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03-23-2014, 05:38 AM   #1
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tele converters

I have a Pentax k200d and use a Tamron 70-300 tele macro and a Sigma APO 150-500 F5-6.3. I am interested in Wild life photography and am just getting to grips with the lenses. Am very pleased with the results so far and will be posting some pics when I get some I consider worthy enough. Being a beginner even I laugh at some of the results. I have and still am reading the forums and trying to put into practice all the great advice given. My question is this, having read a lot about tele-converters I am considering trying one but in the instruction leaflet for the Sigma -150-500 it says the Pentax mount tele-converter is not compatible with this particular lens. Does this mean that no tele-converter can be fitted to the lens or just the Pentax make tele-converter. Has anyone tried a converter on this lens, any feedback would be greatfully received.

03-23-2014, 05:41 AM   #2
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QuoteOriginally posted by brown142 Quote
I have a Pentax k200d and use a Tamron 70-300 tele macro and a Sigma APO 150-500 F5-6.3. I am interested in Wild life photography and am just getting to grips with the lenses. Am very pleased with the results so far and will be posting some pics when I get some I consider worthy enough. Being a beginner even I laugh at some of the results. I have and still am reading the forums and trying to put into practice all the great advice given. My question is this, having read a lot about tele-converters I am considering trying one but in the instruction leaflet for the Sigma -150-500 it says the Pentax mount tele-converter is not compatible with this particular lens. Does this mean that no tele-converter can be fitted to the lens or just the Pentax make tele-converter. Has anyone tried a converter on this lens, any feedback would be greatfully received.
Any TC should work, actually. There's no reason it shouldn't, though not all TC's support AF and auto-aperture.

Users have reported SDM incompatibilities with the new Pentax TC and various Sigma lenses, but this doesn't mean that the converter won't work.

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03-23-2014, 05:49 AM   #3
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The Sigma TC isn't compatible because the front element of the TC protrudes past the front of the lens mount. Only lenses with a recessed rear element can use it.





03-23-2014, 06:35 AM   #4
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Thanks guys I had been told there shouldn't be a problem with other TC's but not the reason why. Will now start looking for one

03-23-2014, 10:52 AM   #5
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Just a heads-up... I wouldn't expect good results with the 150-500 and a TC. Probably better to just get a superzoom/bridge camera.
03-23-2014, 02:02 PM   #6
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QuoteOriginally posted by brown142 Quote
I have a Pentax k200d and use a Tamron 70-300 tele macro and a Sigma APO 150-500 F5-6.3. I am interested in Wild life photography and am just getting to grips with the lenses. Am very pleased with the results so far and will be posting some pics when I get some I consider worthy enough. Being a beginner even I laugh at some of the results. I have and still am reading the forums and trying to put into practice all the great advice given. My question is this, having read a lot about tele-converters I am considering trying one but in the instruction leaflet for the Sigma -150-500 it says the Pentax mount tele-converter is not compatible with this particular lens. Does this mean that no tele-converter can be fitted to the lens or just the Pentax make tele-converter. Has anyone tried a converter on this lens, any feedback would be greatfully received.
Are you discussing the Sogma APO 1.4x EX DG teleconverters?

It may be entirely possible that the sigma TC is not compatible.

The sigma TC had a protruding front element which requires the rear of the lens to have an opening 35mm in diameter, 12mm or more deep.

To my knowledge, the only zoom that can be used 100% with the teleconverters is the non HSM version of the 70-200/2.8EX. And perhaps the 100-400/5.6. The bigma (50-500) cannot be used at all focal lengths (I think the rear of the lens hits the front of the teleconverters for focal lengths shorter than about 100mm) but can couple at longer focal lengths.

You can use sigma HSM lenses like the newer bigma and 70-200/2.8 but without autofocus.

Lenses and teleconverters slower than F6.9 will not reliably autofocus, although they can be coupled and used manually.
03-24-2014, 04:22 PM   #7
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I think with already having a 500mm lens, you'd have to evaluate whether you'd be better off just occasionally cropping by 1.5x or so vs. using a converter on that Sigma lens. When you get to that amount of magnification you need awfully good tripod techniques to hold the camera still, and then have to hope for very good environmental conditions (no wind, haze, etc.) It seems like when you look at a lot of published FF wildlife work, there isn't a huge percentage done with 750mm+ lenses, which is what you'll be creating with an extender.
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