Ask a Question
GoPro Support Hub Ask a question. Share an answer. Find a solution. Stay stoked.
Announcements
Is your GoPro gear up to date? Check to see If it is on our Update page.
Cameras
Reply
Highlighted
Backpacker
Posts: 799

Re: Hero 7 - shoot in Pal or Ntsc to avoid.flicker

Smiley LOL

 

@danielr15... link should work ...it was a fresh uploaded video...it is like in the restaurants... it is about respect to the customers to provide fresh "food" everytime... but cold be hot... Smiley LOL

 

about the fps, shutter speed... just let me do some drawings and tests.

 

have a nice day,

robert

 

 

Highlighted
Backpacker
Posts: 799

Re: Hero 7 - shoot in Pal or Ntsc to avoid.flicker

[ Edited ]

hi all,

 

here is the theory, my vision on flicker.

 

just me robert

 

flickerbmp.png

 

Highlighted
Backpacker
Posts: 799

Re: Hero 7 - shoot in Pal or Ntsc to avoid.flicker

hi all,

 

the sinusoidal form of the mains will give you the "form" of the light.

our eyes makes the average.

 

to me the moments given by fps on the sinusoid form, when the shutter opens, is the one that could induce flickering.

if the same on the sinusoid form, will not flicker, regardless of the shutter speed.

if not, regardless the shutter speed, will flicker.

even at 24fps 1/24...it is like a wave

 

but this is just me.

 

 

 

fps = Hz

 

shutter_lower_fps_no_flicker.png

 

fps = 2 x Hz - no flicker

 

shutter_lower_fps_no_flicker_diff.png

 

fps=2 x Hz, shutter speed equal at limit with 1/fps - no flicker

 

shutter_equal_fps_no_flicker.png

 

 

fps not equal N x Hz

- will flicker...

- the more difference is between fps and shutter speed, the more the flicker

 

 

 

 

shutter_lower_fps_flicker.png

even if shutter speed = 1/fps, if it is not a multiple of Hz, the area will be different, so will be flicker

 

fps_diff_hz_shutter_fps.png

 

 

and here are some tests.

I tried some combinations.

 

if not match the Hz, the flickering is less obvious if use 1/fps, but more obvious as you go lower.

even 24fps 1/24 has flicker more like a wave that traverse the image, but it is there.

at 24 fps 1/192 is bad.

 

only the 25fps, 50fps (not shown), 100fps (not shown) when main is 50Hz will guaranty image quality from this point of view., regardless the shutter speed.

 

https://youtu.be/_SQHOoQ23hE

 

 

thank you,

robert

Highlighted
Explorer
Posts: 12,955

Re: Hero 7 - shoot in Pal or Ntsc to avoid.flicker

Thanks @robert1326
Makes sense.

Still can't watch the videos. Are you sure they are set to public?
Highlighted
Backpacker
Posts: 799

Re: Hero 7 - shoot in Pal or Ntsc to avoid.flicker

sorry @danielr15 were uploaded by default as "private".

 

now should be fine.....

 

have  a good one,

robert

 

Highlighted
Hiker
Posts: 8

Re: Hero 7 - shoot in Pal or Ntsc to avoid.flicker

[ Edited ]

Thanks Robert for the detailed information.

 

another question:

 

this time i will be doing a mixture of snowsports and city. 

i intend to film everything in 4k , 50fps (PAL) with flat colour and edit in premier pro.

 

do you guys think its a good idea?

Highlighted
Hiker
Posts: 8

Re: Hero 7 - shoot in Pal or Ntsc to avoid.flicker

the reason i asked the above is that i want a more cinematic look on the video as it is a family travel video. which means around 25fps.

 

but at the same time, i will also like to have a flexibility of converting some clips to slo-mo.

 

so i am at a bit of dilema here. 

 

is it wise to film in 60fps and convert to 25fps in premier pro? will it achieve the same effect as filming directly in 25fps?

Highlighted
Explorer
Posts: 12,955

Re: Hero 7 - shoot in Pal or Ntsc to avoid.flicker

IMO the "cinematic" look is overused and misunderstood by most people. Honestly, when you say " cinematic" what do you mean?

24fps was chosen by film makers not because of its incredible look, it had to do with the introduction of "talking" movies. Look up Vitaphone to learn more.

The reason people film in 24fps is to increase shutter time and therefore, increase motion blur. The easiest way to create "natural" motion blur is by using the 180 degree rule, or doubling the shutter denominator from whatever the fps is (2x 1/fps). For 30fps you would use a shutter of 1/60.

The 180 degree rule is fine, except when you want to slow your footage down. Now when you apply slow motion, instead of having clean frame by frame motion, you get a blurry mess.

Almost every video you watch is either 30fps or 60fps. 60fps and 30fps are generally accepted as looking more realistic. I honestly don't understand why anyone would want their family video to look less realistic.

The reason people complained about Peter Jackson's The Hobbit movies wasn't because the movie didn't look good, but rather because it looked too real. Since he filmed at 48fps the audience had a harder time suspending disbelief. We naturally want a little disconnect when watching movies on the big screen.

Can you use a 25fps sequence in Premier Pro? Sure, but if you are filming in 60, 120, or 240fps, then using a 30fps sequence is better as now you are dropping a regular and even number of frames. If you are going to be uploading to YouTube then you are better off with 60 or 30fps.

Your best option, just film at 4K/60fps, 2.7K/60fps, 1440p/60fps, or 1080p/60fps. In the evening, drop this to 30fps and turn off your stabilization (or try low light tips given below). When you need super slow motion, bump the fps up to 120.

When filming in low light:
Try locking the MIN and MAX ISO at 400 or even 800 in lower light. Alternatively, film in 60fps with a shutter locked at 1/240. If you want to stick with 24fps, then using the (4:3) format, 4K (4:3)/24fps when in lower light might also be beneficial as it uses a less aggressive stabilization.