[HUG] Re: Digi-Blads Beware!

  • From: Jim Brick <jim@xxxxxxxxx>
  • To: hasselblad@xxxxxxxxxxxxx
  • Date: Tue, 21 Aug 2007 21:48:34 -0700

Sensors are in no way pushing the limits of lenses!

Most engineers are well versed in Nyquist-dom. The resolution of good film camera lenses out performs, by a mile, the ability of the sensor to capture this performance. The image is being 'digitized' by the sensor, even though the sensor is an analog device. The image gets cut-up by the pixel spacing. Nyquist law states that, in order to not loose information, digitization must occur at least a frequency two to four times that of the data frequency. Good film lens resolves far more than can be captured by the spaced out (by comparison) pixels. There is an MTF frequency mis-match. This is solved two ways. One is to use a low pass cut-off filter over the sensor thus 'dumbing down' the lens resolution to be less than the pixel spacing, the second way is to design 'digital' lenses whose 'dumbed down' resolution is designed in and therefore does not need a low pass cut-off filter over the sensor. Either method therefore allowing the sensor to capture the scene without artifacts, aliasing being one of the artifacts.

http://en.wikipedia.org/wiki/Nyquist_frequency

Jim



At 09:14 PM 8/21/2007 -0700, Frank Filippone wrote:
I keep hearing this, but have never seen the proof.....  Can you point out
to me a location where this is proven?

Frank Filippone
red735i@xxxxxxxxxxxxx
=
Their 16MP camera was already pushing most lenses past their limit. I wonder
if
this camera will make things worse.

Bernard




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