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06-09-2009, 06:46 AM   #1
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Pentax 1,7x: are good ?

Excuse I make a new post, is the first for me.

06-09-2009, 06:47 AM   #2
mpg
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Pentax adapter 1,7X: is good ?

Hi I live in Italy and I have the tamron 80-200 2.8 adptall 2 with pka ring adapter. I wish to buy the pentax 1,7x it is good for the AF or there are problems ? Can you see me some photo with or without the pentax 1,7x to see the differences? The photo are good with the 1,7x?
It is possible use the 1,7x witha for example a tokina 400 5,6? In this case the af don't work but I can use the pentax 1,7x so the tokina works like a ka lens?
Many thanks to all.
06-09-2009, 07:14 AM   #3
Dom
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Have a look over in the lens review section.

Pentax Lens Review Database - All Geninue Pentax Teleconverters
06-09-2009, 07:26 AM   #4
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QuoteOriginally posted by mpg Quote
Hi I live in Italy and I have the tamron 80-200 2.8 adptall 2 with pka ring adapter. I wish to buy the pentax 1,7x it is good for the AF or there are problems ? Can you see me some photo with or without the pentax 1,7x to see the differences? The photo are good with the 1,7x?
It is possible use the 1,7x witha for example a tokina 400 5,6? In this case the af don't work but I can use the pentax 1,7x so the tokina works like a ka lens?
Many thanks to all.
It works officially only with F2.8 lenses, but some use it with out problems with 300/4.5 etc. Tokina 400/5.6 might be pushing it. If the lens isn't originally a KA-lens the aperture value isn't transferred to the camera with adapter, so a K-lens doesn't become a KA-lens.

The converter has to be prefocused, but after that the final focus is achieved fast.

06-09-2009, 07:48 AM   #5
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you be the judge

Taken with my SMC 300F4 and the 1.7x (i use it almost exclusively on this lens)

With your lens and adaptor it will work perfectly and also show correct (i.e. adjusted for teleconverter) aperture. You need to close focus then let the AF do the rest. I suspect that you may get come PF and CA if you are too far from correct focus (I find this TC amplifies CA a little under the wrong conditions)

06-09-2009, 08:54 AM   #6
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If you mean the Pentax-F 1.7x AF Adapter, yes they are really, really good.
06-09-2009, 08:33 PM   #7
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Bought one a few weeks ago and am very satisfied with the results.
06-10-2009, 01:32 AM   #8
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It is reasonable combing with brighter glass. Otherwise, it failed to close focus well and suffered significant image degradation using available light.

06-10-2009, 02:50 AM   #9
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Here is one with the 1.7x and 80-200 f2.8 adaptall:

06-10-2009, 03:32 AM   #10
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It is pretty good, actually. It takes some getting used to--you have to manually focus and then activate the AF to get it to make the final AF. It's quite accurate when it does. Like other TCs, it mates with some lenses better than others.

Actually, it will work with slower lenses--I even got it to work with my 1000mm f8 by setting the K20D to AF.C--see the long, convoluted thread on that subject here. In the final analysis, though, we concluded that the results were not quite as good as shooting without the TC and cropping.
06-10-2009, 03:41 AM   #11
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my experience

Hi,

I used my 1,7x with number of lens. Quite good results with FA100/2.8, K500/4.5 and Voigtlander 180/4. Especially with *istDS. With K20D it was better to use K500 without TC and crop the photo. I tested it with other lenses but with some results were very weak : Voigtlander 125/2.5 or Leitz 180/2.8.


Pentax *ist DS ,Pentax smc 500mm f/4.5
+AF1.7X 1/350s iso400 hide


Pentax *ist DS ,Voigtlander 180/4 APO-Lanthar
+AF1.7X, 1/750s f/6.7 iso200


Pentax *ist DS ,Pentax smc P-FA 100mm f/2.8 Macro
+TC1.7 +3tubes (68mm) 1/180s f/32.0 iso200


Pentax *ist DS ,Pentax smc P-FA 100mm f/2.8 Macro
+TC1.7 +3tubes (68mm) 1/180s f/32.0 iso200
06-10-2009, 07:32 AM   #12
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Well, Piotr certainly settled the question of whether it's any good!
06-10-2009, 11:02 AM   #13
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The Pentax F 1.7x AF converter is a fine piece of glass, if you have good prime lenses.

Be aware that the AF converter only offers limited AF possibilities, the small lens does not move enough to allow AF on the full lens range. You do need to prefocus manually the lens, and let the AF converter do the fine focusing.

I use it without any problems on the Voigtlander 125 and DA*300.

A few shots with Voigtlander 125/2.5






A few shots with DA*300


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