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Photography Question 

Christine M. Fackler 		 

telephoto lens


I just purchased a teleconverter lens for my Nikon D40x and it is making everything fisheye. What am I doing wrong? I've tried different apertures as suggested but it's not working. I purchased this lens as it was described for my specific Nikkor lens.


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March 06, 2010

 
- Gregory LaGrange

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Gregory LaGrange's Gallery 		  I know the literal meaning of fisheye when it comes to photos, but could you go ahead and clarify what you mean by fisheye?
I'm leaning towards you mean you're getting darkness around the edges of the image(vignetting) . Also, which teleconverter did you buy? By any chance did you get an extension tube by mistake?


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March 06, 2010

 

Christine M. Fackler 		 
 
 
I got a Bower High Definition Digital 2X Tele Converter Lens... it says it right on the lens. The center of the field is crisp and clear but as the image moves outward towards the edge of the lens, it gets blurry and larger. For instance, if centering on the the TV, the center the TV is crisp, but the outside of the TV frame is blurry and the TV sides/top/bottom become concave - I included a picture of my TV. Any help would be appreciated.


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March 06, 2010

 

Jeffrey R. Whitmoyer 		  Looking at your image leaves me wondering if the 2X converter isn't designed for a full frame lens and that is causing the problem if you are using a DX only lens or if it is designed for DX and you are using full frame. I'm thinking you are seeing the TC or lens internals. I don't use a TC right now so am only speculating about that as a cause of the problem. Also, I'm not sure of the quality of Bower equipment. You may want to email them directly about this problem.
Jeff


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March 07, 2010

 
- Gregory LaGrange

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Gregory LaGrange's Gallery 		  Did you buy something that screws on to the front of your lens? Tell me if you bought what is on this page
http://www.goshotcamera.com/product/LTP001722XB-AMZ/Bower-Hi-Def-2x-Telephoto-Conversion-Lens-72mm-for-DigitalFilm-Cameras-in-Black-color.html

If you bought that one, you bought a cheap one. Teleconverters work by magnifying the central image coming through the lens. A good one like Nikon's and Canon's fits in between the lens and camera and has elements inside that are optically correct and provide a very good image.
The one you bought seems to be essentially like a hand held magnifying glass used for reading fine print, that you're holding against the front of your lens.
You bought a poor quality converter. Extremely poor quality.


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March 07, 2010

 

Lynn R. Powers 		  Christine,

You, like many on this site, are confusing a TC or TE with extension tubes. A Teleconverter or Teleextender be it a 1.4X or 2X, as Greg mentioned, go between the lens and the camera. Nikon makes excellent ones as does Canon and Kenko. These are not to be used with most kit lenses. They are generally used on telephoto lenses of 100mm or longer. They also require the lens to be no smaller than an f4. Remember that f5.6 is smaller than f4 even though the number 4 is a smaller number.

On a full frame camera like the Nikon D3 serie and D700 when adding a 1.4TE that your field of view (FOV) extends to equal that of a 140mm lens. With the DX lenses and the crop of 1.5 a 100mm lens gives you the FOV of 150mm. Add a 1.4X and you get a FOV of 210mm.
And if you add a 2X you wind up with a FOV of 300mm. This comes at a cost and that is light loss. A 1.4 TC added to an f4 100mm becomes an f5.6. Your camera will still autofocus. With a 2X the f4 100mm becomes an f8 and you must use manual focus. Canon only has the ability to use these on prime lenses of 135mm or more, all of the 70-200mm versions and the 100-400mm lenses. Perhaps some of their newer lenses also.
Being that the 100-400mm is a f5.6 at full extension, 400mm, it must be manually focused unless used on a 1D series body. They enlarge the entire image on both cropped and FF lenses and sensors.

Extension tubes will fit just about any lens. Check you camera maker to find out for sure. These do not have glass in them like the TCs do. They allow you to shoot with any lens closer than their normal minimum focus distance. The longer the extension tube the closer you can get. A friend uses his Canon 100-400mm @400mmextension tube and gets near macro images with a 25mm
extension tube attached on an EOS Canon 20D. The only problem is that they also decrease your maximum focus distance. The above lens may only focus to 50 feet* with that combination.
Everything beyond that would be blurred which can be of help when you have a nasty background.


Lynn

*- This is just a guess. It may be more or less. But it definitely cuts down on your maximum distance for focus purposes.


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March 08, 2010

 
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