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Old June 21st, 2017, 12:22 PM   #1
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Shutter speed in 25P

Hello!

I just bougth a LS300 and I am exploring all it has to offer...

I have a question that might sound basic, but I can find any answer.

Would there be any good reason not to film in 1/25 while shooting in 25P? I always see the standard is 1/50, but I don't really get why - I don't see any difference - and most of all, you gain one extra stop.

Thanks a lot for your help!
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Old June 21st, 2017, 12:42 PM   #2
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Re: Shutter speed in 25P

The general rule of thumb is that the shutter speed should be double the frame rate.

If you shoot at 1/25, you'll get a lot of motion blur in each frame, especially in fast moving scenes. Anything over 1/50 could give your footage a kind of strobe effect, depending on the scene.

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Old June 21st, 2017, 05:23 PM   #3
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Re: Shutter speed in 25P

Experienced cinematographers will set their camera, including shutter speed, according to the scene, lighting, action. Those with just enough knowledge to be dangerous will religiously set their shutter to the 180 degree "rule". Not pointing to any particular YouTube commentator. The "180 degree rule" for video, which is a bastardized adaptation of the theoretical maximum shutter opening rule for simple mechanical shutter film cameras isn't a bad rule of thumb, but note most film cameras of this type actually used a smaller angle. 1/25th at 25fps (360 degrees) can be quite appropriate in some circumstances, I tend to like it for slow waltzes at weddings and you do gain that extra light. At 1/25th you just need to be more careful to avoid camera shake, but if it's getting you the image that you want, that's what matters.
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Old June 22nd, 2017, 03:46 PM   #4
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Re: Shutter speed in 25P

1/25, 1/30, 1/24, when ever the shutter is the same as the frame rate at low frame rates (50fps and 60fps don't have this issue) you'll have motion blur somewhere in the frame unless you are filming a still life on a tripod. It can have the effect of making the image seem out of focus, even though it is in focus, especially with hand held filming.
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Old June 22nd, 2017, 09:48 PM   #5
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Re: Shutter speed in 25P

Motion blur is a product of shutter speed and action. Up to you to decide how much is acceptable or desirable in any situation. Keep the camera steady at 1/25th 25fps mostly looks fine, smoother than 1/50th second, but don't take anyone's word for it. Problem I believe with the LS300, (and most video consumer/prosumer cameras) is that's the most motion blur you can get in camera. If you want more you can't undercrank and step the footage, so you have to add it in post, which to me never looks as good.
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Old June 23rd, 2017, 01:26 AM   #6
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Re: Shutter speed in 25P

Wave your hand in front of the camera at 1/25 and then do it at 1/50. The difference in each frame is quite a lot. There are very few situations you'd want to go slower than 1/25, unless its specifically for that effect, so I don't think that's a 'problem' with the LS300 or any other camera. I get what you're saying Rainer, it's up tot he user, but for me 1/25 has too much motion blur. When I pause the video, I want to see sharp edges, and that's what 1/50 gives me, without totally losing the motion blur in movements. I try not to go above 1/100, because I think it makes the frames distracting and unnatural.

In general, I set my aperture first because this will have the biggest effect on the final look, and dictates the DOF. Then I'd use NDs or ISO to make sure the exposure is right, and only budge from 1/50 if I'm still struggling to get the correct exposure OR if there's a lot of motion. 1/25 is reserved for low light situations when I can't add lights, and ISO is already as high as I care to go.
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Old June 23rd, 2017, 02:44 AM   #7
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Re: Shutter speed in 25P

Quote:
Originally Posted by Rainer Listing View Post
but note most film cameras of this type actually used a smaller angle. 1/25th at 25fps (360 degrees) can be quite appropriate in some circumstances, I tend to like it for slow waltzes at weddings and you do gain that extra light. At 1/25th you just need to be more careful to avoid camera shake, but if it's getting you the image that you want, that's what matters.
I would use 1/25th of a shutter when I have no other choice, that means if I run into a situation at a wedding where they kill all the light and I have no light of my own and am shooting at max iso already, then lowering the shutter from 1/50 to 1/25 is fine to get that shot but otherwise 1/25 shutter gives too much motionblur and can make an image appear to look out of focus. There is a reason why many stick to 180 degree rule, rules are there to be broken but if you want natural looking motion your shutter should be double your framerate.
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Old June 23rd, 2017, 12:52 PM   #8
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Re: Shutter speed in 25P

There's nothing magical about 180 degrees, even with a classic film camera. It emerged as the most esthetically pleasing amount of 24fps motion blur over decades of motion picture making. What's open to debate is the practice of extending it as a principle to higher frame rates, e.g. dictating a 1/125 second shutter speed at 60fps. Since motion blur is determined solely by shutter duration, 1/125 second produces much less motion blur than a 1/48 second shutter at 24fps. In practice, 1/125 sec at 60fps is a good choice for sports, where you want the athletic motion to look crisp. For normal conversational movement, a shutter speed of 1/40 - 1/60 second produces smoother results than 1/125 seconds, regardless of the frame rate (limited of course, to a 360-degree shutter). At 1/24 - 1/30 second, however, the motion blur can look unnaturally processed, particularly when panning the camera.

More often, the overriding factor to consider is the interaction of shutter speed with the power line frequency of the scene lighting. In general, the best precaution is to use a shutter speed that is an even multiple of the AC frequency, e.g. 1/60 or 1/30 in the USA; 1/50 or 1/25 in Europe. With LED lighting, however, pulse width modulation dimming circuits operate at higher frequencies that can produce much worse flicker in a video camera than you see with your own eyes. I've often found a shutter speed of 1/40 second to work better with cheap LED lighting.
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