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12-11-2008, 01:56 PM   #1
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Teleconvertor for DA* 50mmm-135mm lens


Just wondering which teleconvertor you would recomend for the DA* 50mm-135mm lens ? and also how does it perform ?



12-11-2008, 02:31 PM   #2
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QuoteOriginally posted by Murphy2004 Quote

Just wondering which teleconvertor you would recomend for the DA* 50mm-135mm lens ? and also how does it perform ?


I'm just waiting for the new 1.4x converter from Pentax.
If you can't wait for that it appears that two older converters (made for power zoom, which gives you the same contacts as Pentas now use for power to the SDM motor in the lens) gives functional autofocus and several threads on this if you search for them: A Tamron 1.4x which work well and a Kenko 1.5x which work less well, non of them currently in production (but sometimes available used for high prices on ebay). All 2x converters appear to loose too much light for SDM focusing to work. See for example the long thread by jgredline.

If you can live without SDM focusing there are probably many more alternatives that are good considering just optics. The different verions of the Kenko MC7 (Teleplus MC7) converter are all quite good general converters as far as I have seen (I've tried two of them on the DA*50-135). The MC4 (four lenses) is far less good optically (but smaller and cheaper). Someone else has to advice you on the older non-autofocus original Pentax converters. I have never tried them.

I made an attempt to convert a 2x Kenko converter, the big brother to the 1.5x that works, so that it would give SDM or at least screw drive focus, but in wain (there is a thread on this if you search). It appears that the K20D will not let screw drive focus activate through a converter, and therefore I doubt that you will find a converter from before power zoom that allow screw drive focusing on the DA*50-135. At least I have never heard of one.

So I'm waiting for the Pentax converter. The real thing
12-11-2008, 02:53 PM   #3
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Too bad we can't switch to screw drive in the menu, my kenko 1.5x shq really hunts too much with the sdm on my da300. The smc f1.7 afa works great on the 300mm (not sure on the zoom)but you have to rough focus manually, actually a plus as it acts as a focus limiter. I hope the new tc comes out soon.
12-12-2008, 05:45 AM   #4
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Any idea when the new Pentax x1.4 convertor will be available ?.


12-12-2008, 11:52 AM   #5
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sometime in the next 10 years, even though they said by spring 2009.

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