Is This Rolling Shutter Problem ?

[BASSAM MSSALATIE]

HI while i was shooting some test footages about coke drink
i couldn't shoot varispeed , i have changed project settings to 2k 2:1
varispeed 89 fps , rec28 , shutter mode is relative under normal neon lamps
i have some bands

What am i doing wrong ?

here is the other test i were doing it .it is quite good without varispeed

http://www.vimeo.com/1592567

do i need to change anything , or varispeed will work in very specific circumstances ?

please help

 

[I Bloom]

The problem is your light source is strobing out of sync with your camera. You need to adjust your shutter angle or get a non-strobing source such as a tungsten head, or flicker free HMI. You would have the same problem with a film camera.

Consult your ASC Handbook for info about shutter angles and strobing sources.

IBloom

 

[BASSAM MSSALATIE]

Thanks Ian , but i have already put the shutter to relative ,
should i adjust it again ? i have tried hard but never fixed , i am sure as you said it is from light source frequency .

 

[Stephen Williams]

The problem is your light source is strobing out of sync with your camera. You need to adjust your shutter angle or get a non-strobing source such as a tungsten head, or flicker free HMI. You would have the same problem with a film camera.

Consult your ASC Handbook for info about shutter angles and strobing sources.

IBloom

Hi Ian,

24 fps should be flicker free in the US at any shutter angle.

Stephen

 

[BASSAM MSSALATIE]

Stephen : should i try to change my project frame rate to suite my
electric frequency ? something like 25 fps for 50 hz electric source ?
without changing shutter angle

 

[buggy]

Go for 180 shutter and 25 frames for 50 Hz ,see what happens

 

[Ariana]

Hi Ian,

24 fps should be flicker free in the US at any shutter angle.

Stephen

Can you explain how 24fps makes all strobing sources flicker
free especially if you're in a 60Hz country?!!!

Seriously, you need to be at a multiple of your refresh
to deal with flicker if you aren't changing your fps.

If you shoot 30 or 60fps with 60Hz lights is the other way to
go but generally that's not feasible.

 

[Joe Gill]

Ian is saying that the frequency of the light and the film speed and the shutter speed are causing this phasing effect with the bar, so you need to switch to a light source that will avoid this issue. What is your light and peep the ACM, if you don't have one, get one (dont get the black one its too unwieldy)

 

[Stephen Williams]

Can you explain how 24fps makes all strobing sources flicker
free especially if you're in a 60Hz country?!!!

Seriously, you need to be at a multiple of your refresh
to deal with flicker if you aren't changing your fps.

If you shoot 30 or 60fps with 60Hz lights is the other way to
go but generally that's not feasible.

Hi,

Normal HMI lights should be fine, strobe lights are supposed to strobe so the strobe speed must be matched to the camera.
At 60Hz the following speeds should be flicker free with a film camera regardless of shutter angle:-
1.00, 1.5, 1.87, 2, 2.5 ,3, 3.75 ,4 ,4.8, 5, 6, 6.666, 7.5, 8, 10, 12, 15, 20, 24, 30, 60. basically any speed that can be divided by 60 and produce

At 50Hz the following shutter speeds should be flicker free with a film camera regardless of shutter angle

1.00, 1.25, 2, 2.5, 3.333, 4, 5, 5.555, 6.25, 6.66, 8.333, 10, 12.5, 16.666, 20, 25, 33.333, 50

It is possible that the rolling shutter on Red may not mimic a film camera.

Stephen

 

[Florian Stadler]

The list of fps that Stephen provides is ABSOLUTELY dependent on a normal shutter angle of 180 degrees. 24 fps @ 90 shutter WILL flicker...