[pizzamaker74]

I've done some interesting tests with teleconverters - I used the 60-250 on the K1 - and then used the Pentax 1.4 APS-C on the lens and the Tamron 1.4X Pz-AF MC4 Tele Convertor against the body - giving 1.4 * 1.4 * 250 at the long end - some strange results but then I got this one which stunned me... at f/8 - ISO 800, 1/250 sec. Seems really sharp. I believe the camera is only reporting the pentax converter accurately - so its a stop greater than 8 I believe... The interesting thing is that you get a full frame image as the Tamron converter zooms past the Pentax APS-C vignetting giving you 36 megapixels at around 490mm. With higher ISO settings you get away with some ok shots.

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[joergens.mi]

is a picture with the tamron 1.4 converter alone vignetting or not?

Thanks for reply. a 5.6 80x350 working with AF would be nice.

[pizzamaker74]

is a picture with the tamron 1.4 converter alone vignetting or not?

Thanks for reply. a 5.6 80x350 working with AF would be nice.

the 60-250 is very good in FF even without any teleconverter (I have performed the baffle modification). Adding the Tamron Teleconverter only reduces the already barely noticeable vignetting. The Pentax HD teleconverter adds vignetting but including the Tamron as well allows the image to be fully full frame capable and with the K1 the autofocussing works very well considering the configuration.