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03/26/2005 11:15:46 AM · #1 |
I shoot a lot of out door sports. I've been using a sigma 70-200mm 2.8 with a 2x quantaray converter. The auto focus was very slow and didn’t lock in very well. Last year I had the 300D body with the same problem, I thought it would improve with the 20D, but nope. So my question is, would a canon 1.4 converter give me better results? The best solution would be to buy a 300mm or 400mm lens, still paying for my last lens, so this isn’t an option. Any body have some suggestions?........Thanks...ace
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03/26/2005 11:23:22 AM · #2 |
Not sure about the sigma 70-200 but I have the canon f/4 and decided to get the 1.4 converter to keep auto focus and image quality after reading many (many) reviews. AF is still fast with the canon 1.4converter
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03/26/2005 11:25:08 AM · #3 |
Once the highest F stop hits 5.6 or more the AF will not work very well if at all. Adding a 2X converter is like adding 2 f-stops, so if you 200mm lens is a 4-5.6 and you are zoomed to 5.6, then add the 2X you are at f11, light wise.
A 1.4 TC will cost you 1 stop, so that'd still be f8.
Some folk see a loss in sharpness and contrast with a lens when using a TC. You might look at Phoenix lenses. //www.photo.net/ezshop/product?product_id=1418 Not too expensive.
Message edited by author 2005-03-26 11:25:17.
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03/26/2005 11:53:32 AM · #4 |
Originally posted by ace flyman:
I shoot a lot of out door sports. I've been using a sigma 70-200mm 2.8 with a 2x quantaray converter. The auto focus was very slow and didn’t lock in very well. Last year I had the 300D body with the same problem, I thought it would improve with the 20D, but nope. So my question is, would a canon 1.4 converter give me better results? The best solution would be to buy a 300mm or 400mm lens, still paying for my last lens, so this isn’t an option. Any body have some suggestions?........Thanks...ace |
Even with the loss of f stops associated with teleconverters your Sigma 70-200 2.8 should still be fast enough for autofocus to work properly. It's difficult to find info on the net about what is compatible and what isn't when mixing brands of cams, teles, and lenses. I'd suggest taking your cam & lens to a camera store and asking to try out the tele before purchasing. Maybe they would give you something for your Quantaray as a trade-in. And I think you should consider a 2x for sports shooting, but it really depends your needs.
Message edited by author 2005-03-26 11:55:22.
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03/26/2005 11:53:49 AM · #5 |
Originally posted by Prof_Fate:
Once the highest F stop hits 5.6 or more the AF will not work very well if at all. |
My 1.4X and 2X canon converters work fine, focus fast and AF well beyond f/8. I don't like the 2X because I believe it softens up the image too much, but the 1.4X has no drawbacks that I have been able to detect.
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03/26/2005 12:13:15 PM · #6 |
Originally posted by Prof_Fate:
Once the highest F stop hits 5.6 or more the AF will not work very well if at all. |
How do you figure that at 5.6 the AF won't work very well, or won't work at all? Where do you do your research so I know to stay away from there?
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03/26/2005 12:42:39 PM · #7 |
Originally posted by deapee:
Originally posted by Prof_Fate:
Once the highest F stop hits 5.6 or more the AF will not work very well if at all. |
How do you figure that at 5.6 the AF won't work very well, or won't work at all? Where do you do your research so I know to stay away from there? |
I think he may be talking about lenses with a max aperture of f/5.6 or less. Many of the manufaturers warn about possible AF failure when using such lenses with the 2X.
But then I wouldn't recomend Phoenix lenses as a alternative either.
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03/26/2005 12:53:17 PM · #8 |
Originally posted by deapee:
Originally posted by Prof_Fate:
Once the highest F stop hits 5.6 or more the AF will not work very well if at all. |
How do you figure that at 5.6 the AF won't work very well, or won't work at all? Where do you do your research so I know to stay away from there? |
I have read it several places, here are some of them:
"Of course you wouldn't expect AF. Canon AF is specified to work only at f5.6 or faster. " - source: //www.bobatkins.com/photography/reviews/tamron_200_500c.html
No specs here, but the math works based on what he says - //www.bobatkins.com/forums/index.php?forum=1&topic=34&page=last
"phili1
01-16-2005, 08:36 AM
The highest F stop the 20D will focus with is F6.3 I beleive the 300D it's F5.6 and when you put the extender on you might get it at 100 & 200 but loose on the 20D but you lost it at 100 with the 300D because you are at F 6.3 and it can only focus at F5.6." sourced from //photography-on-the.net/forum/archive/index.php/t-54116.html
And i know i have read it in magazines. I thought i read it in some camera or lens manual as well. If you notice, practilly no lenses are made beyond 5.6. Less light means less focus reliability.
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03/26/2005 12:59:50 PM · #9 |
Some good feed back, don't know about the speed on higher F-stops, I shoot at f2.8 or f4 max. Even at f2.8 I don't get a blurred back ground with the converter. I agree on how soft/sharpness lost. I set the camera in AV mode, iso 400 to 800 this time of year, shutter speed min. 500, it should be plenty fast enough. Now if I pre-focus on a possible play the AF isn't so bad, but if have to adj. say more than a 60ft distance, its hit and miss. So the 1.4 would not be as soft? and prob. a little sharper.....hmmmm Right now I shoot mostly H/S softball and ASA softball. At times there is plenty of room to get a little closer. I think I'll drop the converter, I get good results with the sigma lens or if I can get in the dugout I'll use my favorite lens...24-70mm 2.8L
Ok, I'll dream a little, anybody have a canon 400mm f2.8L is ?
Thxs..ace
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03/26/2005 01:55:39 PM · #10 |
I dunno...my AF works fine at 5.6. Maybe I'm just special...but thanks for the links, I'll be sure to never go to those sites again.
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