Hello!
And welcome to another 
Technology Connections 2 video!
If you're new to the channel, this is the
channel where I talk about stuff and don't
prepare for anything.
And in today's episode, which is the first
one in a long while by the way, I thought
I would answer a question that a lot of viewers
have asked, and that is "How am I able to
film CRTs and have them look normal?"
Now, if you're surprised at why this would
be a question, I'll show you.
So when you normally film a CRT with something
like a smartphone (and if you suffer from
photosensitive epilepsy you may want to look
away for about 20 seconds) normally the result
is something like this.
Now, the reason why this is happening is that
a CRT screen is drawn very, very quickly,
and when your shutter speed is too fast, you're
only seeing fractions of the screen illuminated
at one time.
So, to get a result such as this, you need
to do something a little bit different.
And what is it that you need to do differently?
Well, that is to set the shutter speed to
either 1/60 or 1/30 of a second.
♫ regrettably smooth jazz ♫
No, OK, of course I'm gonna talk a little
bit more than that.
So this also depends on if we're talking about
an NTSC television or a PAL television, but
basically you need to match the framerate
of the CRT.
So first of all you need to have a camera
that you can manually set the aperture and
the shutter speed, and of course normally,
almost all the time, I'm using my camera in
manual mode.
So whenever I need to film a CRT, I usually
film it at a 60th of a second.
Now, the reason why I wanted to make this
video today is because that proved to actually
be kind of a problem.
Now originally I started filming things at
1/60 of a second because it makes the lines
on the screen more pronounced.
So if we go to the black and white CRT, in
this shot I'm filming it at 1/30 of a second,
which means that both fields--so both halves
of the frame are visible--and the lines are
hard to see.
And if I film it at 1/60 of a second, now
you can see only one of those fields so the
lines become much more pronounced.
Now of course, what I hadn't thought about
was the fact that I'm showing you the closed captioning
data on line 21 and it does not repeat between
fields.
It's only on line 21.
So, oftentimes I'd be filming the TV and you
couldn't even see it.
And it was hard for me to tell because the
screen on my camera is so small.
I couldn't really see what was going on.
So with a 1/30 of a second shutter you would
always be able to see it, but you'd see more
lines which made it harder to see.
With 1/60 of a second, you would see the lines
more sharply but those captioning bars may
actually not be visible.
And what's really interesting here is that
the camera and the TV are not actually synchronized
perfectly.
If you recall, NTSC television is actually
29.97 frames per second, it's not 30 frames
per second.
The reason for that has to do with the color
signal and fudging required for audio doo-dads,
I'll put a card to my video explaining that
(kind of).
And what happens is, they're actually not
quite in sync and in this footage here you
can see a slightly diagonal line, kinda like
a disturbance in The Force almost, moving
up the screen, slowly.
And that is where the camera is now seeing
the other field.
So as it makes its way to the top, suddenly
that caption data is either gonna go away
or reappear, and it's probably gonna be one
or the other because I'm recording this voiceover
before I do any looking through the footage.
Now another thing to keep in mind is that
you may have to shoot things at 1/30 of a
second because some sources are actually only
using the odd or even fields, so one example
of this would be the NES or, I think the PlayStation
1 also only uses one of the fields depending
on the game.
So if you have the shutter set to 1/60 of
a second, that line that you see creeping
up here--that would go between being able
to see the screen, and not being able to see
the screen.
Another thing that you have to keep in mind
is, because cameras have a rolling shutter,
the direction of that shutter may make the
screen kind of all wonky, now in my case I'm
fortunate because the direction of my camera's
rolling shutter is top to bottom, which is
the same direction that a CRT scans, but if
for example the direction were going sideways
across the frame, you might get some weird
artifacts, depending on how things go.
And if you have the camera upside down, so
it's scanning in the opposite direction, even
though you have the shutter speeds matched
you might have chunks of the screen that are
missing and maybe some other things moving
around, so there is some stuff to think about.
But for the most part, to film a CRT all you
gotta do is set your shutter speed to 1/30
of a second or 1/60 of a second.
Now, what I'm unsure of is, in countries that
use PAL or other, uh, other systems that are
50 Hz (like SECAM?)
I'm not sure how common it is for cameras
to have a 1/50 of a second or 1/25 of a second
but I would imagine if your camera can shoot
at 25 frames per second and 50 frames per
second it's gonna have those shutter speeds.
I just can't say for sure and I haven't done
the experimentation with my camera to see
if that's an option, but anyway.
That's all this video is.
If you ever need to film a CRT, get yourself
a camera, get yourself a camera you can set
the shutter speed manually on, and you may
even be able to do it with your phone if you
dig into the settings, and you'll be good
to go!
Thanks so much for watching!
I'll see you next time, probably on the main
channel, but ya never know when stuff comes
up here because basically when I think about
it...
I think about it.
Have a good one.
One interesting quirk I discovered when I
was putting the PS3 away was that even though
this screen is up, the DVD playing in the
background is still sending the vertical blanking
interval information with the captioning to
the decoder, and the decoder is happy to just
slap that on top of this menu screen.
So... that's interesting.
