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Old Feb 28, 2010, 8:50 PM   #51
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I took this simulation and measured the magnifications to each zoom. In pixels I got these numbers:

132mm -> 230298 px
200mm -> 93121 px
250mm -> 55584 px
270mm -> 47700 px

(in absolute values these mean nothing - what matters is the relation between them)

So if we take a picture in 12 MP at 132mm (200mm eq), and crop we wil have:

132mm -> 12.00 MP
crop to "200mm" size -> 4.9 MP
crop to "250mm" size -> 2.9 MP
crop to "270mm" size -> 2.5 MP

If we get a picuture in 12 MP taken with 200mm (300mm eq), and crop, we will get:

200mm -> 12 MP
crop to "250mm" size -> 7.2 MP
crop to "270mm" size -> 6.1 MP

Finally, comparing the last two, if we take a 12 MP picture with 250mm and crop:

250mm -> 12 MP
crop to "270mm" size -> 10.3 MP
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Old Feb 28, 2010, 9:01 PM   #52
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Again, the point is what we WANT...

Of course that having a full resolution picture is good, but maybe to what we intend to do a 7.2 or 6.1 MP picture may be enough - so the 200mm lens suits well. But if resolution is the main target, the higher zoom must be the option (will allow more cropping!)...

My doubt still is if the small reductions of image quality in the Tamron/Sigma lenses compensates the loss of resolution... Or if a cropped lower resolution picture from Nikon 200mm can be better than the full resolution from 250/270mm lenses...

I think again it is still a question of priorities... Reading additional reviews (SLRgear) it seems that the defects are more related to the super-zoom architeture than to differences between them - in other words, despite Nikon is really better, the difference is not so sensible between the super-zooms. So the Tamron may become the best option in this criteria.

The only thing that is clear is that the gain from a 132 lens (200mm eq) is valuable - so the superzoom is still an option to an all purpose fun lens.
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Old Feb 28, 2010, 9:14 PM   #53
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The difference between the 3 megazoom lens, the 200mm to the 250 or 270mm is so trivial that unless you really print VERY VERY LARGE. You will not see it at all.

If you look at it with your RAW pixel count. You are losing 1/2 of your resolution cropping form 200mm to 270mm. But if the subject you are shooting is not standing out at 270mm crop. And you need to crop to say 300mm. That is allot of resolution that will be lost when maxing at 200mm and cropping with the computer. At 270mm when cropping 340mm. You still have a good resolution for a 50% crop. At this range any advantage the 200mm may have had in IQ is complete lost, and the IQ advantage go to the longer zoom.
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Old Mar 26, 2010, 7:50 PM   #54
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for me it was finding a decent zoom on a very tight budget. I have seen lenses rated far better and far more expensive (then I can afford) in hands that have probably set everything on the camera to the fully automatic mode, and it showed...very average photos that could have been attained with far less expensive equipment. I selected the quantaray (re-badged sigma) 18-200mm OS as i picked it up over a year ago on craigslist for $190....If you understand a lenses shortcommings, you can make it work well for you. In the bright florida sunshine I had no problem stepping down to f11 to improve sharpness.

I haven't read everyone's response but...if you do get the sigma 18-200...make sure it is the one with OS. From what I hear (everywhere) it offers much better optics in general. You can check out some photos I took one posting only cropped, the other was touched up...all taken on a D40.


photos taken with older d40/sigma 18-200mm OS lens
Is the Quantaray 18-200mm OS DI f/3.5-6.3 lens any good?

nikon d5000 (just got it....couldn't pass up the deal I got..$525 refurbished with lens from adorama...I sold the 18-55mm lens)
zeikos grip (yes that's my camera and hand in my avatar)
nikon 18-70mm
sigma 18-200mm OS
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Old Mar 29, 2010, 12:45 PM   #55
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Default One camera one lens hmmm

You want it all in one package, Olympus E620 and a Sigma 50 500 lens, toss in a cheap 14 42 for normal use inside and that covers a huge range
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