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11-12-2008, 10:18 PM   #16
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If you're even asking if a $300 lens is as good as a $4000 lens then you should just buy the $300 lens. I won't be giving up my 300 F2.8 any time soon though because there is no comparison.

11-13-2008, 02:46 PM   #17
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These charts are labeled "SUBJECTIVE QUALITY FACTOR" for a reason. The results are entirely subjective and therefore based partly on expectations. People have much higher expectations for a $4000 lens than for a $300 lens, and that is most likely all that the chart reflects. In other words, the 55-300 lens has a lot of "bang for the buck" value; that doesn't make it as good or better than the 300 f2.8. Most likely the evaluators were just more surprised by how good it was. (You could make a good argument against this by showing that the same evaluators looked at the images without any knowledge of what lens they were taken with, but I would be surprised to discover this).
11-14-2008, 08:49 AM   #18
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QuoteOriginally posted by ghelary Quote protocol of testing is coherent.
Yes, and good so!

A little tip for anybody in the need to compare lens tests across bodies, reviewers etc.:

Look, at what aperture a lens resolves best. And this is my scale:

Best at f/2.0 or wider: *****
Best at f/2.8: ****
Best at f/4.0: ***
Best at f/5.6: **
Best at f/8.0: *
Best at f/11: -
Best at f/16: crap

But be aware that you need very precise testing data to use this scale. For instance, Popphoto would give the DA*300/4 a rating of "*" only which is known to be wrong. gives the FA*300/4.5 a rating of "**" (in my scheme) and the DA*300/4 is reported to resolve even just a little better.

Only very, very few lenses can get a "***" (like the FA 31 Ltd.) and I am only aware of one lens which would qualify for a "****" rating. The lens getting a rating of "*****" is still to be made...
11-20-2008, 10:05 AM   #19
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QuoteOriginally posted by CFWhitman Quote
These charts are labeled "SUBJECTIVE QUALITY FACTOR" for a reason. The results are entirely subjective and therefore based partly on expectations.
Not true, the SQF system used in PopPhoto is actually done objectively.

"SQF was developed by Edward Granger"

"Sharp lenses can reproduce more “line pairs per millimeter” (lpm) than can unsharp lenses. MTF numbers, however, are meaningful only to optical engineers, so Granger set about designing tests that could have real-world meaning to most photographers."

Look here for more details: Optic Nerves? Afraid to buy the wrong lens? - - PopPhotoJuly 2006


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