[opendtv] Mark Schubin on HD lenses

  • From: "Manfredi, Albert E" <albert.e.manfredi@xxxxxxxxxx>
  • To: <opendtv@xxxxxxxxxxxxx>
  • Date: Wed, 26 Nov 2008 17:56:22 -0500


This article focuses on the effects of diffraction, caused by small lens
apertures (high f-stop number), on the maximum possible contrast
achievable. For any given lens resolution spec, small lens apertures
cause diffraction and limit contrast. The greater the lp/mm spec of a
lens is, the more pronounced this diffraction-limited contrast ratio

So once again, this points to bigger sensor area being the way to go.
Bigger image area means larger aperture for a given f stop reading,
which results in reduced diffraction of the light. Not to mention,
affordable HD lenses.

Here's a perfect example: the new Canon EOS 5D Mark II. It's a consumer
product, with affordable lens line. Yet, get this, the image area is the
full 24 X 36 mm of 35mm still cameras, and this one offers 22 Mpel
resolution. I think that's a record.

Since most 100 lp/mm lenses are not that good across the entire frame, I
think the 22 mpel sensor is probably about as good as it need to be,
even for really good lenses.

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  • » [opendtv] Mark Schubin on HD lenses - Manfredi, Albert E