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Old March 9th, 2006, 11:53 AM   #1
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opening iris and using nd filters on gs400


I've heard about a lot of people using Neutral density filters on their camcorders and then opening the iris more and using a lot more light to get a better image and also a shallower depth of field. Is this true, and if so what nd filters would you recomend for the panasonic gs400? It has internal nd filters so what would I need? Also if use this mehtod should I be using the nd filters with all my shots to help the visual continnuity? I really would like shallow depth of field for my close ups, don't know if it's possiblt to get good results with a mini dv cam. Also I have a polarizing filter that i believe cuts down 1 1/2 stops, but has the blue look to it.

Any suggestions?

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Old March 9th, 2006, 09:09 PM   #2
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Unfortunately, the size of the CCD is critical in getting a shallow DOF. 1/3" CCD cameras can barely achieve shallow DOF even with open iris and telephoto zoom. The GS400 has an even smaller CCD, so almost everything will be in focus no matter what aperture settings you use. If you want this effect, go to the "Alternative Imaging" forums and read up on 35mm lens adapters that provide shallow DOF capability. I have the Letus35 and the effect is significant.
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Old March 10th, 2006, 10:46 AM   #3
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I am a fellow GS400 owner and amatuer cinematographer. Let me tell you, you won't get the really shallow film look you are seeking, but you can coax a little bit of something out of this little cam.

Obviously DOF is technically shallowest with the iris wide open at F1.6. So, the answer to your ND question is that you need a variety of ND's, so you can get the iris to F1.6 regardless of what the lighting situation is. On a bright sunny day when the camera is exposing F14 or so, you need to cut a full 6 stops to get OPEN, so you'd need an 1.8 ND. In a dimmer interior if the camera were exposing F3.4, you'd only need to cut 2 stops, so a .6 ND would work. You need a set of them, and to combine them as necessary.

As you can imagine, this doesn't work for run and gun shooting. It works for controlled shooting only. Yet, there are more complications.

The iris can only be at F1.6 at the widest zooms, and wide zoom have a different look than telephoto, a little unrealistic and barrell distorted. As soon as you start zooming in, the irisi starts closing, until it's down to F2.8 at full telephoto. So, depending on the zoom, you are limited to a different max wide iris. There is something to be said for zooming in, though. The depth of field may be higher, but the field of view decreases, giving you what appears like shallower depth of field.

It adds up to a lot of work, and not a huge reward. ND's can be useful in general, however. If you know you'll be outside in bright sun, it's good to have some ND on the camera so you don't have the insanely deep DOF that F14 or F16 gives you.

One more thing that you can do to get perceptibly shallower depth of field is to turn down the sharpening level in the GS400. This is done through MENU > ADVANCED > PICTURE ADJ. With default sharpening, the camera is actually sharpening your out of focus areas and making look like they are in focus. It's fighting against you. Turn it down to a level that is acceptable to you, and your footage with look smoother and appear to have slightly shallower DOF.

All of this stuff is fun to test and experiment with. At least it has been for me.

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