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11-07-2009, 12:45 PM   #1
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4 Lenses at 50mm - Very Wide Images

I decided to do a little test of all my lenses at 50mm and f/5.6. I used 5.6 because the DA lenses throw the curve compared to the faster Sigma (F/4 at 50mm) and the M50. Each was processed by Bridge at default settings, manual WB and exposure in camera, on a tripod, with 3s MLU. Here are the 100% crops, which I left wide to demonstrate edge to edge sharpness. Also, leaving the images at full size allows you to see more than one image at any given time.

M50 f/1.4

18-55 DA AL

18-55 DA ALII

Sigma 17-70 DC

It should be noted that I've previously calibrated the camera for each of the auto lenses' focus points. It seems as though the Sigma has a narrower DOF than the other lenses, even with each of them at f/5.6. Another annomily is that the Sigma won't report the proper lens name or a focal length of 50mm. It jumps from 48 to 53 no matter how minute the change in zoom.

Results? I think that the Sigma and the M50 are closest in sharpness directly at the focus point, but the DA lenses seem to be a little more forgiving than the Sigma throughout the range of acceptable focus. The Sigma also demonstrates a very slight PF as seen on the left edge of the clock, which none of the others suffered from.

I think I'll keep the Sigma on the camera when I need the AF, but the M50 will still be my lens of choice for short portraits. The benefit with the Sigma is that the image quality doesn't seem to suffer with the lens wide open. If anyone would like to see one from the Sigma at 50mm and f/4, let me know.

On a side note, I extended the Sigma to 70mm and did a comparison with the Sigma 70-300 DG Macro. The 17-70's "70" was a whole lot shorter than the 70-300's "70." Which is correct, I haven't the foggiest idea how to find.

11-09-2009, 02:11 AM   #2
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Holy wide post Batman!

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50mm, camera, da, edge, f/4, focus, k-mount, lens, lenses, m50, pentax lens, sigma, slr lens
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