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02-19-2009, 06:50 PM   #1
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1.4x vs. 2x tele converter

is the 1.4x better than the 2x? Im still somewhat of a noob and was just wondering about the difference in the 2

02-19-2009, 06:53 PM   #2
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it depends on who's teleconverters. They are all different. I have found both sigma TCs (1.4x and 2x) to be excellent, but they only work on a limited range of lenses due to mechanical design and interference with the rear element of many lenses.

I think, however, this is why they work so well, they are designed specifically for a few lenses.

The pentax AF 1.7x TC is also excellent. can't comment on others.
02-19-2009, 08:21 PM   #3
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QuoteOriginally posted by wilkin Quote
is the 1.4x better than the 2x? Im still somewhat of a noob and was just wondering about the difference in the 2
Note that the way a TC works is that it takes a smaller image from the main lens and magnifies that image to fill the sensor.

Quality thus will degrade. And light will be lost.

1.4X loses 1 stop (e.g. lens set at f/2.8 - effective aperture f/4). 2X loses 2 stops (e.g. lens set at f/2.8 - effective aperture f/5.6).

With 2x TC and lenses slower than f/2.8, you lose autofocus. Manual focus is difficult because the view finder is so dim.

With 1.4x TC, there is a good chance you still have autofocus. My Tamron 18-250 f/3.5-6.3 + Tamron 1.4X TC can still focus at 250mm. It needs something contrasty, is slow, and tends to hunt, however.

Depending on the lens and the TC, sometimes not using TC and cropping instead produces better image.
02-20-2009, 11:23 AM   #4
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QuoteOriginally posted by SOldBear Quote
...
With 2x TC and lenses slower than f/2.8, you lose autofocus. Manual focus is difficult because the view finder is so dim...
Not entirely true. Even though the Sigma web site and owner's manuals say it is not possible, I still have AF capability with my 100-300/4 and the 2x tc. It was a pleasant surprise. (These are pre-DG versions of the lens and tc. Maybe indeed the newer version will not AF.)

02-20-2009, 02:04 PM   #5
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I have a Promaster 1.7 that autofocuses on my Pentax f*300mm and gives decent results. I'm not big on tc's and prefer to get closer and then crop (which gives better results. But, there are those times when a tc is a good alternative. You can get this tc from Wolfs Camera on ebay for $89. At that price its hard to pass up. I thought about a 2x, but then it requires manual focus... not my strong suit. heres a recent pic shot with the 300 and the promaster tc:

Last edited by ivoire; 10-04-2010 at 03:58 PM.
02-20-2009, 02:08 PM   #6
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Over the course of the last six months we had several threads with tc quality comparissons. I would suggest you search for those and will find loads of info, which you may find helpful.

Ben
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