Glass: The Great and Not SO Great Equalizer?

[Barry Green]

[Ron Shook] “are these top of the line $20-30k Zoom lenses really capable of resolving much more than 1000 lines?”
Certainly. But it depends on how big the target is.

See, the thing is, it’s line pairs per millimeter that matter, but it also matters how many millimeters there are to work with. Take the example of 35mm film — there are 24 millimeters of width available in the full-aperture Super35 frame. So if you want 1,000 lines resolved, that’s 500 line-pairs total, divided by the 24 available millimeters, means you need the resolving power of about 21 line-pairs per millimeter.

Now let’s apply the same concept to a 2/3″ CCD. A 2/3″ CCD has a width of about 9.6mm. If you want 1,000 lines (or 500 line-pairs) to be resolved, you’d have to have a lens that’s capable of resolving over 52 line-pairs per millimeter. Yes, the lens has to be 4x as sharp (twice horizontal, twice vertical) to resolve the same amount of resolution on the smaller video CCD. Most high-def lenses are designed for 2/3″ cameras, and I believe I’ve read that they typically aim for around 85 lp/mm for high-def lenses. Standard-def lenses typically aim for more around 30 lp/mm.

So now you want to look at high-def on a 1/3″ chip — Obviously that’s a much tougher task. Now you’ve only got about 5.25 mm horizontally to work with. And with the Canon and Sony claiming 1080 pixels vertically in a 2.95 mm height, to resolve that fully you’d need a lens capable of resolving 183 line-pairs per millimeter!

And then, you start getting into issues such as diffraction. Put one of these high-def 1/3″ cameras at f/2, and yeah, you may get 600 or 700 lines out of it. But stop it down to f/11 and now you’ll be getting more like 400 lines. We’re starting to run into the limits of optics designs and complications actually due to the size of the wavelength of light here. I doubt we’ll ever see high-def cameras with sensors smaller than 1/3″; even Sony’s littlest consumer model has a 1/3″ sensor, and Sanyo’s new super-cheap consumer model actually has a bigger sensor, it’s 1/2.5″.

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[Toke]

I’m also wondering where’s the photodo.com for moving image lenses.
If lense can resolve what 1080p sensor can take, (with kell factor of 0.8) the real resolving power could be 1500×850.
https://www.dvinfo.net/conf/showpost.php?p=407684&postcount=49
Shows some numbers that 1/3″ cameras resolve.
Nowhere near what 1080p could.
I can’t figure out any reason why 2/3″ cameras wouldn’t have double resolution.
Their lenses must have at least the same quality than these sub $10k cameras and with same resolving power (lp/mm) they produce double resolution to 2/3″ imagers.
2/3″ imagers also usually have “full resolution” ie. same resolution that camera records.
So that does not either hinder them.

2/3″ sd cameras have many years had “oversized” imagers ie. more pixels than they record. With this they cold produce full real resolution of recording format (ccd resolution – kell factor = recorded resolution).

Remains to be seen when 2/3″ hd cameras start to use oversized imagers and when imager sensivity allows 1/3″ cameras to use full resolution imagers.

[Toke]

[Barry Green] “A 2/3″ CCD has a width of about 9.6mm
…a 1/3″ chip… …only got about 5.25 mm horizontally… …vertically in a 2.95 mm height…”

16:9 2/3″ chip’s active area size is exactly 9.6 mm x 5.4 mm.

I’ve always been under impression that 1/3″‘s dimensions are exactly half of this.
So it isn’t so?

[Barry Green]

[toke lahti] “I’ve always been under impression that 1/3″‘s dimensions are exactly half of this.
So it isn’t so?”

It may be so, but I haven’t measured one to know for sure. I’m basing my 5.25 x 2.95 guess (and it is only a guess) from the info on Panavision’s frame & format list:
https://www.panavision.co.nz/main/kbase/reference/tbleframelist.asp

On that list, they show a 2/3″ 4:3 chip at 8.8 x 6.6 mm. But a 1/3″ 4:3 is not half of that (which would be 4.4 x 3.3), instead the 1/3″ chip is listed as 4.8 x 3.6. So I calculated the ratio between 4.8 and 8.8, and then applied that ratio to the 9.6 x 5.4 size of a 2/3″ 16:9 chip to come up with a speculative guess as to what the dimensions of a 1/3″ 16:9 chip might be.

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Get the most from your DVX camera. The DVX Book and DVX DVD are now available on ebay and at Amazon (https://www.fiftv.com/db)

[Toke]

[Barry Green] “I’m basing my 5.25 x 2.95 guess (and it is only a guess) from the info on Panavision’s frame & format list: ” target=”_blank”>https://www.panavision.co.nz/main/kbase/reference/tbleframelist.asp”

I think we can trust Panavision in these things, so diameter of 2/3″ is 11mm and 1/3″ is 6mm.
Every day I learn something new and many times something very fundamental… 🙂