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Projection 1:85 Image from Digibeta Tape


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#1 indogold

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Posted 08 July 2005 - 03:49 AM

Just completed a super 16mm short and framed for 1:85. Transferred to
Digibeta at 1.78 (for extra room - just in case). The 1.78 image was streched
to fit the 4:3 frame and will be properly letterboxed to 1:85 in the Avid.

Question is about finishing. I'd like to project from a 1:85 image from digibeta
master created from the avid. How should I finish to tape to allow for this?
Trying to avoid projection the image having black letterbox on top and bottom.
Basically would like it to digibeta image to fill normal 1:85 film screen.

Any thought?

Thanks!

Edited by indogold, 08 July 2005 - 03:52 AM.

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#2 Stephen Williams

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Posted 08 July 2005 - 03:56 AM

Just completed a super 16mm short and framed for 1:85.  Transffered to
Digibeta at 1.78 (for extra room - just in case).  The 1.78 image was streched
to fit the 4:3 frame and will be properly letterboxed to 1:85 in the Avid.

Question is about finishing.  I'd like to project from a 1:85 image from digibeta
master created from the avid.  How should I finish to tape to allow for this?
Trying to avoid projection the image having black letterbox on top and bottom.
Basically would like it to digibeta image to fill normal 1:85 film screen.

Any thought?

Thanks!

<{POST_SNAPBACK}>


Hi,

16x9 anamorphic will get you the full resoloution available from the digibeta. In 2 hours I will see such a demonstration, from the end of the year all commercials for the cinema in Switzerland have to be delivered digitally. The highest quality is SD digibeta, and thats not a Joke!

Stephen Williams DP

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#3 David Mullen ASC

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Posted 08 July 2005 - 10:52 AM

SD video can only be 1.33 (4x3) or 1.78 (16x9) -- any other aspect ratios can only be obtained through using black mattes within those two ratios.

However, 1.78 is so close to 1.85 to be practically the same aspect ratio (it's only a few scan lines different). So if you don't want black mattes, then show it in 1.78.

I'd make a both a 16x9 full-frame and a 4x3 letterboxed version on Digital Beta, in case your particular video projector can't handle 16x9 anamorphic.

If you're talking about transferring the video to 35mm for print projection, then the 1.78 image will be transferred to 35mm negative with a black matte (since 35mm is 1.33) -- but the projector's 1.85 mask will hide the barely taller 1.78 matte around the image and you'll see a normal 1.85 image on the screen.
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#4 Robert Hughes

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Posted 08 July 2005 - 11:05 AM

Question to David et al about 16x9 SD video:

IIRC, DigiBeta normally records square pixels for the 4x3 aspect ratio.

Are the 16x9 SD cameras spitting out square pixels or anamorphically compressed pixels?

If I were to record in 16x9 ratio, do I have more square pixels per line, or the same number of rectangular pixels, merely stretched to fit and lowering the horizontal resolution versus 4x3?

What is the switch or menu setting on the DigiBeta deck that toggles between 4x3 and 16x9?

Edited by Robert Hughes, 08 July 2005 - 11:06 AM.

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#5 David Mullen ASC

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Posted 08 July 2005 - 11:16 AM

Well, even at 4x3, the pixels in NTSC are not perfectly square, as can be discovered when importing a frame into Photoshop. 720 x 486 pixels = 1.48 : 1 aspect ratio if the pixels were perfectly square.

The pixel resolution of SD is always the same for 4x3 and 16x9, so for 16x9 recordings, the pixels are more rectangular (anamorphic.)

I don't think the deck does any conversions to or from 4x3 or 16x9. You'd have to send it a 16x9 signal if that's what you want recorded.

DVD players can convert a 16x9 recording to appear letterboxed on a 4x3 monitor. But I don't think that function is in Digital Betacam decks when sending a signal out to a monitor, but I don't know. But in terms of what gets recorded, it's the format you send into the deck. Either way, the pixel resolution is inherent to NTSC or PAL.
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#6 Stephen Williams

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Posted 08 July 2005 - 12:33 PM

I don't think the deck does any conversions to or from 4x3 or 16x9. You'd have to send it a 16x9 signal if that's what you want recorded.

<{POST_SNAPBACK}>


Hi

Thats correct there is no conversion , a 16x9 will only display correctly on a 16x9 monitor and 4x3 on a 4x3 monitor!

Stephen
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#7 Robert Hughes

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Posted 08 July 2005 - 01:19 PM

So the camera or whatever origination device sends a 16x9 or 4x3 code along in the digital video stream, or is the choice of aspect ratio determined at the monitor or projection unit? How does the cable carrier know that I have a 16x9 program?
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#8 indogold

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Posted 08 July 2005 - 01:30 PM

SD video can only be 1.33 (4x3) or 1.78 (16x9) -- any other aspect ratios can only be obtained through using black mattes within those two ratios.

However, 1.78 is so close to 1.85 to be practically the same aspect ratio (it's only a few scan lines different).  So if you don't want black mattes, then show it in 1.78.

I'd make a both a 16x9 full-frame and a 4x3 letterboxed version on Digital Beta, in case your particular video projector can't handle 16x9 anamorphic.

If you're talking about transferring the video to 35mm for print projection, then the 1.78 image will be transferred to 35mm negative with a black matte (since 35mm is 1.33) -- but the projector's 1.85 mask will hide the barely taller 1.78 matte around the image and you'll see a normal 1.85 image on the screen.

<{POST_SNAPBACK}>



Hey David and Stephen,

Thanks for the responses, one more question for clarification sake. When you say a 16:9 Full-Frame you mean the image is vertically streched to fit the 4:3 ratio? (Trying to get clear
on the terminology, in my readings they've been calling this full-height anamorphic).

So my best bet if I wanted to avoid the mattes would be to treat it as almost an HD
finish (which I wish I could afford) onto the digibeta at a 1.78 ratio. Does that mean the specific projector would have to have the capability to receive the signal and convert it appropriately
for the 1.78 ratio (and then I guess if it can't, then that's what the 4:3 anamorphic would be
for right?)

All right, thanks again, essentially I'll need two masters, which is what I was expecting to create.

best,

Julius

Edited by indogold, 08 July 2005 - 01:31 PM.

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#9 David Mullen ASC

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Posted 08 July 2005 - 01:45 PM

How does the cable carrier know that I have a 16x9 program?

<{POST_SNAPBACK}>


It's labelled as such -- and besides, everyone looks skinny in 4x3, which should be an indication.
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#10 David Mullen ASC

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Posted 08 July 2005 - 01:53 PM

Well, HD is only 16x9 generally, with square pixels. Any other aspect ratios involve matting unless you put a squeezed image on the HD tape (as some 2.39 movies do for DLP-Cinema projection, which has special anamorphic lenses to unsqueeze it.)

In SD, 16x9 is "4x3 anamorphic" in a sense (just not called that.) Your choices in SD for widescreen are 16x9 "anamorphic" or 4x3 with a 1.78 letterbox. Or whatever letterboxing you want to use in either 16x9 or 4x3.

Yes, you'd want to make sure your SD video projector could correctly show a 16x9 recording, hence why it's always good to carry the 4x3 letterboxed version to festival screenings just in case (but odds are high that you'd have to live with seeing the letterbox then unless they can zoom the image to lose it.)
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#11 Stephen Williams

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Posted 08 July 2005 - 02:24 PM

Hey David and Stephen,
All right, thanks again, essentially I'll need two masters, which is what I was expecting to create.

best,

Julius

<{POST_SNAPBACK}>



Julius,

I think all SD projectors are switchable (Phil ?). I was looking at an electronics store last weekend and even the very cheap ones could be switched!

I saw the screening today from Digibeta 16x9 FHA, whilst nothing like as good as film it looked like a big LCD quality wise.


Stephen
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#12 indogold

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Posted 08 July 2005 - 06:56 PM

Well, HD is only 16x9 generally, with square pixels. Any other aspect ratios involve matting unless you put a squeezed image on the HD tape (as some 2.39 movies do for DLP-Cinema projection, which has special anamorphic lenses to unsqueeze it.)

In SD, 16x9 is "4x3 anamorphic" in a sense (just not called that.) Your choices in SD for widescreen are 16x9 "anamorphic" or 4x3 with a 1.78 letterbox. Or whatever letterboxing you want to use in either 16x9 or 4x3.

Yes, you'd want to make sure your SD video projector could correctly show a 16x9 recording, hence why it's always good to carry the 4x3 letterboxed version to festival screenings just in case (but odds are high that you'd have to live with seeing the letterbox then unless they can zoom the image to lose it.)

<{POST_SNAPBACK}>



Thanks so much David, this really clarified a great deal.

best,

Julius
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#13 David Cox

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Posted 09 July 2005 - 06:22 AM

Very few TV systems are "aware" of whether the signal is anamorphic or not, and indeed very few need to be.

The reason for the 16:9 anamorphic format was so that existing TV equipment could be used to record / carry / transmit widescreen without any modification. The singnal is exactly the same as a 4:3 image, its just that it needs to be stretched out horizontally (or squashed vertically) to make people the right shape, wheels round etc. This is done at the point of viewing.

Where a system does need to know is when you want to rotate something in post. Because the anamoric signal has horizontal compression applied, this needs to be accomodated for when you rotate a shot or element in post, otherwise it starts to go a very strange shape. So its important to set your post production software / system to the right standard, even though the actual signal it is handling is the same.

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