Film-Tech Forum ARCHIVE: Panavision "Genesis" Image Sensor Questions

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Posted by Lyle Romer (Member # 1266) on 07-01-2006, 11:16 AM:

I was reading about the Panavision Genesis camera used to shoot Superman Returns. Can somebody please explain the image sensor to me? It is a single CCD sensor that is specified as containing 12.4 Megapixel but it only outputs 2k. It also says it is true RGB (specifically says not Bayer pattern). How is this possible? AFAIK, you can't "stack" CCDs like foveon has done with CMOS sensors.

Posted by Mark Ogden (Member # 43) on 07-01-2006, 01:32 PM:

This just means that they abandoned the Kodak Bayer GBG pattern and its interpolation scheme in favor of their own proprietary one. Apparently, the photosites on this chip are plentiful enough to allow for individual RGB sensors on the same plane. I suppose they mean “full bandwidth” because with this type of interpolation-less sensor array each color would have an equal output right off the chip, feeding a final 4:4:4 equal-sample-rate throughput. Two other HD cinematography cameras, the Arriflex D20 and the Dalsa Origin, are single full size chip Bayer devices.

Also (and this is a rumor I’ve heard, so don’t take this as gospel), from the 12.4 mgpix. chip the camera actually reads two summed-together 6.2 mgpix line-offset images in a detail enhancing scheme. Because of the above, R, G, and B each wind up with about 2 mgpix. apiece, this results in the roughly 2K rez. Or something.

Posted by Bobby Henderson (Member # 840) on 07-01-2006, 04:13 PM:

To explain it in more simple terms, a normal CCD chip really only sees a grayscale image. You can get around that using different approaches.

Consumer-level video cameras use only one CCD along with some filtering and computer guesswork to approximate a color image, but the color is never quite correct. Broadcast quality video cameras (and a growing number of consumer and pro-sumer cameras) use 3 CCD arrays to record much more accurate RGB color.

It sounds like the Panavision Genesis sensor is doing the equivalent of packing in all the pixels and functions of a 3 CCD array onto a single, larger chip. They're counting the total number of pixels on that chip rather than the number of native RGB pixels actually recorded. That's how they wind up with that 12 megapixel claim.

I'm not sure I understand the advantage in taking this single chip approach. A 3 CCD camera needs something like a prism to split the light wavelengths onto the three different chips. A single chip does away with that sort of mechanism. However, the single combined function chip has to be quite a bit larger (and more expensive) to get the same comparable levels of light onto them.

Video camera chips are still really pricey. You get up into the $3000 to $5000 range for video cameras with 1/3" CCD chips (in 3 CCD arrays). You'll shell out tens of thousands for cameras with 2/3" CCD chips.

How big is this Panavision Genesis chip in terms of inches?

Posted by Mark Ogden (Member # 43) on 07-01-2006, 04:47 PM:

I’m not sure of the precise dimensions of the imager, but the active area is said to be exactly that of Super 35mm. This satisfies the whole design philosophy of the camera: to be able to use Panavision’s range of film lenses. It’s for this same reason that you have to lose the prism: if you’re going to use film lenses, the surface of the imager has to be in exactly the same location relative to the rear element of the lens as the film would. If the prism were there in front, the imager would be pushed back away and you’d never get focus.

Posted by Phil Hill (Member # 371) on 07-01-2006, 06:49 PM:

Mark is correct for a reason for the single "big" RGB chip in the Panavision/Sony Camera rather than all the BS optics and horseshit required for the crappy 3-chip stuff.

The Panavision line of lenses act the same for both 35mm film and CinemaTV. That's because the chip picture area is the same for Super35, and the lens back focal distance to the chip is the same as for film.

THE BIG plus is that people familiar with film can compose shots and use Panavision prime and zoom lenses as if they were shooting film since the depth-of-field and other criteria will be the same.

Posted by Lyle Romer (Member # 1266) on 07-01-2006, 07:35 PM:

Does anybody know the aspect ratio of the chip? I had read somewhere that although it is Super 35 width, it isn't Super 35 height. I would guess the imager is 16:9 to allow for use producing HDTV programs but I'm curious if anybody knows for sure.

Posted by Bobby Henderson (Member # 840) on 07-01-2006, 09:08 PM:

I wouldn't see much of any need for that chip to be any taller than 1.77:1. The 1.33:1 standard for televisions and even computer monitors is dying out.

As for the "crappy 3 chip" thing, that's a relative situation in terms of money. Few outfits can afford one of those Panavision cameras, much less the lenses. The rentals on the things have probably got to be really high.

In the consumer level, "pro-sumer" level and even most areas of broadcasting, 3 chips is typically a lot better than one.

The only area where I see single chip solutions gaining a lot of traction in low cost professional use is in digital still photography -for the same reasons Panavision and Arri are approaching: so you can use a wide variety of 35mm camera lenses. Still, some of that stuff is really expensive. I'm considering buying a good digital SLR camera (something in the neighborhood of a Canon EOS 30D, Nikon D200 or even a Canon EOS 5D). Some of those Canon D-SLR lenses are really expensive. They have a 300mm telephoto lens that lists for nearly $4000!

Posted by Phil Hill (Member # 371) on 07-01-2006, 09:11 PM:

quote: Bobby Henderson
As for the "crappy 3 chip" thing, that's a relative situation in terms of money.

Well Bobby, ***IF*** one is a "professional", ya NEED to step up to the plate and be one rather than a "wannabe".

If you want to "film" pornos, then the pro-sumer 3-chip cameras are fine. Been there, done that.

Posted by Bobby Henderson (Member # 840) on 07-01-2006, 09:17 PM:

How many major TV stations have Panavision or Arri single chip video cameras in their studios? I haven't seen many mobile video crews wielding such stuff.

Basically I think the Panavision thing is overkill for most purposes. Few people besides major movie production need to utilize Panavision camera lenses.

Posted by Phil Hill (Member # 371) on 07-01-2006, 09:20 PM:

Oops! Sorry... I thought we were discussing theatrical productions, and not the 11:00 o'clock news on TV...