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08-05-2011, 09:56 AM   #1
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Which teleconverter is considered best?

I just ordered the DA*200mm2.8....now I'm thinking of getting a teleconverter for it.
I've been searching the forums and can't seem to get a consensus on which teleconverter will work with the SDM to keep the lens an autofocus. I'm a real sharpness freak, so I'm looking at something that won't mess with the IQ much. Any ideas? Thx

08-05-2011, 10:15 AM   #2
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There isn't really a great option in terms of a fully functional AF TC for the DA* series.

The Tamron 1.4x Pz-AF will allow the body to control the SDM motor of the lens, however the AF performance become ok at best. Combined with the DA*200, you can get the AF to lock, but it's not fast and it's not always on the first try. In terms of trying to capture fast moving object, I think you would be disappointed in the results. In terms of IQ, as with any TC there will be some level of hit to IQ, but both the DA*200 and 300 are very good on their own and so the results with the 1.4x Tamron is still very good. Whether or not it is good enough is subjective I suppose. They don't make the 1.4x Tamron Pz-AF anymore, so the only option is used and they generally sell around $175-200. There is also a Kenko 1.5x with the PZ contacts that sells for around the same price. I've never used that one specifically, but I've heard they are somewhat similar in terms of performance.

The other main optoin is the Pentax 1.7x AF-A, which is a TC with a focusing mechanism inside. It will work with any lens, including MF lenses, as the focusing takes place in the TC itself. The downside if you have to pre-focus manually as the range inside the TC itself is typically not enough to cover from the MFD to infinity. IQ is very good, on par with the 1.4x as I recall. The other downside is that they're expensive, with used copies going for anywhere between $300-450 depending on what's out there at any given time.
08-05-2011, 10:25 AM   #3
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The Kenko PZ 1.5x works fine with SDM, although the manual clearly states and I've also found it to be true that AF below f4 is unstable. The Kenko I own went for around $159USD.
08-05-2011, 10:31 AM   #4
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QuoteOriginally posted by blackcloudbrew Quote
The Kenko PZ 1.5x works fine with SDM, although the manual clearly states and I've also found it to be true that AF below f4 is unstable. The Kenko I own went for around $159USD.
Again, if it's anything like the Tamron 1.4x Pz-AF (which I fairly certain it is), it will work with SDM lenses. However in practice, even on an f/2.8 lens like the DA*200, the AF performance with the TC is so-so at best based on my experience with the DA*200 and the Tamron 1.4x TC.

08-05-2011, 10:50 AM   #5
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thx for the tips...how about a teleconverter that would have me manual focus? If I'm going IQ over AF ability, is there any better glass out there?
08-05-2011, 10:54 AM   #6
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considering all the issues, perhaps the best, but most expensive option is the SMC-F 1.7x AF TC

this TC has its own focusing mechanism, and is small and fast, making AF very fast.

It will work on SDM lenses because the SDM lens is not used for focusing. The TC also corrects for the aperture, i.e. it converts the 200/2.8 into a 340mm (which you enter manually) F4.5 or something like that and the aperture shows up this way in the EXIF. that is important if you use the lens with a flash because P-TTL nees the correct aperture.

but they sell for about $350 if you can find one.
08-05-2011, 11:03 AM   #7
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I sell pictures, so I'm very critical of sharpness, and I love the quality of the DA* 200mm. A few months ago, a gadget crazy friend was kind enough to let me test a number of TCs for a few months. I found them all totally unacceptable, except the Pentax 1.7. I found the AF actually worked better with it than without, although as someone mentioned, you do have to begin relatively close manually first. In the mid-ranges, it is great, but just as with an extender, you lose IQ close and at infinity, so the extra distance you gain is limited from a practical veiwpoint. You also lose an f-stop or two, and again from a practical standpoint, that is critical for the real wildlife photography (often in low light) that I do. Because I often have to shoot quickly, the extra fiddling to make sure you start near focus in the first place, and not being able to get good IQ at infinity, is a real problem but for back yards and zoos, it would be fine. Because the practical working distance (infinity limitation), the few yards I gain are not enough to make any difference upon whether the animal spooks or not, so I'm better off getting a little closer and shooting with a bare lens. And because I often have to shoot in low light, the extra stop or two is a big deal, but again probably wouldn't be for back yards and zoos.
Despite all that, and despite the fact the fiddle factor and limtiations of TCs in general don't work for me, the Pentax 1.7 was by far the best of the bunch I tested.
08-05-2011, 11:32 AM   #8
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QuoteOriginally posted by Ron Kruger Quote
I sell pictures, so I'm very critical of sharpness, and I love the quality of the DA* 200mm. A few months ago, a gadget crazy friend was kind enough to let me test a number of TCs for a few months. I found them all totally unacceptable, except the Pentax 1.7. I found the AF actually worked better with it than without, although as someone mentioned, you do have to begin relatively close manually first. In the mid-ranges, it is great, but just as with an extender, you lose IQ close and at infinity, so the extra distance you gain is limited from a practical veiwpoint. You also lose an f-stop or two, and again from a practical standpoint, that is critical for the real wildlife photography (often in low light) that I do. Because I often have to shoot quickly, the extra fiddling to make sure you start near focus in the first place, and not being able to get good IQ at infinity, is a real problem but for back yards and zoos, it would be fine. Because the practical working distance (infinity limitation), the few yards I gain are not enough to make any difference upon whether the animal spooks or not, so I'm better off getting a little closer and shooting with a bare lens. And because I often have to shoot in low light, the extra stop or two is a big deal, but again probably wouldn't be for back yards and zoos.
Despite all that, and despite the fact the fiddle factor and limtiations of TCs in general don't work for me, the Pentax 1.7 was by far the best of the bunch I tested.
Good to know, thx.... I like to complicate my life, so maybe going the TC route, isn't the best of ideas...

08-05-2011, 11:40 AM   #9
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Regarding AF, the DA 1.4x prototype that was never released.
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