ND Filters for X5?
- Thread starter Figbar
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Now that we are using standard lenses, we get the benefit of standard filters. All of the approved lenses take standard 46mm filters. Here is a sampling from B+W, a respected producer of filters:
These filters can be combined, so you can attach both an ND filter and the circular polarizing filter.
These filters can be combined, so you can attach both an ND filter and the circular polarizing filter.
I would start with a 3-stop filter. The 6-stop filter is only going to work on super bright conditions. I'm not sure when a 10-stop filter would ever be appropriate.
Why not just drop the f/stop down to f/32 or whatever is needed to get the shutter speed you want?
With the x5 you have a remotely controlled iris (aperture) which you didn't have with the X3.
You only really need ND filters for proper cameras when you want to get the DOF of a large aperture coupled with a low shutter speed.
With the x5 you have a remotely controlled iris (aperture) which you didn't have with the X3.
You only really need ND filters for proper cameras when you want to get the DOF of a large aperture coupled with a low shutter speed.
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This won't affect the overall quality of the video? Shooting at 100 iso? Please forgive my lack of knowledge...I come from a video background where we didn't have to think so much or pay that much attention to all the variables to get good looking stuff.
You are correct; closing the aperture by 3 stops is generally equivalent to adding a 3-stop ND filter. And in general, the increased depth of field is a benefit. But for some shots, you might want a shallower depth of field, so ND filters are still useful.
And there is no substitute for a circular polarizing filter. Those of us who fly over water can really benefit from one of those.
And there is no substitute for a circular polarizing filter. Those of us who fly over water can really benefit from one of those.
If you are from a video background then you surely understand aperture, shutter speed, and ISO and what they mean for your video.
When I shoot video with my Nex 7 I set the shutter speed to what I want and then measure what aperture I require to maintain that shutter speed for the available light. If I can't stop the lens down far enough or I want the small DOF from a large aperture then I apply a ND filter.
Circular polarizers are useful for removing reflections and generally make skies darker with more depth. They also have the effect of reducing the light level by a couple of stops too.
When I shoot video with my Nex 7 I set the shutter speed to what I want and then measure what aperture I require to maintain that shutter speed for the available light. If I can't stop the lens down far enough or I want the small DOF from a large aperture then I apply a ND filter.
Circular polarizers are useful for removing reflections and generally make skies darker with more depth. They also have the effect of reducing the light level by a couple of stops too.
The X3 camera has a fixed aperture of f/2.8, and thus gives us only two controls for exposure: shutter speed and ISO sensitivity. That inflexibility all but demanded the use of ND filters to get appropriate shutter speeds (explanation below). The X5 camera gives us three controls for exposure: aperture, shutter speed, and ISO sensitivity. So in general, the X5 won't require ND filters as much as the X3. But they are still useful.
In video, the general goal is to use a shutter speed that is 1 over (2 x the frame rate). So if your frame rate is 30 frames/second, you want a shutter speed of 1/60 of a second. This video will help explain why this is the case; the quick answer is "to get the correct amount of motion blur, so that the video looks good to the human eye and brain."
Another general goal is to use an ISO sensitivity as low as possible. The higher the ISO sensitivity, the more noise is introduced. I expect the lowest setting on the X5 camera to be ISO 100, which should give an excellent clean image.
So we start from there: ISO 100 at 1/60 of a second. And let's start with my favorite MFT lens, the Olympus M.ZUIKO 12mm, which has a maximum aperture of f/2.0. On a bright day at f/2.0 and ISO 100, a shutter speed of 1/60 is going to be extremely overexposed. Even at f/2.8, a proper exposure might require a shutter speed of 1/1000 of a second. The question: how do we get that 1/1000 shutter speed, which produces jerky motion, down to 1/60, which produces smooth motion?
On the X3, we can't do it via the aperture (fixed at f/2.8), and we can't do it by lowering the ISO sensitivity (we are already at the mimimum of 100), so we have to do it with ND filters. Each "stop" on a filter effectively cuts the exposure in half. So a one-stop filter would allow us to change our shutter speed from 1/1000 to 1/500. A two-stop filter would allow us to lower it to 1/250, and a three-stop filter would allow us to lower it to 1/125. In this imaginary scenario, we would need a four-stop filter to get down to 1/60.
On the X5, however, we have control over the aperture. So instead of adding a 4-stop ND filter, we could instead close the aperture by three stops. That would mean changing it from f/2.8 -> f/4.0 (1 stop) -> f/5.6 (2 stops) -> f/8.0) (3 stops) -> f/11.0 (4 stops). That would give us an equivalent exposure, and allow a 1/60 shutter speed. As an added benefit, closing down the aperture increases the depth of field, which allows more of the scene to be in focus.
So why would we ever need an ND filter? Note that the maximum aperture on the 12mm lens is f/22. That seems like a high number, but it is only one more stop than we are already using (f/11.0). If it's an extremely bright day, then we might need 6 stops of exposure to get to our target shutter speed, and the lens only provides 5.
Further, lenses tend to perform the best in the middle of their aperture (e.g., f/8.0 here), and worst at the edges (f/2.0 and f/22 here). I would expect to see less corner sharpness and more vignetting at these extreme apertures.
The great thing about the DJI app is that it gives us a live histogram during video shooting, so we can see what the exposure is. Learning to read a histogram, and to adjust your exposure to get a good one, is probably the most basic and important skill that the X5 camera requires.
In video, the general goal is to use a shutter speed that is 1 over (2 x the frame rate). So if your frame rate is 30 frames/second, you want a shutter speed of 1/60 of a second. This video will help explain why this is the case; the quick answer is "to get the correct amount of motion blur, so that the video looks good to the human eye and brain."
Another general goal is to use an ISO sensitivity as low as possible. The higher the ISO sensitivity, the more noise is introduced. I expect the lowest setting on the X5 camera to be ISO 100, which should give an excellent clean image.
So we start from there: ISO 100 at 1/60 of a second. And let's start with my favorite MFT lens, the Olympus M.ZUIKO 12mm, which has a maximum aperture of f/2.0. On a bright day at f/2.0 and ISO 100, a shutter speed of 1/60 is going to be extremely overexposed. Even at f/2.8, a proper exposure might require a shutter speed of 1/1000 of a second. The question: how do we get that 1/1000 shutter speed, which produces jerky motion, down to 1/60, which produces smooth motion?
On the X3, we can't do it via the aperture (fixed at f/2.8), and we can't do it by lowering the ISO sensitivity (we are already at the mimimum of 100), so we have to do it with ND filters. Each "stop" on a filter effectively cuts the exposure in half. So a one-stop filter would allow us to change our shutter speed from 1/1000 to 1/500. A two-stop filter would allow us to lower it to 1/250, and a three-stop filter would allow us to lower it to 1/125. In this imaginary scenario, we would need a four-stop filter to get down to 1/60.
On the X5, however, we have control over the aperture. So instead of adding a 4-stop ND filter, we could instead close the aperture by three stops. That would mean changing it from f/2.8 -> f/4.0 (1 stop) -> f/5.6 (2 stops) -> f/8.0) (3 stops) -> f/11.0 (4 stops). That would give us an equivalent exposure, and allow a 1/60 shutter speed. As an added benefit, closing down the aperture increases the depth of field, which allows more of the scene to be in focus.
So why would we ever need an ND filter? Note that the maximum aperture on the 12mm lens is f/22. That seems like a high number, but it is only one more stop than we are already using (f/11.0). If it's an extremely bright day, then we might need 6 stops of exposure to get to our target shutter speed, and the lens only provides 5.
Further, lenses tend to perform the best in the middle of their aperture (e.g., f/8.0 here), and worst at the edges (f/2.0 and f/22 here). I would expect to see less corner sharpness and more vignetting at these extreme apertures.
The great thing about the DJI app is that it gives us a live histogram during video shooting, so we can see what the exposure is. Learning to read a histogram, and to adjust your exposure to get a good one, is probably the most basic and important skill that the X5 camera requires.
A circular polarizing filter decreases glare. It is most useful when filming over water, where reflections cause lots of glare, and when shooting towards the sun.
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Isn't a circular polarizing filter is going to be fiddly to use on a moving camera?
On a stills camera you have to get the angle just right to get rich blue skies and cut back on refracted light on say water (especially on a wide angle lens) but in the air as soon as you change direction its going to throw out how much you have dialled in on the filter.
Best results when using a circular polarizing are at about 90 degrees to the sun I seem to remember.
On a stills camera you have to get the angle just right to get rich blue skies and cut back on refracted light on say water (especially on a wide angle lens) but in the air as soon as you change direction its going to throw out how much you have dialled in on the filter.
Best results when using a circular polarizing are at about 90 degrees to the sun I seem to remember.
The polarizing filter I have for my X3 always holds its position, even when I fly at 37 MPH.
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I ordered a filter kit from B&H, but one is not necessarily needed; InterMurph's post explains it all much better than I would. The fact that you can adjust iris on the fly is huge, and will allow us to get away with properly exposed shots at an appropriate shutter speed without the need for ND filters. I like a polarizing filter though for shooting into the sun so I figured may as well pick up a kit and fool around with some different options.
Thanks, @InterMurph, for an excellent tutorial on getting proper shutter speed for proper motion blur with the tools available on the X5/GO app controls. I would suggest that a UV filter (lens protection), 0.9 ND (3 stop), and CP filter would be an appropriate/useful set of filters for both stills and video.
I've never had a use for a UV/protection filter. Just don't touch the lens, don't scratch anything against it, and put the cover on when you're not using it.
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i think when your hurling your camera hundeds of feet off the ground into bugs, dirty take offs, and general junk flying into your lens, using a protective uv filter is a great idea.
Like @johnmont250, I never fly without a protective filter for the reasons he mentioned. Just make sure it's a good piece of glass, so as not to degrade the optics.
To each his own, I guess.
Edit: I shoot a lot of stills with the X3, so there is no need for NDs, although for overwater or where there is lots of surface reflection, a CP filter would be more appropriate (CPs are a mixed blessing for wide angle lenses, though, due to the reflectance gradation in the sky, depending on sun angle).
I guess I was referring to how I handle my regular camera lenses, which don't fly.
But when I do fly, I almost always have an ND filter on, which protects the front element.
