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True Widescreen vs. Letterboxing


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#1 Jonny Brady

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Posted 24 May 2009 - 11:40 AM

Not sure what forum this best fits into so I put it in General...

I have two main cameras - the Sony A1E and the Panasonic DVX.

I am Standard def. I'm trying to work out whether it's better for me to shoot anamorphic, or letterboxed. And when I say anamorphic, I mean without an anamorphic lens of course - I mean just choosing the 'Squeeze' setting in my cameras.

When shooting widescreen on the A1 it is native widescreen, and this resolution is of course afaik 720x576. As it's anamorphic I presume also that its pixel aspect ratio is 1.456. My first question with this is, when you switch it to 4:3, all it does is crop the sides instead of change the pixel aspect ratio to 1.09, because you can still see the image underneath the cropped area, just darker - so what's happening here? Is it getting rid of horizontal res? Or is it still 720x576? If it is still 720x576 how is it keeping the faded image under the pillarboxes?

With the DVX I prefer to shoot letterbox because it means I can use the viewfinder accurately, as when it letterboxes, it also shaves off the underscan area. If you shoot anamorphic with the DVX it has huge underscan in the viewfinder which makes it difficult to frame (rather annoyingly there is no 'safe zone' marker).

But I figure that if I shoot letterbox on the DVX, I'll be cropping 25% of the vertical 576 res, so I'll have 432 pixels of vertical resolution. If I shoot anamorphic though, you'd expect that you'd get the full 576 height. But surely this is only if you use an anarmorphic LENS? Because surely all the camera is doing is digitally stretching it, so you're losing res JUST as you would if you letterboxed? Basically, aren't letterboxing and digitally anamorphising (if that's even a word) exactly the same, and isn't true wide only achieved through anamorphic lenses?

Sorry if this is the wrong messageboard altogether for this question.

Any help much appreciated!
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#2 David Mullen ASC

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Posted 24 May 2009 - 01:03 PM

You have to separate the pixel dimensions of the sensor from that of the recording -- they are not always 1:1. So if you have a 16:9 shaped sensor, then most likely 4:3 will be extracted from the center of the sensor, but that doesn't mean it is taking 720 x 480 anamorphic, let's say, and cropping the sides of the recording and stretching it back out to create a 4:3 recording. If you created 4:3 in post from a 16:9 anamorphic SD recording, then yes, but in this case, you're talking about cropping a sensor area, not a recording.

Now some cameras use an oversized sensor (or maybe not oversized) and extract both 16:9 and 4:3 from the center of it in a sort of cross-shaped pattern. So the amount of pixels used from the sensor are about the same for both 16:9 and 4:3 shooting. I think the Canon XL2 worked that way.

The DVX100 has a 4:3 sensor so it has to crop the top & bottom of the sensor to get 16:9 before recording that as either a 16:9 anamorphic SD recording or a 4:3 letterboxed recording.
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#3 Sean Lambrecht

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Posted 24 May 2009 - 01:10 PM

The DVX is still going to resolve the same number of lines on a resolution chart whether the top and bottom of the image are blacked out or not. Letterbox mode has the advantage also of allowing more bits being devoted to the 16x9 area of the image.

The anamorphic lens when properly used will give the sharpest results. But focus has to be set using both the zoom and f stop to keep the vertical and horizontal planes in equal focus. Get Barry Green's DVX book if you plan to that!

Anamorphic mode stretches the the center portion of the image to fill the whole 4:3 frame. This is accomplished with better results by post software than in camera, but a lot of people don't claim to notice a huge difference. It's certainly there however.

I'd stick with a mix of the anamorphic lens for wider shots, and letterbox mode where the anamorphic lens starts to struggle. Sorry, no clue how the A1 operates.

Peace,
Sean
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#4 Jonny Brady

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Posted 24 May 2009 - 01:17 PM

Blimey, trying to get my head round that...

So in a nutshell then, is there no difference between shooting anamorphic (NOT lens, digital)/letterboxed on the DVX?

Jonny

Edited by Jonny Brady, 24 May 2009 - 01:18 PM.

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#5 Sean Lambrecht

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Posted 24 May 2009 - 01:25 PM

Blimey, trying to get my head round that...

So in a nutshell then, is there no difference between shooting anamorphic (NOT lens, digital)/letterboxed on the DVX?

Jonny


Not a HUGE difference... I'd personally go with letterboxed mode, because I do notice a difference when looking closely. The in-camera scaling in anamorphic mode isn't as good as software you could use afterwards to rescale.
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#6 Sean Lambrecht

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Posted 24 May 2009 - 01:36 PM

Just pulled out the DVX book and found some interesting numbers from resolution charts. I'm assuming these are from the NTSC model.

350 lines: in-camera squeeze mode
380 lines: letterbox mode
540 lines: anamorphic adapter
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#7 Jonny Brady

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Posted 24 May 2009 - 03:25 PM

Just pulled out the DVX book and found some interesting numbers from resolution charts. I'm assuming these are from the NTSC model.

350 lines: in-camera squeeze mode
380 lines: letterbox mode
540 lines: anamorphic adapter


Woah, that's very interesting. Thing is, I use a 35mm adapter, so I doubt I could use an anamorphic adapter on that as well... unless you can get converters that fit onto that sort of setup... then I'd have to use my monitor rather than my viewfinder to squash the image (which wouldn't be a problem I guess)...

But that's not relevant anyway, thanks for that information, that's helped - I'm glad letterbox is better because of the fact that it also shaves off underscan!

Cheers for your help guys!
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