[opendtv] Re: Line Pairs/millimeter vs. Price vs. Image Format Area
- From: "Manfredi, Albert E" <albert.e.manfredi@xxxxxxxxxx>
- To: <opendtv@xxxxxxxxxxxxx>
- Date: Sun, 3 Jun 2007 19:33:10 -0400
Dan Grimes wrote:
> I don't blame you for not trusting me.
It's not a question of trust, as much as I think we are talking past one
another. I never said, for example, that slapping a $139 lens on an
existing video camera would create a miracle. It clearly will not,
because the imager is way, way too small for these 35mm/APS lenses. I'm
simply trying to figure out what's actually going on.
I'm not a broadcaster. My guess is that the TV industry years ago
evolved a set of 2/3", 1/2", and 1/3" standards for electronic image
acquisition that were convenient, and lower cost, than the movie
industry's standards. And my guess is that this happened because the
image quality of analog TV could afford to be *very* inferior to that of
the movie industry. So, while TV shows were shot and archived in 35mm or
16mm film, live studio or on-location video was acquired to a much lower
image quality standard. Hence, tiny lenses and tiny imagers.
Furthermore, my guess is that when DTV came about, there was a real
incentive for the TV production chain to stick with these PAL/NTSC image
acquisition hardware standards (cameras, lenses, lens mounts), and this
was still feasible with SDTV.
Furthemore, my guess is that for HDTV, the TV industry naturally wanted
to continue to use their 1/3", 1/2", and 2/3" equipment, but that this
required the sort of heroic lens improvements that the BE articles Craig
posted talk about. So that's why everyone seems to operate on the
assumption that HDTV lenses must be amazingly expensive. These lenses
are only used for TV, they are very small comparatively, and they must
be made to very high optical standards to compensate for their
diminutive size.
The articles don't dwell on "what ifs," such as "what if" studio HDTV
cameras were built to 35mm movie camera standards. "What if" the
economies of scale of consumer or movie camera lenses could be brought
to bear.
I think Mark Schubin listed many larger HDTV camera standards that aim
to get beyond the restraints caused by the tiny lens formats. I added
the diagonal dimensions that correspond to the 1/3", 1/2", and 2/3"
sizes that the BE articles talk about, to show where they fall in the
long list. (Possibly these are not meant to represent exact diagonal
dimensions.) Also, I added medium format and 35mm frame formats on top
of the list, to show that they fall right up there with the biggest
options listed, and could make use of very competitively priced lenses
to easily achieve 2 Mpel image quality, and posssibly much more, with
the better 35mm lenses.
75.0 mm diagonal (4.5 X 6 cm medium format)
43.3 mm diagonal (still 35mm or VistaVision formats)
30.0 mm diagonal (35mm movie and approx APS formats)
-------Mark Schubin's list--------
59.6-mm diagonal 4096x2440
38.1-mm diagonal 4000x2048
35.6-mm diagonal 1280x1024
30.8-mm diagonal 3018x2200
29.1-mm diagonal 2048x2048
28-mm diagonal 4520x2540
27.5-mm diagonal 5760x2160 (16:9 aspect ratio)
24.6-mm diagonal 1024x1024
20-mm diagonal 1536x1024
19-mm diagonal 1280x1024
*** 16.9 mm diagonal = 2/3" ***
16-mm diagonal 1920x1080
16-mm diagonal 1280x720
*** 12.7 mm diagonal = 1/2" ***
11-mm diagonal 1920x1080 with 2nd green with half-pixel diagonal offset
11-mm diagonal 1920x1080 - most common high-end professional
11-mm diagonal 1280x720
11-mm diagonal 960x540 with half-pixel diagonal offset between green and
red/blue (16:9)
*** 8.5 mm diagonal = 1/3" ***
8-mm diagonal 1440x1080 (16:9)
7.1-mm diagonal 1280x720 effective (from higher-resolution filtered)
6-mm diagonal 1920x1080
6-mm diagonal 1440x1080 with half-pixel horizontal offset (16:9)
6-mm diagonal 960x1080 with horizontal offset (16:9)
6-mm diagonal 960x1080 with diagonal offset (16:9)
4.5-mm diagonal with pixel-grid rotated 45 degrees, (960x540)x2 (16:9)
4.5-mm diagonal 960x540 with diagonal offset
-------------------------------
Bert
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