Specifically, for photogrammetry work. They recommend flying on an overcast day so the shadows aren't as harsh and don't exceed the dynamic range of the camera. But here in SoCal, besides the start and end of the day, the sun is almost always out in full force. Would ND filters help in this case or would it simply shift everything darker and not have any impact? Or does the dimming effectively shrink the dynamic range of the scene? Does anyone have direct experience with this?
Does ND filters help/hinder the dynamic range of the drone camera?
- Thread starter SoCal2S
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JooB
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I'm no pro but I suppose ND filters will not shrink the dynamic range generally but they move the dynamic window to the brighter side. They reduce the amount of light that hits the lens like sunglasses do with your eyes. So if you win or loose dynamic depends on your specific situation.
If you have dark areas in your photo with minimum lights the NDs will erase this "minimum" and the dark areas will have no details anymore and will just be black. But NDs will solve problems with overexposure in the bright areas of the photo because they "erase parts of the overexpose" and give you back some details.
Because too much sun is your problem I would give it a try. The other and easier option of cause is to change the expose value at your drone, but your drone must have that option.
If you have dark areas in your photo with minimum lights the NDs will erase this "minimum" and the dark areas will have no details anymore and will just be black. But NDs will solve problems with overexposure in the bright areas of the photo because they "erase parts of the overexpose" and give you back some details.
Because too much sun is your problem I would give it a try. The other and easier option of cause is to change the expose value at your drone, but your drone must have that option.
waynorth
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ND-filters does one thing - they reduce the amount of light reaching to your sensor.
To get a correct exposure you need to either use a slower shutter speed or open up the aperture.
For example an ND16 filter reduces light with 4 stops.
So if correct exposure for a given scene is 1/125 sec at f/4 without filter, you must reduce the shutter speed
to 1/8 sec to get the same exposure. The photos with and without ND-filter should look the same.
A good quality ND-filter has no effect on dynamic range. A very dense filter can give a slight colour cast.
To get a correct exposure you need to either use a slower shutter speed or open up the aperture.
For example an ND16 filter reduces light with 4 stops.
So if correct exposure for a given scene is 1/125 sec at f/4 without filter, you must reduce the shutter speed
to 1/8 sec to get the same exposure. The photos with and without ND-filter should look the same.
A good quality ND-filter has no effect on dynamic range. A very dense filter can give a slight colour cast.
That's good advice.
All the ND filter will do is cut the light getting through (probably by much more than you imagine).
That forces a much slower shutter speed, which is the last thing you want for photogrammetry.
Leave the ND filters off and let the camera's meter adjust the exposure to suit the scene.
Your camera can shoot at up to 1/8000th sec, which is more than fast enough to deal with any amount of bright sun.
ND filters do absolutely nothing for dynamic range. They just reduce the total light reaching the sensor.
So higher iso or lower shutter speed required for a correctly exposed image.
Both of which reduces the quality of your photogrammetry.
Don't use them for it.
(There are plenty of utterly bonkers myths about NDs affecting saturation or dynamic range. They don't. They're literally a piece of dark glass.)
There are very few good uses of ND filters. One is for decreasing image sharpness when shooting video with rapid movement to hide the strobing that can occur with these moves. The other, with still images, when you want blur in parts of the image for artistic reasons, like with moving water framed by rocks and trees.
ND filters are only good for video and then, only good if you need to lower your shutter speed for a particular visual affect. There is no other reason to use such a filter for video.
In still photography, the only reason you would ever want to use ND filters is if you have lighting conditions that are too bright for you to reduce the shutter speed enough and still get a correctly exposed image and at the same time, get blurring of moving subjects in your frame.
So, for example, say it is middle of the afternoon on a sunny day and you want to show the thin tree branches or blowing leaves in the wind, moving and showing a blurred image, you will most likely need to use ND filters to lower the shutter speed enough. Or if you want to show flowers blowing in the wind on their stems and see the blurred motion, or as has been stated, to show the flowing water of a river or possibly blur the wave action at a coastal location to get that sort of milky water look, though shot on a sunny day, then you would need ND filters to lower the shutter speed enough to get that motion blur, yet still capture a correctly exposed image.
There is never a reason to use ND filters outside of the above-mentioned situations. Hope that clears up the use of ND filters for anyone wondering when and why to use them.
In still photography, the only reason you would ever want to use ND filters is if you have lighting conditions that are too bright for you to reduce the shutter speed enough and still get a correctly exposed image and at the same time, get blurring of moving subjects in your frame.
So, for example, say it is middle of the afternoon on a sunny day and you want to show the thin tree branches or blowing leaves in the wind, moving and showing a blurred image, you will most likely need to use ND filters to lower the shutter speed enough. Or if you want to show flowers blowing in the wind on their stems and see the blurred motion, or as has been stated, to show the flowing water of a river or possibly blur the wave action at a coastal location to get that sort of milky water look, though shot on a sunny day, then you would need ND filters to lower the shutter speed enough to get that motion blur, yet still capture a correctly exposed image.
There is never a reason to use ND filters outside of the above-mentioned situations. Hope that clears up the use of ND filters for anyone wondering when and why to use them.
Not just for video. As you noted later, there are also uses for still photography. I've seen some stunning waterfall shots using an ND on a drone. (Got to try that myself this year!)
Debaser_AZ
Well-Known Member
Do not use any filter (except UV) for photogrammetry work, as almost all the comments pointed out. Adjust your camera manually to the best exposure and fastest shutter speed for your target altitude (with respect to the total flight time--changing brightness), then you shouldn't have any blow outs. I work in southern Arizona and there's no time to wait for full cloud coverage AND no rain, but it happens once or twice a year. Instead, I plan large areas/longer flights around solar noon. This helps minimize long shadows.
Since we are on a drone forum, these are drone size ND filters and the drone is rarely if ever, used for long time still image exposure. Of course, there are other larger diameter ND filters for still photography DSLR cameras (or film of course) and such use is always used with a tripod because the exposure is usually very long, but the OP was speaking about his drone use.
That is why I started off saying only for video, since the OP was talking about his still image use with his drone and assumed readers would understand from my further comments that ND filters can also be used for still images, without those readers needing to tell me that the ND filters are not only for video.
As I said, I've seen wonderful long-exposure images from drones. I have no idea how many attempts it took to get them, but they were quite nice. Waterfalls, but also cityscapes with even pedestrian traffic a blur.
Haven't tried it myself yet, because my ND filters haven't arrived. Planning on it, though.
Oh sure, anything is possible, and I said rarely used for such uses that a still camera is vastly better suited for, because you will see from the number of uses of a drone for that purpose, the number of people doing it is miniscule. It's also so hit and miss, though sometimes, with luck, it can work out.
However, when using a still camera on a tripod for such long exposures, when properly done, it will give you a sharp exposure with the motion blur the photographer was looking for, every time. But we are getting way off the point of the OP's post now, which was using ND filters for his still shot purpose. I don't think it's fair to hijack his posting.
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So how tall is your tripod? I know dozens of people doing long exposure drone photography and entirely for subjects that won't work with a tripod. I guess I am further hijacking but people who like doing long exposures but think they should use one specific tool for it aren't using much imagination IMO
My question was answered in detail, hijack away as long as the mods don’t care.
That's a nice image however, looking at the wave motion very close to the shoreline, it's clear that it is not a very long exposure, just a slower shutter speed. When I speak of long exposures to really show motion, I'm talking of many seconds, like 10-20 or more.
You won't be getting that done with a drone in hover. A few seconds is of course possible when you have a bit of luck about you, with a drone hovering. When you show me a 20 second drone image while in hover mode that shows sharp stationary subject matter but with the 20 seconds worth of blurred motion from moving matter, then I'll concede.
Agree - its that fairly jarring no-mans land between fast and long exposure. Tends to look blurred rather than smoothed.
Ive yet to see any drone that can hover and stabilise a shot for true long exposure.
I did experiment on a perfectly still day and by taking a sequence of 20 shots then selecting the sharpest got an acceptable image of 3 seconds. That was my record though. Still far too short to be a long exposure.
That's the best way, when shooting with the drone or a still camera, if forced to do a longish exposure without the help of a tripod to steady it. Shoot a bunch of images in succession and pick the best of the lot of that extended exposure. You will often be lucky and get a relatively sharp one amongst the lot.
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