A GL-2 Imaging Bug / Attribute

Ken Tanaka · May 22nd, 2003, 11:11 PM

I think Bud's "pulsing" problem was the same problem. His pulsing probably related to his use of the digital zoom.

Hard to say about the Sony's problem. It sure looked like the same problem (on an enormous screen). I really doubt that it was a hood problem, though. This was an experienced camera operator not likely to make such a boo boo.

I actually use the WD58 adapter on my GL2 most of the time and have yet to encounter the problem with it mounted. Not saying that the adapter is the prophlactic, just that I haven't experienced it.

Dan Holly · May 22nd, 2003, 11:44 PM

How close were the serial numbers on the pair of GL2's you've had this issue with.

I checked my GL1 for this issue, and am not seeing it.
Have any clips or photos you want to show for a visual descripton?

Ken Tanaka · May 23rd, 2003, 12:09 AM

Couldn't say, Dan. I didn't record the s/n of the first GL2 that I exchanged for the second. I'd bet that they may have been close numbers, as both came from the same dealer within days.

Day's shot reflects the problem pretty much dead-on.

Aaron and Randy Wisman (XM2) have also encountered this. I think Jeff Donald's supposition of slight variations in lens manufacture hits the nail on the head. Apparently the GL2/XM2's lens' design is such that it's just on the fringe of some boundary optical property. One micrometer of grind variation too much and...

Dany Nativel · May 23rd, 2003, 05:58 AM

I wasn't using digital zoom at this time!

So what would be your suggestion ? return or keep ?

Thanks to everybody.
Dany

Ken Tanaka · May 23rd, 2003, 10:25 AM

I can't tell you what you should do, Dany. I can only tell you the decision I made long ago and why I made it, which I did above. It's just not a very big issue to me.

Val Rodriguez · May 23rd, 2003, 09:13 PM

If the origin of this "imaging bug" is of a mechanical nature, obviously a lens/camera redesign would be required to eliminate the problem. There's another intriguing possibility...what if the problem was caused by limitations of the camera's current ROM drivers and if that's the case, wouldn't Canon be able to fix it with a drivers/software update?. Since this bug shows up under unique filming situations, not likely to be encountered or noticed under most filming conditions, the only thing that would move Canon to come up with a fix would be if they heard from a lot of their GL2 customers.

Mario Lauria · May 24th, 2003, 01:46 AM

I bought my XM2 almost a month ago.

I've found the problem of "key hole" on my camcorder too.
The factory continues to make so priced units with this "bug".
I don't know if they will do something to solve the problem considering that mine is a very new machine.
Is it possible that they haven't yet noted the problem?
I don’t think so.

Anyway, I hope that all these reports from us will lead somebody at the factory to do something.

I can say that at the beginning I worried a lot about this shortcoming.
Now I’m learning to manage it.
In my experience, the “key hole” effect is mostly visible in low light and in particular conditions.
The effect is more noticeable operating the zoom.
It seems that the worst point is in the middle of zoom range.
I've tried to modify the "key hole" in manual mode but no control has effect in it except the zoom.

On the other hand, in most cases the machine makes really outstanding beautiful images (even good photos!)
Colours are never excessive but well saturated and balanced.
Images have a good sharpness and noise is almost invisible even in reasonable low light.

Hope this may help.
Ciao

Barry Goyette · May 24th, 2003, 12:30 PM

I don't know...I guess I've been listening to this discussion so long that I'm getting crabby...The so called keyhole problem is nothing more than an "uneveness of field" issue, which effects every zoom lens on the planet...(make that every lens, period). The gl2 as well as gl1 and and xl1s will all exhibit this problem in varying degrees due to the "longer than industry standard" zoom lengths. While we would all like a perfect zoom lens with a fisheye to moon crater zoom range with no vignetting (let's get the term right) or chromatic aberation. I'd also like a lens would bring us (god help us) peace without honor....

But it ain't gonna happen. There is a reason that a good cine zoom lens costs upwards of $20,000, and even then, I guarantee you if you pushed the film 3 stops (equivalent of 18db gain) and then did a rack zoom, you would find some unevenness of field visible in the footage.

The gl2 produces amazing results for a camera with a 20x zoom (oops I guess it's the only one)...I'm not trying to be a cheerleader when I say that perhaps we shouldn't be so amazed at its shortcomings as we should at the fact that the zoom is as good as it is. Canon engineers have pulled off a miracle zoom in my opinion...look at the size of the thing and then compare it to the zoom on the xl1s...(the lens alone is almost as big as the gl2).

I've been in commercial photography for almost 20 years, and I've never seen a perfect lens yet...especially a zoom. All systems have their limitations, and its one of the exciting things about being in this biz...learning what the limitations are, and then figuring out ways to succeed anyway...

This discussion is useful. Hopefully it encourages Canon to continue to advance their technology to produce even better cameras....but the point that is being made...that somehow the gl2 is a defective camera and why isn't Canon doing anything to fix it...I think this is heading down the wrong path.

Barry

Val Rodriguez · May 24th, 2003, 12:44 PM

Barry,
Thanks for putting the issue in proper perspective.

Don Berube · May 25th, 2003, 06:02 PM

Barry, very well said!

Too many times people forget that these cameras achieve a level of performance that was attainable in the past only with cameras costing thousands of dollars more.

- don

Jeff Donald · May 25th, 2003, 07:01 PM

Since terms are being discussed, I would like to offer two explanations of commonly confused terms, Vignetting and Light Fall Off. At first glance these might seem to be the same. But they have different causes and behave differently when the aperture is stopped down (use a numerically larger F number).

Vignetting is caused by an external source, such as hoods, stacked filters, or wide angle adapters. The effect is similar (dark corners) except the dark corners become sharper (more in focus) as the lens is stopped down.

Light Fall Off is caused by internal design of the lens. It is present in all lenses, but is usually not noticeable if the difference from the center to the corner is less than 1/3 F stop. Light Fall Off is most noticeable at maximum aperture and almost always is decreased by stopping down the lens. It is more common at the wide angle position of the zoom, but can occur at any position. The use of aspherical lens elements helps reduce light fall off.

Steve Withers · May 27th, 2003, 06:07 PM

I just got my GL2 today. It has this keyhole problem.. quite noticeable. It sucks especially for me because I will be doing a lot of greenscreen work. I guess I'll have to keep on experimenting to find ways around it. It seems as if the only way I can get rid of the effect is if I go outside and film. heh. There must be some way I can light the screen to reduce this effect...

Here's what I'm getting at the moment... http://www.scifi-pics.com/images/gl2error2.jpg

Ken Tanaka · May 27th, 2003, 09:02 PM

What settings produced this? (Shutter, aperture, zoom, etc.) There's alot of grain in that frame, suggesting that it was shot under very low light.

Chroma work will require quite a bit of light meticulously distributed evenly across the background with no reflections back to the talent.

Steve Withers · May 28th, 2003, 03:11 PM

The settings were factory default I think. There wasn't a whole lot of light that was hitting the screen (ok, bed sheet) because I had two 600watt lights directed at white boards which were aimed at the screen (hey, it worked with the canon ZR's, heh) so yes that shot was relatively dark. However, I just did another test with the two lights aimed directly at the screen. The fading was still present, although a little bit less noticeable.

Joe Sacher · May 28th, 2003, 03:43 PM

I got my GL2 yesterday and played around. Today, I shot my first video to actually bring into the computer and edit for someone. I'm seeing the keyhole effect, but it looks that it would be off normal televisions. I was shooting for the web, so I planned to crop it anyhow. If this is as bad as it gets, I'll be fine with it.

http://joesacher.com/video/edges.jpg

Settings:
Movie Frame mode
Full Wide on Zoom, with stock lense.
F1.6, 0db Gain
Don't remember shutter, probably near 1/60, as I seem to remember it being just bright enough.

Nice to see that Canon is filling the 720 frame with the GL2, instead of the 706 or so plus black vertical bars that I got out of the GL1 I had used before.

May 22nd, 2003, 11:11 PM	#31
Ken Tanaka Retired DV Info Net Almunus Join Date: Dec 2001 Location: Chicago, IL Posts: 6,943	I think Bud's "pulsing" problem was the same problem. His pulsing probably related to his use of the digital zoom. Hard to say about the Sony's problem. It sure looked like the same problem (on an enormous screen). I really doubt that it was a hood problem, though. This was an experienced camera operator not likely to make such a boo boo. I actually use the WD58 adapter on my GL2 most of the time and have yet to encounter the problem with it mounted. Not saying that the adapter is the prophlactic, just that I haven't experienced it. __________________ 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

May 22nd, 2003, 11:44 PM	#32
Dan Holly Major Player Join Date: Jul 2002 Location: Anchorage, Alaska Posts: 336	Just a thought Ken How close were the serial numbers on the pair of GL2's you've had this issue with. I checked my GL1 for this issue, and am not seeing it. Have any clips or photos you want to show for a visual descripton? __________________ Dan Holly Anchorage, Alaska

May 23rd, 2003, 12:09 AM	#33
Ken Tanaka Retired DV Info Net Almunus Join Date: Dec 2001 Location: Chicago, IL Posts: 6,943	Couldn't say, Dan. I didn't record the s/n of the first GL2 that I exchanged for the second. I'd bet that they may have been close numbers, as both came from the same dealer within days. Day's shot reflects the problem pretty much dead-on. Aaron and Randy Wisman (XM2) have also encountered this. I think Jeff Donald's supposition of slight variations in lens manufacture hits the nail on the head. Apparently the GL2/XM2's lens' design is such that it's just on the fringe of some boundary optical property. One micrometer of grind variation too much and... __________________ 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

May 23rd, 2003, 10:25 AM	#35
Ken Tanaka Retired DV Info Net Almunus Join Date: Dec 2001 Location: Chicago, IL Posts: 6,943	I can't tell you what you should do, Dany. I can only tell you the decision I made long ago and why I made it, which I did above. It's just not a very big issue to me. __________________ 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

May 23rd, 2003, 09:13 PM	#36
Val Rodriguez Regular Crew Join Date: May 2003 Location: Mission Viejo, CA Posts: 35	If the origin of this "imaging bug" is of a mechanical nature, obviously a lens/camera redesign would be required to eliminate the problem. There's another intriguing possibility...what if the problem was caused by limitations of the camera's current ROM drivers and if that's the case, wouldn't Canon be able to fix it with a drivers/software update?. Since this bug shows up under unique filming situations, not likely to be encountered or noticed under most filming conditions, the only thing that would move Canon to come up with a fix would be if they heard from a lot of their GL2 customers. __________________ Val Rod

May 23rd, 2003, 05:58 AM	#34
Dany Nativel Regular Crew Join Date: Dec 2002 Location: Odenton, MD Posts: 106	I wasn't using digital zoom at this time! So what would be your suggestion ? return or keep ? Thanks to everybody. Dany

May 24th, 2003, 01:46 AM	#37
Mario Lauria New Boot Join Date: May 2003 Location: Taranto Italy Posts: 14	I bought my XM2 almost a month ago. I've found the problem of "key hole" on my camcorder too. The factory continues to make so priced units with this "bug". I don't know if they will do something to solve the problem considering that mine is a very new machine. Is it possible that they haven't yet noted the problem? I don’t think so. Anyway, I hope that all these reports from us will lead somebody at the factory to do something. I can say that at the beginning I worried a lot about this shortcoming. Now I’m learning to manage it. In my experience, the “key hole” effect is mostly visible in low light and in particular conditions. The effect is more noticeable operating the zoom. It seems that the worst point is in the middle of zoom range. I've tried to modify the "key hole" in manual mode but no control has effect in it except the zoom. On the other hand, in most cases the machine makes really outstanding beautiful images (even good photos!) Colours are never excessive but well saturated and balanced. Images have a good sharpness and noise is almost invisible even in reasonable low light. Hope this may help. Ciao

May 24th, 2003, 12:30 PM	#38
Barry Goyette Trustee Join Date: Oct 2001 Location: San Luis Obispo CA Posts: 1,195	I don't know...I guess I've been listening to this discussion so long that I'm getting crabby...The so called keyhole problem is nothing more than an "uneveness of field" issue, which effects every zoom lens on the planet...(make that every lens, period). The gl2 as well as gl1 and and xl1s will all exhibit this problem in varying degrees due to the "longer than industry standard" zoom lengths. While we would all like a perfect zoom lens with a fisheye to moon crater zoom range with no vignetting (let's get the term right) or chromatic aberation. I'd also like a lens would bring us (god help us) peace without honor.... But it ain't gonna happen. There is a reason that a good cine zoom lens costs upwards of $20,000, and even then, I guarantee you if you pushed the film 3 stops (equivalent of 18db gain) and then did a rack zoom, you would find some unevenness of field visible in the footage. The gl2 produces amazing results for a camera with a 20x zoom (oops I guess it's the only one)...I'm not trying to be a cheerleader when I say that perhaps we shouldn't be so amazed at its shortcomings as we should at the fact that the zoom is as good as it is. Canon engineers have pulled off a miracle zoom in my opinion...look at the size of the thing and then compare it to the zoom on the xl1s...(the lens alone is almost as big as the gl2). I've been in commercial photography for almost 20 years, and I've never seen a perfect lens yet...especially a zoom. All systems have their limitations, and its one of the exciting things about being in this biz...learning what the limitations are, and then figuring out ways to succeed anyway... This discussion is useful. Hopefully it encourages Canon to continue to advance their technology to produce even better cameras....but the point that is being made...that somehow the gl2 is a defective camera and why isn't Canon doing anything to fix it...I think this is heading down the wrong path. Barry

May 24th, 2003, 12:44 PM	#39
Val Rodriguez Regular Crew Join Date: May 2003 Location: Mission Viejo, CA Posts: 35	Barry, Thanks for putting the issue in proper perspective. __________________ Val Rod

May 25th, 2003, 06:02 PM	#40
Don Berube Moderator Join Date: Mar 2002 Location: Boston, MA (travel frequently) Posts: 837	Barry, very well said! Too many times people forget that these cameras achieve a level of performance that was attainable in the past only with cameras costing thousands of dollars more. - don __________________ DONALD BERUBE - noisybrain. Productions, LLC Director Of Photography/ Producer/ Consultant http://noisybrain.com/donbio.html CREATE and NETWORK with http://www.bosfcpug.org and also http://fcpugnetwork.org

May 25th, 2003, 07:01 PM	#41
Jeff Donald Warden Join Date: Mar 2002 Location: Clearwater, FL Posts: 8,287	Since terms are being discussed, I would like to offer two explanations of commonly confused terms, Vignetting and Light Fall Off. At first glance these might seem to be the same. But they have different causes and behave differently when the aperture is stopped down (use a numerically larger F number). Vignetting is caused by an external source, such as hoods, stacked filters, or wide angle adapters. The effect is similar (dark corners) except the dark corners become sharper (more in focus) as the lens is stopped down. Light Fall Off is caused by internal design of the lens. It is present in all lenses, but is usually not noticeable if the difference from the center to the corner is less than 1/3 F stop. Light Fall Off is most noticeable at maximum aperture and almost always is decreased by stopping down the lens. It is more common at the wide angle position of the zoom, but can occur at any position. The use of aspherical lens elements helps reduce light fall off. __________________ Jeff Donald Carpe Diem Search DVinfo.net for quick answers \| Where to Buy? From the best in the business: DVinfo.net sponsors

May 27th, 2003, 06:07 PM	#42
Steve Withers Regular Crew Join Date: May 2003 Location: New Haven, CT, USA Posts: 59	I just got my GL2 today. It has this keyhole problem.. quite noticeable. It sucks especially for me because I will be doing a lot of greenscreen work. I guess I'll have to keep on experimenting to find ways around it. It seems as if the only way I can get rid of the effect is if I go outside and film. heh. There must be some way I can light the screen to reduce this effect... Here's what I'm getting at the moment... http://www.scifi-pics.com/images/gl2error2.jpg

May 27th, 2003, 09:02 PM	#43
Ken Tanaka Retired DV Info Net Almunus Join Date: Dec 2001 Location: Chicago, IL Posts: 6,943	What settings produced this? (Shutter, aperture, zoom, etc.) There's alot of grain in that frame, suggesting that it was shot under very low light. Chroma work will require quite a bit of light meticulously distributed evenly across the background with no reflections back to the talent. __________________ 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

May 28th, 2003, 03:11 PM	#44
Steve Withers Regular Crew Join Date: May 2003 Location: New Haven, CT, USA Posts: 59	The settings were factory default I think. There wasn't a whole lot of light that was hitting the screen (ok, bed sheet) because I had two 600watt lights directed at white boards which were aimed at the screen (hey, it worked with the canon ZR's, heh) so yes that shot was relatively dark. However, I just did another test with the two lights aimed directly at the screen. The fading was still present, although a little bit less noticeable.

May 28th, 2003, 03:43 PM	#45
Joe Sacher Regular Crew Join Date: May 2003 Location: Indianapolis, IN Posts: 177	I got my GL2 yesterday and played around. Today, I shot my first video to actually bring into the computer and edit for someone. I'm seeing the keyhole effect, but it looks that it would be off normal televisions. I was shooting for the web, so I planned to crop it anyhow. If this is as bad as it gets, I'll be fine with it. http://joesacher.com/video/edges.jpg Settings: Movie Frame mode Full Wide on Zoom, with stock lense. F1.6, 0db Gain Don't remember shutter, probably near 1/60, as I seem to remember it being just bright enough. Nice to see that Canon is filling the 720 frame with the GL2, instead of the 706 or so plus black vertical bars that I got out of the GL1 I had used before.