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01-13-2008, 07:33 AM   #1
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Teleconverter question

I have been looking at teleconverters to use on a couple of long lenses. Unfortunately the price range for these devices range from $40 to over $400! I purchased an inexpensive Kenko Pz-AF 1.5x Teleplus SHQ for $40 from KEH and tried it on a few lenses and haven't noticed much degradation of sharpness. I did notice that any defects present in the lens, were magnified by the TC (Like CA, color fringing, etc.)

What is the most inexpensive TC to use with manual focus older M or A lenses, and what about the newer zooms like the DA* 50-135? What do I look for to determine why a TC is low quality? Lack of sharpness or contrast?

Thanks in advance!


Last edited by TomInJax; 01-13-2008 at 09:19 AM. Reason: Grammar
01-13-2008, 08:35 AM   #2
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I'd also be interested in hearing from the experts out there using TC's. I'm in the market for a TC and would be interested in hearing more. From all I've read it seems that most of the 1.4/1.5 TC's seem to be roughly equal, with the 2.0 TC's not as good. I've also heard the Pentax 1.7 being the best of the bunch.

NaCl(not much experience here in TC's)H2O
01-13-2008, 09:41 AM   #3
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I have both the Pentax 1,7 and the Kenko 1,5x SHQ, I've tested them both over the FA*300/2,8, and the Kenko was better. Not by much, but it was easy to see on 100% crop.

In any case the degradation of the image was noticeable.
01-13-2008, 11:48 AM   #4
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Let me tell you a little story. I bought the sam TC from KEH a couple of years ago, for about the same price. I have not used it much because I did not like the results I was getting. I then bought the Pentax F1.7 AF TC. I sold that a few months ago. A couple of months back I picked up a Sigma 100-300 f4.0 EX DG with the matching Sigma 1.4x TC. This combo seemed OK.

Last week, I was out at the beach with this combo. I dropped the TC on the beach. Well to make a long story short, the TC won't AF, so off it goes to Sigma to be cleaned and repaired.

Yesterday, just out of curiosity, I decided to test the Kenko with the 100-300. I mounted it on a tripod in my studio, set the aperture at F8 and did 3 test shots at 100, 200,300mm (150,300,450 with the TC). My test target was my Silver 77 Limited. I was shocked at how good this combo is. Better than the matched Sigma. I then decided to test the Kenko + 100-300 at 300mm at each aperture from wide open f4.0 to f32. I chose 300mm because I am most likely to use it at that FL. I was very pleasantly surprised. Wide open it is a touch soft but very usable. A little USM brings it right in. Between f8.0 and f16 you would not know a TC was used, it is that good. Beyond f16, defraction effect sets in and you can see the image soften. I am very sorry, but I deleted the test shots when I finished.

My conclusions are the Kenko you bought is a bargain, A more expensive TC will not get you noticeably better images. The key is too use it with top draw glass. So save your money and buy a better lens to go with the Kenko TC.

01-13-2008, 12:42 PM   #5
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Kenko Ditto

I also did the Kenko/KEH dance and though I have not used it much the QI of the images I have taken have made it a worthwile $40 expenditure. IMO.
01-13-2008, 04:03 PM   #6
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Can anybody here tell something about Sigma 1.4X EX DG TC?
I bought this expensive TC recently but it was said not supporting the SDM of DA*, is it true?
Thanks!
01-13-2008, 06:25 PM   #7
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This TC has a protruding front element that is only compatible with certain lenses with recessed rear elements. Sigma publishes a list of Sigma lenses it is compatible with. Other brands, you need to test on your own.
01-13-2008, 06:29 PM   #8
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QuoteOriginally posted by jianshi Quote
Can anybody here tell something about Sigma 1.4X EX DG TC?
I bought this expensive TC recently but it was said not supporting the SDM of DA*, is it true?
Thanks!
Well, I've got a signma 1.4x converter that has a drive shaft through it for auto focus (which of course the SDM on the K10 doesn't use. With my DA*16-50, the system is completely baffled. there may be a working combination some how, but if you just screw them together, it doesn't work.

01-13-2008, 06:34 PM   #9
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I was bored watching football this afternoon, so I decided to repeat my test of the Kenko Pz-AF 1.5X Teleplus SHQ TC with the 100-300's little brother, the Sigma 70-200mm f/2.8 EX APO IF.

The set up was in my studio, lit by 2 monolights. I adjusted the power to get the exposure I wanted for each shot. When I got down to F22 and F32 , I had to incrementally increase ISO to compensate, as my strobes were at full power by then.

I shot each exposure at 70mm, 118mm and 200mm.

Here are the results can be seen here.
Lens Tests Photo Gallery by Alan H. Glassman Photography at pbase.com

I hope this proves helpful. (I really don't like doing lens testing)
01-13-2008, 07:30 PM   #10
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Where is the best/cheapest place to buy a Kenko Pz-AF 1.5X Teleplus SHQ TC? Any input or experience with the 2x one?

I am very interested in trying one out.

Last edited by harv3589; 01-13-2008 at 07:38 PM.
01-13-2008, 07:56 PM   #11
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QuoteOriginally posted by roscot Quote
This TC has a protruding front element that is only compatible with certain lenses with recessed rear elements. Sigma publishes a list of Sigma lenses it is compatible with. Other brands, you need to test on your own.
QuoteOriginally posted by rvannatta Quote
Well, I've got a signma 1.4x converter that has a drive shaft through it for auto focus (which of course the SDM on the K10 doesn't use. With my DA*16-50, the system is completely baffled. there may be a working combination some how, but if you just screw them together, it doesn't work.
Thanks!
Could you give me more information about this: "there may be a working combination some how"? Did it ever work before? Or just a rumor?
01-13-2008, 08:09 PM   #12
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QuoteOriginally posted by roscot Quote
I was bored watching football this afternoon, so I decided to repeat my test of the Kenko Pz-AF 1.5X Teleplus SHQ TC with the 100-300's little brother, the Sigma 70-200mm f/2.8 EX APO IF.

The set up was in my studio, lit by 2 monolights. I adjusted the power to get the exposure I wanted for each shot. When I got down to F22 and F32 , I had to incrementally increase ISO to compensate, as my strobes were at full power by then.

I shot each exposure at 70mm, 118mm and 200mm.

Here are the results can be seen here.
Lens Tests Photo Gallery by Alan H. Glassman Photography at pbase.com

I hope this proves helpful. (I really don't like doing lens testing)
Thanks Alan for your testing! It does answer a lot of questions for most of us. You are right about f/8 to f/16! Those shots are very crisp and sharp. The wide open one seems to be a bit soft, as you said. Considering that I will be using it on a long lens, the results will do in a pinch. I should be getting the 300mm f/4 any day now. I also put in an order for the Voigtlander 125 too. Both of these are manual focus primes that will probably work well with this TC.

B&H has one of these tele-extenders for Pentax available at:

Kenko | 1.5x DG AF Tele-Converter for Pentax AF | K15AFDGPK
01-13-2008, 11:32 PM   #13
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QuoteOriginally posted by roscot Quote
My conclusions are the Kenko you bought is a bargain, A more expensive TC will not get you noticeably better images. The key is too use it with top draw glass. So save your money and buy a better lens to go with the Kenko TC.
+1 to that! (as the programmers here will relate to) I was dealing with this recently too, and I came to the conclusion of "garbage in, [magnified] garbage out".

I did keep and post my test series of a Bower 2x that you can see here... Use the filename for focal length, and whether with or w/o TC. That worked better then I thought, just a tad of red cast that could have been negated with a lowering of WB in post, but I wanted to leave it there for comparison sake:
Bower 2x TC Tests album | m8o | Fotki.com
01-14-2008, 06:48 AM   #14
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I have 6 different TCs

vivitar MC-22 2x and 3x
Takumar 2x in KA mount
Pentax 1.7x AF adaptor
Sigma EX 1.4x and EX 2x DG

I have been quite pleased with the sigma 1.4x and the pentax 1.7x (note they are expensive)

I have just gotten the sigma 2x

I have not tried enough with the TAK and vivitar reciently.
01-14-2008, 07:56 AM   #15
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When looking at the results at 200mm, which with the TC is really 300mm, be aware that quite a bit of the preceived softness is in reality lack of DOF. The image is a bit soft at f2.8, but the DOF can be measured in mm, it is so thin. That is what is causing the "halo" effect. As you go through each image decreasing the aperture, you can see the increase in DOF. FYI, the focus point of all these shots was the green dot.
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