Qn about tele converters


agentxq49

New Member
Jun 1, 2009
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#1
Hi, ok heres a qn that i think i asked before, but did not get a good answer.

Do teleconverters change your lens focal length? or do they crop the image?


So for example on a full frame camera, does a 50mm lens + 1.5 teleconverter produce the same image as that of a 75mm lens? or does it produce a 50mm image on a 1.5 crop sensor?

If its the latter, does it mean that in theory, full frame bodies can use non-full frame lenses with a 1.5x teleconverter attached to them? :D
 

May 5, 2009
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#3
Hi, ok heres a qn that i think i asked before, but did not get a good answer.

Do teleconverters change your lens focal length? or do they crop the image?


So for example on a full frame camera, does a 50mm lens + 1.5 teleconverter produce the same image as that of a 75mm lens? or does it produce a 50mm image on a 1.5 crop sensor?

If its the latter, does it mean that in theory, full frame bodies can use non-full frame lenses with a 1.5x teleconverter attached to them? :D
no, teleconverter will not change your focal length, they also do not crop the image, read the following link on how they work:
http://en.wikipedia.org/wiki/Teleconverter

in short, the teleconverter works by enlarging the image circle produced by the lens, so in theory, by using a 1.5x teleconverter with a DX lens (Nikon system), the image circle will cover or barely cover the FX sensor.

but the truth is, most of the DX lenses are not compatible with TC(or all?). and most DX lenses have slow maximum aperture, typically 3.5-5.6, adding a TC will often cause the AF hard to or impossible to work, not to mention the degradation in IQ with TC.
 

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