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Old 08-12-2009, 10:26 PM
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bojan is offline
Join Date: Jul 2006
Location: Mt Waverley, VIC
Posts: 6,132
Originally Posted by Waxing_Gibbous View Post
I've had the 70-200 NON IS. IMHO its superior to the IS version. I don't know why. Perhaps its having fewer elements to interfere with the light path.
I would also suggest purchasing an older version from around the mid-90's to early 00ies.
The 70-200 was introduced to replace the 80-200L (a VERY underrated lens) and primarily intended for photojournalists, so they had to be (and were) real corkers. If memory serves, IS came in around 97/98 (?).
The non-IS seems to me sharper, to have more 'bite' and better (more natural)colour.
Plus its a lot cheaper used.
But you won't go wrong with either.
The ONLY proper test for lens, easily available to most of us, is a photo of the star field, with fully opened iris.
If the un-saturated stars are round and smaller than, say 3-6 pixels (everywhere in the 10 Mp frame) the lens is good.
Otherwise it is compromised. And that's it.

To say the lens "have more 'bite' and better (more natural) colour " is very vague and not very scientific.. and means different things to different people.
Star test is, on the other hand, absolute.

MTF method, while supposed to be non-biased, is also subject to interpretation.. . However, this number is more accurate and less "artistic" and subjective description of the performance of the lens.

Recently I bought (relatively cheap) Canon 200mm F2.8 FD and mechanically modified it (to reach the infinity focus) and I can say this lens is pretty good, but with some tricks I discovered in desperation: for example, it has A LOT of lateral CA in corners, which does not go away with its own iris closed down even to f5,6n or f8.. but it does go away with external iris (mask in front of the lens).
So despite some good reports for this lens, I would not recommend it for terrestrial work, simply because it does not perform OK with its own iris. But if it is permanently mounted on EQ it is not a big problem to use external iris to have good sharp image across all of the frame.

So, to conclude this long lecture: do a star test, and be prepared for (unpleasant) surprises.. or pleasant ones, that depends.. . Some old and underrated lenses will perform MUCH better than than many modern, 10x or more expensive specimens.
Then it is up to you to decide if it is worth the money or not.
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