Adding ND filter to GoPro with Gimbal

[alex covo]

So I managed to balance my gimbal with the Paeu Modded GoPro 4 Black + 5.4 lense and ND8 filter. I also balanced props and hubs. I shot a test today to see how it performed. I was happy with the overall results. Here is the video with no post stabilization. Any wobble or drift is just pilot error. It was shot at 2.7K 60fps and scaled down to 1080p. Quick and dirty edit in Premiere. Really looking forward to shooting a real video with the Solo.

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[Maddog]

So I managed to balance my gimbal with the Paeu Modded GoPro 4 Black + 5.4 lense and ND8 filter. I also balanced props and hubs. I shot a test today to see how it performed. I was happy with the overall results. Here is the video with no post stabilization. Any wobble or drift is just pilot error. It was shot at 2.7K 60fps and scaled down to 1080p. Quick and dirty edit in Premiere. Really looking forward to shooting a real video with the Solo.

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Looks good- nice job!

 

[erikgraham]

On a sunny day should I use my ND8 or ND8-PL (polarizer) filter?

I use the ND8/PL most of the time. Even if the camera angle of a shot isn't such that I'll get the benefit of the polarizer, it won't hurt anything.

If your gonna film water, and if you have the time, and want to use the polarizer right, then take it off the GoPro and rotate the filter while looking through to find the right rotation (when there is noticeably less glare off the water). If possible you'll want to do that from the same angle (relative to the Suns position) that the drone will be shooting from. Obviously this can be tricky, but sometimes you can do it. Anyway, once you have the polarizer rotated how you like it, slip it onto the GoPro without twisting.

 

[Maddog]

I use the ND8/PL most of the time. Even if the camera angle of a shot isn't such that I'll get the benefit of the polarizer, it won't hurt anything.

If your gonna film water, and if you have the time, and want to use the polarizer right, then take it off the GoPro and rotate the filter while looking through to find the right rotation (when there is noticeably less glare off the water). If possible you'll want to do that from the same angle (relative to the Suns position) that the drone will be shooting from. Obviously this can be tricky, but sometimes you can do it. Anyway, once you have the polarizer rotated how you like it, slip it onto the GoPro without twisting.

Great tip! I hadn't thought of that but I understand what you mean.

 

[Maddog]

Also, I have used the ND8-PL and when I reviewed the video, one side of the sky was bluer than the other.

Could that have been caused by the angle/rotation of the filter?

 

[Steven Ackerman]

Also, I have used the ND8-PL and when I reviewed the video, one side of the sky was bluer than the other.

Could that have been caused by the angle/rotation of the filter?

Yes. And the maximum effect of the polarization occurs at a 90 degree angle from the sun.

 

[Maddog]

Yes. And the maximum effect of the polarization occurs at a 90 degree angle from the sun.

Thanks- something I need to think about and experiment with. Or just use the straight ND-8.

 

[erikgraham]

So I managed to balance my gimbal with the Paeu Modded GoPro 4 Black + 5.4 lense and ND8 filter. I also balanced props and hubs. I shot a test today to see how it performed. I was happy with the overall results. Here is the video with no post stabilization. Any wobble or drift is just pilot error. It was shot at 2.7K 60fps and scaled down to 1080p. Quick and dirty edit in Premiere. Really looking forward to shooting a real video with the Solo.

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Also, I have used the ND8-PL and when I reviewed the video, one side of the sky was bluer than the other.

Could that have been caused by the angle/rotation of the filter?

yes. But usually it's not that noticeable. The sky isn't uniform in nature... maybe it was darker on that side. I assume your using a circular polarizer, by the way, not a 'linear' or graduated filter of any kind. Anyway, an ND/PL can do that to the sky, but it shouldn't be so much that it looks artificial. you can use it to your advantage when shooting the sky. Have to keep a consistent heading to maximize the effect.

 

[Maddog]

yes. But usually it's not that noticeable. The sky isn't uniform in nature... maybe it was darker on that side. I assume your using a circular polarizer, by the way, not a 'linear' or graduated filter of any kind. Anyway, an ND/PL can do that to the sky, but it shouldn't be so much that it looks artificial. you can use it to your advantage when shooting the sky. Have to keep a consistent heading to maximize the effect.

Ok, thanks. Yes, circular polarizer.

 

[EyeWingsuit]

I have to strongly disagree with you. On a GoPro, there is a clear loss of image quality between 30 and 60 fps. Depending on the subject matter and lighting conditions it may not be obvious at first, but it's there if you know what to look for. Just search YouTube for side-by-side comparisons.

As for ev comp... it has absolutely no effect on shutter speed on a GoPro. It's applied in camera after shutter speed has been calculated and set. I'm not saying you should not make adjustments to ev comp. I'm just saying it won't effect shutter speed.

We'll have to agree to disagree on what constitutes "quality loss." 60p isn't lesser quality, it's a different image altogether. Those who understand codecs, frame rates, shutterspeeds, etc do know what to look for, and understand that it's not about "better" or "worse" but rather "different."

Some mistakenly believe that p60 is best for everything. It's not.
Even more mistakenly believe that shutterspeed at frame rate are not relevant in combination.
Yet even more mistakenly believe that shutterspeed and frame rate are the same thing.

I didn't realize you'd read my post to suggest that ev would affect shutter speed, of course it doesn't.
Given the weather is getting colder for some, and flying is a challenge; take your GoPro (or other camera) and put it on a tripod in a dark room, set to p30. Light a brightly colored object with a small flashlight and record it for 10 seconds. Then put on an ND filter. Record some. Remove from the tripod. Hand-hold, shoot some more. Add a polarizer and put back on tripod. Record more. Now hand-hold.

After all that, reset the camera to p60 and repeat.

When it's sunny outside, take the same brightly colored object and put in direct sunlight. Repeat all the steps above.

Put the resulting footage into a video editor, watch the footage. Pay particular attention to the saturation and edging of the contrasts. You'll see big differences, and have a more clear understanding of what these tools and settings do for (and to) your footage.

 

[twitchyzero]

Were you able to use the foam protector that came with the gimbal without having to remove the balance coins each time?

I have 2 ND filters: an ND8 for bright sunny days, and an ND4 for hazy, thin overcast days. Haven't had them that long, but so far, they make my aerial videos look SO much better, especially the ND8, since I like to shoot on bright clear days.

When the naked camera is installed in the gimbal and the two small included weights are added to the top & bottom, as specified, the camera stays where you put it, which is what a powered-off gimbal is supposed to do. Regardless of the position of the camera, a perfectly balanced gimbal will not move at all, so when powered on, it's not fighting to keep it level, which would put added strain on the motors.

I have a Hero 4 Silver, and purchased my two BlurFix Air filters for it because they're very light. But "very light" does not equal no weight at all. So of course the filter causes the camera to fall forward and to the left (when standing behind the camera), since the lens & filter are on the front left side.

So the goal was to find the amount of weight, and the correct position, to add weight to the rear and right side to offset both off-level situations (fore-and-aft & side-to-side).

I tried several different combinations of coins to see what worked, attaching them lightly with Scotch tape to test. If either side, or front or rear of the camera fall, the motor has to work to make up the difference. I came pretty close with combinations of pennies and dimes. But when I was pretty close, but not quite there, firing up the gimbal would result in an audible motor noise coming from it, letting me know that it was fighting to stay level, instead of falling there naturally.

I finally found the closest weight and position, that resulted in almost-perfect level in all directions, and no motor noise whatsoever: a nickel on the rear and a nickel on the right side (again, standing behind the camera).

I attached a small square of industrial-strength velcro (available on Amazon: http://bit.ly/velcro-1-inch-industrial-strength) to the rear and right side, and the opposing piece to the nickels (cut perfectly round to fit).

I've flown about 9 batteries since setting this up, regularly checking the balance of the un-powered camera/gimbal and for any sign of motor noise when powered up. So far, so good, with great, smooth flights, and no sign that I'm stressing the gimbal motors.

Attached photos show the exact placement of velcro and coins. Again, this is for a Hero 4 Silver. Might be different for other models. If anyone has tried anything else that works well too, please share! The difference in quality with an ND filter is too good to omit just because 3DR didn't make weights for them.

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[texmur]

Here is very light photographic filter designed for Solo gimbals with Gopro which are sensitive for additional weight
ND4 or ND8 filer veight only 1.2gram!!!
http://greyfilter.webnode.cz/

 

[Robert Rose]

I got my ND filters from PolarPro 3DR Solo Accessories Prop Guards and Filters The set of ND4, ND8 and Polarizer (their Frame 2.0 three pack) is advertised as useable on the Solo without added weight. So far, I have found that to be true. The frame is plastic and sized to press fit over the GoPro lens. No problem with the Gimbal and the PolarPro ND filters on a Hero 4 Black. The advertised weight is 5.5g for the ND and 6.7g for the CP. I have not tried the Polarizer yet, but expect that will work only when the Solo is turned at the correct angle to the sun.

As for the need for the ND, it really depends on how bright it is when you are flying.

It helps to appreciate that the GoPro has a fixed aperture f/2.8 lens (with a 3mm focal length corresponding to a 15 mm super wide angle lens focused at infinity), so in order to deliver auto exposed images the only inputs it can adjust are the shutter speed and ISO. In very bright light, and ISO 100, it is not unusual for the GoPro shutter speed to be 1/8000 second. An ND8 will reduce that by 3 stops, e.g., from 1/8000 to 1/2000 (each stop doubles the light). Even that is very fast.

Just a guess, but if you are not experiencing jello in your video, then you probably won't see much difference by using the ND filters. But the cost of a set is low enough to try it for yourself.

The polarizer is another matter. If the sun is at the right angle then a polarizer can have dramatic effects on the image, cut reflections, and increase saturation. At the highest effect it will also provide one stop of neutral density (e.g., like an ND 2). Before takeoff you can estimate the direction you want to take the picture, and rotate the CP filter while looking through it. The rotation angle that gives you the darkest image is the one to use. Place it on the camera so that when the Solo is in the air and pointed where you want to take the picture it is oriented correctly.

 

[Perry Lawrence]

The Frame 2.0 3 pack lists a 2 stop and a 3 stop filter. Is this what you are referring to? I want to make sure I get the right set.

Thanks Robert!

 

[Robert Rose]

Yes; the third filter is a polarizer. If you want some details on the filters check the information at the 6 filter set page here: GoPro Frame2.0 - Professional Filter 6-Pack

They on occasion have coupons and promotions.

The "3 filter case" in the box was really 3 soft bags (like filter cloth material) with draw strings. It is perfectly fine to keep the filter from being scratched. If you throw things around, are really particular, or lose small items often (guilty on all counts) you can add the $5 case (cheap enough) for three filters: 3-Pack Filter Case - Phantom 4/3 / Inspire 1 / Frame2.0
There is also a $10 version for 6 filters:
6-Pack Filter Case - Phantom 3 / Inspire 1 / X5

 

[DJ Wes]

Does anyone know if these filters can be stacked? I purchased this Basic GoPro Hero Filter Pack – Peau Productions
I'd like to use the ND4/ND8 and the CP lens. I know that would add a good bit of weight and would require a re-balance of the gimble. But, can it be done?

 

[Robert Rose]

I know that there are combined ND/PL filters (Polar Pro GoPro Frame2.0 - Professional Filter 6-Pack is one example). If you could stack them I think that the polarizer should go in front. If you have the 30mm kind that go into a push-on filter adapter there may be female threads on the front of the ND that could take the male threads from the polarizer then yes, physically they could be stacked, BUT you are likely to get significant vignetting (darkening or even cut-off) at the corners. Depending on whether you got the glass or plastic filters, you could be talking about hanging more than 16 grams on the front, and that means gimbal balancing big time.

The Polar Pros can't be stacked because they are friction fit, e.g., it is like they already are placed in a push-on filter adapter, and the width of the filter exceeds the width of the adapter.