for it. The wide angle converter lens is at lest 3x wider than the actual lens on the camera is! It is designed specifically to work with the lens when it is wide open. It is wide enough it doesn't block the light or view. Also it is designed so that is the correct distance from the mounted lens. So when the lens is zoomed in, the image circle from the attachment still covers the whole frame.

    The genaric attachments are not made for specific lenses. So, they have alot of limitations.
     
    Last edited: Dec 24, 2008

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