overscan - thank goodness it's behind us

[tom hardwick]

All my camcorders except my latest one (the Sony NX5) have had overscanned viewfinders. What this means is the viewfinder and side-screen only show you approximately 90% of the image that's being recorded, and this can give you nasty surprises at the editing stage where invariably your timeline (and very nearly all modern flat-screen TVs) will show you the entire frame as recorded. With all NLE systems you can call up a 'safe area' rectangle and this is pretty close to my Z1's v'finder cutoff.

Boom microphones can appear in shot, annoying and distracting details (white doors?) can arrive at the edge of the frame, vignetted corners from inadvertently using too long a lens hood or using too many stacked filters - all these can and do appear.

The list goes on but the most disturbing aspect of how composition is compromised. I've been watching some of my 2004 - 2009 films shot on my Sony Z1 and I've been unpleasantly surprised at how the camera's viewfinder overscan has made my framing look pretty awful.

Without examples to show you let me describe a typical scene. Four people walk into shot and stand, chatting. I would film such a scene as a ¾ length composition, so the tallest person's head was included and I cut everybody off through their thighs.

When you see this on an overscanning TV (a typical CRT) the framing looks correct. The top of the tallest head nearly touches the top of the screen and they all disappear out of frame bottom. But when this footage is viewed on an underscanning TV (ie a TV that shows you the entire movie frame as shot by the Z1) the people appear to be sinking in the frame. There's now far too much air above the tallest head and it just looks wrong. It looks ok if you've shot the group from head to toe by the way.

I was first alerted to this by Godfrey Dyan of Simcha Video. He took one look at my DVD and immediately spotted my 'unusual' framing. Prodded in the ribs like this I went and had a fresh-eyed look at my films and sure enough he was right. People all had far too much fresh air over their heads yet in my Z1's viewfinder all had looked fine, and I generally pride myself on my composition.

So thank goodness modern camcorders show us the entire frame as we film. It's hard enough making a movie as it is without being kept in the dark as to what's being included.

tom.

[Michael Slowe]

Another problem Tom is you don't know how people have their TV's set up. I see so many with the aspects all over the place and when I mention it I get a comment like "Oh, I don't know about all that". The modern TV's have so many options available that it can be confusing and to make things worse it does seem that incoming signals also vary. On camera screens by the way the Sony EX 1 gives choices of various safety margins, you've used this camera so you'll know about this.

[TimStannard]

Funnily enough I was acting as third cameraman, doing wide angle/safety shots last week using a Z1 supplied by the producer/director. The camera had a x2 converter which vignetted badly towards the wide end of the scale. The director drummed into me that it was essential, whenever I turned the camera on, I pressed one of the assignable buttons as he had assigned to this the facility to show the entire frame rather than the overscanned image. I'm guessing this is what Michael is alluding to.

So, maybe you had the answer all along (albeit in a convoluted way as there seems to be no way of saving the setting permanently) but didn't know it!

However, given that the vast majority of users aren't even aware of this issue, doing away with overscanning in the viewfinder can only be a good thing.

[tom hardwick]

Tim, I most certainly know that the Z1 has an underscan facility for its viewfinders, but when I've paid for a 3½" top screen I don't want to be filming, composing, checking focus and colour on a 2½" screen. Whatever came over Sony's design department, huh?

[TimStannard]

Fair comment, Tom.
Do you happen to know if the AV out suffers the same problem? I'm asking as we are planning on shooting a drama on an FX1 and will be reviewing footage on location with an external monitor. (Of course I accept that this might differ between the two models but I think it's unlikely).

[tom hardwick]

The A/V out doesn't suffer the same problem but the screen you connect it to might. As you probably know the FX1 doesn't have the ability to switch to the (useless) underscan for its v'finders.

[TimStannard]

Thanks Tom.

[Jill Lampert]

I read what you wrote, Tom, with great interest. I have had exactly the same experience. I have a Canon XM2, and when I used to shoot in 4x3 I was often disappointed with the positioning of interviewees. I try to get their eyes moreorless a third of the way down the screen. When I played the video back, the interviewees seemed much too low on the screen. This happened again and again. I would sometimes try to compensate by positioning them higher than felt right as I looked through the LCD screen, but was probably not bold enough. I would also occasionally find a bit of a microphone or something unwanted on the side of the screen.

I wonder if you can tell me why it is that at least part of this problem seems to have disappeared now that I am shooting 16x9 with the same camcorder. Magically, my interviewees seem to be moreorless where I thought they would be. And I haven't noticed any disastrous extra bits and pieces at the side of the screen. Of course what I see on the LCD screen doesn't look 16x9 and that is rather off-putting.

Jill

[tom hardwick]

A very good question Jill and the answer might well be that when you switch the XM to it's 16:9 mode it doesn't overscan in the vertical direction - only in the horizontal. Like you say the XM Canons didn't letterbox when switched to 16:9 (unlike the Sony VX2000, say) so you have to compose with a distorted - vertically expanded - viewfinder. Not clever, Canon.

My big 34" 4:3 Sony TV is like this. It overscanns horribly in 4:3 but when it shows 16:9 transmissions or DVDs it shows the entire frame top to bottom. It's so overscanned horizontally it's showing a 15:9 image.

You can test your XM's overscan in the 16:9 mode. Simply shoot a couple of seconds of tape with the camera framed up on a building. Align the camera so that obvious roof lines or windows hit the extremities of your v'finder frame and compare this with what your timeline monitor shows.

tom.

[chrisk]

My Canons suffer the same problem, the XH-A1s losing about 4% all round and the HV40 more like 6% with no underscan facility on either of them. There are times when I like to monitor the whole picture but don't have the luxury of a proper field monitor, and cheapo lcd monitors that I have tried overscan more than the camera viewfinders. I have found a solution by using my netbook with a composite video to usb adaptor (£8 on Ebay) taking the video out from the camera and displaying it full screen on the 10 inch computer display. As the resolution is 1024 by 576, the 16:9 display fits perfectly and shows the fulll picture right to the edges with no overscan. Sound can also be monitored with a suitable connection.

The netbook (Lenovo S10e, bought on Ebay) is light, portable and has other uses on a shoot such as taking notes, logging and maybe a copy of the script. It also takes a firewire adaptor in its express cardbus slot that allows me to capture DV and do some simple editing when away from home.

Chris