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Sony NXCAM NEX-FS700 CineAlta
4K EXMOR sensor with SDI, slow-motion recording.


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Old January 17th, 2013, 02:21 PM   #1
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The 180 degree rule with S&Q and super slow-mo question

My recording format is set to 1080/24P FX. In the shutter display within the menu I've selected degree then set the camera to 180 degree. In the Slow & Quick menu I've selected 60 fps as my frame rate. When I hit the S&Q button on the side of the camera the degree jumps from 180 to 360 degree (1/60). If I hit super slow motion the frame rate goes to 85 degree if I selected 240 fps (1/250) or 170 degree (1/125) if 120 fps was selected. I was expecting it to remain at 180 degree, why does it shift to a different degree? Even when I select seconds in the shutter display I still get a shift in shutter speed. I want to keep the 180 degree shutter rule to maintain the “film look." When filming with high frame rate in S&Q or super slow motion if using 240fps should I just adjust the shutter to 1/500 , 1/250 for 120fps or 1/125 for 60fps or just leave it to what the camera defaults to?
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Old January 17th, 2013, 03:23 PM   #2
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Re: The 180 degree rule with S&Q and super slow-mo question

It does get confusing because there is no actual mechanical shutter in the camera. It helps if you forget about the term "shutter degree" for a bit and think about the fractional equivalent. When shooting overcranked, the camera does the math automatically. If you are shooting at 120fps, the shutter has to be equal to or shorter (faster) than 120th of a second. The closest standard shutter setting is 125th, which is what is displayed. In actuality, it is probably a exponential fraction of the actual frame rate. (23.98 x 5 = 119.9~/shutter speed). Shooting at normal speeds, the shutter can be set to times longer than the actual frame rate (slower than 1/24th or 360x degrees), which creates image blur and would not generally be desired in overcranked footage.

Shooting shutter speeds longer than the actual frame rate requires image buffering. It might be that the camera doesn't have the processing power to do this and buffer the higher frame rates.

I usually shoot at the default shutter speed since it is the longest setting for a given frame rate and lighting requirements are always higher when overcranking.
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Old January 17th, 2013, 05:54 PM   #3
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Re: The 180 degree rule with S&Q and super slow-mo question

I figured the camera was automatically doing something behind the scene but I wasn't sure. So just leave it at the default got it. thanks man!
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Old January 17th, 2013, 10:25 PM   #4
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Re: The 180 degree rule with S&Q and super slow-mo question

IMHO the engineers messed up the shutter angle function, which entirely defeats the purpose of mimicking a film camera's shutter.

If you are set to 180 at 24p (1/48th of a second), and switch to 60p, I would normally expect the shutter to stay at 180 (1/30th of a second) but it doesn't. It automatically switches to 1/60th of a second (360) and displays that value in degrees. But that's just a little pet peeve, not the real problem.

When going into super slow motion at 120 or 240fps, the camera also effectively switches the shutter to 360 (or just short of it), but instead displays degrees relative to 24fps! It makes no sense to switch from 24p to 240p and see 85 displayed when it should say 360. As soon as I see 85 I wonder why I'm not exposing the full time available?

Until Sony can fix this with a firmware update I am keeping my display in fractions of a second.
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Old January 18th, 2013, 02:38 AM   #5
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Re: The 180 degree rule with S&Q and super slow-mo question

I'm not sure I fully understand the obsession with using degrees on video cameras. (That's not an excuse for Sony's poor implementation of degrees on the FS700).

When you use degree's your having to continually make a mental calculation of your shutter speed in fractions of a second to ensure that you don't run into phase issues with your lighting etc. If you use fractions of a second you know exactly where you are. I know of many film cameramen, myself included that found degrees to be a nuisance with the shutter speed changing all over the place depending on frame rate and angle. Fractions of a second are far easier to work with. For example, when shooting in 50hz areas use a shutter speed that is a multiple of 1/50 and in 60hz countries use a fraction of 1/60, no matter what your frame rate to ensure flicker free pictures under artificial lighting. Try figuring out what angle you need to shoot 24p in a 50hz country (the answer is 1/172.8). Degrees is a hangover from film days that is seen as fashionable because it make you sound like a cinematographer, but this is fashion for the sake of fashion, not because it makes sense or is a better way to work. If you want to mimic a film camera with a 180 degree shutter then all you have to do is halve the frame rate, so 24p = 1/48, 25p = 1/50, 30p = 1/60. Very simple. Then if you need to match the local mains frequency simply use the next highest mains multiple. So if shooting 24p in a 50hz country use 1/50th or shooting 24p in a 60hz country use 1/60th, much easier to figure out than degrees.
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Old January 18th, 2013, 09:55 AM   #6
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Re: The 180 degree rule with S&Q and super slow-mo question

I would rather use shutter speed instead of degrees unfortunately when in Cine mode my new
Sekonic light meter uses degree or angle instead of shutter although I could switch over to
HD mode which uses shutter speed but then it won't allow me to set the shutter to 1/48 only
1/50. I can't imagine anyone using degrees to look fabulous but then again who knows.
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Old January 18th, 2013, 07:24 PM   #7
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Re: The 180 degree rule with S&Q and super slow-mo question

Quote:
Originally Posted by Alister Chapman View Post
I'm not sure I fully understand the obsession with using degrees...is fashion for the sake of fashion, not because it makes sense or is a better way to work.
Unfortunately degrees are not dying off with film, especially for those of us who use Alexa Studio or F65.
I was recently involved in HFR tests for Christie that used both the F65 and Alexa Studio at various shutter angles, so we still need to be versed in the relationship between exposure time and shutter angle.
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