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02-29-2016, 12:15 PM   #1
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Teleconverters on the Full Frame

Just wondering if we may see improvement with focus speed and functionality of the Kenko Teleconverters on the Full Frame. Right now I have two with SDM contacts., a Kenko Pz-AF 1.5 Teleplus MC and another no name 2x. The kenko works great on the DA* 50-135, DA 18-135 and my FA 300 F4.5, but it suffers when using the Sigma 70-200 F2.8 HSM OS. Also the 2x converters spends most of the day just searching, and once in awhile it locks in, but rarely.

02-29-2016, 12:51 PM   #2
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QuoteOriginally posted by bobell69 Quote
Just wondering if we may see improvement with focus speed and functionality of the Kenko Teleconverters on the Full Frame. Right now I have two with SDM contacts., a Kenko Pz-AF 1.5 Teleplus MC and another no name 2x. The kenko works great on the DA* 50-135, DA 18-135 and my FA 300 F4.5, but it suffers when using the Sigma 70-200 F2.8 HSM OS. Also the 2x converters spends most of the day just searching, and once in awhile it locks in, but rarely.
Performance should be very similar, since both cameras have the same AF sensitivity and similar hardware. The K-1 has a few more AF points, which might help with tracking.

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02-29-2016, 07:14 PM   #3
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Another nifty thing -- using your kenko 1.5x, your crop sensor lenses will cover the full frame - the 50-135 will have the same field of view as it does on your K-5.
03-01-2016, 06:03 PM   #4
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QuoteOriginally posted by narual Quote
Another nifty thing -- using your kenko 1.5x, your crop sensor lenses will cover the full frame - the 50-135 will have the same field of view as it does on your K-5.
That's a good point, never thought of that. Will be interesting to try it when I get a K1

03-01-2016, 06:44 PM   #5
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How about the "old" SMC Pentax-F 1.7x AF Adapter ?
That should be interesting.
03-02-2016, 08:43 AM   #6
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I don't want to hijack this thread but i didn't want to open another thread for this. I am on the edge to get myself a converter on eBay or so. Auto focus is not that important to me but IQ should be ok. It seems that kenko produces some anyways, there are 2x CFE there are KAX I think PAX is in there too and the Internet is not full of any reviews or comparison between them. Someone has insight into these different models? I have an offer for kenko 2X CEF MC 7. Is this one recommendable?
Thanks in advanced friends!
03-02-2016, 10:47 AM   #7
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There are reviews of a number of converters on the Pentax forums lens review pages. You may want to check it out to see if there are any reviews on what you are interested in.
03-02-2016, 11:06 AM   #8
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QuoteOriginally posted by bobell69 Quote
Just wondering if we may see improvement with focus speed and functionality of the Kenko Teleconverters on the Full Frame. Right now I have two with SDM contacts., a Kenko Pz-AF 1.5 Teleplus MC and another no name 2x. The kenko works great on the DA* 50-135, DA 18-135 and my FA 300 F4.5, but it suffers when using the Sigma 70-200 F2.8 HSM OS. Also the 2x converters spends most of the day just searching, and once in awhile it locks in, but rarely.
Compared to what body? The K-5? Any of the newer bodies should be a big improvement as they are much more sensitive and so should deal with light loss from the TC better.

If you are having problems with the Sigma 2.8 that is probably more to do with firmware as it should be plenty bright enough -- Sigma does have updated firmware for some of their lenses. I needed to get an update to on a 150-400 Sigma model to get it to work with on live view, for instance. (Does it work fine w/o the TC?) Firmware update is free, only the cost to ship there. In the US, they pay for return shipping from their NY facility -- where to send it from Canada I don't know, but worth inquiring to see if there is an update. Also highly possible the OS on the lens makes it not compatible with the TC, at least a non-Sigma one.

03-02-2016, 11:28 AM   #9
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QuoteOriginally posted by jpzk Quote
How about the "old" SMC Pentax-F 1.7x AF Adapter ?
That should be interesting.
I own one and will report, however, I am probably not the first one here... Looking forward for some tests ;-)
03-02-2016, 03:06 PM   #10
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QuoteOriginally posted by i5_david Quote
I am on the edge to get myself a converter on eBay or so. Auto focus is not that important to me but IQ should be ok
FWIW, I have 4 K-mount teleconvertors. In terms of image quality, I'd rank them like this [best to not-so-good]:

- Pentax DA AF REAR CONVERTER 1.4X AW [AF support, WR too, but expensive]
- Kenko Pz-AF 1.5X TELEPLUS SHQ [AF support, SDM usually works]
- Pentax REAR CONVERTER-A 2X-S
- Kenko P-AF 1.4X TELEPLUS MC4 DG
03-02-2016, 09:33 PM   #11
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Is the hs AW tc ff compatible? (I feel like I should have had more acronyms to throw in there...)
03-04-2016, 12:56 PM   #12
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QuoteOriginally posted by infoomatic Quote
I own one and will report, however, I am probably not the first one here... Looking forward for some tests ;-)
It will be interesting to find out how this works with the K-1.
This TC was manufactured eons ago, at the time when digital was simply `not there".
Reading the review pages: the description does mention " Image Format Full-frame / 35mm film "
03-04-2016, 05:50 PM   #13
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QuoteOriginally posted by narual Quote
Another nifty thing -- using your kenko 1.5x, your crop sensor lenses will cover the full frame - the 50-135 will have the same field of view as it does on your K-5.
I tested this today and it's not true. There is visible dark corners that's noticeable. I didn't have a chance to try multiple focal lengths but it's definitely not exactly like on a crop sensor.
03-04-2016, 07:49 PM   #14
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QuoteOriginally posted by Dr_who Quote
I tested this today and it's not true. There is visible dark corners that's noticeable. I didn't have a chance to try multiple focal lengths but it's definitely not exactly like on a crop sensor.
Hm. Works fine on my ZX-L, for the couple lenses I've tried it with.

Were you using a 1.5x TC? A 1.4x wouldn't cover the full frame.
03-04-2016, 08:03 PM   #15
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QuoteOriginally posted by narual Quote
Hm. Works fine on my ZX-L, for the couple lenses I've tried it with.

Were you using a 1.5x TC? A 1.4x wouldn't cover the full frame.
Sorry I was indeed using the 1.4 converter. It still is usable but not ideal. Which 1.5x converter do you use, and can it run SDM lenses?
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