Tele convertors
Posted 19/07/2009 - 17:58
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What kind of lens is it, 100-300mm doesn't say a lot but I can already say that you will most likely are getting troubles since the AF needs a minimum aperture of 5.6 to work proper.
So that means that your lens needs to be at least f/2.8 for a 2x TC to let it work good with AF.
The best thing is to get a 1.4X, your lens will only lose one stop instead of two and the image quality would be better. With 2X you will really pushing the lens.
There are enough 1.4X available simply ask in your shop or look on SRS.
If you need SDM or HSM to focus then things get problematic but since you use a *ist dl that wouldn't be a problem since the camera doesn't support SDM.
So that means that your lens needs to be at least f/2.8 for a 2x TC to let it work good with AF.
The best thing is to get a 1.4X, your lens will only lose one stop instead of two and the image quality would be better. With 2X you will really pushing the lens.
There are enough 1.4X available simply ask in your shop or look on SRS.
If you need SDM or HSM to focus then things get problematic but since you use a *ist dl that wouldn't be a problem since the camera doesn't support SDM.
Stefan
K10D, K5
DA* 16-50, DA* 50-135, D-FA 100 Macro, DA 40 Ltd, DA 18-55
AF-540FGZ
K10D, K5
DA* 16-50, DA* 50-135, D-FA 100 Macro, DA 40 Ltd, DA 18-55
AF-540FGZ
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37 posts
22 years
Bangalore India
Lens: smc pentax-da 1:3.5-5.6 18-55mm al
smc pentax-fa 1:3.5-5.6 28-80 mm
smc pentax-f 1:4.5-5.6 100-300 mm
Flash: af-540fgz