ND's for Video vs Photos

[malbowski85]

I have bought a set of Skyreat ND/PL filters (4/8/16/32/64). On one tutorial on youtube, the guy is using a 64 and hoping he gets the shot before the sun comes out. He is taking stills not video, of the sea rolling in from above for the motion blur effect. As far as I can gather, the sub64 filters are only useful for video, is that correct, and why?

 

[tck444]

Quite a few variables and seems it would depend on the current lighting and what effect, composition, or exposure you are trying to create?

This guy likely has the best explanation and has 3 videos on the subject.

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[slup]

...He is taking stills not video ...for the motion blur effect.
As far as I can gather, the sub64 filters are only useful for video...

A plain ND-filter only have one effect ... It prevents light to reach the sensor, it's like sunglasses for your lens.

The reason you want to get in less light, usually is due to that you want to modify the shutter speed ... & specifically make it slower.

You can make the shutter slower in other ways also ... you can stop down the aperture if it's not fixed. You can adjust the ISO to a lower value making the sensor less sensitive.

But if you have a fixed aperture ... already use the lowest possible ISO ... & using the camera during bright daylight ... then the shutter will be around 1/1000sec. So if you want to to get a slower shutter the ND-filter is the only thing you then can use.

Why you want a slower shutter have nothing to do with if you're videoing or taking stills ... it's only depending on what you want to achieve.

With a slower shutter moving objects in the motif will move slightly during the exposure ... meaning they will have motion blur. How dark the ND is will regulate how slow the shutter will be & by that how much motion blur the object will have.

In video you want motion blur to get rid of that "sticky" look you get when all frames are pin sharp ... & also get away from the stuttering that easily occur when to little motion blur is introduced ... search for "the 180 degree rule"

Here 3 levels of blur introduced in the video ...



When you're taking stills this is the effect you are after for instance...


Or like here... getting smooth water.

 

[Brockrock]

@slup Great post! A nice and clear explanation regarding something that many folks do not understand.

 

[malbowski85]

A plain ND-filter only have one effect ... It prevent less light to reach the sensor, it's like sunglasses for your lens.

The reason you want to get in less light, usually is due to that you want to modify the shutter speed ... & specifically make it slower.

You can make the shutter slower in other ways also ... you can stop down the aperture if it's not fixed. You can adjust the ISO to a lower value making the sensor less sensitive.

But if you have a fixed aperture ... already use the lowest possible ISO ... & using the camera during bright daylight ... then the shutter will be around 1/1000sec. So if you want to to get a slower shutter the ND-filter is the only thing you then can use.

Why you want a slower shutter have nothing to do with if you're videoing or taking stills ... it's only depending on what you want to achieve.

With a slower shutter moving objects in the motif will move slightly during the exposure ... meaning they will have motion blur. How dark the ND is will regulate how slow the shutter will be & by that how much motion blur the object will have.

In video you want motion blur to get rid of that "sticky" look you get when all frames are pin sharp ... & also get away from the stuttering that easily occur when to little motion blur is introduced ... search for "the 180 degree rule"

Here 3 levels of blur introduced in the video ...
View attachment 125858


When you're taking stills this is the effect you are after for instance...
View attachment 125859

Or like here... getting smooth water.
View attachment 125860

Awesome. Thanks for that

 

[Cymruflyer]

A plain ND-filter only have one effect ... It prevent less light to reach the sensor, it's like sunglasses for your lens.

The reason you want to get in less light, usually is due to that you want to modify the shutter speed ... & specifically make it slower.

You can make the shutter slower in other ways also ... you can stop down the aperture if it's not fixed. You can adjust the ISO to a lower value making the sensor less sensitive.

But if you have a fixed aperture ... already use the lowest possible ISO ... & using the camera during bright daylight ... then the shutter will be around 1/1000sec. So if you want to to get a slower shutter the ND-filter is the only thing you then can use.

Why you want a slower shutter have nothing to do with if you're videoing or taking stills ... it's only depending on what you want to achieve.

With a slower shutter moving objects in the motif will move slightly during the exposure ... meaning they will have motion blur. How dark the ND is will regulate how slow the shutter will be & by that how much motion blur the object will have.

In video you want motion blur to get rid of that "sticky" look you get when all frames are pin sharp ... & also get away from the stuttering that easily occur when to little motion blur is introduced ... search for "the 180 degree rule"

Here 3 levels of blur introduced in the video ...
View attachment 125858


When you're taking stills this is the effect you are after for instance...
View attachment 125859

Or like here... getting smooth water.
View attachment 125860

Oopps, Let me clear that statement up for you/others to avoid confusion here. We know what you mean but you stated it incorrectly. It does NOT prevent less light, it actually allows for letting in less light. To prevent less light would mean that it would allows more light to enter.

Jag förstår att du är svenska och att engelska inte är ditt första språk. So correctly stated to avoid confusion, it would be better stated to say it prevents light from entering the camera, or better yet, it reduces the light entering the camera. Most of us understand what you meant to say but some, just may get confused.

As you mentioned,, allowing less light in means the shutter would stay open longer, which would cause motion blur in still image photography. Usually not something a photographer wants to do, unless they want to show light blur or water motion blur, such as a waterfall, or flowing river, or a seascape, usually early morning or early evening. Then you want to reduce/limit the light entering the camera and the best way to do that is with ND filters.

 

[Cymruflyer]

I have bought a set of Skyreat ND/PL filters (4/8/16/32/64). On one tutorial on youtube, the guy is using a 64 and hoping he gets the shot before the sun comes out. He is taking stills not video, of the sea rolling in from above for the motion blur effect. As far as I can gather, the sub64 filters are only useful for video, is that correct, and why?

Using ND filters for video allows for a slower shutter speed to give a more film like look to your moving images, rather than a digital video look, such as that often seen on, say, soap operas, that harsh sharp look. It allows the motion to look more fluid in video.

In still images, it allows for a much slower shutter speed, or larger aperture, or both together, when shooting in bright light conditions. Normally not something a still photographer wants to do, unless they are striving for that effect. Examples are getting light trails in starry skies at night, or vehicle light trails on a shot of a road/highway, as we have all seen at some point. Or to make a waterfall look fluid or a river more streaky/fluid looking. Or to get a sea photo showing a sort of milky look, especially close to shore where waves would be breaking.

The only problem getting such shots is keeping the camera dead still during exposure, otherwise you just have a blurred photo, all over. A good solid tripod is essential when going after this sort of effect in still photography. Drones are slowly getting better and better at also being able to keep amazingly still to allow for these sort of shots to be done while hovering. Hope that explains what you asked about. Not to be confusing here but a PL filter is a very different filter, with different uses and needs by a photographer, than an ND filter. Plus PL filters need to be used only at certain angles to the sun to be effective, whereby an ND filter can be used in any direction to the sun. The effect it makes to an image is not affected by the angle it is being used, to the sun position.

 

[slup]

Oopps, We know what you mean but...

? Jeez ... yeah, that sentence didn't turn out as planned... thank's for the heads-up, corrected

 

[malbowski85]

So the filter I choose depends on how bright it is? Think I need to do a lot of tests to see the differences....

One more thing. I'm trying to stick to the 180 rule. This goes out the window though if i want to drastically adjust my shutter speed, no? I am a photography/videography beginner so bare with me

 

[slup]

So the filter I choose depends on how bright it is?

Yes ... the ND filters are sunglasses for the lens, no more. The brighter light the darker ND you need to use to keep the shutter speed the same without not changing anything else.

One more thing. I'm trying to stick to the 180 rule. This goes out the window though if i want to drastically adjust my shutter speed, no?

Using the same FPS ... then yes, this as the shutter speed is a function of the frame rate.

Then keep in mind that the 180 degree thumb rule is just a guidance ... & that flying above 30m above ground usually means that motion blur can't be seen any how ... so the rule can be disregarded.

 

[Karlewski]

"Then keep in mind that the 180 degree thumb rule is just a guidance ... & that flying above 30m above ground usually means that motion blur can't be seen any how ... so the rule can be disregarded."
This is KEY!
I'm going to only use ND on rare occasion due to this, a CLP filter alone or with ND CLP is going to have more effect improving image quality by cutting glare and adding saturation. When I'm skimming stuff or shooting a gap, ND for blur, even then it is not a big deal to introduce blur in post and not fiddle with the filters in the field. . . that is a PITA IMO.