Whats the use of SMTP bars?
 

Hi, I have recently bought a GL2 (XM2 since I live in Sweden). I feel that there is something I should know about the colour bars, but I have no clue as to what, since the manual doesn't say very much at all. I read somewhere that you should always record a few seconds of bars on a new tape. I don't get the use of them though.
Can some on fill me in on this?

Fredrik, Sweden

What is the true colour?
 

Hello, i forgot to ask in my thread about colour bars that about colours. When I watch a dv tape on one tv, it looks darker or more colourful then the other, same with watching a dv file on different computers; you perhaps have to adjust the brightness or color gain to get a good picture. That led me to the question: what are my taped materials TRUE colour, brightness and so fourth?? (I have a Canon XM2). Is this what the colour bars are for perhaps?

Color bars provided a standard signal on tape that can be used as a reference to check/setup/adjust analog components in the signal path, incluing the monitor. (Note that the original XL1 and GL1 did not have standard color bars.) However, typical full-field camcorder bars are not the best for montior adjustment.

There is a lot of difference in default adjustment of TV sets, so video is likely to look different on differnet sets. This is especially an issue with NTSC (never the same color).

I don't know, but maybe you should record 10 or so seconds of color bars at the beginning of your footage.

The only way to know how your footage actually looks is to use
calibrated (professional) monitors/TV's.

There is a current thread about this here.

If you have a specific broadcast organization in mind, check with them to see what they expect Exampels may include bars and tone at the start, no program material in the first 60 seconds of tape, and so on.

You could also take the footage into a computer and examine the data pixel by pixel, or with a waveform monitor/vectorscope.

I suppose that it depends on how you want the cameras to match.

Do you want the GL2 (XM2 over here) to match the warmth of the XL1s or do you want your XL1s to match the GL2's more neutral look?

It would be interesting to hear from other users of both cameras and how they achieve this balance...

I am by no means an expert here, but I might be able to help you out a bit more.

Like Don answered before me, the purpose of the bars is to provide a tool for adjustment of monitors etc.

If you show the final result of your product on a consumer TV set (or a monitor for that matter), most people will adjust the picture to "look good". However most people have no clue how to accurately adjusting the controls, so the picture will end up being too bright or too dark off in colors etc.

One important setting is the "brightness". A bit of a misnomer, since it is actually an adjustment of the level of black. Imagine if you turn brightness down too far. Then all parts of your picture that were supposed to be varying shades of darkness (but not black) will all appear equally black. Ie. the details are lost in blackness.

If you turn black level up too highly, what was supposed to look black, will actually look grey.

Part of the SMPTE color bars can let you adjust precisely this. Take a look at this pattern:

http://www.greatdv.com/video/smptebars.htm

Near the bottom right is a "pluge" pattern. On a black background are 2 vertical stripes. One is "blacker than black" meaning it is slightly below reference black. The other is slightly lighter than black.

The point is that "blacker than black" is supposed to look just like black, whereas the slightly lighter than black stripe is supposed to stand out from the black background. You adjust the brightness control to accomplish this.

Likewise the contrast can be adjusted for good greyscale and so low that the picture doesn't "bloom" - white lines get distorted.

Color shift can be adjusted too. This is explained on the page I linked to.

This was a brief explanation. To get a thorough introduction to this subject, buy "Video Essentials" or "Avia" on DVD. Both include excellent audio and video calibration procedures.

Last, the SMPTE stems from the NTSC world. Test signals usually look different in the PAL world - I live in Denmark. I usually use NTSC though, so cannot help you out there.

Hope that helped a bit.

Hans Henrik

broadcast
 

The local TV stations here are pretty flexible, I can take them just about anything.........they have no problem with DV tapes or DVD's. (DV tapes they need us to bring in a camera so they can capture it)

But, I do put a 3 second tone, and 9 seconds of color bars up front and they've never asked for anything other than what I've listed here.

The local NBC affiliate is the easiest to work with since they outsource most of their work to a production company in the same building.

We were over there last week delivering a commercial, and while we were "ogling" their gear....the production dude said "I can't get anything off your camera, there's nothing on the tape".
After looking at the camera, I realized that he had shut the door on the XL1s, but never pushed the tape mechanism closed.......duh........I guess even the pros do it <;~)

If you are shooting outdoors try the sunlight icon setting or white balance the GL2 by using a white sheet of paper outdoors, which for me gave an even warmer shot than the sunlight icon setting. I think the GL2 is a tad sharper, so I would bring the sharpness down maybe a notch.

display ?
 

on both the lcd/viewfinder in the upper left hand corner there is a display (horizontal sliding bar) that indicates when you zoom from telephoto to wide. a couple of seconds later this zoom status indicator becomes a + and - indicator. it appears to be some type of light sensor. does anyone know what the function of this indictor is? i can't find any info in the manual.

mb4

This bar appears when you're shooting in Manual mode. The +/- format shows your relative exposure, with the centerpoint being the "proper" balance from the camera's point of view. Just watch the indicator as you adjust exposure settings or point towards brighter or darker subjects.

GL-2 Weather Cover
 

I will be shooting a lot of video at the scene of major EMS and fire operations for training purposes. This will put me and my camera outside in all sorts of weather conditions. Any comments on experience with weather covers for the GL-2? I've seen adds on three: Camcote, Kata and Portabrace.

Mark Haas

I've used the Kata and the PortaBrace. Both are functional and will keep the camera dry in wet (but not necessarily soaking-wet) conditions.

I prefer the PortaBrace cover. Better detailing. For example, the Kata's lens closure pull has a nasty tendency to bounce into the frame.

For cold weather protection I use a PortaBrace Polar mitten cover. Excellent detailing, although a bit awkward by nature. But it works pretty well at preventing freeze-ups and premature battery drain.