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Old Oct 31, 2008, 4:29 PM   #1
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do you know of any compatible teleconverters that is compatible with the 50-135.

preferable 1.7 or 2x



Dave
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Old Oct 31, 2008, 9:15 PM   #2
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Hi Dave,

I don't think there is any clear consensus at this time. I've read on different fora that Tamron F 1.4x TCs work, but Kenko 1.5x TCs don't, and I've read the exact reverse from others (both of which are curious since I've always heard that theTamon is a rebadge of the Kenko) -- my take is that it just depends on the particular copy of the lens, body, and TC. These are the only reputable TCs that I know of that have the necessary power contacts to work with SDM on the 50-135, and I assume that this is a prime consideration for you here.

I can offer my experience. I have a 4 yr old Tamron F 1.4x and an early DA*50-135 (probably from the first batch shipped to the US). With my copies of these, on both my K10 and K20, AF hunts back and forth 3 times then quits showing a flashing focus indicator in the VF. The same thing happens for two more tries at focusing, then on the 4th try, it locks focus instantly. This happens consistantly indoors and outside in bright sunlight. I find this to be unacceptable, and don't even consider using his combo anymore. I was very surprised to see that this combo worked for others, but don't doubt their experiences, and since I like the range of the 50-135, I'm okay with not having an SDM TC for it. I will buy one of the new SDM TCs from Pentax when they are released, but will most likely be using it with mostly screw drive lenses.

On another note, myPentax F 1.7x AFA AFs veryquickly and right on the money with either body and the DA* 50-135which is a littleremarkable considering thatthe lensalonedoesn't focus with any consistancy on my K10, but is brilliant on my K20. I've never before experienced a situation where a lens' performance increased significantly when a TC was added, but this is a unique TC, and it obviously doesn't use the SDM motor in the lens.

I attribute this to the K10's AF system, but AF still baffles me to agreat degree, so I just accept this as one of those magic things that technology has wrought, and don't use this lens with that body.Luckily, with the exceptionof this lens and afew others, my K10 focuses all the lenses I use regularlypretty well, so I figure there's little to gain by sending it in for repair (and paying for it since it's out of warranty), at lleast at this time.

Probably not what you wanted to hear. . .

Scott
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Old Oct 31, 2008, 11:16 PM   #3
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snostorm wrote:
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On another note, myPentax F 1.7x AFA AFs veryquickly and right on the money with either body and the DA* 50-135which is a littleremarkable considering thatthe lensalonedoesn't focus with any consistancy on my K10, but is brilliant on my K20. I've never before experienced a situation where a lens' performance increased significantly when a TC was added, but this is a unique TC, and it obviously doesn't use the SDM motor in the lens.

I attribute this to the K10's AF system, but AF still baffles me to agreat degree, so I just accept this as one of those magic things that technology has wrought, and don't use this lens with that body.Luckily, with the exceptionof this lens and afew others, my K10 focuses all the lenses I use regularlypretty well, so I figure there's little to gain by sending it in for repair (and paying for it since it's out of warranty), at lleast at this time.

Scott, I find your comments interesting because I use my 50-135 frequently on each body with little real difference between the two when it comes to focusing, although there is an appreciable difference when it comes to overall photo quality. The K20 and the 50-135 are just a beautiful combo.

Just an example of a low-light shot of a stage performance with the k10/50-135 combo.



Paul
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Old Nov 1, 2008, 8:39 PM   #4
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Trojansoc wrote:
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Scott, I find your comments interesting because I use my 50-135 frequently on each body with little real difference between the two when it comes to focusing, although there is an appreciable difference when it comes to overall photo quality.* The K20 and the 50-135 are just a beautiful combo.
Hi Paul,

I really wanted my K10 to work with my first SDM lens, but it just doesn't focus well -- 100% of the time, at all distances and FLs. I was ready to send it back to Pentax for calibration, but instead waited until I got the K20. As it turned out, the K20 focuses it spot on (with the "best in the bag" IQ that I was expecting and hearing about from others), so I'm not gonna fix something that ain't broke -- I just won't be using this DA* with the K10. This actually works out okay since I like to use both the DA* 50-135 and the Tamron 28-75/2.8 (which focuses great with the K10, even in low light) for shooting people at events, and I can use a 2 camera setup with flash and not have to change lenses.

I considered sending in my K10 for focusing errors and paying the $160 for the reported upgrade to the AF hardware, but decided against doing it at this time since it does focus accurately with all my long glass, as well as most of my other favorite lenses.

It's also possible that this is just a sample thing -- my K10 body just might not like this particular 50-135. . .


Scott
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Old Nov 2, 2008, 9:08 PM   #5
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I'm not totally surprised about Scott's experience, since I had a similar situation. I've always thought it had more to do with early model K10's than it did with the lens, but even then it's been inconsistent. I was going to return my 50-135 but its always been reliable on the K100 and also now on the K20.
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