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Old Sep 15, 2004, 7:23 PM   #1
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In my instance, I just purchased my *ist, but I think this applies to most any digital SLR so I am posting in this forum. While I'm at it, I'd also like to get a 28-300mm lens so that I can just take one lens with me on vacation. It looks like the Tamron is the way to go based on reviews. I was going to get an older one off ebay (model 285DP) on the assumption that the only real difference between that and a newer model would be the weight. Now, I found a special digital lens on the tamron site. this is way more expensive than the $200 I planned on spending. Is the special digital lens really needed?

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Old Sep 15, 2004, 9:49 PM   #2
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Digital sensors (well actually the AA filter) are shiny and reflect light, compared to film which absorb light. If the lens was made in the time of film's dominance, the rear element may not be coated. Using such a lens on a digital camera could increase internal light reflections. This leads to loss of contrast and a sub-optimal image quality.

I have noticed this with my collection of older MF Nikkor lenses when used on the D70. The lenses which were renouned for good contrast with film have basically yielded washed out pictures on digital. Thus, it is my belief that specially designated "optimised for digital" lenses by the various companies are not merely marketing gimmick (and I'm usually skeptical of most things).
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Old Sep 16, 2004, 5:49 AM   #3
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if am not mistaken the ist has a 1.5x magnification factor due to its sensor size. Therefore the 28-300mm lens will become a 42-450mm. May be you need a wider lens for "all purposes".
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Old Sep 16, 2004, 6:52 AM   #4
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One other thing to consider about the 'made for digital lenses' - they are designed for specifc image sensor sizes. For instance the new lenses Canon is developing will only work on the digital rebel and 20-D cameras - the more professional grade cameras cannot use them because they have a larger sensor size. You may not care now, but in 5 years when you want to upgrade your camera (and lets say by then D-SLRs have full size sensors at the lower end) the digital specific lense you own will be useless with the new camera. Just something to consider. Most camera manufacturers will state which of their lenses are fully compatible with their DSLR's so you still may want to consider a 'normal' lense. Just food for thought
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