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02-17-2009, 03:42 PM   #481
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QuoteOriginally posted by Miserere Quote
Hmmm...I'll have to try that!
In fact, I have heard this is a fix for many lens to body issues. Who knows.

02-21-2009, 06:05 PM   #482
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Sigma 1.4x DG EX APO AF???

I did not see any mention or review of the Sigma 1.4x DG EX APO AF. Any thoughts on it's performance or limitations?
Thanks!
02-21-2009, 06:12 PM   #483
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The Sigma TCs are tricky because they won't fit all lenses. The front of the element sticks out pretty far and can hit the rear element of the lens. Sigma keeps a compatibility list of their lenses that fit and anything other then that it is trial and error.

That being said it is a very good TC but does not work with SDM lenses (not even the Sigma HSM lenses). I would imagine they will come out with a compatible version sometime soon.

John


QuoteOriginally posted by mstolt Quote
I did not see any mention or review of the Sigma 1.4x DG EX APO AF. Any thoughts on it's performance or limitations?
Thanks!
03-04-2009, 09:24 AM   #484
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The lack of the ''NEW PENTAX SDM 1.4TC'' from the latest road map is a huge disappointment....i mean to remove it from the road map tells me that it is gone...no mas...So what does this mean?...Well it means that the prices of the Tamron MC-4 1.4 TC will rise again in the $300.00 to $500.00 range as they did before. I am glad I have a great copy of one..I am sure the rare Pentax 1.7tc will also go through the roof...



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03-04-2009, 09:53 AM   #485
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QuoteOriginally posted by jgredline Quote
The lack of the ''NEW PENTAX SDM 1.4TC'' from the latest road map is a huge disappointment....i mean to remove it from the road map tells me that it is gone...no mas...So what does this mean?...Well it means that the prices of the Tamron MC-4 1.4 TC will rise again in the $300.00 to $500.00 range as they did before. I am glad I have a great copy of one..I am sure the rare Pentax 1.7tc will also go through the roof...
Javier, I wouldn't be so pessimistic. I think Pentax have just decided to be like all the other brands and not have a lens road map.
03-04-2009, 09:56 AM   #486
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QuoteOriginally posted by Miserere Quote
Javier, I wouldn't be so pessimistic. I think Pentax have just decided to be like all the other brands and not have a lens road map.
I've seen a few people suggest this.. or imply it by saying that they got so burnt by the 60-250mm that they are they tightening up. My only rebuttal to this is that they are still showing the "DA Super Telephoto" on the map. If they decided to be less forthcoming on future plans then they should have removed that as well.



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03-04-2009, 05:13 PM   #487
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I fear that this means no more and no less than that all open investments at Pentax are at stall.
03-04-2009, 05:39 PM   #488
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Mis, I would like to be optimistic...but I need a carrot and so far there is only a rotten apple dangling in front of me...

03-04-2009, 06:53 PM   #489
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QuoteOriginally posted by jgredline Quote
The lack of the ''NEW PENTAX SDM 1.4TC'' from the latest road map is a huge disappointment....i mean to remove it from the road map tells me that it is gone...no mas...So what does this mean?...Well it means that the prices of the Tamron MC-4 1.4 TC will rise again in the $300.00 to $500.00 range as they did before. I am glad I have a great copy of one..I am sure the rare Pentax 1.7tc will also go through the roof...
I am glad that I was wise enough to keep a Kenko 1.5x TC for myself
03-05-2009, 02:10 PM   #490
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QuoteOriginally posted by mstolt Quote
I did not see any mention or review of the Sigma 1.4x DG EX APO AF. Any thoughts on it's performance or limitations?
Thanks!
Used on the Sigma 70-200/2.8 (the only Sigma I have, I would use this tc with, I find the Bigma too slow for the tc) it is simply excellent. The resulting 105-280/4 lens shows no visible IQ loss. There sure is some loss inquality, but it is simply not visible at any normal print size (I never print smaller than DIN A4).

Ben
03-06-2009, 08:10 PM   #491
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The Sigma 1.4TC when used with the sigma glass is a true extension of the lens. I see no loss of detail. I use it on two lenses. My 100-300F/4 and Sigma 500 F/4.5 with great results....
05-22-2009, 06:19 PM   #492
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I have a new Tamron 1.4x MC4 with 6 contacts TC, and it works fine in AF. However, with some of my AF lenses and the camera set to manual focus, the TC does not disengage its AF gear & because of this it is making manual focus a problem. Similar effect to trying to turn a focus ring with the camera's AF turned on. The problem exists with the lens & TC removed from the camera body, and the same problem exists mounted on either my K100Ds or ZX-7. From inspecting the TC, the spring-loaded AF gear creates additional drag and it does not disengage from the lens' AF gear. Doing a quick search, I found a couple other people that have had similar issues -

https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/22091-tamron-1...4-telecon.html

https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/29913-tamron-t...erter-bad.html

With my Takumar F 70-210mm 4-5.6, there is no real problem, the focus ring moves freely & although the TC gear spins with the focusing of the lens, it's difficult to notice the difference with the added drag of the TC.

With my 18-55mm DA, no problems since the AF gear isn't even engaged when manually focusing this lens.

With my Tamron 70-300mm LD Macro, gears are again engaged and it does add a little bit of drag, enough to be annoying and add noise as you hear the TC gear spinning.

And with my Sigma 28-300mm Macro, manually focusing with TC adds enough drag that it's almost impossible. Apparently because the lens has a very short focus throw, the addition of the TC's drag with the high gear ratio makes turning the focus ring tough and not practical.

This may have been discussed in more detail somewhere, but I read through this thread and didn't notice mention of it. It would seem as though, unless my TC is defective and I don't think it is, that this would be an issue brought up in this thread. The problem seems to be that either the TC gear should retract if the camera is set to MF mode, and/or the TC gear has too much resistance and because of this it creates a lot of additional drag in MF with shorter focus throw lenses.

It may be that this has not been brought up much or even noticed by some that may be using this TC on longer lenses that have relatively long focus throw. But on shorter focus throw lenses like 'Super zooms' of 28-200, 18-200, and some newer AF lenses with very short focus throw, this is an issue. And unless other TCs are designed to retract the focus gear or have very little resistance, I would think that similar problems exist with other TCs than just the Tamron 1.4x.

So, has anyone else with this or other AF TCs noticed added drag issues in manual focus, especially with short focus throw lenses? I don't think anything is wrong with my TC, so I suspect that others will also find some of these issues. For my Sigma lens in particular, the only solution is to press in the TC's lens dismount button while manually focusing, as it retracts the TC gear. Sorry for the long post, just wanted to provide plenty of detail. I've been spoiled by my other AF system with TC's and extension tubes, a Canon system with no mechanical linkages...
05-23-2009, 01:28 AM   #493
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Tamron TC - Sigma lenses

I have a similar problem with all of my Sigma lenses, and as a work-around, I cut a 25mmx10mm slice from a thin blade from an old set of feeler gauges.

I insert this blade between the TC and lens to disengage the AF shafts.

It looks a bit untidy but the MF is friction free.

Geoff
05-23-2009, 03:19 PM   #494
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I had thought about making the lens detachment button able to be pushed back in some manner, but that leaves the chance for the lens to rotate on the TC. So maybe a very thin shim like you mention would be better in some ways, hopefully it's thin enough to not impact image quality. It's definitely an issue deserving attention IMO, as using a TC will often end up with focusing issues that lead to the need to manually focus. Hopefully most lenses are not effected by it as much as it effects my Sigma 28-300mm.
08-14-2009, 10:22 AM   #495
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Was the Tamron 1.4 MC4 teleconverter originally made to be mated with a particular lens?
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