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Old Nov 16, 2005, 3:27 PM   #1
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Can anyone tell I'm a newbie???? Looking at getting the 75-300mm lens so I can learn on it and then I'll upgrade to better glass but what is the difference between the two. My friend has one they can sell me but it has a small insect on the front inside lens, she reckons it doesn't affect the photos, I can't see it on hers but surely it would affect your focus or something!

Thanks for any info or advice

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Old Nov 16, 2005, 6:28 PM   #2
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Since the introduction of the EOS system Canon has offered 3 different motors in the auto focus lenses.
Arc Form Drive: this was the original AF motor for Canon lenses, I guess this would be the "standard" you are talking about. It is generally slow, noisy and doesn't allow for simultaneous auto focus with manual override.
Ring Ultrasonic: This is the good one, fast, silent, and will allow for manual override of the autofocus if you don't like what you see. This motor is used on most of Canons high priced lenses since 1987.
Micro Ultrasonic: Cheaper ultrasonic motor, doesn't allow for manual override, not as noisy as the AFD, but noisier than the Ring Ultrasonic. Basically a very cost effective ultrasonic motor, used on the cheaper consumer grade canon lenses.
The 75-300 lens your friend is offering is probably the first incarnation of this lens(there have now been 4 if you count the new 70-300 in the mix). It should have the AFD motor and is an OK lens although it will be soft at the long end. The bug shouldn't show on your photos if it's on the front element, although I certainly wouldn't want one on my lens. The age of the lens and the bug should garner you a huge discount on the price. Check KEH.com for lens prices, their price list can usually be considered a blue book for lens prices.
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Old Nov 18, 2005, 10:17 AM   #3
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Yes, as eosthree said very well, the 75-300 is an early version of the ultrasonic focusing mechanism, and it really isn't fast focusing at all compared to the newer USM lenses. I'd go for the new 70-300, or if that's out of budget, the Sigma 70-300 APO Macro lens. Much better image quality than the Canon 75-300, but without IS...

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Old Nov 18, 2005, 2:15 PM   #4
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Thanks for that! Lens has gone back....new model lens is a 90-300 so now just shopping around.
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