Use of 72mm ND filter in combination with built in ND filters at DVinfo.net

Tim Bickford · July 22nd, 2006, 03:35 PM

Forgive me if this has been asked and answered before. A search of ND filters yields a vast array of results.

I was wondering if a 72mm ND lens filter can be used on the XL2 in combination with the built in ND filters? I have never used any ND filters other than the ones that are built into the 20X lens.

Also - I believe the filter size is 72mm. If not what is the correct size?

Thanks...

Tim

Brendon Whateley · July 22nd, 2006, 04:02 PM

Yes and Yes. A 72mm ND filter can be added to the lens. You can then fine tune the amount of ND by adjusting the built in filter. Just remember that stacking multiple filters does degrade the image due to all the extra surfaces in the light path.

Tim Bickford · July 22nd, 2006, 05:27 PM

Brendon-

Thanks.... How noticeable would the image degrade due to all the extra surfaces in the light path? Is it typically a substantial amount.

Thanks again!

Tim

Bill Hamell · July 22nd, 2006, 06:32 PM

Tim,

The general rule of thumb is no more than two pieces of glass in front of the lens.
Using this guide line you should not notice the difference and you should not get any vignetting.

Bill

Joe Barker · July 22nd, 2006, 07:43 PM

When and why would you need to use another ND filter on the XL2? I have never had to use more than the number 1 built in filter, and that was filming in bright summmer sunlight ? Just curious ?

Brendon Whateley · July 22nd, 2006, 07:55 PM

Quote:

Originally Posted by Joe Barker

When and why would you need to use another ND filter on the XL2? I have never had to use more than the number 1 built in filter, and that was filming in bright summmer sunlight ? Just curious ?

What apeture and shutter speed were you using? As others have noted elsewhere, shutter speed is a "motion effect" control while the apeture is the "depth of field" control. So, in the bright sun, if you want to use 1/48 shutter (film look) and F2.0 or similar, you will be way, way, overexposed without additional ND filters. If the look and/or DOF is not important to what you are doing, then you could get away with making other changes.

Tim Bickford · July 22nd, 2006, 09:01 PM

Thanks for all the information and comments.

I was recently shooting some video on a sunny day. I was using zebras at 90 IRE and closed the iris down (a lot - not sure what the F stop was) with the built-in ND at 1/32. I was getting a lot of stripes - mostly in the sky and on shinny surfaces.

I've noticed whenever I strive to properly expose (eliminate all the stripes) that my footage looks dark (see original post - http://www.dvinfo.net/conf/showthread.php?t=71681)

I'm shooting in 24P at 1/48 shutter the gain was at -3db. I was using this preset http://www.dvinfo.net/conf/showthrea...t=Globetrotter

It was suggested that I look into additional filters. I will seriously try to resolve this issue with the tools that the camera provides. I was more curious than anything about the filters.

I'm still learning. Please forgive the ignorance

Thanks again!

Cole McDonald · July 23rd, 2006, 10:40 AM

Do a search for zebras here...there was just a thread on how to expose using zebras. I tend to just dial the zebras @100 out and get slightly dark footage. I also take pains to make sure the forground and background is lit to fit within the lattitude constraints of MiniDV.

caucasian skin is properly exposed at the 85 setting of the zebras. Anything that shows zebras is over 85. If you have bright spots in your image that blow out when you properly expose your faces, you need to either bring up the light values on the subject or bring down the light values on the over exposed portions of your frame.

If you were to look for something to help bring the bright sky into compliance...you may want to look at getting a Circular Polarizer. This will allow you to dial the skies bluer/darker and the colors richer in your scene.

In MiniDV, it's slightly easier to recover from too dark than too light. Darks compress and can be slightly expanded. Brights clip and cannot be recovered. If we were concerned with film on negatives, we'd be more concerned with darks as the chemical solutions would wash the grain from that area away never to return.

July 22nd, 2006, 03:35 PM	#1
Tim Bickford Major Player Join Date: Sep 2005 Location: New Hampshire Posts: 448	Use of 72mm ND filter in combination with built in ND filters Forgive me if this has been asked and answered before. A search of ND filters yields a vast array of results. I was wondering if a 72mm ND lens filter can be used on the XL2 in combination with the built in ND filters? I have never used any ND filters other than the ones that are built into the 20X lens. Also - I believe the filter size is 72mm. If not what is the correct size? Thanks... Tim

July 22nd, 2006, 06:32 PM	#4
Bill Hamell Major Player Join Date: Aug 2004 Location: Mystic Ct. Posts: 477	Tim, The general rule of thumb is no more than two pieces of glass in front of the lens. Using this guide line you should not notice the difference and you should not get any vignetting. Bill __________________ Cinematographers Bring Shadow To Light

July 22nd, 2006, 09:01 PM	#7
Tim Bickford Major Player Join Date: Sep 2005 Location: New Hampshire Posts: 448	Thanks for all the information and comments. I was recently shooting some video on a sunny day. I was using zebras at 90 IRE and closed the iris down (a lot - not sure what the F stop was) with the built-in ND at 1/32. I was getting a lot of stripes - mostly in the sky and on shinny surfaces. I've noticed whenever I strive to properly expose (eliminate all the stripes) that my footage looks dark (see original post - http://www.dvinfo.net/conf/showthread.php?t=71681) I'm shooting in 24P at 1/48 shutter the gain was at -3db. I was using this preset http://www.dvinfo.net/conf/showthrea...t=Globetrotter It was suggested that I look into additional filters. I will seriously try to resolve this issue with the tools that the camera provides. I was more curious than anything about the filters. I'm still learning. Please forgive the ignorance Thanks again! __________________ Tim Bickford

July 23rd, 2006, 10:40 AM	#8
Cole McDonald Trustee Join Date: Nov 2005 Location: Sauk Rapids, MN, USA Posts: 1,675	Do a search for zebras here...there was just a thread on how to expose using zebras. I tend to just dial the zebras @100 out and get slightly dark footage. I also take pains to make sure the forground and background is lit to fit within the lattitude constraints of MiniDV. caucasian skin is properly exposed at the 85 setting of the zebras. Anything that shows zebras is over 85. If you have bright spots in your image that blow out when you properly expose your faces, you need to either bring up the light values on the subject or bring down the light values on the over exposed portions of your frame. If you were to look for something to help bring the bright sky into compliance...you may want to look at getting a Circular Polarizer. This will allow you to dial the skies bluer/darker and the colors richer in your scene. In MiniDV, it's slightly easier to recover from too dark than too light. Darks compress and can be slightly expanded. Brights clip and cannot be recovered. If we were concerned with film on negatives, we'd be more concerned with darks as the chemical solutions would wash the grain from that area away never to return. __________________ Web Youtube Facebook

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July 22nd, 2006, 04:02 PM	#2
Brendon Whateley Regular Crew Join Date: Jul 2006 Location: Fremont, CA Posts: 59	Yes and Yes. A 72mm ND filter can be added to the lens. You can then fine tune the amount of ND by adjusting the built in filter. Just remember that stacking multiple filters does degrade the image due to all the extra surfaces in the light path.

July 22nd, 2006, 05:27 PM	#3
Tim Bickford Major Player Join Date: Sep 2005 Location: New Hampshire Posts: 448	Brendon- Thanks.... How noticeable would the image degrade due to all the extra surfaces in the light path? Is it typically a substantial amount. Thanks again! Tim

July 22nd, 2006, 07:43 PM	#5
Joe Barker Regular Crew Join Date: Jul 2005 Location: Perth WA Australia Posts: 124	When and why would you need to use another ND filter on the XL2? I have never had to use more than the number 1 built in filter, and that was filming in bright summmer sunlight ? Just curious ?