[HUG] Re: Digi-Blads Beware!
- From: Bob Adler <rgacpa@xxxxxxxxx>
- To: hasselblad@xxxxxxxxxxxxx
- Date: Wed, 22 Aug 2007 08:13:18 -0700 (PDT)
So going the other way here, if lenses have greater resolving power than
sensors can use, wouldn't a good H lens mounted on a 35mm DSLR provide as good
results (if not better because of their extraordinary optics) as any other well
made 35mm film lens?
As I have collection of H lenses, I'm thinking this may be a good secondary
use for them...
Bob
Jim Brick <jim@xxxxxxxxx> wrote:
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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Bob Adler
Palo Alto, CA
http://www.raflexions.com
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