is here -
There are a lot of complications and misunderstandings
with videotape widescreen formats nowadays. Everybody
wants to plan ahead for 16:9 widescreen TVs while
keeping the 4:3 format for today’s telecasts.
That’s what we did with Blackly and Salter
Street is shooting all their new shows widescreen.
In Britain they are shooting 16:9 transmitted two
ways - a 16:9 TV set receives the full wide picture
- a 4:3 set gets a 14:9 picture which minimizes
the letterbox effect. In the USA, HDTV transmission
is now ongoing with networks eventually broadcasting
in two formats (old and new) for the next several
years - TV sets will have black boxes to sort out
the frame sizing. Canada’s approach to new
formats is not up and running yet, so producers
are just prioritizing in 4:3 for now and any shows
shot on 16:9 or HDTV will have to wait to be reformatted
later. There is an consortium assigned to Canada’s
digital television future. If you want to get an
update, they have a website - www.cdtv.ca.
The numbers -
I really find the television standard of defining
frame ratios annoying. Motion pictures have
always used a real ratio as the description
- 1.33 to 1 is standard TV - 1.85 to 1 is widescreen
- 2.35:1 is CinemaScope. So the width of the
screen is either 1.33, 1.85, or 2.35 times
the height - easy to understand, easy to compare.
But TV uses unrelated numbers like 4:3, 16:9,
and 14:9. But there is a quick solution to
convert TV numbers to basic ratios. Take 4
and divide by 3 = 1.33 - Viola! 16:9 is 1.77
- which is inbetween Super 16mm (1.66) and
standard widescreen film (1.85).
TV FRAME 1.33:1
LETTERBOX WIDESCREEN 2.35:1
WIDESCREEN IN TV FRAME
Unknown facts -
There is a problem with switchable widescreen
cameras that Sony doesn’t like to publicize.
If you take a regular 4:3 digital Betacam camera,
the 4:3 rectangular CCD fits to the edges of
the circular image which the lens creates.
But to provide a widescreen 16:9 image, which
is a narrower rectangle, when that CCD is placed
with the same circle, it ends up being smaller.
The resolution rating on a 4:3 Sony Digital
Betacam is 850 but that drops to 680 for a
16:9 switchable camera. Then if you only use
the inside part of the widescreen (the 4:3
section of that) you are using even less of
the CCD and the rating drops to 650. Now, 650
is still a lot better than several years ago,
but there is a loss. Canon research says that
on a 2/3” CCD chip the full 4:3 image
is 58 sq mm - but the 4:3 part of a switchable
widescreen image is only 38.75 sq mm (a reduction
of 65%). This also creates a problems with
zoom lenses - you require wider lens to give
the same effect with the smaller image. This
issue might be a problem if networks get fussy
about the resolution going into HDTV transmission.
So, you’ve got the widescreen, but what
about the resolution?
HDTV cameras use the same 2/3” space as
described above but the chip’s resolution
is so high that even the 4:3 portion of the picture
exceeds any present NTSC quality. 35mm film has
always carved up its frame size in varying ways
but again the resolution of even a smaller area
of the film frame is quite high. Super 16mm has
met the needs of widescreen by letting the picture
go into the (unused) sound track to maximize
the area, but the ratio is only 1.66.
Frames lines and cutoff -
It is important for anybody viewing a monitor
to understand widescreen frame lines and cutoff.
Before widescreen, 4:3 monitoring was easy
- the underscan button showed the maximum “raster” image
- when the underscan button is off, the monitor
cuts off about 10% which represents what most
TVs show - the operator usually sees both the
maximum image and a cutoff frame line in the
viewfinder. If you see a boom mike in the full
image, it’s on tape, but so long as you
don’t see in the cutoff image you should
Now along comes widescreen. Most non-HDTV shoots
nowadays use the 4:3 monitor with a 16:9 switch.
When you switch to 16:9, you get a letterbox
image (some monitors have an under / overscan
choice, others might not). In 16:9 mode, the
operator’s viewfinder will show full 16:9,
16:9 cutoff, and 4:3 cutoff (there are many options,
but this is what I had on Blackfly). What you
don’t see in the color monitor is - one,
any 4:3 reference lines and - two, top and bottom
16:9 cutoff (you may or may not see side to side
16:9 cutoff). So, you should mark these on the
monitor with tape - although the depth of the
monitor glass creates a problem seeing a consistant
Another issue is dealing with head room on 16:9.
When the program is telecast on a widescreen
TV where all the edges of the frame go right
to the TV edges, there is about 10% cutoff, so
you have to allow for that as we have in the
above case by marking the monitor. But when the
program is letterboxed, the side edges are cut
off, but top and bottom are masked by black -
right to the edge with almost no cutoff. So when
it comes to headroom you have to think “a
head” as to how the program will be shown.
When ever you are viewing a widescreen monitor
on set, review the options with the operator
and mentally compensate or mark out the frame
lines. I hate when the director says there too
much headroom on a 16:9 shot because he can’t
see the cutoff line.
BBC producers are calling for 14:9 which complicate
things even more. Most cameras do not have that
option in the viewfinder. 14:9 = 1.55 which is
in between 4:3 (1.33) and 16:9 (1.77). I’m
not 100% sure but I believe 14:9 involves cutting
the side edges rather than effecting head room.
Use a chart! -
In film, operators always shoot frame charts
to confirm what they are using for frame lines
and to make sure the film to tape transfer
is correct (sometimes this is called “rack
leader”). When I brought out a chart
on my HDTV vs film test, the video guys thought
I was nuts because they don’t usually
shoot them. But it is an excellent way of showing
any potential cutoff from tape machines or
TVs. You will find a lot of TVs show more on
one side than another. With Blackfly, the VHS
rushes were letterboxed, so directors appreciated
my frame charts, which allowed them to mark
4:3 frame lines (or at least the corners) on
Mini DV and 16:9 -
Mini DV cameras use electronic squeezing to form
16:9 images. It would seem to be a good idea
(copying the anamorphic lens concept) but the
Mini DV lenses don’t see any more side
to side and the squeezing is actually a digital
effect similar to digital zoom, so it’s
not a perfect option, but probably better than
cropping the frame.