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Canon GL Series DV Camcorders
Canon GL2, GL1 and PAL versions XM2, XM1.


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Old January 7th, 2004, 10:04 AM   #1
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zebra, frame/not frame and more

Hi all,
I have a few questions here for you experts.
I have a PAL XM2 purchased in Italy and up to now i used it mainly during some trips in ‘strange’ places like Afghanistan, Pakistan, India, Burkina faso, Thailand and so on.
Since the quality of the footage that the XM2 produces can be pretty good and since many of the places I’ve been and I’m planning to go are really strange and interesting, I’m thinking about trying to do things a bit more seriously and producing some kind of low budget documentary movies.
I’m not a pro, at all, but i know more or less how to manage presets (but setup level! –see previous post), manual exposition and depth of field. What I’m absolutely new to is NLE, i know something about FCP and Premeire but I actually never put my hands on a serious project.
Now, getting to the point:

-Is there anything I should know before shooting to get the best picture quality after editing? I’ve seen a post by Jeff Donald about exposure and picture treatment in NLE wich was very interesting. Do you guys all agree with him? Anything else?

-I use zebra, 100%. Usually when shooting i always try to keep some zebra visible on the LCD. Is it correct? I mean: is it ok if part of the picture (ex.: part of a face) is a bit overexposed? Zebra stripes are not there just to be killed, I guess...


-I like to use the frame mode (not only for the ‘film look’, it’s a matter of taste, I like how the picture is, may be the vertical resolution is increased as the owner’s manual says...) but i know that in some particular situations it can give a not so nice stroboscopic effect. By keeping the shutter slow as 1/50 or better 1/25 the flow of frames (or the movement inside the frames) seems to be quite smooth and regular and it’s ok but sometimes it is simply not possible to use such a slow exposition. Did you ever consider the idea of using a mix of frame and non frame mode footage for the same project? What I’m thinking is to shoot in frame mode when the movement of the camera or inside the field is slow enough and do the rest in non frame mode. Do you see any problem in editing and -overall- do you see any aesthetical problem?

-I guess I’ll have to buy a wide angle converter and a microphone. Which microphone? Why, in a few words, shall I get the XLR adapter?

Ok, sorry for the long post and sorry for the bad english, I hope I explained myself well enough.
ANY comment/suggestion would be highly appreciated!!!
pietro
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Old January 7th, 2004, 12:24 PM   #2
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Basically editing will work with whatever pictures you shoot.
Ofcourse high quality pictures will help your movie a great way,
especially if you need manipulate them.

Your resolution will DECREASE when shooting in frame mode,
not INCREASE (as the manual states). If output is primarely
web then that shouldn't be any issue since it is a lower
resolution anyway. If your output is going to a TV station
they might prefer interlaced.

I would not mix interlaced and progressive/frame mode. That
would be too dangerous in my opinion.

A lower shutter speed (like 1/25th) will decrease your resolution
as well in interlaced mode (should not do that in frame mode).
The lower the number the more jerky the footage should become.
The moving of objects should appear smoother at 1/100 than
1/50 than 1/25.

If you set your zebra stripes to appear at 100% and you are
seeing them on a face then you are already loosing information.
Whether this is a problem, depends. On a face it is probably
not going to look very nice (unless you want to wash out the
face in a pool of light, ofcourse). On lamps in the scene it is
probably unavoidable as perhaps some things in the sky.

I prefer to set my zebra stripes a bit less (not too much) so that
I have some room to play. When they start appearing I know I
have a little bit more to go before it clips.
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Old January 7th, 2004, 12:27 PM   #3
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Hello Pietro,
It sounds like your work takes you and your GL2 to some very exotic locations!

My brief, but not necessarily definitive, answers to some of your questions.

1. Considerations for getting the best imaging after editing are the same as for getting the best image before editing. Yes, I agree with my colleague Jeff's remarks concerning getting the brightest exposure without blowing-out or crushing parts of the image. It leaves you with more options during color correction.

Also be sure to leave yourself a good head and tail before and after each clip. You'll thank yourself for leaving those trimmable seconds of footage while editing. Again, it leaves you with more options.

2. Consider setting zebras just below 100% and then striving to eliminate them from your viewfinder while shooting. This may seem contrary to the advice above, but it's not. The fact is that the GL2/XM2 only has about 5 stops of exposure latitude. Shooting in bright daylight with strong contrast you will often be faced with a choice to perserve the bright or the dark areas of your shot. In the absence of other considerations, I would always choose to preserve the detail of the brightest areas. Why? Remember that relative brightness is one of the key factors for controlling your viewer's eye. They will look first at the brightest portions of your frame, as the instinctive tendency is to assume that the brightest parts are the most important. Again, you may have aesthetic reasons to do otherwise for a specific situation. But consider having a natural bias for preserving light areas. Using a 95% zebra has been handy for me in this regard.

3. Mixing frame mode and normal mode will not present a technical issue during editing, per se. But consider remaining consistent throughout a project. Depending on the scenes you may see a marked difference if similar subjects and action are shot in mixed modes.

4. Spend time in our "Now Hear This" forum for advice on mics. There's plenty there. Personally, I use a BeachTek XLR adapter with my GL2.

Have fun and stay safe!
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Old January 7th, 2004, 05:50 PM   #4
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Ok, no mix, I’m persuaded.

-About the shutter speed: I thought that moving objects had a blur effect with low speed and a stroboscopic one with high speed. I understand that ‘the lower the number the more jerky the footage’ but only if there’s anything moving in the picture (this happens in photography). But I don’t understand why a lower shutter speed decreases the resolution. Do you say that resolution decrease in any case with low speed, not depending on motion?

-About the frame mode: why did they say the resolution increases and why did I believe it was true?

Thank you for the explanations.
I have to learn a lot before traveling in exotic locations again...

Pietro
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Old January 8th, 2004, 04:39 AM   #5
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In the manual it clearly states that vertical resolution in frame mode is 1.5x enchanced. It is correct.
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Old January 8th, 2004, 09:12 AM   #6
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De-interlacing or blending of fields (which the camera is doing in
some specialist way when shooting in frame mode) always looses
resolution.

Shutter speeds (below 1/50 or 1/60) will lower resolution because
one field is dropped and the one remaining is used to fill both
fields in the final output.

The Canon's use a very special frame mode algorithm that doesn't
seem to introduce (much) extra resolution loss when going into
low shutter speeds (they do in interlaced it seems).
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