Which ND filter to use?

[henkster]

Which ND filter to use for which video FPS? I always was guessing. I created a sheet for everyone to use to know ND filter you should be using!Fill in the FPS (for example 30) and what the camera of the drone measures for the light exposure (for example at a bright day 1/4000 s) and the sheet calculates the ND filter you should use:

Video and use ND filters

docs.google.com

Feedback is welcome

 

[slup]

Hi there & welcome to the forum

You need to make that Google sheet public ... (if you don't want everyone to ask you for access).

The formula to figure out what filter factor number you need can be made really simple... it's enough to just divide the measured shutter time with the the shutter time you want, that gives the filter factor.

Measured: 1/4000s
Wanted: 1/120 for a frame rate of 60fps (as you want to follow the 180 degree rule (shutter=2xFPS) for a natural motion blur)

4000/120=33,33
Meaning a ND32 will do the job... the exposure will be a tad bright if locking the shutter as the required ND33,33 is slightly darker than the ND32 you put on & if you can live with a changing exposure you could go with a AUTO shutter... otherwise a slight brightness adjustment might be needed in post if going with a locked shutter on 1/120s (probably not though...).

 

[henkster]

Hi there & welcome to the forum

You need to make that Google sheet public ... (if you don't want everyone to ask you for access).

The formula to figure out what filter factor number you need is really simple... just divide the measured shutter time with the the shutter time you want, that gives the filter factor.

Measured: 1/4000s
Wanted: 1/120 for a frame rate of 60fps (as you want to follow the 180 degree rule (shutter=2xFPS) for a natural motion blur)

4000/120=33,33
Meaning a ND 32 will do the job... the exposure will be a tad bright if locking the shutter as the required ND33,33 is slightly darker than the ND32 you put on & if you can live with a changing exposure you could go with a AUTO shutter... otherwise a slight brightness adjustment might be needed in post if going with a locked shutter on 1/120s (probably not though...).

I thought it was public..Change it! Sorry for that!

 

[GFields]

Hi there & welcome to the forum

You need to make that Google sheet public ... (if you don't want everyone to ask you for access).

The formula to figure out what filter factor number you need can be made really simple... it's enough to just divide the measured shutter time with the the shutter time you want, that gives the filter factor.

Measured: 1/4000s
Wanted: 1/120 for a frame rate of 60fps (as you want to follow the 180 degree rule (shutter=2xFPS) for a natural motion blur)

4000/120=33,33
Meaning a ND32 will do the job... the exposure will be a tad bright if locking the shutter as the required ND33,33 is slightly darker than the ND32 you put on & if you can live with a changing exposure you could go with a AUTO shutter... otherwise a slight brightness adjustment might be needed in post if going with a locked shutter on 1/120s (probably not though...).

Greetings from Birmingham Alabama USA, welcome to the forum!

Drop by the pilot’s check-in to introduce yourself

 

[FlySkyJumper]

Which ND filter to use for which video FPS? I always was guessing. I created a sheet for everyone to use to know ND filter you should be using!Fill in the FPS (for example 30) and what the camera of the drone measures for the light exposure (for example at a bright day 1/4000 s) and the sheet calculates the ND filter you should use:

Video and use ND filters

docs.google.com

Feedback is welcome

Love this idea...but are you wanting the community to contribute is that what you meant as far as feedback goes? I just see one line.

Edit: Ahhh I see, from what I can tell you already created the formulas, we simply can use this in excel now or google sheets and put in our own numbers to get the settings we will likely need to use. This can be a great learning tool!

Thanks OP!

 

[henkster]

Love this idea...but are you wanting the community to contribute is that what you meant as far as feedback goes? I just see one line.

Edit: Ahhh I see, from what I can tell you already created the formulas, we simply can use this in excel now or google sheets and put in our own numbers to get the settings we will likely need to use. This can be a great learning tool!

Thanks OP!

You are welcome

 

[Auencam]

I am about to give up on filters and just let the AE do it's job. Works really well most of the time.

 

[Jug's Life]

for video
Sunny days - ND64
Cloudy days - ND32

for photos
automatic is perfect unless you want some effect like long exposure on water, traffic, etc.

 

[slup]

for video
Sunny days - ND64
Cloudy days - ND32

for photos
automatic is perfect unless you want some effect like long exposure on water, traffic, etc.

That guideline (regarding that for video) seems first of all a bit rough & secondly intended for a really bright environment (snow or a desert) or a camera that have a really wide fixed aperture... both generating really fast shutter speeds.

The use of ND's is mainly for keeping the shutter in control, achieving a special effect... for instance get motion blur according to the 180 degree rule and/or minimize stutter in the video when the camera moves in relation to the surroundings (like pannings or flights close to ground & obstacles).

Below is a cheat chart showing how the shutter i slowed down with different ND strengths...


Here a bit guidance over in which lightening conditions different ND strengths can be good...