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Canon XL and GL Series DV Camcorders
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Old July 17th, 2006, 07:57 PM   #1
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Basic zebra stripes question

I set my zebra stripes to 90 and sometimes 95 IRE. When shooting outside (sunny day) I'll use the built in ND filter(s) and will close the iris to further reduce the zebra. Unfortunatly, to eliminate all the zebras I have to close the Iris down a lot.

I am not using a field monitor, therefore it's sometimes difficult to tell just how dark my image will be. I find that my video looks good on my NTSC monitor but it looks dark on my PC monitor. I've viewed the footage on other PC monitors and it looks the same.

Most recently I used the 'Globetrotter' XL2 settings: "Nature" http://www.dvinfo.net/conf/showthrea...t=Globetrotter - 24P at 48 fps

Should I strive to reduce all zebras? I'm sure it depends on the look that you are after.

Sorry for the basic question... I'm still learning.

Thanks...

Tim
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Old July 17th, 2006, 10:22 PM   #2
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Why are you only closing the iris to reduce the zebra? Why not increase the shutter speed? I usually just keep the iris full open and increase the shutter as necessary... While many people don't like the stuttered look of a fast shutter, I tend to think it makes it look more cinematic. Plus, keeping the iris open ensures you get as shallow a depth-of-field as possible.

It depends on the scene, but I find that in many cases a properly exposed shot will have significant zebra in it. Remember, you want to expose for midtones not highlights, so be careful not to try to reduce every little shining surface to nothing.

If I'm really not confident that I'm exposing a shot well, I'll give the dial a quick flip to shutter (or aperture) priority to see what the camera thinks.

I hope that helps, I'm not sure what your skill level is, so I hope I didn't say anything too obvious.
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Old July 18th, 2006, 12:03 AM   #3
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Hi,
Have you seen this site?
http://thedvshow.com/faq-pro/?action...002&id=2&lang=
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Old July 18th, 2006, 06:50 AM   #4
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Thanks for the replys.

Guess it has been drilled into my brain to use 48 fps when in 24P. I'm a "newbe" still. I'll try your advice + look into this web site.


Thank you again!

Tim
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Old July 18th, 2006, 08:16 AM   #5
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Quote:
Originally Posted by Tim Bickford
Thanks for the replys.

Guess it has been drilled into my brain to use 48 fps when in 24P. I'm a "newbe" still. I'll try your advice + look into this web site.


Thank you again!

Tim
Tim, you can stick with 48fps if that's the motion signature you want. There are other options such as screwing an additional ND filter on the front of the lens and make sure that you have the camera gain set to -3 if not already there.

-gb-
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Old July 18th, 2006, 10:04 AM   #6
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In all honestly, I think it is dificult to judge exposure settings by zebra-patterns alone with the XL2 for outdoor work, and mainly prefer to not always use them (although a friend swears by them for judging his Z1 exposures).

I prefer to keep the aperture set at f/8-f/4 or wider and then control light using shutter speed (like Justin remarked) and use extra control via the ND filters or polarizer (I like to keep a circular polarising filter screwed on the lens for most outdoor shooting).

Film does not have the latitude of the human eye, and video has even less, so it is rare to have an evenly lit oudoor subject throughout each clip section (especially if you are doing slow pans or tilts) - so on many occasions a perfectly lit subject for your preference will also have a lot of zebra patterns screaming at you that the exposure is way off (even though it actually isn't).

Try to remember that an underexposed or overexposed exposure can often look better than the average grey card correct exposure - depending on your preferences and the mood you are trying to convey.

Modern DSLR still cameras also have the option to use the Zebra patterns to help with exposure, but like I do with SLR film cameras, I prefer to not judge exposures by Zebra patterns when using a DSLR.

Tim - I should also mention that since I posted my 'globetrotter' Nature XL2 preset I have changed the main setting slightly and lowered the red to one stop above middle and upped the Colour enhance preset slightly. This was mainly because I was on a shoot recently where I needed to match the XL2 with a Z1, and found that boosting the red alone gave too pink skin tones and that increasing Color Gain in the presets is far better than upping the Red Gain alone (If you are only shooting wildlife it shouldn't matter so mutch).

These are the setings that I've been using recently for my 'A' Preset for nature/adventure fishing/outdoor work:

Main dial on 50i
16:9 mode
AV or M on dial.
-3dB gain
White Balance: on Outdoor sunlight (daylight temperature)
Gamma: Cine
Knee: Low
Black: Press
Color Matrix: Cine
Color gain: +4
Color phase: Middle
R-Gain: +1
G-Gain: Middle
Blue-gain: Middle
V-detail: Normal
Sharpness: +1
Coring: Middle
Setup level: Middle
Master Ped: -1
NR: Off
Skin detail : Off


I also have two different settings logged in on my 'B' & 'C' pesets for when I need to shoot different subjects.
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Old July 19th, 2006, 03:15 PM   #7
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Thank you again for all the advice. I'm going to soak it all in.

Thanks
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Old July 19th, 2006, 04:02 PM   #8
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Tim,

Read this thread…
http://www.dvinfo.net/conf/showpost....9&postcount=13

In particular Tom Tanquary’s post #13.
I think you will find it enlightening.
I did.

Bill
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Old July 19th, 2006, 07:11 PM   #9
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I dont recommend it for anyone without EXTENSIVE knowledge of a particular camera, but I do not use zebras... then again, I have logged more hours on the XL2 than probably anybody. When I shoot Varicam I always use them but your setup depends on what yoy are shooting. On a Vari I set the Zebras to 80 for shooting people and aim for no zebras on the face.

On thing I can tell that is an absolute mistake is using the shutter to control light. The shutter is a perceived motion control, while it does effect the light, it is NOT a light adjustment. This is also an EFFECT that is IRREVERSIBLE. ND filters and Iris should be used to control light, you can also use the -3dB gain. You should also never go below F8 or so, get yourself some screw on ND filters if you are having problems (snow and sand and particularly bad). Shutter adjustments should only be done when you want the specific EFFECT they create. My only personal rule for breaking this code is in situations where there is almost NO light and you must lower the shutter to get an image. .



ash =o)
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Old July 19th, 2006, 07:28 PM   #10
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Quote:
Originally Posted by Greg Boston
Tim, you can stick with 48fps if that's the motion signature you want. There are other options such as screwing an additional ND filter on the front of the lens and make sure that you have the camera gain set to -3 if not already there.

-gb-
Greg/Tim, are you talking about 48fps or 1/48s shutter? I'm a bit confused about how you can have 48fps and 24P at the same time (because you can't).

Richard
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Old July 19th, 2006, 08:31 PM   #11
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1/48th shutter which equals the 180 degree shutter in film



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Old July 19th, 2006, 10:25 PM   #12
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Originally Posted by Richard Hunter
Greg/Tim, are you talking about 48fps or 1/48s shutter? I'm a bit confused about how you can have 48fps and 24P at the same time (because you can't).

Richard

Sorry Richard, I meant 1/48 sec. not 48fps. The 180 degree shutter on a motion film camera exposes each frame of film twice so you get a double exposure on each frame 1/48 sec apart(at 24fps). The 1/48 sec electronic shutter on the camera is aimed at creating the same motion blur in each frame of film caused by the double exposure. The slight blur helps create the illusion of smooth motion with less strobe like appearance.

Like Ash stated, shutter should be set for a particular look and not used to control exposure. Iris yes, but within limits. Don't close it too far because you'll start to get a nasty looking image.

-gb-
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Old July 20th, 2006, 02:35 PM   #13
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I was recently wondering about this subject as well. Recently the wife and I went out to the mountains and I decided to take a video of a small water fall in Banff Alberta. According to the zebra stripes it was very over exposed so I cranked up the ND filter closed the iris as small as I could go. The water still was full of stripes (probably because it was foamy and white) so I thought ok I'l switch to manual and speed the shutter up as well. After viewing the video when I got home I found the entire picture to be very under exposed including the waterfall. I think I'll put a little less reliance on the zebra stripes from now on.
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Old July 20th, 2006, 07:29 PM   #14
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Quote:
Originally Posted by Kelly Harmsworth
I was recently wondering about this subject as well. Recently the wife and I went out to the mountains and I decided to take a video of a small water fall in Banff Alberta. According to the zebra stripes it was very over exposed so I cranked up the ND filter closed the iris as small as I could go. The water still was full of stripes (probably because it was foamy and white) so I thought ok I'l switch to manual and speed the shutter up as well. After viewing the video when I got home I found the entire picture to be very under exposed including the waterfall. I think I'll put a little less reliance on the zebra stripes from now on.
Hi Kelly. What have you got your zebra stripes set to? For example, if they are set to 70% that would explain why the image is underexposed.

Richard
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Old July 21st, 2006, 06:23 AM   #15
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Thank you all again. This is great stuff. The links are great too.

Going foward (in 24 P - for outdoor work) I'll continue to use a shutter speed of 48 and will only experiment with the shutter in an attempt to get different looks. Advice from Ash is always good advice.

I always have my gain set to -3 when shooting outdoors and use the built in ND filters. I agree that additional ND filters would help. Not sure where to turn here. Any advice (link) to some inexpensive filters would be greatly appreciated.

As for footage being dark on my PC monitor? Like I mentioned, the footage looks dark on my PC monitor (model ViewSonic 21) but looks ok on my NTSC monitor. Well.... it's a little dark on the NTSC too - but not too bad. I've looked at footage on another monitor and see the same results.

Perhaps I should not worry about "washout" in those areas where I do not need detail (i.e. some background images. In most cases it's part of the sky or some reflective surface in the backgroung. Like anything else I suppose it's just going to take some experimentation to get it down.

Thank you again. I learned a lot.

Tim
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