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Old May 18th, 2007, 04:00 PM   #1
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ND Filters?

I just got my brevis today, I was playing around with it, every thing was great. In the manual it talked about the optimal camera settings being around f5.0-f8.0 while keeping the lens wide open (assuming you want that kind of depth of field for that shot). It said not to stop the camera down beyond f8.0 if it is too bright, and to use Neutral Density filters.

I am just wonder if this is a quality of image thing, or some thing that could damage the adapter in some way. That might sound stupid, but I just want to make sure. Or is it that the washed out parts will stay washed out even if you stop down your camera?

Just trying to figure it out before I go buy 2-3 ND filters for my lenses.
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Old May 18th, 2007, 05:05 PM   #2
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By not immediately applying the ND filter in front of the Brevis, you have probably already damaged it beyond repair.

JK!

The use of an ND filter will simply let you control your environment so your lenses are working in their optimal settings. Most lenses are not as sharp at the extremes, so it is recommended that you keep things towards the middle. There are always exceptions, but it is most likely you will get the sharpest image at the middle of your camera's lens iris and you get a narrow depth of field at the 35mm lens most open setting. In most situations, you may actually want to stop the 35mm lens down a bit so the depth of field is not razor-thin. Try F2 to F4 to get the depth of field effects you are accustomed to from big-budget film features.

You probably just need one ND filter to get you close to optimal range. I just ordered an ND .6 (1/4) which is two f-stops of reduction. I also have some gradual ND filters for situations where I just need to bring down the sky a bit. I have the Cokin "P" series filter system and ND filters are very affordable. The polarizers they have can be used simultaneously with other square filters and they also reduce light. A polarizer and a moderate ND filter together should be more than enough light reduction for even the brightest scenes.

The Cokin filter system is definitely the most affordable system with drop-in filters for video cameras. They don't have every filter type available in their sizes, but the basic ND and polarizers are mostly what you need. You can even order a hood that fits the Cokin adapter if you want to get more impressive visual impact on people that see your rig.
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Old May 19th, 2007, 01:09 PM   #3
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I have a set of ND filters... I think you'll want a few options. In the Florida sun at mid day, I've had to use a circular polarizer and a 0.9 ND.
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Old May 19th, 2007, 09:41 PM   #4
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Jon, I figured that a polarizer and an ND .6 would be enough in front of the lens and I could use the camera's own ND filters for really bright sun. Of course, the 35mm lens can be stopped down a bit to reduce the light hitting the adapter screen while still retaining a fairly shallow DOF. Using F2.8 is still fairly shallow but adds about another stop of light reduction. Sure, you can get away with using the video camera to reduce all the light, but Dennis Wood has stated that it is better to keep excess light of the adapter screen to prevent blooming.

I also have graduated ND filters but I'm not sure I would use an ND, a graduated ND, and a polarizer all together. That's a lot of extra glass in the image path.
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Old May 20th, 2007, 12:13 PM   #5
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Well, now that my CF1L has arrived... I can stop down and use less filters.
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Old May 20th, 2007, 10:18 PM   #6
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Grad filters. Somehow, this has got past me over the years. I had thought the effect was added in post.

However on recent music video shoot looking over the shoulder of a professional DP, I observed he stuck one into the matte box to deal with a sunset sky burning out and the foreground subject, a couple on a park bench, being underlit.

This was on front of a Mini35 / JVC HD250. It worked its peculiar magic well.
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