resource. Wide screen explained
By Dr Ivan B. Tonklemousse;
12 August, 2004
Today we’re in the midst of a massive change from
4:3 to 16:9 ‘Widescreen’ aspect ratio television.
Most broadcast television is now shot in 16:9 aspect
ratio and this means that to be future proof we all
need to equip for Widescreen and understand how it is
achieved within today’s PAL Standard Definition
(SD) broadcast transmission system.
It’s a common misconception that there are more
pixels in a recorded 16:9 SD image than a 4:3 one because
in reality all PAL D:1 images are actually 720x576 pixels,
it’s just that a true 16:9 image is anamorphically
squeezed into 720x576 pixels…
720:576 is not even 4:3 because D:1 images incorporate
non-square pixels to achieve the correct aspect ratio,
i.e. each pixel is 1.067 times wider than it is tall,
so when you multiply 720x1.067 you get 768pixels, 4/3
of the 576 frame height.
In simple terms: A true Widescreen image looks
tall and thin if viewed on a non-Widescreen monitor
and conversely a 4:3 image looks short and squat if
forced to fill a Widescreen monitor or television.
Low end cameras with 4:3 CCD blocks often offer a ‘Widescreen’
shooting mode but beware: This is not true Widescreen.
The camera circuitry merely inserts a ‘letterbox’
effect into the viewed and recorded image and the net
result of this approach is that the actual image area
does not utilise the full 576 vertical lines, meaning
that it is much lower resolution and of course lower
quality. To view this image on a Widescreen monitor
or television the picture has to be zoomed into.
The result is poor.
So how can you record true 16:9 images on a 4:3 Camcorder?
Enter the Anamorphic Lens or anamorphic lens converter
attachment. These devices cleverly squeeze a wider
16:9 image into the camera’s 4:3 optics &
CCD block, forcing the camcorder to acquire a true 16:9
Anamorphic image that will display correctly on a 16:9
monitor, using the full 576 lines of vertical resolution.
We offer converters for Canon XM1, XL1, Sony VX2000,
DSR-PD150, Toshiba TU-48P etc…
The only down-side of these converters is that whilst
shooting and monitoring your shots using the viewfinder
(or flip out screen) you will actually see a tall thin
image (anamorphically compressed) because 4:3 camcorders
have 4:3 viewfinders, not Widescreen ones. Of
course if you attach an external monitor with a 16:9
display mode your pictures will display properly with
no distortion.
True 16:9 cameras and camcorders have a 16:9 CCD aspect
ratio, meaning that they record true 16:9 images into
720x576 pixels and their integrated Widescreen viewfinders
ensure that whilst shooting you always see an undistorted
16:9 image.
So, in a nutshell – To shoot good quality true
Widescreen you need either:
1. A true 16:9 camcorder such as the JVC DV700WE or
Sony DSR-500WSP.
2. An Anamorphic lens / attachment plus maybe a Widescreen
monitor.
Aspect Ratio Converters (ARCs)
An aspect ratio converter provides a high quality electronic
conversion of a 4:3 image into a 16:9 image and vice-versa
by utilising special interpolation techniques.
ARCs are widely used in television post production and
broadcasting to allow the use of 4:3 images in 16:9
programmes and vice-versa. ARCs also provide multiple
simultaneous transmission formats from any source.
Ultimately though, an ARC is no match for shooting in
the correct format in the first place, so if you want
great Widescreen images you’ll need a great Widescreen
camcorder.
Now I’m not going to add too much confusion to
the matter by discussing 16:9 / 4:3 switchable camcorders
or HDTV (HD) equipment in detail in this article.
I’ll just comment that HD is true widescreen from
start to finish and that when you shoot 4:3 on a switchable
camcorder you add between 10 and 15% to the effective
focal length of your lens… Meaning that
your subject appears closer and your angle of view is
narrowed.
If you found this article useful or if there’s
a subject you’d like to be covered in a future
feature then please let us know.
Article kindly provided
by www.creativevideo.co.uk
VIP use this company for all our corporate video production
uk hardware needs.
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