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Old January 20th, 2004, 01:55 PM   #1
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Controlling exposure, DOF with mini35

Hey guys--Well I'm very intrigued by this device and have read, nearly, the entire dvinfo board on it. The issues of exposure and seeing the ground glass are a little concerning however. It is my understanding that you can control exposure using the mini35 via the following methods:

1. ND filters in a matte box.
2. Stopping down the 35mm lens (but not below 5.6 right?)
3. Adjusting the iris system built in to the mini35 (how many stops can you regulate with this system? Does stopping down with this system affect image quality?
4. Negative gain on camera.

With the DVX100, could you also do the following:

1. Internal ND filters in Cam.
2. Internal camera iris

Am I missing anything here? Lastly, I realize that shallow DOF is the main reason to use this cam, but let's say hypothetically I have a shot and I want deeper DOF. If I can't stop down the lens, and I don't want to shoot with a wider lens, how could I accomplish this? Another example, I have a long lens that, wide open, has incredibly shallow DOF. I want to stop down to an 8 to get more DOF, is this practical. Basically I want to make sure that the system is not a one-trick pony (albeit a really awesome trick), that it can deliver shallow DOF but nothing else. Thanks!

Peter

Also, Charles I read on an old post, before you bought your mini35, that you had concerns about color and contrast with the system. Now that you've been able to use it, what's your assessment? Is it going to negatively affect the image of the DVX100 in any way?
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Old January 20th, 2004, 02:12 PM   #2
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Peter,

Def not a one trick pony, but does need further consideration under certain conditions.

Be aware that an iris is only incorporated in the Mini35 with the XL1(s) version.

The official recomendation is that with the fixed lens cameras you should rely on ND filters. That being said, the DP for Ed Burns' piece has been very satisfied with the Panasonic internal iris. It really does a nice job.

Negative gain is something a lot of people will tell you to shoot with whether with the Mini35 or not. It is always better to underexpose video. Gamma can be brought up, but once you clip that information is gone.

As far as stopping up to increase the DoF, it's not completely impossible, it just becomes harder and harder to control how much the ground glass disappears. To say it another way, as you hit 5.6 and head higher the ground glass is more likely to appear and extra steps might be needed to assist in it's disappearance, so be aware of them. One place the ground glass can be troublesome is on shots of static, flat backgrounds e.g. a white wall or a deep blue sky. Certain Pan/Tilts can troublesome. So you just have to keep in mind what you are doing in the shot where you want to say use an T-8 and plan accordingly.

mizell
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Old January 20th, 2004, 02:35 PM   #3
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Thanks Mizell. I assume that using the internal iris on the Panasonic does not affect DOF, as the camera is simply recording the flat plane of the image the mini35 projects, correct? Also, can the internal ND's on the DVX100 be used to achieve the same quality as if ND's were dropped into the matte box? So just as a rule of thumb, the max tstop that could safely be used is around a T8 (simply as a ballpark)? Your point about shooting in ways to minimize the ground glass effect is well taken, but it is nice to know an approximate ballpark of what sort of DOF I would have available. Thanks again!

Peter
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Old January 20th, 2004, 02:50 PM   #4
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My initial preference would be to use NDs unless I could confirm that the Panasonic iris is an iris and not some form of electronic control. But as I said, I've seen good results using the in camera.

I'm not sure anyone has ever said how far down they've been able to stop and still get no/minimal ground glass. Something tells me it gets exceptionally harder at 8 and above, but 8 is prolly a good starting point.

There is also the speed control on the spinning motor and I've actually witnessed the pattern "magically" disappear when manipulated. The situation was a poorly lit desk with a woodgrain pattern. We stopped the lens way down, can't remember how far, and slowly adjusted the speed and when it hit the right frquency we all caught our breath as we saw it disappear.

mizell
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Old January 20th, 2004, 03:31 PM   #5
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Hi guys, thumb-typing on my Treo from the set today, so I must be brief...Peter, my initial concerns about the system turned into an appreciation for the look it creates, not just the Dof but the textural feel.
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Old January 20th, 2004, 03:59 PM   #6
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sounds good, Charles. Time to check this thing out at a rental facility!

Peter
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