16:9, Anamorphic Lenses - HELP!!!!!!!!!!!

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billyh
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Joined: Dec 2 2000

Help, I'm confused!

I would like to shoot in true 16:9 format but I want to retain the maximum resolution when presenting my work to broadcasters.

Now I assume that the anamorphic lens "squashes" the footage and then must be "unsquashed" by some form of adaptor on your playback/editing equipment. Am I right?

If you use an anamorphic lens to shoot 16:9 what does your footage look like when it is then replayed straight back from the camera to your tv/editing equipment?

Quite a few DV and Digi8 cams have the 16:9 facility which apears to "squash" your footage which you then "unsquash" using the "widescreen" facility on your 16:9 telly.

What does the anamorphic lens actually do that means that you don't lose this vertical resolution (as I'm led to believe happens with the 16:9 emulation on the cheaper cameras)?

Basically what I can't get my head around is that if I buy an anamorphic lens will the viewer have to have some form of anamorphic adaptor to view my footage and will I also need some sort of anamorphic adaptor to edit my work?

Billy Hepburn

Alan Roberts at work
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Joined: May 6 1999

We've been round this one several times now.

Cheap cameras use 4:3 ccd(s) and mask off the 576 line raster to 576*3/4=432 lines. So you lose resolution and there's no way you can get it back. The picture you get looks widescreen on a 4:3 tv and looks soft when zoomed to fill a 16:9 tv. Naff on both counts.

Expensive cameras have 16:9 ccd(s) and do it right. The image fills the 720*576 raster, which fills the widescreen display.

Intermediate solution is to use an anamorphic adaptor to squeeze the image to 3/4 horizontally, so getting a 16:9 image onto a 4:3 raster. You lose some horizontal resolution because the lenses aren't perfect. There's no need to do any stretching in post production because the 16:9 image fills the 16:9 raster, and that's why you shot it that way. The only need to stretch and crop is if you want to make a 4:3 or 14:9 edit from the material to show on a 4:3 tv display, and then you'll lose resolution both horizontally and vertically, something you'll want to avoid after you've done it once or twice (unless you paya a lot to use a decent aspect ratio converter).

Hope that helps. It has done several times before

------------------
alan@mugswellvillage.freeserve.co.uk. Delete village for a spam-free diet.

pcwells
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Joined: Jun 10 1999

quote:Originally posted by Alan Roberts at work:
Hope that helps. It has done several times before

Alan,

That, in my book, would make it a Frequently Asked Question.

Will you do the honours or shall I?

Pete

Alan Roberts at work
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Be my guest Pete. I've been dropping stuff into the FAQ forum quite a bit lately. I'm sure you know as much as I do about this now

------------------
alan@mugswellvillage.freeserve.co.uk. Delete village for a spam-free diet.

Angelo
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Joined: Feb 27 2001

Alan Roberts

You've totally missed the point of the question!

The reason that this question has been asked so many times is because all you self proclaimed "experts" don't bother to explain the bloody answer properly!

While you may think snide self-righteous remarks like you've "been round this one several times now" or "hope that helps, it has done several times before" will get you a snigger from your anorak techie pals, the bloody bottom line is that you have not answered the guys (totally relevant) question!

As far as I can determine the question was not concerning 16:9 rasters or 4:3 rasters etc but whether the resulting image can be viewed in the correct proportions on a normal television set.

Now look at your "expert" reply. Have you answered that question? No you haven't!

If you took the time to answer questions sensibly in laymans terms instead of diving straight in and trying to impress with your specs and endless technical jargon everyone might learn something.

Angelo

[This message has been edited by Angelo (edited 27 February 2001).]

Alan Roberts
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Angelo, you may notice if you bother to read some of this thread, that Alan Wells hasn't contributed to this at all. If you have any beef with this thread, aim it at me. In what way did I not answer the original questions? As for anoraks, I have never owned one and wouldn't be seen dead within a hindred yards of one. You might like to read the messages a little more closely, you'll find I try to help, not to nit pick. If you can supply better answers, lets have them.

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.

billyh
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Joined: Dec 2 2000

Alan

Maybe I'm probably not making myself too clear on what I'm confused with!

I fully understand the fact that pseudo 16:9 cuts the vertical resolution from 576 lines to 432 lines.

I also understand that the anamorphic lens will squash the image by 3/4 horizontally but it is the resulting video tape format that is causing confusion.

What I basically want to know is:-

If I stick an anamorphic lens on the front of a Canon XL-1 and then play the resulting footage back (straight from the camera) on a normal TV i.e. 4:3 will I see a widescreen image with black top and bottom or will I see an image thats squashed horizontally by 3/4?

Also, if I was to import the resulting footage to Premiere or another editing package, would I be editing an image that was "squashed" or could I edit the image in true 16:9?

Billy Hepburn

P.S. How would I export the 16:9 footage to VHS so that it could be viewed by viewers with both 4:3 and 16:9 televisions?

Angelo
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Joined: Feb 27 2001

Alan Roberts (apologies to Alan Wells)

What part of the original question did you answer?

The guy has asked his question again, so obviously you did not answer it?

The original question was obvious to me and probably many others.

The bottom line is you did not bother to look at the actual question and jumped in with your snide and patronising comments.

It is obvious to everyone that if the 16:9 / 4:3 question is asked time and time again it is only because it is not being answered or explained correctly!

I am willing to admit that I do not fully understand the use of anamorphic convertors or 16:9 formats in cheap cameras, but again it is only because this type of question is never answered fully or correctly.

To answer the question however I would think that if a movie is made using an anamorphic then the resulting images would not appear in the correct proportions on a 4:3 television unless they had had some sort of post-production treatment i.e. they would be squashed!

That's all you had to answer!

Simple laymans terms, no techie anorak figures or specs!

Angelo

billyh
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Joined: Dec 2 2000

Alan

Maybe I'm probably not making myself too clear on what I'm confused with!

I fully understand the fact that pseudo 16:9 cuts the vertical resolution from 576 lines to 432 lines.

I also understand that the anamorphic lens will squash the image by 3/4 horizontally but it is the resulting video tape format that is causing confusion.

What I basically want to know is:-

If I stick an anamorphic lens on the front of a Canon XL-1 and then play the resulting footage back (straight from the camera) on a normal TV i.e. 4:3 will I see a widescreen image with black top and bottom or will I see an image thats squashed horizontally by 3/4?

Also, if I was to import the resulting footage to Premiere or another editing package, would I be editing an image that was "squashed" or could I edit the image in true 16:9?

Billy Hepburn

P.S. How would I export the 16:9 footage to VHS so that it could be viewed by viewers with both 4:3 and 16:9 televisions?

Rookie
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Joined: Sep 27 1999

Originally posted by Angelo:
Alan Roberts

...all you self proclaimed "experts" don't bother to explain the bloody answer properly!

...snide self-righteous remarks...

...get you a snigger from your anorak techie pals...

Temper, temper.

Although I do agree with some of the things you are saying, I find Alan Roberts to be one of (if not THE) most helpful guy(s) around here.

However Alan, sometimes I think you might forget that we don't all share your level of expertise...

Now, shake hands, and let's all be friends.

Rookie

[This message has been edited by Rookie (edited 28 February 2001).]

pcwells
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Joined: Jun 10 1999

Billy,

If you stick an anamorphic 16:9 converter on the front of your camcorder, what you see in the viewfinder will be a squashed image in which everything is tall and thin.

I notice, however, that you mention the Canon XL1, which displays 16:9 in this manner regardless of whether it's using an add-on anamorphic lens or just shooting with its own widescreen settings.

If you then play the tape, it will appear squashed when seen on your TV set, and no deck or camcorder will recognise the video as being 16:9.

However, Adobe Premiere 6 allows you to have video identified as 16:9 at the capture stage. This means that the video on your hard drive - and subsequently the final edit you send out to tape - will be recognised as kosher 16:9 video.

Hope this helps,

Pete

pcwells
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As for viewing 16:9 on different TVs, the safest option when making VHS copies is to copy the video with black bars top and bottom - so that the video itself is optimised for a 4x3 frame.

Most modern TV sets have 16:9 buttons on the handsets which alter the proportions of the frame to account for video made for different aspect ratios, but many don't - and many TV viewers don't know it's there when they have it as they seldom need to use it.

Where true 16:9 really comes into its own is in DVD, where the player can be set up to play video in its anamorphic state, or between black bars to suit the TV set. That way you really do get the best of both worlds.

The other benefit, of course, is for broadcasters who will now only commission material shot in a 16:9 format. In that respect the main objective is to make a good video in the correct format and let the broadcaster worry about getting it on the screen.

Pete

billyh
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Joined: Dec 2 2000

Thanks Pete

That clears that up (for me anyway)!

Definately a subject for both Computer Video and the board FAQ I think however.

Billy Hepburn

billyh
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Thanks Pete

That clears that up (for me anyway)!

Definately a subject for both Computer Video and the board FAQ I think however.

Billy Hepburn

Alan Roberts at work
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Joined: May 6 1999

Gentlemen, I apoliogise for getting irate, I was tired, feeling, unwell, in a hurry, in that order. And then I get a hail of abuse. So...

To reiterate:

If you squeeze the picture with an anamorphic lens, so that it fills the 720*576 raster, then you've retained all the resolution that you can, subject to the performance of the lens.

If you play that tape into a 4:3 tv set, you'll hget squeezed pistures, tall thin people.

If you play it into a 16:9 tv set, you'll get the original shape.

On either type of tv set, you may have some control over the picture shape, but I'm assuming that you are getting the video to fill the screen. If you use any of these tricks to change the picture shape, you will lose some resolution in the process, how much depends on how well it is done in the tv set, but is limited by the information in the signal.

Masking off parts of a 4:3 picture doesn't get you widescreen, it gets you short screen.

There now, Angelo, will that do?

And by the way, the reason for my silence between Tuesday night and now is that I was away from home and office, working.

billyh
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Joined: Dec 2 2000

Alan

Sorry to keep this going!

But, when the video is "squashed" anamorphically onto the 720*576 raster and then resolution is lost when it is later expanded, is the resolution loss much less (to the viewer) compared to the pseudo 16:9 offered by the cheaper cameras?

Will broadcasters then not rather have video work submitted in 4:3 which going by what has been said earlier retains the full resolution of the 720*576 raster?

Billy Hepburn

P.S. Does anyone know why some of my messages are appearing twice on the board when I am only submitting them once?

StevenBagley at Uni
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Joined: Oct 31 2000

>>Will broadcasters then not rather have video work submitted in 4:3 which going by what has been said earlier retains the full resolution of the 720*576 raster?<<

16:9 or 4:3 material both have a horizontal resolution of 720 pixels. Its the width of each pixel that changes. Suffice to say -- that shooting with a 16:9 anamorphic lens will give far better results (lots of feature films are shot with anamorphic lenses). What DV cameras do is to take the middle 432 lines of the image and blow it up digitally -- think of it as the difference between using an optical zoom (where there is no loss in resolution) and a digital zoom (where it can clearly be seen.

See you earlier,

Steven

billyh
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Joined: Dec 2 2000

Thanks Steven

While I understand what you are saying, that the pixel size increases, surely this would soften the image compared to the unstretched pixels of the 4:3 image.

Therefore would broadcasters rather have the 4:3 with the full quality or the 16:9 with the stretched pixels.

On a channel like the Discovery channel which commisions loads of lower cost programming (i.e. <50K per show/series) I notice that almost everything from the UK such as Fishing shows are all shot on 4:3.

Now the use of anamorphic lenses must be viable for the producers of these shows therefore I can't understand why they don't shoot in 16:9 if the quality would be acceptable.

Billy Hepburn

tom hardwick
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Joined: Apr 8 1999

Fascinating thread, and a difficult subject to tackle using words alone.

Might I give my own situation and maybe that'll help. I don't pretend to answer any of the preceding questions but just maybe there's help to be had here. I've removed my anorak because the slide rules in the pockets were making a mess of the jam sandwiches, so here goes.

The TRV900 has a "widescreen" mode. The two viewfinders show black bars top and bottom to aid picture composition (unlike the XL1). If this is played out to a 4:3 TV the picture is stretched vertically - and people incorrectly state that it's squashed horizontally.

On a 16:9 tv the film plays perfectly - the pixels are stretched out horizontally (so there's no loss of vertical or horizontal resolution over the 4:3 set, it still only has 432 lines of info to display).

What's interesting is how acceptable this 16:9 viewing is, and there's a fascinating web site that says, and shows: "As you can see, the "16x9 mode" footage is signficantly sharper vertically. Since the image is compressed after it's been enlarged on
the vertical axis, it's seeing detail on the CCD that normally would be "fudged" by the DV compression."

http://members.macconnect.com/users/b/ben/widescreen/index.html

Read, and breathe freely again.

tom.

Alan Roberts at work
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Right. To explain exactly what's going on and why, I'll have to provide some of the background. Maybe I can't do all this in one go because of time pressures.

About 15 years ago (maybe more) when ITU Rec.BT-R 601 was being polished, a 16:9 variant was introduced. Remember that 601 was, and still is, the standard for digital sampling and coding of 625 and 525 pictures for studio interchange of material. That means it's a production standard across the entire broadcast and pro video world. DV etc. have jumped onto the bandwagon only recently.

Rec.601 defined, as the base system (4:3), that the sampling rate should be 13.5MHz. Taking the active line (i.e. the unblanked, visible part excluding the blanking introduced by overscan) duration for both system is about 702 pixels. For simplicity this was rounded up to 720, being a multiple of 16. And that's the standard that all DV and Digital 8 and most broadcast kit adhere to.

The wide-screen variant specified a sampling rate of 18MHz and an aspect ratio of 16:9. So, if you sample your 16:9 video at 18MHz and chop out the central 720 pixels of that sampled image, you get a 4:3 image with the correct resolution. Nothing is lost, no compromises. At the time, it was widely assumed that all wide-screen cameras would have wide-screen tubes or ccds. And that a wide-screen display would have the same height as it's companion 4:3 version, and thus greater width (hence the name) but the same horizontal and vertical resolution in terms of cycles per inch, which is what we actually see. Remember, this was the early 80s and clever electronics was still (very) expensive.

Sadly, or possible happily, only one vtr was ever built in production quantities to work at 18MHz, the Panasonic D5, which itself was a high-speed variant of the D3. So the 18MHz ideal system was never properly implemented in real hardware.

So, the accommodation of wide-screen into conventional shooting has to be a compromise. All digital video production is done using the 13.5MHz 601 structure, with 720 pixels by 576 or 480ish depending on which side of the pond you live. You could say therefore, that wide-screen pictures are softer than conventional horizontally because the pixels are stretched 4/3 if the height is kept constant, or that they are sharper vertically if the width is kept constant because the pixels are squeezed 3/4 vertically. Both interpretations are valid. It is this compromise that makes it difficult if not impossible to give precise definitions of what will happen to the images; it depends on how you use them.

One this that is certain though, is that shooting only 432 lines on a 576 line 4:3 camera will give you short-screen pictures, not wide-screen. The interpolation of those 432 lines back up to 576 to get the 16:9 image to properly fill a wide-screen display is a costly process because it involves deinterlacing and interpolation. In a tv set it is rarely done well enough for its effects to be invisible. Once you are used to spotting the artefacts, you won't like them.

Using an anamporhic lens is one way to get genuine wide-screen pictures from a 4:3 camera. It will keep full vertical resolution, and thus eliminate the need for vertical interpolation, but will not do full justice either to the camera or the display. That's because a genuine 16:9 camera will probably have many more than 720 pixels horizontally, and likely a lot more than the 960 you'ld expect (960=720*4/3). It's common practice in high end cameras for there to be up to 1200 pixels horizontally these days. This oversampling makes it possible to do really good filtering of the image, in the video signal, to get it to make a good filling job of the bandwdith made available by the 13.5MHz sampling. That's why good tv pictures are so sharp, the cameras have oversampled the scene and filled the 5.5MHz we have available. So, using an anamorphic adaptor will squeeze the image into the camera's ccds well enough, but you won't get the perceived sharpness that a genuine 16:9 camera can give.

Anamorphic lenses have been around a long time, certainly over 80 years. The film industry has been using them without problem for that time, but they almost always use prime (fixed focal length) lenses, hardly ever using zooms except in the past few years. Anamorphics work well at one focal length, but to zoom through them is asking for trouble, chromatica and spherical aberrations become visible and you get pincushion and/or barrel distortion as well. It's all a compromise.

Hope that's helped. If Pete Wells reads this, I'd be happy for him to use any or all of it in the FAQ that he suggested that I write, and that I turned into an offer for him to write.

[This message has been edited by Alan Roberts at work (edited 01 March 2001).]

Keitht
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Joined: Jan 8 2001

Alan

Can your explanation be copied into FAQ along with the other detailed answers you have provided for other recent queries. That way even if people have to be redirected to FAQ for a reply to questions the answer would be easier to find.

Regards Keith

Alan Roberts
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Working on it. Either Pete or I will do something soon.

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.

billyh
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Joined: Dec 2 2000

As originally stated, the Discovery Channel accepts DV/miniDV for most of its UK commissioned work.

These shows are all 4:3!

Why do the producers of these shows never use 16:9?

Is the quality unnaceptable due to the horizontal pixel stretching from the use of the anamorphic lens.

Billy Hepburn

billyh
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Re:- Discovery Channel 4:3 Programming

I've just had an email from a contact in the USA and he points out that 16:9 anamorphics are rarely used for "live action" programming due to the fact that the 16:9 anamorphic does not hold focus throughout a zoom.

This would also confirm Alan Roberts last posting to the board.

This would certainly explain why Discovery programs, such as fishing, where zooms are an integral part of the style would not use anamorphics.

My USA contact also says that he is using 2.35:1 aspect ratio in his current production which is achieved by using the psuedo 16:9 built into the camera and also an 16:9 anamorphic which then squashes the cameras 16:9 to 2.35:1.

It all getting confusing again!

Billy Hepburn

[This message has been edited by billyh (edited 02 March 2001).]

Alan Roberts at work
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Thanks for that Billy. It confirms what I've long suspected. Don't look to the USA for examples of how to do widescreen, look to the UK.

In the US, they've confused digital tv with widescreen with HDTV, it's all one package. In just about 2 years since launch, the US HD/widescreen/digital system has shipped about 100,000 receivers (STBs and integrated) to dealers, no data on how many are in real homes.

In the UK, widescreen and digital go together, and we're holding off HDTV until the dust settles. In the same 2 year period, about 2,000,000 receivers (integrated and STBs) have reach UK homes. The UK is where widescreen production is at the most productive at present.

Discovery is basicaly a 4:3 broadcaster. Their only widescreen output is in HD and only for a few hours/week. It isn't big business yet. They aren't very interested in getting 16:9 right until there's a significant installed base of receivers, and that will take years at the present rate of US progress.

P.S., do the sums on the 2.35 job. He's blanking his 480 line raster down to 480*3/4=360 lines, then putting an anamorphic adaptor on as well. Cor, that's going to look unbelievably soft. Why on earth would anyone want to do that? Still, if it keeps him happy, who are we to complain?

P.P.S, and Pete's promised to do a FAQ on widescreen.

[This message has been edited by Alan Roberts at work (edited 02 March 2001).]