Losing light with 2/3 lens adaptor?

[Greg Boston]

Originally Posted by Bob Willis

There are at least 2 adaptors available as explained in this thread:

http://www.dvinfo.net/conf/showthrea...=Canon+adaptor

Absolutely, Bob. We used the Canon adapter last April in the Texas HD shootout as we didn't have a 1/2 lens available for the second F350 body. I was the one who removed the lens and adapter at the conclusion of the shoot and I will verify that the Canon adapter has no glass in it.

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[Alister Chapman]

My Canon adapter has glass in it. It is an optical flat, it is there to help compensate for the shorter glass optical path in the 1/2" CCD block compared to a 2/3" block. It helps minimise registration errors cause by the differences in refraction in the different length prisms. There used to be a cheaper adapter on the market without any glass and this is not recommended for HD without the glass you will get registration errors which may be mistaken for CA (red/blue fringes).

[Bob Willis]

The Canon adapter does indeed have the glass. The Century Optics has no glass in the adapter.

[Greg Boston]

Originally Posted by Alister Chapman

There used to be a cheaper adapter on the market without any glass and this is not recommended for HD without the glass you will get registration errors which may be mistaken for CA (red/blue fringes).

Must be the one we had. Mea culpa for thinking all the Canon units had no glass unlike the Sony units. Thanks for the clarification, Bob and Alister.

Makes sense that the adapter would need to have glass to correct for having the lens further away from the CCD block.

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[Jonathan Ames]

Alister is spot-on on that one. As for the other comments, that's what this board is all about; learned, informed opinions supported by experience and facts. That's what sets this board apart from virtually all of the others. I guess for me it goes to the bottom line that we want the best shot and that means light, lens and camera. There are going to be times when I have to have the 2/3" as the shot I'm looking for simply surpasses the XDCAM's inherent capabilities. But for the vast majorioty of our work in drama and especially sports, the 1/2" is excellent and, more importantly, saves money and that's where my point lies. The glass is so very, very important that if you understand lens, light and camera, you can build for the shot. If a 1/2" camera works, you can spend the difference between the 1/2" and 2/3" rental or purchase cost on precisely the right lens. Nothing beats quality glass so know what you want and why you want it and buy or rent the best and settle for nothing less.

[Bob Willis]

"There are going to be times when I have to have the 2/3" as the shot I'm looking for simply surpasses the XDCAM's inherent capabilities."

I'm not sure I understand the point you are trying to make here Jonathan. If you are looking for something that surpasses the inherent capabilities of XDCAM HD I would guess that you would choose to shoot 35mm film or high end HD with prime lenses. That way you could actually see the difference in the quality of the images.

The difference between shooting XDCAM HD with either a high end 1/2" or 2/3" video HD zoom lens would not be something that would make a noticeable difference. Maybe I am missing your point.

[Jonathan Ames]

Oh, I don't think you're missing something. Rather, maybe I'm not explaining enough. The point I was making is that there are times when I need the extra capabilities that, for example, an expanded colorspace recording capability offers relative to contrast range. I take great pride in setting the exact look and feel of shots and alot of times, as with El Papel, they're under challenging light settings. Being able to change the color balance of the mid-tones without affecting black and white balance is easier in a 4:4:4 colorspace than in a 4:2:2 or especially a 4:2:0 space available as with the XDCAM going direct to biscuit. Another expands on that in being able to finely adjust tonal reproduction in the shadows of the shot. These are things that are available in a 2/3" camera like the 900R.

The inside of the apartment scene we shot El Papel in for 18 minutes was dark because the storyline had the electricity off. The only light was 1) from a window to the street (that was green screened because of inalterable conditions on the set we were using making keying via alpha channel mandatory in post) and 2) some candles the occupants were using to study by. The scene involved one character upstage and one down stage and the convergence of the two while in dialogue. Being able to pull detail out of specific areas while leaving other areas black and illuminating the faces but still maintaining, even through movement up and down stage, 3-dimensional depth was imperative. Also important was being able to bring out details from the dark parts of the picture without affecting mid-tones and leaving absolute black level unchanged. We got the shot to work perfectly to the point that it'll be shown in the Sony, Fujinon and Adobe booths next week at NAB proviing the capabilities of the XDCAM BUT it would have been so much easier working in the 4:4:4 colospace of say the 900R.

Would film do it better? There are those who would say yes but the benefits of shooting digitally, the inherent cost savings, the immediate, on-set review of the shot and not having to wait for dailies, things like this have, I guess, spoiled me. The point I was trying to make was not so much reserved to lens but to the camera choice as well. The 900R and other 2/3" cameras have capabilities that surpass the XDCAM but not to the extent that most people would argue. Putting the right lens on the XDCAM and lighting it correctly will allow the XDCAM to serve the filmmaker astonishingly well. It's not until you get into the challenges of highly saturated colors that tend to bleed at lower sampling rates and difficult keys that you really appreciate a 2/3" camera. Again, this is simply my humble opinion and there are far more accomplished cinematographers out there than I who probably have differing viewpoints. Further, I could go on for pages delving into other areas where a 2/3" out-performs a 1/2" but the point is that we took the XDCAM and, through proper light, lens and camera, achieved shots that, while we were setting them up, people were telling us we'd never be able to pull off with a 1/2" camera... and we pulled them off to the point they'll be on-stage throughout NAB this April. I'm just really proud of what people like Paolo Ciccone and Scott Chambers, John Salemme and Matt Garret were able to do, especially when it came to keying the green screen window in I mentioned before. Remember, the whole apartment was black. How'd you like to light a green screen leaving everything and I mean everything else black? Let's say it wasn't the brightest of green screens to key and yet the XDCAM at 4:2:0 and Adobe AE made it possible. It may sound like a shameless plug but we'll show you how we did it at the Adobe showcase at NAB on Wednesday from 2-3 pm.

[Alister Chapman]

I don't believe there HAS to be a difference between 2/3" and 1/2" CCD's other than depth of field. There IS a difference between the current XDCAM and HDCAM front ends and this is down to the use of lower cost, lower spec components, but if Sony or someone else wanted to I am sure they could produce a 1/2" front end equal to or better that the current crop of 2/3" blocks.

The Sony 900R HDCAM's recorded color space is 4:1:1 not 4:2:2.

HDCAM's 4(3):1:1 colour space is far from ideal and contains no more color information than XDCAM's 4(3):2:0. I have seen amazing restoration of color space with adaptive interpolation. In a non-linear environment if you transcoded from HDCAM or XDCAM HD to uncompressed you would have roughly the same amount of color information for both. The HDCAM is a little less compressed (although with a less efficient codec) and that gives it a marginal edge when pushing colors hard, but the difference is very very small. The BIG problem is that many don't know about the different sample rates and for ease they often dub XDCAM (or HDV) to HDCAM tape for editing. Then you get 4:1:0 which is pretty much useless and then start complaining that XDCAM is no good for grading or color work.

I am still assessing the best post production path for programmes originating on XDCAM HD for delivery on HDCAM. In the past I would have said stay native until the dub to tape, but with the different color space problems it may be better to convert to uncompressed and work in a 4:2:2 or 4:4:4 colour space first. Avid's DNxHD codec is also another very valid option.

Now what would be nice is 50Mb 4:2:2 XDCAM HD, or HDCAM SR at XDCAM prices! I guess we'll have to wait and see what goodies Sony are going to be offering at NAB. Before anyone asks .... no I don't know what's coming other than lots of nice things!

[Greg Boston]

Originally Posted by Alister Chapman

I don't believe there HAS to be a difference between 2/3" and 1/2" CCD's other than depth of field. There IS a difference between the current XDCAM and HDCAM front ends and this is down to the use of lower cost, lower spec components, but if Sony or someone else wanted to I am sure they could produce a 1/2" front end equal to or better that the current crop of 2/3" blocks.

There's also the issue of dynamic range. If you put X and Y number of pixels on a 1/2 piece of silicon, then put the same number of pixels on a 2/3 piece of silicon, the physical size of the pixels would be larger on the 2/3 chip. This makes it easier for each pixel to suck up light. But there have been so many advances with micro-lens technology, etc., that today's 1/2 imagers are pretty good at grabbing an image with less than stellar lighting.

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