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02-16-2009, 12:53 PM   #1
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Help Setting the Focal Distance with Teleconverters

When using the shake reduction off of a tripod, the camera (K10) upon startup, asks for a focal distance. I understand that if you are using a 400mm lens, that is the setting for focal distance. If you use a 1.4 or 2.0 teleconverter, what should the focal distance be set at.

Thanks!

02-16-2009, 01:20 PM   #2
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560 or 800.
02-16-2009, 01:29 PM   #3
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You simply multiply the focal length of the lens with the factor of the tc:
- a 1.4x tc gives you 1.4 times the focal length of the lens attached. Thus a 400mm lens gets a 560mm lens
- a 2x tc exactly doubles the focal length, thus a 400mm lens gets a 800mm one.

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02-16-2009, 08:48 PM   #4
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I also have a question
what happen if I attach a 2x teleconverter on a 500mm lens ? my K200D only reconizes up to 800mm.

I 've once put two "2xTC" on a 55-300mm lens an the images were awful

02-16-2009, 11:05 PM   #5
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Thanks for all of the quick answers
02-16-2009, 11:42 PM   #6
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QuoteOriginally posted by XATN3q Quote
I also have a question
what happen if I attach a 2x teleconverter on a 500mm lens ? my K200D only reconizes up to 800mm.

I 've once put two "2xTC" on a 55-300mm lens an the images were awful
That is entirely expected. Generally speaking, teleconverters work best on single focal length lenses. There are two considerations to keep in mind. The first is that whatever the defects in the lens, they will be multiplied by the converter, and the converter will add its own defects to the mix. The other consideration is that when you have, for example, a 400/5.6, the first 2x converter will give you an 800/11 and the second would create a 1600mm f/22 lens. The 1600mm on its own is problematic, and the slow f/stop just makes your life worse. Rather than using two doublers on the lens, use one if you must, and then simply crop the image to create the larger view.
02-17-2009, 03:47 AM   #7
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If you end up beyond the means of the camers, max it out and hope for the best. But as said, most won't find anything of quality at those levels.
02-17-2009, 06:50 AM   #8
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QuoteOriginally posted by tscip22 Quote
When using the shake reduction off of a tripod, the camera (K10) upon startup, asks for a focal distance. I understand that if you are using a 400mm lens, that is the setting for focal distance. If you use a 1.4 or 2.0 teleconverter, what should the focal distance be set at.

Thanks!
Mathematics, the lost science.

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