[Ben_Edict]

Fine. You've convinced me. Your Tamron TC is crap, so you win.

I still like my Tamron TC, so I win too.

An advantage of Tamron TC over Canon and Nikon own TC's is the Tamron mounts on any lens, not just lenses with recessed rear lens elements. The snout on both Canon and Nikon TC's limits their teleconverters use.

It sure limits the amount of useable lenses, if a tc sports that "snout". On the other hand, the IQ of these tcs is usually much higher, as this reduces the air space between the rear element of the lens and the front element of the tc. Also, these tcs can only be used with select lenses (for instance the Sigma Apo tcs or the Pentax L-tcs), which makes it possible, to optimize them for these few lenses, whereas a "Jack of all trades" always affords much more compromises.

So, universality is not really an advantage, it is also limiting the possible perfomance at the same time. I think, this is not overstating it. It reflects for once my own experiences with the Sigma Apos and the Pentax L modells, which are simply better than for example the Pentax S modells (which are of the universal type) or the Kenko 1.5x SHQ.

This already has been discussed to some length during the last months and I think, there is no general wisdom, that a certain tc performs superbly with all lenses. And as such, there is no "winner" or "loser" in this discussion.

It is a game of hit and miss optically - and also electrically, as neither the Tamron nor the Kenko where developed for SDM. It is just coincidence, that the Pentax engineers decided to put the SDM contacts in place of the power zoom contacts (or may be some economical design issue). So, it is not really a surprise that SDM works sometimes and sometimes not or not to a useful degree.

Ben

[thibs]

Coïncidence ? Nô way. Thé KAF3 was ready 10 years ago AFAIR.

[Rees]

Found this in another forum:



Source: Pentax F 1.7x AF teleconverter -LIVES AGAIN! - ClubSNAP Photography Forums

Well I would certainly be interested in this

[jpzk]

Well I would certainly be interested in this

I have made some inquiries and will let all know if I am successful.
Cheers.

JP

[NeverSatisfied]

Hi Samsungian,

I guess you did misunderstand.

You did a disservice to C/N TCs by comparing them by price only to the Tamron, and giving the impression that they are equivalent products. I would think that owning a Canon TC you could see the difference in build quality easily, but apparently that got by you. The only reason I mentioned what I paid for one was to illustrate the disparity in original price (which would indicate a difference in practical build quality, BTW) compared to the current market value.

You did a disservice to SDM lens owners looking for a TC that will AF with their lens by stating that the Tamron will work with it. Is it a lock that it actually will work as well as it one would expect with a screw drive lens? No, I think not. My experience coupled with the exact same experience from others says that compatibility might be an issue. This isn't the case with screw drive TCs (or the screw drive functionality of the Tamron) -- sure there are probably bad examples, but I've never experienced one, and don't recall any testimonials of this.

The actual or relative cost of the N/C TCs was never an issue. Neither is the fact that Pentax hasn't offered any AF TCs other than the AFA. Neither is AF speed, or any other difference in performance between brands. The fact that the Tamron TC is probably the best chance of getting a working TC for SDM is not the issue. I like my Tamron TC also, otherwise I wouldn't still own it and use it, but that's not the issue either. I stated that equating the Tamron with N/C TCs because of the price the market demands was not really reasonable because of differences in build quality. I stated that it was a great bargain for me because it offered very good optics at a very low price.

Yes, I've always felt that either the TC or my particular lens is at fault. I didn't and don't care which it is because I don't use them in combination and never intended to. It's probably not the body, as the lens TC combo acts the same with 4 different SDM capable bodies. But this wasn't the issue either. The fact that others have had exactly the same response from their combos leads me to believe that my situation is not unique, but a symptom of example variation where the PZ contacts in the TC allow the focusing motor in the lens to operate, but not to the precision needed to AF reliably. There's something amiss with the feedback system. Since the lens functions well alone on all the bodies, the most likely source of the problem is with the TC.

I was not and am not knocking the Tamron. It was designed as a PZ TC, for which purpose, it works fine. SDM uses similar contacts, but that doesn't guarantee that a TC designed and discontinued before SDM was ever offered would offer full functionality and precision of this feature. Tamron never stated that their PZ contacts would work with SDM, and neither has Pentax. The precision of an AF feedback loop is of a totally different nature than just supplying power to a motor to operate the zoom ring on the lens. You gave the overwhelming impression that they work with all SDM lenses. I gave a counterexample and argument that maybe this might not be the case. You respond with a sentence from a previous post, a rant about Pentax missing the ball on AF TCs, an unnecessary statement that I use faulty gear, and comparisons of Canon and Nikon TC prices. . .

Here, I'll make it simple. . .

1. Can you state with certainty that a Tamron F 1.4x AF PZ MC4 will allow full functionality with any SDM lens -- that it will focus as well as the bare lens with minor considerations for possible image degradation and light loss?

2. Can you state that the above mentioned Tamron TC is the equal to Canon and Nikon AF TCs in build quality, and therefore they are of the same intrinsic value as long as they function as expected? In other words, if you compared them physically, with no regard for optical quality, brand, or market influences (availability and demand), would you pay the same price for the Tamron considering only how the TCs look and feel?

Those were the issues I was talking about. If you can answer either or both of these questions affirmatively, then we'll have to disagree. I doubt that I could convince you, and you certainly haven't convinced me. If you answer negatively, then there is no disagreement here.

Scott

Hi Samsungian,

I'll disagree about the crazy money thing. . . $300 is not unreasonable for a pro quality TC (ala Canon and Nikon), but the Tamron F 1.4x AF PZ MC4, although a very good TC optically, doesn't have nearly the same build quality, and this has to be a factor when comparing prices, IMO. The greatly inflated prices for the Tamron TC are due to market perception (availability/demand), not its intrinsic value. As I mentioned in a previous post, they commonly sold for $69 brand new until stock levels dropped and demand started to exceed supply, maybe 2-3 years ago. At this price, they were considered a great deal -- very good optics at a bargain price. . .

Also, my Tamron TC does not play well with my DA*50-135 as it hunts and quits after 3 tries. It only can get an accurate lock if the initial focus plane the lens is set to is within a fraction of an inch of the desired one -- and I've heard others who have had the same experience. I don't really have a use for this combo as I have 3 other lenses that cover the range nicely, but I wanted to see if it would work -- and AFAIC, it doesn't. The tests I've done were in bright sunlight, and on multiple occasions.

Because of this experience, I would not flatly state that either the Tamron or the Kenko PZ TCs are SDM compatible -- they may work well with your particular SDM lens, or possibly with with certain models of SDM/HSM lenses, but if they don't work reliably with all SDM lenses (by "reliably", I mean just mount the TC and it will focus as well as without the TC, with due consideration to the light loss), they should not be touted as being "compatible". "Potentially compatible" or "SDM contact compatible" is as close as I'd put them, and I'd consider these marketing euphemisms. I can easily state that they are truly compatible with screw drive lenses with appropriate max apertures though. . .

I think you do a disservice in your post to both the C/N TCs and to SDM/HSM lens owners looking for a truly compatible TC.

Scott

My two cents: My Tamron 1.4 works pretty well with my DA*300, and my Tamron 70-200/2.8, but is practically useless on my DA*50-135. So it is NOT universally functional/reliable on all SDM lenses. Question: Could the difference be that the DA*50-135 is a zoom while the 300 is a prime?

[Samsungian]

Inconsistent results makes me wonder how precise SDM manufacturing is.

Or how precise Tamron manufacturing is.

Its one or the other you know?

I follow three brands of gear and never read of problems with Tamron 1.4x on Canon or Nikon cameras and lenses so I'll guess Pentax SDM manufacturing specs are not precise enough to give consistent results with a TC attached.

Maybe this is why something as simple as a publically roadmapped, and then shown off at camera gear trade shows, the long awaited Pentax SDM 1.4x Teleconverter got pulled right before its release ???



As it is, I still like my 1.4x MC4 Tamron Teleconverter.


Sure I'd rather buy a Pentax made AF 1.4x TC but for some reason they are incapable of manufacturing one with autofocus function that has power zoom contacts which double as SDM contacts. Then again theres other lenses I'd buy from pentax brand new, but they are history now.

[jpzk]

My two cents: My Tamron 1.4 works pretty well with my DA*300, and my Tamron 70-200/2.8, but is practically useless on my DA*50-135. So it is NOT universally functional/reliable on all SDM lenses. Question: Could the difference be that the DA*50-135 is a zoom while the 300 is a prime?

I also have the Tamron 1.4x and it does a good job with the DA*300/4 and, just like you, the Tamron 70-200/2.8. This latter combination actually works better than with the DA*300.
I wouldn't try it on my DA*16-50/2.8.

JP

[Ben_Edict]

Inconsistent results makes me wonder how precise SDM manufacturing is.

Or how precise Tamron manufacturing is.

Its one or the other you know?

I follow three brands of gear and never read of problems with Tamron 1.4x on Canon or Nikon cameras and lenses so I'll guess Pentax SDM manufacturing specs are not precise enough to give consistent results with a TC attached.

Maybe this is why something as simple as a publically roadmapped, and then shown off at camera gear trade shows, the long awaited Pentax SDM 1.4x Teleconverter got pulled right before its release ???

As it is, I still like my 1.4x MC4 Tamron Teleconverter.

Sure I'd rather buy a Pentax made AF 1.4x TC but for some reason they are incapable of manufacturing one with autofocus function that has power zoom contacts which double as SDM contacts. Then again theres other lenses I'd buy from pentax brand new, but they are history now.

The Tamron tc was never manufactured to be SDM compatible. That's what I meant by coincidence. At least Tamron could not anticipate, that Pentax would re-use the PZ contacts for SDM. So, it is no wonder, the tc works not universally. It is more of a miracle, that it works at all as a SDM tc.

Ben

[jpzk]

I have made some inquiries and will let all know if I am successful.
Cheers.

JP

Inquiries made and the answer was that I should try myself to order from this country (Asian) .... when I got there, there was a button to have the site in English .... I clicked on it: title in English ... godd! The rest ... foreign language.
That takes care of my inquiry: I didn't get anywhere with this.
If someone was willing to order from Japan, I'd jump in to get one of those TC's.

JP

[Lage]

After some googling, i found this site showing the price trend in japan for the Pentax F 1.7x AF TC :
Google Translate

Good indication what you should pay if you buy one.
21262 Yen is about 235 USD, 173€

/Lage

[ogl]

Can anybody post the names of Japanese internet shops where to buy Pentax F 1.7x AF TC?

[dadipentak]

FYI: I posted a sample shot here.

[baldeagle21b]

Can anybody post the names of Japanese internet shops where to buy Pentax F 1.7x AF TC?

Well, it isn't a Japanese internet shop, but you can order them here:
japan exposures | a personal introduction to Japanese photography. Click on the Shop tab, then select Pentax from
the manufacturers list on the left.

[baldeagle21b]

After some googling, i found this site showing the price trend in japan for the Pentax F 1.7x AF TC :
Google Translate

Good indication what you should pay if you buy one.
21262 Yen is about 235 USD, 173€

/Lage

Unfortunately, I don't think you will find a new TC outside of Japan for anywhere near that price. Of the two sellers I know about, a Hong Kong based dealer on Ebay charges USD 400 and japanexposures charges USD 335.

[netuser]

Check here

https://www.pentaxforums.com/forums/sold-items/93467-sale-%5Bsold%5D-pentax-f...worldwide.html