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Old Feb 10, 2005, 8:49 PM   #11
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I am reading everyone's replies (thanx guys, much appreciated). I haven't done much of the sigma/tamron research yet. I am thinking of sticking with Canon (but if anyone has anything else to say about 3rd party lenses I will be happy to hear it!) esp. if the lens quality is better, the extra bucks isn't such a big deal for me. It would be more of a big deal if one of these other lenses was lighter or smaller. This is why I like Timmy's suggestion, to get the Canon EF 24-70mm f/2.8L USMand then get the Canon EF 70-300mm f/4.5-5.6 DO IS USM. I am concerned about the quality of this 70-300mm lens. I know it is compact which is what I love about itbut can anyone tell me the quality of this lens? I always thought that lenses that change fstops when you zoom aren't as high of quality as the ones that have a constant fstop throughout the zoom range, is that correct?I do like the idea of the 1.4 teleconvertor also. I will probably get the 24-70mm lens to start off with, I figure in total with accessories and a 2 gig card I am looking at spending about $3,300 for the whole thing. Then I will shop around for the telephoto situation. Plus, I will be doing mostly indoor stuff until it gets warm outside, but I would like to just figure out what I am going to need and start buying accordingly. Thank you all for your help (and if anyone knows how to turn the text back 2 white....I get a list of colors but white ain't one of 'em!)
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Old Feb 10, 2005, 9:28 PM   #12
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Nancy Gabby wrote:
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I always thought that lenses that change fstops when you zoom aren't as high of quality as the ones that have a constant fstop throughout the zoom range, is that correct?
It's not always the case but in general that's true because they require more optics to maintain the aperture when a focal lenght is increased - also most lenses that varies aperture while zooming are also not true 'zoom': In the older days of manual focus SLRs theses lenses are referred to as vari-focal because their focus do not hold while one zoom in or out as opposed to 'true zoom' which are parafocal in design and hold their focus while the zooming is changed...

This is less important today with AF camera, but it indicates how 'dedicated' a lens designers are in their craft or for someone who values manual focusing!
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Old Feb 10, 2005, 11:22 PM   #13
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Thanks for all of your help NHL, I really appreciate it. And I know I might be barking up the wrong tree, and I will most definitely purchase the D20, but how is the similarity with the Nikon line, and lenses?
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Old Feb 11, 2005, 7:15 AM   #14
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You probably know it already, but unlike the EOS most Nikon lenses will hold focus while zooming

... and so is Tokina of Hoya fame!
"... meaning when focus is achieved at a telephoto focal length, it is possible to zoom back to a wide angle and maintain focus on the subject." - http://www.fredmiranda.com/reviews/s...rt=7&thecat=29
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Old Feb 11, 2005, 9:06 AM   #15
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In case you haven't seen there is some discussion of the 70-300 DO in the lenses forum.

http://www.stevesforums.com/forums/v...50&forum_id=65

Also I had to choose between the EF-S 17-85mm IS USM and the 24-70mm L USM, I ended up going with the 17-85mm, not an easy choice.

http://www.stevesforums.com/forums/v...82&forum_id=65

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Old Feb 11, 2005, 1:40 PM   #16
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thank you for the link, and thanx again, NHL about the focusing issue. I just want to get it straight. It's the EOS lenses that don't hold their focus, not the camera, right? So the Tokina's and Sigma's do hold focus? And for those who have the EOS lenses, how big a deal is this, doesn't it focus very fast anyway? Or when you zoom in or out, you look into the camera and see one big blur until you focus?
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Old Feb 11, 2005, 1:56 PM   #17
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Focus speed with 20D and 17-85 or 70-300 is fast. Unless you're shooting sports of wildlife it's instantaneous for all practical purposes.

Even in poor light I reckon 90% of shots focus in maybe 1/10s?? In really poor light where the camera has no vertical lines to work with the AF can fail.

I can only imagine how fast it is with a 2.8 lens. But surely fast enough that you normally don't need to worry about it.

Bird people will be able to give you more feedback and me too after this year's British GP. :-)

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Old Feb 11, 2005, 2:07 PM   #18
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Thanks so much, I am just reading all of the links now, and I am thinking of doing exactly what you did, Peripatetic, getting those two lenses. At least the 17-85 to start, it is cheaper than the 24-70, plus better range. I do like the idea of the faster lens, though. Everything costs ya.
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