Noob ND Filter Question

[Dakrisht]

Struggling with some incredibly basic.

180 degree rule states to have your shutter 2x your frame rate. So shooting at 30fps = 1/60th of a shutter for smooth video. Got it.

Using the PolarPro app shows me what ND filter I should use based on current metering. Got that too.

So do I simply keep my shutter at 1/60th and apply the correct filter and boom?

Example:

Metering at 1/800th shows that I should use an ND16 which is a 4-stop filter. But 4-stops from 1/800th is actually 1/50th which I guess is close enough?

Same with the app showing me to also use an ND16 with a 1/1600 shutter. But 1/1600 less 4-stops is 1/100th - not 1/60th.

I guess the golden rule is to also use a 1/60th shutter and simply apply the proper ND will keeping 30fps.

Finally, given the adjustable aperture of the M2P - any insight on optimal aperture for the scene. The PolarPro doesn’t allow for aperture calculations and the rule from photography here is the smaller, the sharper.

Thanks!

 

[brett8883]

Struggling with some incredibly basic.

180 degree rule states to have your shutter 2x your frame rate. So shooting at 30fps = 1/60th of a shutter for smooth video. Got it.

Using the PolarPro app shows me what ND filter I should use based on current metering. Got that too.

So do I simply keep my shutter at 1/60th and apply the correct filter and boom?

Example:

Metering at 1/800th shows that I should use an ND16 which is a 4-stop filter. But 4-stops from 1/800th is actually 1/50th which I guess is close enough?

Same with the app showing me to also use an ND16 with a 1/1600 shutter. But 1/1600 less 4-stops is 1/100th - not 1/60th.

I guess the golden rule is to also use a 1/60th shutter and simply apply the proper ND will keeping 30fps.

Finally, given the adjustable aperture of the M2P - any insight on optimal aperture for the scene. The PolarPro doesn’t allow for aperture calculations and the rule from photography here is the smaller, the sharper.

Thanks!

View attachment 70213

That chart is just a guid to kinda get you in the general area.

As to aperture, set your aperture before choosing an ND filter. Then choose the ND Filter that will get your shutter speed where you want it at double your frame rate.

Aperture determines the depth of field which is to say the feeling of depth in the video. Maybe you want your audience to focus just in your subject and not be distracted by the background then a lower aperture value would be desired but generally the higher the aperture the greater the sense of “richness” in a frame. This is a creative choice and less a formula to follow.

 

[Dakrisht]

I’ve learned that F/4 is the sharpest aperture on the M2P with sharpness fading after. F/2.8 seems to be sharp as well and F/5.6 is where you start to lose sharpness.

Currently metering at F/4, ISO 100 and a shutter of 1/800 so ND16 seems to be ok for smoothness and the 180° rule.