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Old Mar 7, 2007, 4:52 AM   #1
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two lenses.Tamron XR28-300 and a Tamron AF 28-300. There is $100 dollar difference between the two lenses and dont know that much about lenses to know the difference.

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Old Mar 7, 2007, 5:09 AM   #2
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Without looking them up, my guess one is APO and the other isn't. As $70-100 is often the spread for that (depending on how many elements the lens has)

Personally I'd think twice about a 28-300mm

I have never used the Tamron, but my SIGMA 28-300m turned out to be a mistake.

Asking a lens to be wide plus long zoom necessitates some not so minor compromises, and 10x is a lot to ask of an inexpensive lens.

And most of the other 10x lenses like the SIGMA 50-500mm start from at least a normal (vs wide) FL range.

Personall I went with the kit lens (18-55mm) and a SIGMA 70-300mm (Tamron makes one too) Works out well and both lenses are very consistant and crisp across there ranges.

Again I haven't use the Tamron but the SIGMA 28-300mm got rather soft towards 300mm and poor contrast in all but bright daylight in that range too.

Boths companies lower end lenses are very simillar in nearly identical specs and build, so I'd guess the Tamron might have similar problems.

Where as I know of no one disappointed in the 70-300mm lenses from either of them. (The 50-200mm's too)
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Old Mar 7, 2007, 5:23 AM   #3
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Sorry what does APO mean? And thanks for responding.
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Old Mar 7, 2007, 3:01 PM   #4
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APO stands for Aprochromat.... it is a specially treated glass, that reduces chromatic aberation (so called purple and yellow fringing at high contrast edges), and generally better color purity.

Its effective difference depends a lot on the type of things you shoot as to how noticeable the difference. You will notice it a lot more if you shoot lots of fine detailed stuff. Most who are big into macros for istance will usually go for APO lenses for doing that.

Here is a reather technical explanation
http://geogdata.csun.edu/~voltaire/tmb/definition.html
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