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Canon XL and GL Series DV Camcorders
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Old November 2nd, 2004, 05:57 AM   #1
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Circular polarizer and ND filters = grain

hello all
I was lucky enough to be recently shooting the Victoria Falls in Zambia using my new XL2.

It was extremely bright so I had my ND filter on (I use the 16x manual) and a circular polarizer on the front of the lense.

I noticed this combination created a lot of grain in the picture.

Has anyone else noticed this?

I then used my polarizer filter without the in built ND filters, and just increased my shutter speed to keep the camera at about F6. (F6 used to be the optimal setting on the XL1S, I imagine it's the same for the XL2??)

The footage I shot was amazing. I shot local game, schools, jeeps off roading. The 16:9 is just incredible!

your thoughts would be interesting.

Mark
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Old November 2nd, 2004, 10:37 AM   #2
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Mark, dumb question, but did you make sure the gain was not set at a higher value than 0? Were you in automatic mode?

I have not tested the automatic mode on the XL2 yet (nor am I planing to) but sometimes those settings can have weird effects on the image in extreme conditions. I remember when I was using my old CCD-VX3 camcorder, when set to automatic, it would often crank up the gain BEFORE lowering the F-stop number, which is plain non-sense. I will assume it's better on the XL2, but this is something to at least double-check.

Also, what brand of filters are you using? Cheapo resine filters can sometimes have unusual and unwanted effects on your image quality.

As for the sweet spot for the XL2, it's more related to the lens itself than the camcorder, but usually I think you can fairly say between F4 and F5.6 should give you excellent results every time.

I cannot comment on the quality of the built-in NDs on the 16x manual, as I don't own this lens, but I'd be surprised if the problem came from those.
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Old November 2nd, 2004, 10:42 AM   #3
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Hi David
thanks for your reply.
No I only ever use my camera in Manual mode. I've never even tried the other modes!
It's a decent Tiffen polariser and my gain was at -3.
When I used the polariser without using the in built ND filter on the 16x lense the picture was fine.
It must be a 'glass on glass' issue of some sort.
regards
Mark
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Old November 2nd, 2004, 10:45 AM   #4
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A good thing for you to do Mark would be to use your polarizer with an external ND filter and see if the problem shows again. This will at least enable you to isolate the problematic factors.
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Old November 2nd, 2004, 11:03 AM   #5
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Hi David
this could be worth a try.
At the time I was so suprised it happened. And when you're on location, you don't really have time to experiment.
Mark
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Old November 2nd, 2004, 11:32 AM   #6
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I also seem to see a lot of "grain" with the ND filters in on my 16xmanual lens. I thought at first, that it might be the "Film Grain" effect accidentally switched on, but no. It just seems... grainier with the ND filters in.
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Old November 2nd, 2004, 11:57 AM   #7
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Hi Richard, interesting isn't it.
I now resort to increasing the shutter speed now instead of using the in build ND's. I have never noticed any loss in picture quality doing this.
I wonder if the ND filters on the new 20x lens have the same problem.
mark
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Old November 2nd, 2004, 01:19 PM   #8
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<<<-- Originally posted by Mark McCarthy : Hi Richard, interesting isn't it.
I now resort to increasing the shutter speed now instead of using the in build ND's. I have never noticed any loss in picture quality doing this.
I wonder if the ND filters on the new 20x lens have the same problem.
mark -->>>

I don't know if this is a similar issue but on the 20x I see some of the same type of things. I haven't used my polarizing filter yet but if I am shooting outside and have to use a ND 1/6 to get a good exposure. I have the lens almost open.....1.8-2.8 area. I see grain in darker areas of the shot. If I turn off the neutral density filter and then compensate for the light but simply stopping way down......I don't see the grain. In fact I notice a great improvement of the colors in the shot.

This has been a pet peave of mine since I got the XL2. It seems uber sensitive to minor changes in iris settings. I can be shooting a red flower at 1.8 and the colors are gorgeous....but if the sun comes out and I have to stop down to 3 or 4 I notice the colors start to lose their pop. I know that all lenses exhibit this to some extent but there is little margin for this issue on the XL2. My old DVX had much more range before I noticed the colors going flat.
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Old November 2nd, 2004, 01:20 PM   #9
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Mark,
I made the same choice, up the shutter speed. I never noticed this difference while shooting with the XL1 with the ND filters on. I wonder if there is a difference in resolving power, with the increased pixel numbers in the smaller target area of these new ccd's, that would make the "Grain" of the ND filters more visible?
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Old November 2nd, 2004, 01:43 PM   #10
 
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I shot some exteriors recently, using the ND filters (the light in Miami is extraordinarily bright), and I didn't notice any grain.

Jay
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Old November 2nd, 2004, 03:27 PM   #11
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I haven't noticed a grain increase either with the 20X and NDs but I'll have to check that out more closely just to make sure.
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Old November 2nd, 2004, 03:27 PM   #12
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Guys,
don't see how any "grain" in the ND filters could possibly show up on the screen. To see grain means that it has to be sharp - it has to be focussed - so I don't see how a filter that isn't exactly near the CCD can project a sharp image onto it...

Robin
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Old November 2nd, 2004, 04:02 PM   #13
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JUst for the record it is electronic grain that I am seeing. Not grain that would actually be on the element of the ND filter itself. Again...I am not sure why but the image just seems to suffer a little when I have the ND on. If I can shoot without it on and stop down I find i get better colors and less noise. And this is with the gain at 0 or -3.
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Old November 2nd, 2004, 04:15 PM   #14
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Robin
There's the rub. How close are the nd filters within the lenses to the actual ccd elements? And since the same image is now being projected onto a smaller (In the case of the 4:3 target) chip area, with an INCREASE in pixels...Compared to the target area with the same lens on the XL1/s - my question is are we seeing some sort of corresponding increase in resolution that allows the 'appearance' of the nd filters???

I have no scientific facts or figures in mind, just wondering if that is possible. Again, as I mentioned earlier in another thread, this might NOT be a case of "graininess" so much as a case of increased scrutiny that comes with new equipment and expectations.

I will be in Houston, where I can compare to the XL1 I used to shoot with in a few days. A side by side would settle the issue in my mind.
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Old November 4th, 2004, 04:05 AM   #15
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...no chance you'd used any of the custom settings to decrease contrasts in the darker areas (can't remember the name of the setting does this...master ped?) anyhow just a thought...I'm about to use my XL2 for the first time in South Africa with amps of sunshine and yer post's got me a tad nervous...
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