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06-25-2012, 09:26 AM   #1
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looking for teleconverter to match the Tamron SP AF 70-200mm f/2.8

Hi, I am thinking about buying the Tamron 70-200mm f/2.8 lens, but I am in need of a bigger zoom and therefore looking for a suitable teleconverter to match this lens. I am quite new to TC, I would be grateful for recommendations! Pros and cons to the TC would also be great!

06-25-2012, 09:37 AM   #2
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QuoteOriginally posted by larshalvar Quote
Hi, I am thinking about buying the Tamron 70-200mm f/2.8 lens, but I am in need of a bigger zoom and therefore looking for a suitable teleconverter to match this lens. I am quite new to TC, I would be grateful for recommendations! Pros and cons to the TC would also be great!
Hi!

I do have the Tamron 70-200 F2.8 too and the "matching" TC: Tamron-F 1.4X Pz-AF MC4.
This is supposedly the best match.

However, and that is a personal thing: TC's degrade IQ, not matter how you look at it.

If you are not too fussy regarding the end results, this is the best TC to match your lens.

JP
06-25-2012, 11:05 AM   #3
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I used the Vivitar 1.4x TC on the Tamron that I just traded and I got some great results. I am selling the TC in the Marketplace if you are interested in it.
06-25-2012, 11:40 AM   #4
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I have the promaster 1.7x, which I got for $25. I haven't tested it with this lens yet, but have heard good things. I could test it out for you and let you know. It worked well on the DA 55-300, with some contrast loss.

06-25-2012, 11:53 AM   #5
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beware the Tamron F 1.4x Pz AF MC4, as it is not recommended for use with the 70-200/2,8. I have both and it does not allow the AF motor to disengage, so maual focusing drags the gears.

Tamron cust service says:
"The teleconverter is not compatible with the 70-200 F/2.8 lens and we cannot provide support for its use. I would recommend discontinuing use of the teleconverter with that lens as they are not compatible. "


I have since heard someone say it is possible to simply hold the lens release button (if you still have one, lol) to temporarily disengage the gears for manual focusing. I have not tried this but will do so shortly and report back.

As for optics, i do like the results from the Tamron F but will keep looking for another TC that is fully compatible with the lens.
06-25-2012, 11:55 AM   #6
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QuoteOriginally posted by jpzk Quote

I do have the Tamron 70-200 F2.8 too and the "matching" TC: Tamron-F 1.4X Pz-AF MC4.
This is supposedly the best match.
I am curious why you say they are a match as Tamron does not recommend they be used together.
06-25-2012, 12:06 PM   #7
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Mike, I followed the same guideline about the lens release button for manual focusing with the TC and can vouch for its effectiveness. Just be sure to have a good grip on the lens, since it's heavy and you want to make sure that you don't let it slip.
06-25-2012, 12:17 PM   #8
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ok, i just tried pressing the lens release button to disengage the screw drive and I find it works perfectly with just the 70-200 lens by itself. however, with the Tamron F TC attached, it still drags. Mr b, are you saying you can get this to work with the 70-200 connected to the TC with no dragging?

06-25-2012, 01:49 PM   #9
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I have only done the lens release trick during certain shots, making sure that my hands were always on the lens and the TC. I never used the method for prolonged use, so I can't say about rapid-fire shooting/focusing (like at events) when using the TC and lens as indicated. It definitely works when you need to fine-tune your focus and AF won't cut the cake.
06-25-2012, 04:15 PM - 2 Likes   #10
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QuoteOriginally posted by mikeSF Quote
beware the Tamron F 1.4x Pz AF MC4, as it is not recommended for use with the 70-200/2,8. I have both and it does not allow the AF motor to disengage, so maual focusing drags the gears.

Tamron cust service says:
"The teleconverter is not compatible with the 70-200 F/2.8 lens and we cannot provide support for its use. I would recommend discontinuing use of the teleconverter with that lens as they are not compatible. "


I have since heard someone say it is possible to simply hold the lens release button (if you still have one, lol) to temporarily disengage the gears for manual focusing. I have not tried this but will do so shortly and report back.

As for optics, i do like the results from the Tamron F but will keep looking for another TC that is fully compatible with the lens.
Saying, "it does not allow the AF motor to disengage" is an ambiguous statement because there are two motors and two sets of gears you could be referring to - the micro-motor and gears in the lens, and the camera body AF motor and gears.

I have the Tamrom 70-200mm f/2.8 AF lens as well as three Pz-AF teleconverters, so I can describe what's going on from first-hand experience.

On Pentax AF camera bodies, the MF/AF switch is both electronic (telling the camera what mode you are shooting in) as well as mechanical. MF physically retracts the screw drive into the body, AF extends it out, something visible if you move the switch while looking at the mount with no lens on it. When the switch is in MF mode on a Pentax body, nothing can move the gears or AF motor in the body.

On an AF lens like the Tamron, the AF/MF clutch is a simple mechanical clutch. All it does is connect or disconnect the focus grip part of the lens from the internal focus part of the lens. Nothing stops you from having the camera body in AF mode and putting the lens clutch in MF, resulting in the camera driving not just the internal focus lens parts but the outer focus grip as well, slowing AF due to increased mass and risking a negative impact on the AF drive system should you grab the focus grip and 'fight' or counteract any of the AF action. With the lens focus clutch in MF, any physical force imparted to the grip is translated to the AF drive shaft, connected or not. With a body in MF, and the focus clutch in MF on the Tamron lens, the lens will spin it's AF screw drive merrily but it will not be connected to the body because the body has retracted its end of the screw drive.

Now, let's introduce an AF teleconverter. It has a screw drive extension. That extension doesn't retract or extend, it's fixed. So if a lens like the Tamron still moves it's screw drive in MF mode, then you have a screw drive extension shaft in the teleconverter that will also move, even if it's not connected to the screw drive coming out the camera body.

That is the the source of the 'drag' you'll feel in that Tamron lens (and many other lenses) when using them with an AF teleconverter - the extra effort in spinning the little screw drive shaft in the teleconverter. Now in my experience, I only find it mildly annoying, but that's because I don't really try to use my Tamron 70-200mm f/2.8 lens AF lens in MF that often at all. The lens has a very short focus throw because it was designed to be very fast in AF, so MF is just an afterthought at best. It's probably the last lens I would go to if I wanted to MF.

I have a hard time seeing how having the lens in MF mode and Pentax body in MF mode with an AF teleconverter between them could cause any harm though. The extra effort required to spin the the screw drive shaft in the teleconverter isn't that significant in my experience. It makes me wonder if the Tamron support people know what they're talking about. More likely I think that since the teleconverter is a discontinued part, they're just throwing out a 'safe' answer because they don't know or don't want to take the time to give a thorough answer and understand the situation.

This does bring me to another point I think I've made before and bears repeating - MF/AF switches on Pentax lenses can be implemented better than they typically are in most third-party lenses. Let's take the Pentax FA 100 f/2.8 Macro lens as a counterpoint. When you rotate the focus mode dial on the side of that lens to MF, it physically disengages the screw drive inside the lens. There is no need to move the switch on the body of a Pentax camera with the FA100 lens from AF to MF to use that lens in MF, you just need to move the dial on the lens. That is the right way to do an AF-MF switch on a lens, and though its not quite as elegant as the quick-shift focus system found on some Pentax lenses and some recent Sigma HSM lenses like the 85mm, I think reviews should acknowledge that a manual clutch in a non-SDM/HSM lens can and ideally should disengage (or retract) the screw drive of a lens in the lens body. It's unfortunate more lenses don't work like the FA100 in that regard.

Now regarding your quest for "another TC that is fully compatible with the lens", if you are adamant about getting manual focus on that Tamron lens without the 'drag' you don't like, while also getting some AF, your one and only option will be the Pentax-F 1.7x AF Adapter. The reason is this adapter has no AF connection to the lens at all, just to the camera body. Your lens will no longer AF, but the adapter will. You'll need to do some manual focus to get the lens close to the focus point, and then you can use the camera body AF to move the elements in the adapter to focus the rest of the way. I'm not sure that counts as the 'fully compatible' you're looking for, but that's the closest you're going to get.
06-25-2012, 06:35 PM   #11
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i am happy to see your response, nater, as i have asked many but not gotten any response with the degree of detail you have provided here. So, if i understand your description of the mechanics of the linkage, there is no harm done to the camera or lens by manually focusing through the additional dragging that is introduced by the TC, correct?
THANKS and I now feel better pushing through the grinding, as I have been worried about doing this in the past.

I did find your comment about MF peculiar since we don't really get to choose when the AF will work or not work. I use my 70-200 at the long end, and almost always around twilight (pre sunrise/post sunset) when AF is unreliable. If i am shooting a tele landscape, I prefer to use live view for focusing and my experience with this lens is that contrast AF with live view does not work at all with this lens, so i generally switch to MF and focus using live view zoom. I get that consumers want faster AF speeds so lens builders make them with shorter throws which makes it very difficult to achieve precision of manual focus when one wants to move the collar a mere fraction of a millimeter, but I will get over it. I do also have a lovely S-M-C Tak 200 with a nice long and smooth focus ring that is a dream for MF...but I prefer the IQ of the Tamron.
06-25-2012, 06:40 PM   #12
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Heck, you may also be able to help answer my other Tamron issue involving a stuck aperture. I bought a Tamron SP 90/2.8 macro Di, lightly used and in excellent condition from another forumite here. I literally took one picture with it and the aperture has become loocked in wide open position, whether on or off the camera.
I have read several accounts of the issue in the reviews and Tamron's response is to submit the lens for repair (i will be paying out of pocket). Do you know of an easy fix to release the locked aperture? I will send it in if need be (im not THAT cheap), but prefer a DIY solution.

thanks in advance for any info.
06-25-2012, 07:00 PM   #13
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FYI, Lenstip.com's review of the Tamron 70-200 has some interesting resolution graphs that include using a Sigma 1.4 teleconvertor on the Tamron (in Canon mount). The result is very good - only moderate resolution loss. There are even some sample images with and without the Sigma TC:

Tamron SP AF 70-200 mm f/2.8 Di LD (IF) MACRO review - Image resolution - Lenstip.com
06-25-2012, 08:09 PM   #14
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QuoteOriginally posted by mikeSF Quote
i am happy to see your response, nater, as i have asked many but not gotten any response with the degree of detail you have provided here. So, if i understand your description of the mechanics of the linkage, there is no harm done to the camera or lens by manually focusing through the additional dragging that is introduced by the TC, correct?
THANKS and I now feel better pushing through the grinding, as I have been worried about doing this in the past.
As long as you have the Pentax body in MF mode, the only force slowing down your MF focus of the Tamron lens will be the little shaft extension in the teleconverter. You can test how much friction it adds by holding just the teleconverter in your hand and turning the little screw-drive extension on the side that would attach to the lens with your fingers, it should turn very easily. (I suppose it's possible the shaft in your teleconverter is adding an undue amount of drag due to some sort of alignment problem, and that could be one way to find out.)

QuoteOriginally posted by mikeSF Quote
I did find your comment about MF peculiar since we don't really get to choose when the AF will work or not work. I use my 70-200 at the long end, and almost always around twilight (pre sunrise/post sunset) when AF is unreliable. If i am shooting a tele landscape, I prefer to use live view for focusing and my experience with this lens is that contrast AF with live view does not work at all with this lens, so i generally switch to MF and focus using live view zoom. I get that consumers want faster AF speeds so lens builders make them with shorter throws which makes it very difficult to achieve precision of manual focus when one wants to move the collar a mere fraction of a millimeter, but I will get over it. I do also have a lovely S-M-C Tak 200 with a nice long and smooth focus ring that is a dream for MF...but I prefer the IQ of the Tamron.
Ah, yes I understand your frustration better now. Most of my Tamron 70-200mm f/2.8 shooting so far has been with enough light to AF without problems, the majority of shots during the day. I also have a Tokina 70-200mm f/2.8 manual focus lens, and while the manual focus is a much better experience, it can't dynamically communicate focal length like an AF lens and inputting an average or expected focal length when mounting the lens isn't ideal, especially for low-light photography when in-body shake reduction matters the most. As a result, I've done all my serious low-light photography with manual focus prime lenses, my longest of which is 85mm. I've been thinking about picking up a 135mm, 180mm, or 200mm MF prime lens for a while now.
06-25-2012, 08:22 PM   #15
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QuoteOriginally posted by mikeSF Quote
Heck, you may also be able to help answer my other Tamron issue involving a stuck aperture. I bought a Tamron SP 90/2.8 macro Di, lightly used and in excellent condition from another forumite here. I literally took one picture with it and the aperture has become loocked in wide open position, whether on or off the camera.
I have read several accounts of the issue in the reviews and Tamron's response is to submit the lens for repair (i will be paying out of pocket). Do you know of an easy fix to release the locked aperture? I will send it in if need be (im not THAT cheap), but prefer a DIY solution.

thanks in advance for any info.
I've taken apart some manual focus lenses to fix minor aperture problems, and they are very delicate inside, sometimes with tiny ball bearings and springs as part of the electrical contacts in the mount. I wouldn't attempt it without the right tools, lots of light, a contained area that would prevent tiny parts from bouncing or rolling away, magnifying glass, etc. Even if you do fix it, putting things back together in just the right way can be a real challenge too (speaking from experience).

I don't know anyone who's attempted to fix the Tamron 'sticky aperture' problem on their own, probably because Tamron has a really long warranty period if you register the lens after buying it (5 or 7 years as I recall?) I'd guess most of the lenses with the problem got fixed under warranty (I knew some people had been affected when I bought my Tamron 70-200mm, haven't had a problem with it myself though).

I also don't know if Tamron replaces a faulty part or just adjusts something, so I have no way of giving you a sense of whether a self-repair would hold up long term, unfortunately.
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