Actualy shooting in widescreen on DV

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twister!
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Joined: Dec 22 2001

How do you actually go about shooting in widescreen. I'm thinking of buying a Canon XL1s and from what I can gather the only ways of achieving widescreen are to a) stretch the footage in post (urgh!) or b) crop the footage in post.

Neither of these seem very satisfactory - I want to be able to see my framing through the lens of the camera as I shoot.

PS sorry if these seem niave questions but I'm new to this game.

[This message has been edited by twister! (edited 22 December 2001).]

Jim Bird
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Joined: Sep 15 2000

Hi,

I think you need to buy a Sony DSR 500 at approx. £8,000.00 each if you want the cheapest camera with 16:9, widescreen.

Alternatively, you can buy a lens converter for a camcorder. It has a funny name but it changes your 4:3 into 16:9, I don't know the price or what the quality is like.

Jim Bird.

twister!
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Joined: Dec 22 2001

Thanks Jim

What is the funny name?

Alan Roberts
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Joined: May 3 1999

Anamorphic. It's an adjective that describes something that's not the same horzontally as it is vertically. It squeezes the picture by 4:3 horizontally. The film industry's been using them for decades to get widescreen on 35mm. They cost around £500, Optex and Century each do one, both are ok but you need to check performance as they're somewhat variable. Don't consider using the full zoom range with it attached, you'll lose focus, wide's ok though.

In image quality terms, you'll always be better off going for a natice widescreen camera. But the costs are higher becasue sales volume's much lower.

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twister!
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Joined: Dec 22 2001

How come in this day and age widescreen isn't the standard on DV cameras?

Alan Roberts
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1 Widescreen costs more because the lens has to cover a wider angle.

2 Only a very small portion of the viewing public actually watch widescreen. In the US, only those actually receiving HDTV pictures get widescreen, all SDTV is 4:3.

Get my test cards document, and cards for 625, 525, 720 and 1080. Thanks to Gavin Gration for hosting them.
Camera settings documents are held by Daniel Browning and at the EBU
My book, 'Circles of Confusion' is available here.
Also EBU Tech.3335 tells how to test cameras, and R.118 tells how to use the results.

Keitht
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Joined: Jan 8 2001

I use a Canon MV10 and although I have never had cause to use it I'm sure it has a 16:9 option. That being the case I'd be surprised if more modern consumer cams don't have the same option.

------------------
Regards

Keith

Regards Keith

Unicorn
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Joined: Apr 12 1999

quote:Originally posted by Keitht:
I use a Canon MV10 and although I have never had cause to use it I'm sure it has a 16:9 option. That being the case I'd be surprised if more modern consumer cams don't have the same option.

They have the option, but it uses digital scaling rather than an expensive 16:9 CCD; it simply takes the middle 400-odd horizontal lines of the image and scales them up to fill the frame.

As to whether it's better or worse than the alternatives, really it's a toss-up. An anamorphic lens will look better but is a pain to use, and scaling in the camera will look slightly better then scaling up in post-production, but will probably look worse if you then scale back down to letterboxed 4:3 for normal TVs. So all the options have their advantages and problems.

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twister!
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Joined: Dec 22 2001

So what method do you guys use?

Alan Roberts at work
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Joined: May 6 1999

Let's list the options:

1 The final display is a 4:3 tv.

1.1 Shoot 4:3 material and it will fill the screen.
1.2 Shoot 4:3 material and mask it in NLE, down to 432 lines ("letterbox"). It will look exactly like a 16:9 composition on tv, and nothing is lost (apart from the top and bottom bits that you blanked out).
1.3 Shoot with a genuine widescreen camera, the 16:9 image fills all 576 lines. You'll have to squeeze it vertically in NLE to get it to fill only the wanted 432 lines for display. The squeezer must have a decent filter to remove the higher vertical frequencies that would cause twitter in the output picture. The result will look exactly as in 1.2.
1.4 Shoot in a normal 4:3 camera with an anamorphic lens. This squeezes the image horizontally so that a 16:9 image fits on the 4:3 camera, but it's still 576 lines high. You still have to squeeze it down to 432 lines for display and in 1.3. Results are not as good as 1.3 because the lenses aren't perfect (don't use the extremes of zoom, the image will go out of focus and you might get barrell distortion.

2 The final display is a widescreen 16:9 display.

2.1 Shoot 4:3 in a normal camera. Squeeze it down to 540 pixels in NLE. The output has black bars at each side, doesn't fill the width ("postbox"). Some horizontal resolution is loost in the squeeze, pictures may look soft.
2.2 Shoot 4:3 in a normal camera. Stretch it vertically in NLE so that 432 lines of the input fill the full 576 lines of the output, lose the top/bottom parts. The output now fills the screen and is the right shape, but is soft vertically because resolution is stretched out. It's actually worse than it sounds because you started and ended with interlaced pictures, but you had to deinterlace in the NLE to do the stretch, so some twitter will end up built in at the wrong frequencies.
2.3 Shoot with a genuine widescreen camera. No problem, the picture fills the screen.
2.4 Shoot with a 4:3 camera and anamorphic lens. The picture fills the screen but looks alittle soft. Done't use extrenmes of zoom etc.

The compromise solution, 14:9, is ok when you have to feed both displays via different networks, but it makes sense to shoot either 4:3 or 16:9 depending on who you main audience is going to be. Don't shoot 14:9 because you compromise both output routes.

Hope that helped.

twister!
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Joined: Dec 22 2001

Thanks Alan, that's great!

Sounds like the best option for someone without a widescreen camera is 1.2. Is there a good way of previewing in the viewfinder what the cropped image will be like by say taping some black card over the viewfinder or something....?

One minor query which will probably sound very naive, sorry, but what's NLE?

[This message has been edited by twister! (edited 02 January 2002).]

Keitht
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Joined: Jan 8 2001

NLE = Non Linear Editing.

------------------
Regards

Keith

Regards Keith

Mad_mardy
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Joined: Oct 19 2000

quote:Originally posted by twister!:
Is there a good way of previewing in the viewfinder what the cropped image will be like by say taping some black card over the viewfinder or something....?

The new XL1/s has this capability

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Alan Roberts at work
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Joined: May 6 1999

Many 4:3 DV camcorders shoot "widescreen" simply by masking down to 432 lines. The viewfinder shows it letterboxed. If yours doesn't, then a couple of bits of masking tape will simulate it, but, beware.....

Your viewfinder will overscan, i.e. you never see all 576 lines or all 720 pixels. The excat amount of picture you lose in the viewfinder is set at manufacturing time. A conventional tv will lose between 3% and 6% of height/width at each edge, so it sort of makes sense to do so, but viewfinders in consumer camcorders tend to lose rather more even than that. You can calibrate your viefinder using a test signal that I've prepared for exactly this purpose, go to the URL below and download the document, I can't remember excatly what the file's called, but it's there. Using your NLE, import it as a still image, and view your NLE output on the camcorder viewfinder. Simply count off the lines/pixels and set your mask so that the central 432 lines show (i.e. top mask down to 576/8=72, bottom mask up to 576-72=504) and Robert's your father's brother.

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twister!
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Joined: Dec 22 2001

Cheers!

Mark Dicker
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Joined: Aug 31 2000

I read an article that argued, because of the way DV is compressed the centre cut-out approach required less compression therefore reduced the chance of artifacts.

This is a summary of the maths used to argue the case.

I am using PAL figures here. DV uses macro blocks, in a PAL frame there are N blocks. I can't remember how many blocks but lets use 50 for illustrative purposes only.

Standard 4x3 :-

720 x 576 = 414720 Pixels / 50 blocks = 8295 pixels per block

Cut-out 16x9 :-

720 x 432 = 311040 Pixels / 50 blocks = 6221 pixels per block

As each block takes up the same amount of space on the tape the Cut-out 16x9 requires less compression to fit. Less compression means better quality fewer artifacts.

I would be interested to see any comments on this. Also seeing as either way you only use 432 rows would there be much difference in quality?

How is a true widescreen DV frame compressed? Does a true 16x9 frame take up more storage than a 4x3 frame?

Finally I hope you all have a Happy and Prosperous 2002.

Mark

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Mark Dicker
mark@markdickermedia.co.uk

Alan Roberts at work
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Joined: May 6 1999

No, it's not that clever.

DV is 720x576, whatever the picture shape. There's no dynamic re-allocation of bits to more complex blocks if some blocks are simple (e.g. black). The number of pixels/compression block is fixed (IIRC it's 8pixels x 8lines). If some blocks are black then there'll be a very good, artefact-free compression of them, but it won't make any difference to the other, more complex, blocks.

All this is explained in a very big SMPTE document, I'll try and find out which one.

CMBmovies
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Joined: Aug 4 2001

TWSISTER!!!!

you said you were thinking of buying an xl1s... and wanted to see what it would look like through the view finder..

well the xl1s has an option of turning on letterbox lines in the view finder.. so even tho your shooting regular 4:3 you can frame it correclty through the viewfinder for cropping in post.

hope that helps

Colin B

CMBmovies
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Joined: Aug 4 2001

i just noticed someone had pointed that out... bah.. thought i was first..