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Author Topic: What will be a sharper print (crop vs full)?  (Read 1592 times)

FlyPenFly

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What will be a sharper print (crop vs full)?
« on: June 16, 2011, 09:25:46 am »

I'm trying to decide whether to pick up a Tamron 70-200mm F2.8 for my Nikon D7000 or for my Sony A850. One is 16mpx and one is 24mpx.

Lets say I took a picture of a landscape with a certain framing at 200mm on the A850 which I then had to crop a bit to get to the 275mm equivalent. On the D7000 that same framing would simply be within the zoom range because of the crop factor.

Now lets say I'm making a large movie poster sized print of this image, would I have better quality with the A850 or D7000? The dynamic range of both is very similar and lets assume base ISO.
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Bart_van_der_Wolf

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Re: What will be a sharper print (crop vs full)?
« Reply #1 on: June 16, 2011, 11:37:39 am »

I'm trying to decide whether to pick up a Tamron 70-200mm F2.8 for my Nikon D7000 or for my Sony A850. One is 16mpx and one is 24mpx.

Lets say I took a picture of a landscape with a certain framing at 200mm on the A850 which I then had to crop a bit to get to the 275mm equivalent. On the D7000 that same framing would simply be within the zoom range because of the crop factor.

Now lets say I'm making a large movie poster sized print of this image, would I have better quality with the A850 or D7000? The dynamic range of both is very similar and lets assume base ISO.

Assuming:
  • Similar vertical framing,
  • Similar lens resolution at different zoom factors,
  • Sony A850 has a sensor with a Nyquist frequency of 84 cy/mm,
  • Nikon D7000 has a sensor with a Nyquist frequency of  104.6 cy/mm,
  • Nikon relatively keeps 68 cy/mm Nyquist frequency at the same/normalized sensor size,
    because the Nikon requires 53.8% more magnification for similar size output,
  • the Nikon's denser sampling squeezes only a little (not enough) more resolution out of the lens

Leads to the assumption that the Sony will produce significantly sharper output on magnifications of more than, say, 10 inches on the short dimension. There are complicating factors such as differences in AA-filter which change the MTF of the system. However the Sony leads far enough to be safe.

Cheers,
Bart
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FlyPenFly

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Re: What will be a sharper print (crop vs full)?
« Reply #2 on: June 16, 2011, 12:28:51 pm »

Thanks, I'm currently trying to evaluate if I should get the Tamron 70-200mm F2.8 lens for my D7000 or my A850. I'm trying to find out if there are instances if it would be better to use the Tamron 70-200 on the Nikon over the A850 or vice versa.

The Sony A850 does have in body stabilization but the Nikon with the crop factor will also only use the sweet spot of the lens...
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ErikKaffehr

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Re: What will be a sharper print (crop vs full)?
« Reply #3 on: June 16, 2011, 02:05:41 pm »

Hi,

If you crop the A850 image to APS-C size the Nikon will be better, if you utilize the full frame the Sony will be better.


Best regards
Erik


Thanks, I'm currently trying to evaluate if I should get the Tamron 70-200mm F2.8 lens for my D7000 or my A850. I'm trying to find out if there are instances if it would be better to use the Tamron 70-200 on the Nikon over the A850 or vice versa.

The Sony A850 does have in body stabilization but the Nikon with the crop factor will also only use the sweet spot of the lens...
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Erik Kaffehr
 

bill t.

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Re: What will be a sharper print (crop vs full)?
« Reply #4 on: June 16, 2011, 03:31:25 pm »

I suspect that in the long term things like IS, focus accuracy, feel in the hand, balance on the tripod, control feel and location, and other basically mechanical issues would have more impact on image quality than sensor issues.  A clumsy, flailing camera/lens combo will produce bad pictures no matter how good the sensor is.

Just hefting the two cameras with the same lens might give you 90% of a practical answer.  Easy to arrange if you live in a very big city, but otherwise not.
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