Pentax 1.4 rear converter comparison


cedricd

Link Posted 09/05/2015 - 20:02
Just having random thoughts ref the newish rear converter from Pentax. I have a Tamron -F 1.4 Pz-AF MC4 which I use with the DA 300* and it works quite well especially in bright light conditions. The AF is pretty quick and the results are acceptable but I`m guessing it`s the DA 300* that`s cutting the mustard. Wondering if there is an advantage in switching to the Pentax unit other than the obvious WR provision.

Would appreciate any thoughts or observations.
Enjoy life

stu62

Link Posted 09/05/2015 - 20:26
if you are happy with the results i cant se the point of changing

johnriley

Link Posted 09/05/2015 - 20:29
I'd expect the advantage to be image quality as the Pentax converter is designed with such lenses specifically in mind.
Best regards, John

Mike-P

Link Posted 09/05/2015 - 21:20
The main advantage is that unlike the Tamron it is a reporting teleconverter with Pentax lenses so will show (and will use) the correct aperture and because the camera knows it is there it will use the correct lens length for SR.

It's also WR and gives slightly better IQ (and AF is a bit more precise)
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JAK

Link Posted 09/05/2015 - 23:11
johnriley wrote:
I'd expect the advantage to be image quality as the Pentax converter is designed with such lenses specifically in mind.

Surely the Tamron one is too?? If not what is it designed for?
John K

johnriley

Link Posted 09/05/2015 - 23:36
The Tamron is designed generically and will be used with different marques.

What I meant was that the Pentax converter is designed by Pentax for its own lenses, making it possible to have a more specific set of design parameters.
Best regards, John

McGregNi

Link Posted 10/05/2015 - 06:34
Certainly it's always nice to have a perfect match where possible. Those other practical features mentioned by Mike sound like they're worth paying for ...( correct aperture and shake reduction set automatically in particular ....I can well imagine that last one would be easily forgotten in all the excitement as you arrive and get things set up), plus the WR is an obvious plus ... This sort of lens TC combination is always used outside in the elements isn't it?
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Pentax K7 with BG-4 Grip / Samyang 14mm f2.8 ED AS IF UMC / DA18-55mm f3.5-5.6 AL WR / SMC A28mm f2.8 / D FA 28-105mm / SMC F35-70 f3.5-4.5 / SMC A50mm f1.7 / Tamron AF70-300mm f4-5.6 Di LD macro / SMC M75-150mm f4.0 / Tamron Adaptall (CT-135) 135mm f2.8 / Asahi Takumar-A 2X tele-converter / Pentax AF-540FGZ (I & II) Flashes / Cactus RF60/X Flashes & V6/V6II Transceiver

johnriley

Link Posted 10/05/2015 - 08:25
I use the TC outdoors, but it can also be used to increase magnification at macro distances. The focusing distance doesn't change, so you close in on the subject.
Best regards, John

Daronl

Link Posted 10/05/2015 - 14:17
Tamron 1.4 Converter vs Pentax HD

I have both (now)

Several Months back I had the same dilemma and wrote on PU that proper testing under strictly controlled conditions confirmed no difference between either in optical performance.

They were so uncannily identical I suspected they were from the same stable.I returned the Pentax and got a refund and quite happily used the Tamron.

However, in the depths of winter I spent some considerable time out on a nearby, very exposed estuary photographing migrant wild fowl and despite performing "optically" very well, the Tamron developed a tangible lack of "tightness" (security) with the 300 DA* mounted on it.

It still performed well optically (see Water Rail below);
Clearly however, I was concerned about potential problems given the very extreme weather conditions I was exposing my equipment too out on the marsh.


I duly "re-purchased" the Pentax HD; This time however I not only found the Pentax HD Converter was very different to the Tamron but very different to the firsts Pentax HD Converter I purchased (directly from Pentax on the release date)

This unit actually seems to improve focus speed when coupled with the 300 DA* and as we know maintains good IQ

So the bottom line: I do think there is a performance improvement, certainly a weather sealing advantage but in IQ terms I honestly can detect a discernible difference but can't help but think there must be and over time it will become apparent, and I am sorry to end on such a nebulous and unscientific final comment.
Daronl

cedricd

Link Posted 13/05/2015 - 20:35
Many thanks for all of your comments. It was basically what I was thinking. Not a huge difference but probably more comptaible with the Pentax lenses. Not sure that it would communicate any better than the Tamron.
Enjoy life

Mike-P

Link Posted 13/05/2015 - 20:49
cedricd wrote:
Many thanks for all of your comments. It was basically what I was thinking. Not a huge difference but probably more comptaible with the Pentax lenses. Not sure that it would communicate any better than the Tamron.

The Tamron doesn't communicate with the camera whatsoever whereas the Pentax does therefore it stands to reason it communicates better.
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Last Edited by Mike-P on 13/05/2015 - 20:50

andy_bell

Link Posted 14/05/2015 - 08:49
Also the electronics in the Pentax converter will convey corrected information to the camera which will record the correct (1.4X) focal length for use with SR & the EXIF data, i do also think that the Pentax performs better with Pentax lenses, and strangely the Tamron seems to have an edge on my Sigma 70-200 HSM.....(which is why i kept mine)

Andy
A few bits & Bobs

cedricd

Link Posted 04/07/2015 - 21:10
Pack up all preconceived thoughts and ideas about teleconverters into a parcel, wrap well and send via white van delivery man (that way you are guaranteed of ridding yourself of them). Once you have done this buy yourself a Pentax 1.4 AW rear converter and nail it to your Pentax DSLR. Be prepared because whatever 3rd party device you had before, the Pentax one will not dissapoint.

Well mine is great on a K3 and DA300* need a bit of practice with it especialy for moving subjects but that`s a combination of my inabilities and the AF on the K3 not being up to much.
Enjoy life

wvbarnes

Link Posted 04/07/2015 - 21:21
I have the K3, the 300 star F4 and the 1.4 convertor. I think it's a wonderful combination. The loss of depth of field does though make you work for the results as you would expect.
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