 William R. Turcotte |
Teleconverters and Aperture When using a teleconverter what is the calculation to find aperture? i.e. using a 1.7 teleconverter with a 300mm at 5.6? Thank you
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- Gregory LaGrange Contact Gregory LaGrange Gregory LaGrange's Gallery |
The amount of conversion is how many f-stops you loose. 2x converter is 2 f-stops. A 1.5 converter is 1&1/2 f-stops. So your 1.7 is around 1&2/3 f-stops. But you may not have f-stops in thirds on your camera so make it 2 f-stops.
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William R. Turcotte |
Thank you very much, Bill
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Jon Close |
Almost, but picking nits... whole f-stops are factors of 1.4x (actually 1.4141214, the square root of 2), so a 1.7x teleconverter will effect a 1 1/2 stop aperture change (f/5.6 becomes f/9.5). 1.4x is one stop (f/5.6 ==> f/8) and 2x is two stops (f/5.6 ==> f/11).
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