[normhead]

I was just poking around a bit, looking for geek stuff, in this case lens comparisons. So of course I found an article that lead to the DxO site where they have a lens comparison thing chart.

I looked at three different lenses, and came up smiling because my lens , the Sigma with a pentax mount came up just short of the much more expensive Nikkor by a single point (in resolution) but was listed as about $400 dollars less expensive. ( The pentax lens was rated very poorly, which didn't surprise meat all since that's what the Heny's salesman told me when he sold me the Sigma, and those guys are almost always right.) But, the thing I was looking for was similar comparisons for various 300-500mm prime lenses. ANyone know where I can find something?

http://www.dxomark.com/index.php/en/Lens-with-Camera/Compare-lenses

[northcoastgreg]

These lens comparisons are misleading: they are comparing what the DA 55-300 can do on a 14mpx APS-C camera with what can be accomplished on two very expensive 20+ mpx FF sensors. It's highly unlikely that the Sigma 70-300 is a better lens than the Pentax 55-300. The Pentax did very well with the Pop Photo tests and it achieved a higher scorer over at the lens reviews database on this forum. I suspect that salesman from "Heny's" didn't know what he was talking about.

[boriscleto]

IMNSHO a much better comparison.

[paperbag846]

Yes, it is best to compare all lenses with the same body. Otherwise you are never sure whether you are seein' a good piece or a good bod (amiright)?

[normhead]

Next time I'll match the bodies, but looks like the same result to me. A better lens for much cheaper. Thanks for that.

I suspect that salesman from "Heny's" didn't know what he was talking about.

Years ago, the guys from popular photography went through about every lens on the planet, and made a list of 10 best lenses. The expected parties were there, Zies, Nikon had the most, Canon and Pentax were represented. But when it got to the zooms, Sigma and Tamron were represented with one lens each. I'm not saying you can apply that information today, 20 years later, but I wouldn't dismiss third party lenses without testing. You didn't like the comparison I did. Cool, you have valid points, but to assume that the Pentax lens is better, that's just an assumption, third party lenses have been the best in class before in the past, and they will probably continue to be in some cases in the future. By the way, what sold me on that lens was the macro feature. Great for insects. It had nothing to do with the salesman, but, he was the one who got it out of the case, put it on my camera and said, here try this out, everybody seems to like this one." Whether he's wrong or right, this is the best low end lens I ever bought and it continues to be useful years later on a camera with 3 times the MP of the camera I bought it for.

But that's not the point. I've already made that purchase. Now I'm looking at either a 200mm or 300 mm prime. Sigma has 300 Prime and a 500 prime and the 300 is f2.6 and will take the Sigma 2x converter. It's a bit pricey, but, still I'd like to know how it stacks up against the Pentax 300.

It's ironic though, comparing cheaper lenses there is lots of data. Comparing the ones where you have to re-mortage your house, not so much.. at Henry's these things have to be special ordered. You have to order two if you want to compare, even if you only want one.

[northcoastgreg]

but to assume that the Pentax lens is better, that's just an assumption

I'm not assuming the Pentax lens is better (though it wouldn't surprise me if it is); I'm questioning whether the Dx0 comparisons can be relied on to make these kinds of comparisons. Over at photozone.de they issue the following warning: "Please note that the tests results are not comparable across the different systems!" You want accurate tests comparing lenses, they have to be done with the same camera.

A German magazine tested these lenses a year or so ago, using the same camera. The results were posted by falconeye as follows:

Measurements:
- Resolution 300mm f/5.6 [Lp/PH] Pentax/Sigma/Tamron: 2447 / 2156 / 1785
- Resolution 100mm f/8.0 [Lp/PH] Pentax/Sigma/Tamron: 2941 / 2905 / 2937

Now I'm not suggesting that this test is conclusive or decisive; but it's likely more accurate than comparing Dx0 scores across different systems. And it is more consistent with what people who have actually used the lenses in real world situations report.