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03-19-2014, 05:48 AM   #331
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The only one with perfect focus is the 300+1.4x at 5.6, you can see that by comparing the twig in the background. But yeah, my 150-500 was also glowy wide open at 400-500mm but some clarity fixed most of it.

03-19-2014, 05:53 AM   #332
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The converter also seems to be FF compatible (as also dpreview states: "Max Format size 35mm FF") and "converts" an APS-C lens into a FF lens (both tested with a PK-EOS adapter and a Canon 5DIII):
DA 15 (works, despite the incompatibility claimed by Pentax; hood may cause a problem).

Similar test (using another converter) from "noodlelow"
03-19-2014, 07:21 AM   #333
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My 150-500 is soft wide open. At f8 it is quite good. The DA*300 is better wide open. In low light conditions I leave the 150-500 at home, but use it when I need reach in good light. I suspect the tc + DA*300 may replace the sigma in use.
03-21-2014, 03:18 AM   #334
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My Sigma 150-500 is no longer mine. After I bought the DA*300 I found that upsampling a DA*300 picture making the object at the same size as a Sigma 150-500@500 the former was much sharper and more detailed even with the Sigma stopped down.

03-21-2014, 03:38 AM   #335
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I'm not surprised, Tjompen, although I'm surprised by preliminary reports stating that this converter is indeed of very nice quality (optically) if not better.
Good job, RI.
03-21-2014, 08:01 AM   #336
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Well, that's my old 150-500 and I found the opposite to be true, especially at F8. But I use two K-5's so it could be that you lose much less when cropping with your K-3.
03-21-2014, 08:37 AM   #337
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QuoteOriginally posted by VisualDarkness Quote
Well, that's my old 150-500 and I found the opposite to be true, especially at F8. But I use two K-5's so it could be that you lose much less when cropping with your K-3.
It might just be the extra sharpness you get from the K-3 that sees the flaws in the Sigma when @500. I don't know. Sigma and I never became good friends but she's in good hands now.
03-22-2014, 06:18 AM   #338
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QuoteOriginally posted by audiobomber Quote
No, like this: K-3 -> Kenko TC -> Pentax TC -> lens.



Yes, with the configuration above, the combo focusses normally. It doesn't stop trying to focus before lock is achieved, and when it indicates focus lock, it is actually in focus. Acquiring focus lock is not as sure as without the Kenko, but that is to be expected with an f/8.4 lens. The Pentax TC counteracts the weirdness of focussing with an SDM lens and Kenko TC.
I was too hasty with my test. I have tried using this combo in the field, and I retract my statement. Any combination of Kenko 1.5X and DA*300 provides terrible auto-focus. IQ with two converters is not impressive either, I will be cropping with the HD 1.4X from now on, no Kenko for me. I am very sorry if my premature and false announcement has caused any inconvenience.


Last edited by audiobomber; 03-22-2014 at 04:44 PM.
03-22-2014, 06:24 AM   #339
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QuoteOriginally posted by audiobomber Quote
I was too hasty with my test. I have tried using this combo in the field, and I retract my statement. Any combination of Kenko 1.5X and DA*300 provides terrible auto-focus. IQ is not impressive either, I will be cropping with the HD 1.4X from now on, no Kenko for me. I am very sorry if my premature and false announcement has caused any inconvenience.
I have the same experence. Not working =(
03-22-2014, 08:15 AM   #340
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I just received the Pentax 1.4x, and trying it out with the Sigma 500/4.5, AF (screwdrive) works fine, accurate and responsive, but exposure metering in all modes is off by up to 1ev, underexposing. It's fairly consistent, so once you learn the behavior, it's easy enough to dial in compensation, but still, unexpected behavior..

Sharpness, from only short first impressions, is very good, better than the sigma 1.4x

Chris
03-23-2014, 05:27 AM   #341
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QuoteOriginally posted by froeschle Quote
and "converts" an APS-C lens into a FF lens
Wow!
Is this where Pentax is going?
O.K. Albeit at a loss of 1 fstop, does every APS-C lens become FF? i.e. does the 15mm f4 become 15mm f5.6 on FF?
03-23-2014, 06:23 AM   #342
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Conceptually, yes. A T/C "spreads" the light by a factor of, say, 1.4, very close to the 1.55ish required.

So the lens would be a 21mm f/5.6, with some bad vignetting wide open.


Practically, the T/C could be shrouded , or physically incompatible (glass hits glass). Generally T/C's are optimized for the relatively telecentric long focal length lenses... so performance on ultra wide angles usually isnt good.
03-23-2014, 12:27 PM   #343
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QuoteOriginally posted by ElJamoquio Quote
... so performance on ultra wide angles usually isnt good.
Correct........

........but the pecuiar thing is, that RICOH/Pentax actually and specific mentions that THIS TC is compatible with some specific of those lenses and where there are restrictions these are explicitly mentioned.

Unfortunately, most of the detailed information has vanished from the homepage in English (it was there last time I looked before today), but you can still find it in the Japanes version (try Google Translate on the foot notes, and you will get an idea):

HD PENTAX-DA AF REAR CONVERTER 1.4X AW / ???????AF????? / K??????? / ??? / ?? | RICOH IMAGING
03-23-2014, 11:58 PM   #344
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QuoteOriginally posted by climbertrev Quote
Wow!
Is this where Pentax is going?
O.K. Albeit at a loss of 1 fstop, does every APS-C lens become FF? i.e. does the 15mm f4 become 15mm f5.6 on FF?
QuoteOriginally posted by ElJamoquio Quote
Conceptually, yes. A T/C "spreads" the light by a factor of, say, 1.4, very close to the 1.55ish required.

So the lens would be a 21mm f/5.6, with some bad vignetting wide open.

Practically, the T/C could be shrouded , or physically incompatible (glass hits glass). Generally T/C's are optimized for the relatively telecentric long focal length lenses... so performance on ultra wide angles usually isnt good.
The first thing I did when my Pentax 1.4x Teleconverter arrived was to attach it to a Pentax Z-1p film camera. Then I attached various lenses (below) that might be expected to hard-vignette. None of them showed signs of vignetting, looking through the viewfinder at a well-lit surface. This isn't a test of image quality in the corners, just a test of whether there is any image in the corners.

The lenses I tested that apparently didn't hard-vignette at any focal length , showing image right to the corners, were:

DA 10-17mm Fisheye. (Not on the Pentax list of supported lenses!). This hard-vignettes on the Z-1p at 10mm and 12mm without a Teleconverter.

DA 12-24mm. This hard-vignettes badly on the Z-1p at wide angles without a Teleconverter.

DA 17-70mm. This hard-vignettes at all focal lengths on the Z-1p without a Teleconverter.

DA* 60-250mm.

I haven't yet tested any other lenses on the Z-1p with this Teleconverter. I may shoot my last roll of film with a range of lenses using this Teleconverter on the Z-1p to complete my previous tests of lenses on the Z-1p. That will test image quality in the corners.
03-24-2014, 03:39 AM   #345
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QuoteOriginally posted by Barry Pearson Quote
The first thing I did when my Pentax 1.4x Teleconverter arrived was to attach it to a Pentax Z-1p film camera. Then I attached various lenses (below) that might be expected to hard-vignette.
I have to say that this is way beyond my understanding

The most important reason for getting a FF camera is getting better image quality than possible with aps-c. By using these lenses with a converter, you are reducing IQ enough that the whole point of using a FF in the first place disappears. The DA12-24/4 gives you a better IQ on a K-5 or K-3 than on a FF camera with a converter between.
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