Total drone noob here from video/photo world but looking at drones in photogrammetry application and took the plunge with an
EVO II Pro V2.
This is a great thread. After reading it, I was all set to return the Freewell filters I had bought based on "some article I read on the internet". Then I came across
this paper entitled
"The effect of Neutral Density Filters on drones orthomosaics classifications for land-use mapping"
that tested ND filters on a P4P specifically for the use case of making orthomosaics where the name of the game is capturing detail. FWIW
I will caveat this entire statement by saying I know next to nothing about photogrammetry and obviously the paper is very detailed in many areas. But the part that makes no sense to me is that the shots without the ND filters and with the ND32 filter were completely out of focus/lacking detail. ND filters have nothing to do with improving sharpness, detail, or focusing and if they did this they would be well documented in many other areas of photography.
ND filters perform a single function; reduce the light reaching the camera lens which allows the camera operator to reduce the shutter speed
or open the aperture. The most important key detail was the one left out within the Materials and Methods section; how they maintained identical exposure between the tests with and without ND filters. If they adjusted the Aperture to achieve that then everything would make sense; without the ND filters the aperture was stopped down to something like F11 which is not the sharpest aperture for the camera; at ND32 the camera was shot wide open at F2,8 which also explains why ND32 was so devoid of detail. At ND4, ND8, and ND16, they were probably somewhere around F4.0, F5.6, and F6.3 which are going to resolve more detail.
On a bright sunny day in direct sunlight pointing directly at the ground for a photogrammetry project, if you shot at F4.0,F5,6, or F6.3 you will always have enough available shutter speed remaining to properly expose the image without an ND filter. I suspect the authors decided instead to adjust the Aperture for their tests vs the shutter speed; without this key piece of information every other aspect of the test conclusions are highly suspect to me.
I am intrigued enough to discover if they made such a simple error in an otherwise very detailed analysis that I emailed the author requesting additional information on how they maintained identical exposure from test to test. If they simply did not know about the effects of lens distortion they could have very well made this mistake.
I don’t care what Herein says but professional operators will always use ND filters! It’s a matter of simple physics. if you want professional results you have to use them to slow down the shutter speed. If you’re filming a friends wedding, then you can maybe get away with it.
End of story!
The first rule of photography/video is there are no rules so you don't
have to do anything and there's definitely no rules about
always doing anything; an entire feature length film was shot on nothing but
GoPros and I am certain many people like you said you must always use a cinema camera and no "professional" would use a GoPro to film a feature length movie yet it grossed
$16.8M. If you shoot and deliver footage that your client is willing to pay for then you have met the client's requirements and you also fall into the category of professional; and if it is a matter of simple physics I would definitely be open to reading which law of physics states that the only way to achieve proper exposure for a given scene is to use an ND filter.
Thanks for posting the video. I see what you mean that the fast shutter speeds do not interfere with pleasant videos at 30fps. Even the jet ski clips looked fine. However, the sped up sections looked very jerky to me, hard to watch. Also, many of the early clips looked over exposed. Was that intentional?
I also shoot 4K/30 LOG 10-bit and produce in 4K/30 10-bit 4.2.0 using DaVinci Resolve Studio. However, I usually use ND16 filter in bright sunny days. I've attached an eyebrow to the filter to help shade the front lens. When I tried shooting without that ND filter using a fast shutter, I got prop shadow flickering at certain angles to the sun. I'm wondering if its the eyebrow that prevents the prop shadow flickering or the slower shutter speed. More testing...
Actually every clip was sped up in the video with the exception of maybe one or two. Due to the camera to subject distance of typical drone footage and the fact that I typically only use a few seconds of it in a project that otherwise has none of it; I speed up the footage to get more motion. I will admit I spent less than 20min on the sample video because the only intent was to demonstrate high shutter speed footage.
The portions that probably look jerky to you are the ones where there was already a lot of motion such as with the waves on the water and the flags. For a paying client I would have left those at their default speeds due to that very reason.
The early clips were not overexposed, a Rec709 WFM will show all of the footage was graded to fit within the Rec709 color space but since I only spent about 20min on the whole thing I did not focus on bringing down the lows or adding contrast which would have countered the highs and given it more DR. My only focus really was just showing high shutter speed footage in different scenarios.
The problem with drone cameras is that they not only do not have lens hoods, they also have props which can come between the sun and the lens at certain angles. An ND filter could lower the shutter speed to the point to where the shadow is such a blur that it is nearly imperceptible or the eyebrow may add just enough shade to do the same thing. My own personal solution is to simply angle the camera more towards the ground, or change the relationship between the drone and the sun.
I do think that's a very valid use case for a drone ND filter.....if you need to reduce prop shadow and do not want to change the relationship between the drone and the sun or angle the camera further down then the ND filter could reduce that shadow effect. I am not entirely convinced that it would completely remove it however and I would not risk it for a paying client; I'd either wait for clouds, wait for the sun to change positions, angle the camera down more, or change the way the drone is pointed at the subject material. The eyebrow on the other hand would definitely completely remove it if you manage to also keep the eyebrow out of the image while it is also somehow long enough to shade the entire lens.