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.