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05-16-2014, 06:52 PM   #211
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Will this have better IQ than the DA* 55?

05-17-2014, 02:21 AM   #212
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I suppose so, those ART series are really tempting but...
05-17-2014, 03:12 AM   #213
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QuoteOriginally posted by Newtophotos Quote
Will this have better IQ than the DA* 55?
To get an idea:

Pentax smc DA* 55 mm f/1.4 SDM review - Introduction - Lenstip.com

Sigma A 50 mm f/1.4 DG HSM review - Introduction - Lenstip.com
05-17-2014, 01:18 PM   #214
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Well, sadly this needs some perspective which is lacking on lenstips.

The graphs show results in lines per mm, so they are not normalized for sensor size (LP/PH). Generally my rule of thumb is that the same lens on same pixelcount 36x24 sensor resolves about +20% better than on 24x16 Sensor. That would mean, you have to divide the Sigma values by 1,2 to compare.

Then you also have the hugely different pixelcounts of 14,6 MPx Pentax K20D versus 22,3 MPx Canon 5D3 (153%), which means about +24% Pixel resolution in linear dimension. That again needs to be taken into account. Just look at D800 resolutions and you know what effects pixelcount has. So a division by 1,24 might be in order as well.

Suddenly the DA*55 does look quite good.

05-17-2014, 04:22 PM - 1 Like   #215
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QuoteOriginally posted by HavelockV Quote
Well, sadly this needs some perspective which is lacking on lenstips.

The graphs show results in lines per mm, so they are not normalized for sensor size (LP/PH). Generally my rule of thumb is that the same lens on same pixelcount 36x24 sensor resolves about +20% better than on 24x16 Sensor. That would mean, you have to divide the Sigma values by 1,2 to compare.

Then you also have the hugely different pixelcounts of 14,6 MPx Pentax K20D versus 22,3 MPx Canon 5D3 (153%), which means about +24% Pixel resolution in linear dimension. That again needs to be taken into account. Just look at D800 resolutions and you know what effects pixelcount has. So a division by 1,24 might be in order as well.

Suddenly the DA*55 does look quite good.
It's the opposite of that. lines/mm are normalized for sensor size, and more-closely evaluate the lens performance only. Lines/ph is NOT normalized for sensor size, and combine the lens performance with the sensor size.

15MP to 22MP is worth ~10-20% on some lenses. FF is worth ~30% linearly on some lenses, in a perfect scenario FF would be worth ~52% more linearly.

Dr. Camera: Have the recent improvements in sensors changed the optimum sensor size?


The 55mm is good. The sigma is better, basically class-leading performance.
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