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Old May 18, 2007, 9:03 PM   #1
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I have a canonXTI, and a EF70-300mm IS lens. I want even furtherreach but don't have the money for a 400-500mm lens. I have been looking at the Sigma 1.4, and 2.0 TCs. I'm asking for feedback if anyone has used these, especially on the same, or similiar set up.

THX in advance!
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Old May 19, 2007, 6:12 PM   #2
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I have not used either, although it is my understanding that they are not bad... just not as good as the Canon versions.

You should be warned, though, that you will loose autofocus with either TC on that camera and lens. You will have to focus manually.


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Old May 19, 2007, 8:25 PM   #3
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I don't know about the Canon and Sigma TCs. Just keep in mind that you'll loose 1 stop of maximum aperture with the 1.4 and 2 stops with the 2x. That translates into lower shutter speeds atlong focal lengths where shutter speed becomes important.

I use a 1.4x on a different make with a brighter lense and get along well with the setup. If I were you, I'd narrow the choice to the 1.4 and forget the 2x with a f5.6 lens that long.

The 2x would yield nearly 1000mm (35mm terms) reach and f11 brightness. IS or not, I don't think that will do well.
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Old May 20, 2007, 7:41 AM   #4
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Mine isn't a Canon I have a Sony and I just bought one yesterday and it was very nice to have now just need some time to get some shots off so far so good.
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Old May 20, 2007, 7:57 AM   #5
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Teleconverters were big back in the 70's, but were of very poor quality and so fell out of favor.

As stated you will lose 1 or 2 aperatures, depending on model, and that will impact you greatly at longer focal lengths, which is where you need speed the most.

Personally, I'll never use a TC again.
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Old May 20, 2007, 8:00 AM   #6
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amazingthailand wrote:
Quote:
Teleconverters were big back in the 70's, but were of very poor quality and so fell out of favor.

As stated you will lose 1 or 2 aperatures, depending on model, and that will impact you greatly at longer focal lengths, which is where you need speed the most.

Personally, I'll never use a TC again.
So you feel they are not worth it huh?
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Old May 20, 2007, 10:19 AM   #7
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That's interesting, but my father always said "never say never".

A TC will never improve image resolution, but if you start with a very sharp lens (such as the 70-300) and buy a good quality teleconverter, the results can still be very good. The loss of a stop of light is a consideration, but in good light where you may consider stopping down anyway, it becomes moot. In poor light, it may be best to use lens alone.

I shoot Olympus and the results were with the 50-200 f2.8-3.5 / EC14 teleconverter and I believe it would not have been as good without the EC-14.


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Old May 20, 2007, 1:51 PM   #8
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It is very much dependent on the quality of the lens.
I have the Canon 600mm f4, an absolutely amazing lens (not the sharpest, but very close) and it takes the Canon 1.4TC without any noticable loss in quality. If there is enough like, I almost never take it off. There just isn't a point with the subjects I shoot (whild animals.)

But if you have an only "ok" lens (or worse) then you'll definitely see the difference. It's all rather logical, actually. The TC enlarges a portion of the lens to make it larger on the sensor. It enlarges the flaws in the lens as well as the image... the more flaws you have, the worse the image will look.

I don't know anything about that lens, but others here have refered to it as being "good." I honestly don't know.

And in case you don't know, when you loose "1 stop of light" you 1/2 your shutter speed. This can be the difference between getting the shot and not. Its as simple as that. Of course, so can using the TC... so there is always a tradeoff.

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Old May 20, 2007, 3:20 PM   #9
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Cyberf828 wrote:
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amazingthailand wrote:
Quote:
Teleconverters were big back in the 70's, but were of very poor quality and so fell out of favor.

As stated you will lose 1 or 2 aperatures, depending on model, and that will impact you greatly at longer focal lengths, which is where you need speed the most.

Personally, I'll never use a TC again.
So you feel they are not worth it huh?*
Correct.

However, back in the 70's, Nikon and Canon were not making TC's, so all TC's were third party, and pretty uniformly abysmal.

The other difference is that back then I really could not afford good quality glass, something I can afford now. What a difference 30 years makes. LOL.
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Old May 20, 2007, 4:27 PM   #10
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I don't know if this is relevant or not, but a few years ago I purchased a Canon (1.5X I believe) TC to use with the Canon A75 I had at the time. It was, in a word, AWFUL.Distortionwasn't bad butCA wasterrible, enough to render the TC all but useless. I took it back for arefund the same day.:-)
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