Using Gain for low light causes artifacts..help at DVinfo.net

Go Back   DV Info Net > Canon EOS / MXF / AVCHD / HDV / DV Camera Systems > Canon HDV and DV Camera Systems > Canon XL and GL Series DV Camcorders > Canon XL1S / XL1 Watchdog

Canon XL1S / XL1 Watchdog
Can't find it on the XL1 Watchdog site? Discuss it here.


Reply
 
Thread Tools Search this Thread
Old March 4th, 2003, 11:45 AM   #1
John Schuster
 
Posts: n/a
Using Gain for low light causes artifacts..help

I shot a wedding video with another videographer who has a Sony PD-150. We both adjusted db gain to +12. The video from my XL1S looked much more artifacted/grainy than his.

What am I doing wrong? What is the best way to capture footage in a dark setting. What setting should I be utilizing on my XL1 to get the subject light enough, but not make the video too grainy?

I am using the stock 16x zoom.

Thanks
  Reply With Quote
Old March 4th, 2003, 01:36 PM   #2
Wrangler
 
Join Date: Sep 2001
Location: Northern VA
Posts: 4,298
Adding gain adds noise and grain. No way around that - if you have to use gain. Consider using 1/30 shutter - that may help, if the motion artifacts are not too great for your purposes. Avoid high zoom settings, that can give up a stop or so of lens speed.

If you can add a bit of light to the scenes. Easy to do at a reception, but often not possible at the vows.
Don Palomaki is offline   Reply With Quote
Old March 4th, 2003, 01:49 PM   #3
John Schuster
 
Posts: n/a
Can using the AE shift brighten up the image? Does AE shift actually cause noise like DB gain? I have read through the user manual and it doesn't actually give you a lot of detail about AE shift other than it can lighten or darken an image. I also wonder if the Custom Preset "Setup Level" can be used for a brighter picture as it says or if that only concerns the viewfinder and not the recorded image.

Thanks for your advice.
  Reply With Quote
Old March 4th, 2003, 02:11 PM   #4
Retired DV Info Net Almunus
 
Join Date: Dec 2001
Location: Chicago, IL
Posts: 6,943
Hello John,
Yes, increasing the XL1S' gain will cause grain to appear. The PD-150 is a bit better in poor light so it's normal for it to look cleaner on dim scenes.

Adjusting AE effectively changes the camera's overall exposure logic slightly. It will make a difference but not as marked as gain.

Adjusting Setup Level basically adjust the black level, not the image's brightness. Be a bit careful with this one.

Just experiment. No single method will work well for all situations, particularly for uncontrolled indoor event coverage such as weddings. But the more you experiment with these adjustments the closer you will come to mastering the XL1S, something that very, very few owners really ever do.
__________________
Lady X Films: A lady with a boring wardrobe...and a global mission.

Hey, you don't have enough stuff!
Buy with confidence from our sponsors. Hand-picked as the best in the business...Really!

See some of my work one frame at a time: www.KenTanaka.com
Ken Tanaka is offline   Reply With Quote
Old March 4th, 2003, 02:37 PM   #5
John Schuster
 
Posts: n/a
Thanks Don and Ken

I will experiment with all the settings. I am meeting with the other videographer who has the PD-150. We are going to test out all the different setting on our cameras while connected to a studio monitor. We want to find settings we can both use to keep the image consistant for the video. Currently there is a marked difference when we cover a wedding with low light. It makes it difficult to edit when he has to compensate one of the shots to make them simmilar. Meaning when he cuts to one of my shots from his you can notice the grain. So basically he has to add a little "grain" to his so to the viewer there is not a change between shots. This adds a lot of work and rendering time to the final product. If we can find settings on both our cameras than procude a consistant image, even if it might be a little grainy (at least on dark shots), it will make the editing that much faster.

Then again maybe he can trade his PD-150 in for an XL1S....(har har) Actually, I think the PD-150 is a great camera I just ended up going with the XL1S. Hopefully the 2nd camera we both get soon will be the same. Maybe the replacement for the XL1S? or the Panasonic DVX100 which so far looks like a great deal even without the 24P option.

Thanks,
John
  Reply With Quote
Old March 4th, 2003, 06:03 PM   #6
RED Code Chef
 
Join Date: Oct 2001
Location: Holland
Posts: 12,514
If you had to shoot at +12 db it must have been pretty dim. At
what Iris and Shutter settings where you shooting? Try adjusting
these (if possible) BEFORE you alter the Gain.

With my own XL1s the viewfinder is darker than the actual
footage being recorded. So I can dial in less Gain than I usually
think.

Playing with your camera certainly helps!!

Were you in frame or interlaced mode? Because if I'm not
mistaken frame mode reduces your light input as well a bit.
__________________

Rob Lohman, visuar@iname.com
DV Info Wrangler & RED Code Chef

Join the DV Challenge | Lady X

Search DVinfo.net for quick answers | Buy from the best: DVinfo.net sponsors
Rob Lohman is offline   Reply With Quote
Old March 4th, 2003, 06:43 PM   #7
Retired DV Info Net Almunus
 
Join Date: Dec 2001
Location: Chicago, IL
Posts: 6,943
<< Because if I'm not
mistaken frame mode reduces your light input as well a bit. >>

Funny you should make that observation, Rob. I've noticed that Canon's Frame-mode process can make certain scenes appear darker than you expected. I've also noticed that it can be hard to predict this by simply watching the camera on a field monitor. I've not seen this effect documented anywhere. Have you?
__________________
Lady X Films: A lady with a boring wardrobe...and a global mission.

Hey, you don't have enough stuff!
Buy with confidence from our sponsors. Hand-picked as the best in the business...Really!

See some of my work one frame at a time: www.KenTanaka.com
Ken Tanaka is offline   Reply With Quote
Old March 5th, 2003, 10:03 AM   #8
John Schuster
 
Posts: n/a
"Were you in frame or interlaced mode? Because if I'm not
mistaken frame mode reduces your light input as well a bit"
--I was in interlaced mode. Will test that as well on his Sony studio monitor to see the difference.

"If you had to shoot at +12 db it must have been pretty dim. At
what Iris and Shutter settings where you shooting? Try adjusting
these (if possible) BEFORE you alter the Gain."
--It was very dark. They only had 3 chandaleers(spell?) and they were not too keen on adding more light to the are where the ceremony was taking place. I was on auto but locked (used "exposure lock" button on lens) my iris wide open at 1/6 and set the shutter at 60. Looks like I could have went down to 30 on the shutter and +6 on the gain based on what you and the other gentlemen have shared.

"With my own XL1s the viewfinder is darker than the actual
footage being recorded. So I can dial in less Gain than I usually
think."
--I am going to compare my viewfinder to the monitor image. I susspect you are right in that my viewfinder may show it a little dark and I can get away with +6db instead of +12 in a low light shoot like the last one we did.

I am going to adjust my brightness pot (potentiometer) on the viewfinder to reflect what the studio calibrated monitor shows. This way I might be less apt to overcompensate the image I used to see in my viewfinder.

Note* I know if I slow the shutter speed down I will get a little more light, but should I limit the low end to 30 on the shutter? I know most of the wedding shots are pretty static so I think 30 would be fine, but wonder if less than 30 will start to frame movement (don't know what the technical term is).

Other thought.. It would seem from what I have read that the low light capabilities are mainly due to the CCD chips and not the lens so I am assuming (oh boy) that if I had used a 3X wide angle lens (that I wish I had) that it would NOT increase the light hitting the CCD's allowing me to add less gain and grain?
Thoughts?

Thanks,
John
  Reply With Quote
Old March 5th, 2003, 10:42 AM   #9
Wrangler
 
Join Date: Jun 2002
Location: Vancouver, British Columbia
Posts: 8,308
Low light capabilities are a function of several things. However bigger CCDs = better low light shooting. I believe lower pixel count per same size CCD = better low light shooting (larger pixels absorb more light per pixel).

As far as lenses go, the 16x and 3x lens both have a reasonably large aperture, that let alot of light in. They are both about (or are) the same, although with a shorter focal length, the 3x lens might lose less light in the "tunneling" or "portholing" aspect, but it might be a negligable amount.

Limit your shutter to 1/30th. You will notice choppyness if your frame shows any real movement. Anything slower than 1/30th will fall under the "special effect" look.


The best way to get your pictures brighter for a wedding reception?
Rent an on camera light next time.
__________________
Need to rent camera gear in Vancouver BC?
Check me out at camerarentalsvancouver.com
Dylan Couper is offline   Reply With Quote
Old March 5th, 2003, 02:21 PM   #10
Warden
 
Join Date: Mar 2002
Location: Clearwater, FL
Posts: 8,267
The 16X IS zoom and the 3X wide angle are variable aperture lenses. This is common in most zoom lenses today. It allows for lighter lenses and reduces costs. The drawback is that you lose a stop of light (light is reduced by 50%). The 16X is F1.6 at 5.5mm and F2.6 at 88mm. The decrease in light (going from F1.6 to F2.6) happens gradually as you zoom through the range.

The 3X wide angle only loses a 1/2 stop while zooming. It goes from F1.8 at 3.4mm to F2.2 at 10.2mm. This 1/2 stop loss makes it a better choice for low light conditions in most situations.

The key holing effect may be more pronounced at certain apertures and zoom settings (focal lengths) than others. It may be worth experimenting with to learn the limitations of your equipment under different conditions (light levels, focal length, gain etc.
__________________
Jeff Donald
Carpe Diem




Search DVinfo.net for quick answers | Where to Buy? From the best in the business: DVinfo.net sponsors
Jeff Donald is offline   Reply
Reply

DV Info Net refers all where-to-buy and where-to-rent questions exclusively to these trusted full line dealers and rental houses...

Professional Video
(800) 833-4801
Portland, OR

B&H Photo Video
(866) 521-7381
New York, NY

Z.G.C.
(973) 335-4460
Mountain Lakes, NJ

Abel Cine Tech
(888) 700-4416
N.Y. NY & L.A. CA

Precision Camera
(800) 677-1023
Austin, TX

DV Info Net also encourages you to support local businesses and buy from an authorized dealer in your neighborhood.
  You are here: DV Info Net > Canon EOS / MXF / AVCHD / HDV / DV Camera Systems > Canon HDV and DV Camera Systems > Canon XL and GL Series DV Camcorders > Canon XL1S / XL1 Watchdog

Thread Tools Search this Thread
Search this Thread:

Advanced Search

 



Google
 

All times are GMT -6. The time now is 05:25 AM.


DV Info Net -- Real Names, Real People, Real Info!
1998-2017 The Digital Video Information Network