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converters

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beccles View Drop Down
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Post Options Post Options   Quote beccles Quote  Post ReplyReply Direct Link To This Post Topic: converters
    Posted: 20 April 2019 at 10:40
just how good are converters? i use a sony A77ii/tamron sp 70-300 for my birding. Was looking at a longer lens for some situations, but then someone said to try a 2x converter. i last used one back in the 60s, and got a bit of halation on the pics. Have they improved a lot (they are a lot more expensive!) or would i be best still looking at a longer lens?
 



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QuietOC View Drop Down
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Post Options Post Options   Quote QuietOC Quote  Post ReplyReply Direct Link To This Post Posted: 20 April 2019 at 11:08
The Kenko MC7 2X teleconverters are quite good optically, but the flaws of the lens are magnified. I find they maintain resolution pretty well.

The Kenko MC4 teleconverters aren't as good optically, but the 1.4x version has less degradation of AF performance.

The Minolta 100-400 APO performs similar to my 55-300 on a 1.4X. I don't often use either.

My impression is a 150-600 would be a better option.

Edited by QuietOC - 20 April 2019 at 11:15
Sony A68 A77II A6000 A7II LA-EA3 LA-EA4 MC-11
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beccles View Drop Down
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Post Options Post Options   Quote beccles Quote  Post ReplyReply Direct Link To This Post Posted: 20 April 2019 at 11:18
how about the MINOLTA AF 2X AF Tele Converter ii APO ?
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pegelli View Drop Down
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Post Options Post Options   Quote pegelli Quote  Post ReplyReply Direct Link To This Post Posted: 20 April 2019 at 11:29
Originally posted by beccles beccles wrote:

how about the MINOLTA AF 2X AF Tele Converter ii APO ?
It only fits certain Minolta G-lenses and a few Sony ones, and doesn't fit on your Tamron 70-300

See here for why that is and which lenses are compatible

Edited by pegelli - 20 April 2019 at 11:33
Mind the bandwidth of others, don't link pictures larger then 1024 wide or 960 pix high, see here
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Roger Rex View Drop Down
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Post Options Post Options   Quote Roger Rex Quote  Post ReplyReply Direct Link To This Post Posted: 20 April 2019 at 11:35
An obvious consideration of tele converter vs. lens is weight. I have had good experiences with Kenko tele converters but I am not a pixel peeper and have not used them extensively and I certainly am not a wildlife or bird shooter. As to a real long lens, consider renting one to see if the weight and other issues are acceptable to you.
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addy landzaat View Drop Down
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Post Options Post Options   Quote addy landzaat Quote  Post ReplyReply Direct Link To This Post Posted: 20 April 2019 at 12:20
Your Tamron is the newer one, it seems a pretty okay lens. I think a 1.4x tele converter might be a good option. Seeing the results of others, I do not think a 2x would be a good idea (but if you do, go MC7). Like QuietOC said, a tele converter not only magnifies the picture but also the flaws of the lens.

If you rely on AF, an converter wil either not focus (if it is properly chipped) or it will have reduced AF capabilities as less light will hit the AF system.

The first generation Tamron 150-600 are not that expensive on the used market and it has proper AF, if you can stretch it and can live with the bulk, I would look into one of those (or the Sigma equivalent).
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Miranda F View Drop Down
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Post Options Post Options   Quote Miranda F Quote  Post ReplyReply Direct Link To This Post Posted: 21 April 2019 at 07:32
Teleconverters were designed to give a cheap alternative to expensive telephoto lenses on film cameras, and they have little relevance to modern high-res digital cameras. My opinion, confirmed by numerous experiments on a large number of lenses but (I admit) not entirely shared on this forum, is that teleconverters are almost invariably complete waste of time with long telephoto lenses on high-mega-pixel cameras, for one simple reason.
Most such cameras have a greater resolution than the lenses you fit on them, so adding a teleconverter makes the image larger but gives you no more detail. Adding a 2x TC is almost invariably a waste of time because it loses you one stop in shutter speed, and without it you could have stopped the lens down by one stop and gained resolution that way. A 3x or 4x TC is amusing but unhelpful, and the loss of contrast is huge (though you may be able to correct that in PP).

However previous threads here confirm that there are a few cases when a TC is still useful:
1) very wide aperture medium-focal-length telephoto primes such as the Minolta 200mm and 300mm f2.8 which have a resolution that exceeds some of the cameras they are used with, and a 1.4x TC is a good partner. But if you have an adapted A7r, for example, I very much doubt you'd see any gain in detail.
2) Those who use old cameras with an OVF. Getting the image bigger in the VF can be very useful irrespective of the detail.
3) Those who need the extra magnification in order to nail the focus, eg on small birds.
4) Anyone faced with a small high-contrast subject like the moon, where the magnification and contrast loss of a TC can occasionally give better pictures. I've even found this to be true on the Tamron 500mm mirror lens, though most other mirror lenses have low resolution and very low contrast.
That's my experience, anyway, and to be frank, results weren't that good in film days, unless you had nothing longer than a 135mm f2.8 lens. In film days I had 2x and 3x TCs for my Miranda cameras and hardly ever used them due to the poor results obtained.
5) TCs can be quite useful on short FL lenses which *do* have a very high resolution. A 2x TC can make a surprisingly good partner for a near-macro lens, to increase the working distance and get more magnification, such as the Minolta 35-70 f4 and various 90-100mm macros.
6) Old-fashioned short-focal-length lenses with a small number of elements, like your typical 50mm prime, often have a good centre and terrible corners, and a TC may give good results as well as saving weight. But usually a digital zoom works even better ...

Edited by Miranda F - 21 April 2019 at 07:45
Miranda F & Sensorex, Sony A58, Nex-6, Dynax 4, 5, 60, 500si/600si/700si/800si, various Sony & Minolta lenses, several Tamrons, lots of MF primes and *far* too many old film cameras . . .
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