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Polarising filter - only darkens my problem

Discussion in 'Photos and Video' started by SurlyBiff, Jul 3, 2014.

  1. SurlyBiff

    SurlyBiff Guest

    First let me apologise if you're sick of GoPro exposure questions. I did a search and couldn't find an answer, so thought I'd post.
    This is as much a GoPro question as it is a Phantom one, but the problem is affecting my aerial videos.

    I keep getting huge washed out areas in the sky. Even in shots that don't have a lot of white clouds. I bought a polarizer filter, hoping this would help. But it only darkens the whole scene. The sky, relative to the ground, is still hugely overexposed. I'm not using spot metering.

    So I tried using Protune. Which helped balance the scene out a bit, but added noise to the video. I'm considering an ND filter, but I'm guessing this will only further darken the ground in the shots a lot too. So any editing in post to brighten up the ground, will mean the sky goes back to being super overexposed once again.

    I'm wondering if a Cokin graduated glass filter (the the type used in SLRs), cut down and fitted to the GoPro might be the only way.

    Unfortunately nothing makes an aerial video look more amateurish (apart from jerky panning!) than a washed out sky.

    Does anyone have any tips for overcoming sky burnout?

    Any pointers hugely appreciated :)

    SB
     
  2. poostik

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    ND filter has helped my shots that were done in the middle of the day and on the beach...
    Not sure about the Cokin filters.

    I got this one as recommended by a few users on this board.

    The beachy one has that weird color grade done in post, but you can still get an idea of the ND filter's affect.
    The construction one has a lot less processing.

    [vimeo]97788911[/vimeo]

    [vimeo]97063605[/vimeo]
     
  3. SurlyBiff

    SurlyBiff Guest

    Great work. Your exposures are perfect. Are you also filming with protune on? Thanks for the tip. I'll try an ND instead of the polarizer and see if that helps my shots.
     
  4. 4wd

    4wd

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    I don't see how an ND will do anything other than darken the whole scene too, or make the camera shutter go slower (which may be desirable).

    Surely all you need do is reduce the exposure by 1/3 or 2/3
    In Adobe Premier you can quite easily apply a grad to darken the sky to the horizon, and/or lighten the land, or the shadow highlight filter can be used *sparingly*.
    A Grad filter on the camera is hardly suitable for video when your camera is moving about all the time.
     
  5. Gizmo3000

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    what GoPro?
    the new Hero3+ actually has the ability to lower exposure. (I've not tried, but imagine it might help some people)

    you could also look further into tweaking Protune footage, as it should not add noise,
    it's actually recording non-processed footage at a higher bit-rate. - it should have more latitude for exposure compensation, with no added noise.
     
  6. poostik

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    I'm not using protune. I don't have the option on the Silver. I should have the Black soon so I'll be able to mess around with that.

    As far as it "darkens the whole scene" - that may be the case sometimes but it's much easier to get detail out of something that's underexposed than it is out of something overexposed. I find that no matter what I use (filter/no filter) I end up adjusting exposure anyway, in post.

    I took this video yesterday, right after a storm, about an hour before sunset. No filter. Cloudy as hell. I didn't adjust exposure at all for this. Just made some changes to saturation and graded the sky a bit. I was just doing a distance test with some new antennas, so nothing fancy here.

    https://www.facebook.com/photo.php?v=10 ... 3210896050
     
  7. SurlyBiff

    SurlyBiff Guest

    Nice. I've been having to overlay gradients in the sky on my videos. And they do work ok, until there's vertical movement (like the 0:35s mark in your speed boat video) where it's hard to match the gradient movement to the video movement. I've bought an ND filter, but the weather hasn't been great for flying the past few days. Hopefully tomorrow. And I agree - it's easier to lighten dark areas than to darken what isn't there!

    Thanks again.
     
  8. Paul K

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    I use polar Pro polarizing filter ,before you put the filter on, turn it against the sky for the effect ,but the polarizer is most effective in 90 degree with the sun, try to aim at something non metallic (leaf water etc) you will se the glare will minimize or despair.
    The use of the ND filter is to lower exposure ,because ,if the camera burns highlights (you have no data in the area,like sky and there is no way to fix ) and even if you try to fix it in post process to correct the exposure you can't do anything with highlights.
    If I will be photographing landscape that includes sky ,I will underexpose o.7 to 2 stops depends on situation ;or you put ND filter
    (grad ND is the best for landscape to go the best way ) If you use polarizing filter instead of ND you will darken the scene plus will get rid of (or portly remove) the unwonted reflections from water leafs and another shiny non-metallic objects ,which badly effect camera exposure metering. If GoPro 3+ has exposure control you can experiment with that ,or to increase shutter speed (helps little bit to)
     
  9. Elfman12

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    The Polar is a circular polarizer, isn't it? That should work fine for video, just be sure and spin it around while viewing the image to make sure it's doing what you want.
     
  10. Flying Cephlopod

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    I am convinced that there must be a huge batch of defective GoPro Hero 3 cameras out there that are out of spec.

    I have had two Hero 3 Black Editions and one Hero 3+ Black Edition.

    My first Hero 3, which was an early production run took stunningly beautiful videos--good contrast, moderate colors, good exposure--but unfortunately, it would lock up intermittently. I had gone through a number of firmware updates, but to no avail.

    While under manufacturer's warranty, I exchanged my original Hero 3 for a warranty replacement Hero 3. Instantly, I knew something was really really wrong. In fact, your description fits the same problems that I had encountered, but GoPro refused to replace it even though I was getting blown-out highlights, nearly psychedelic reds and cyans, etc.

    Unfortunately--but fortunately in another sense--someone broke into my car one day and stole my wonky GoPro Hero 3.

    I bought a new Hero Black Edition, which was the model 3+. Performance has been great--no wonky exposures, no washed out highlights. It reminded me of my first Hero 3 other than the fact that it did not lock up.

    Regarding polarizers and neutral density filters, I doubt that either will fix your defective Hero 3's problems. Also, given that the GoPro is fixed focus, I don't think it should matter whether your polarizer is linear or circular. Circular polarizers came into popular practice 20-odd years ago because the linear models interfered with the autofocus function of SLRs.
     
  11. Paul K

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    The polarizer for GoPro is linear not circular (linear has only 1 glass and circular has 2 and you can turn them to get the polarizing effect ) Polar Pro glass one is linear ,but still to heavy ,I am trying to modify it from 8 gr. to 5 or6 gr.; you can get also gelatine one ,but quality is not same and is easy to get scratched .
     
  12. Elfman12

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    Gotcha. I saw a YouTube video with MicBergsma comparing 2 Polarizers for GoPro, and I thought that the Polar version WAS circular, since he "dialed in" the look on it. Thanks for the info!
     
  13. Flying Cephlopod

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    Both types of polarizing filters--linear or circular--would need to be "dialed" or rotated to achieve optimum effect.
     
  14. SurlyBiff

    SurlyBiff Guest

    I have a feeling you might be right. A few months ago I went for a motorbike ride with my mate. We both have Hero 3 Blacks. Both cameras shot at the same settings, from helmet cams. His footage was fine, mine had a terribly washed out sky. That made me wonder even then if my cam may have been slightly defective. The over exposure problem also seems a bit intermittent and random. Some days the problem is much worse than others. Occasionally it even gets the exposure perfect.

    I'll try the ND filter anyway and see how it goes. I'd hate to have to spend yet more money and get a Hero 3 + as a solution.

    Thanks :)
     
  15. Paul K

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    You are right both filters have to be rotated . I have GoPro 3 Black and ordered Gopro 3+ just now and I am going to install 5.4 lens even if there are rumours the GOPro 4 is coming out soon ,but until this happens and all bugs cleaned out I will have enough time to use it .
     
  16. Birdu2

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    Great info guys, i have on my way a Phantom 2 with a gimbal 3D, im getting next week a gopro black, my question after i ready this post is, where can i get a ND filter for it, and wich one is the best.
    I have ready as well that using a gopro with a filter ona P2 with the 3D gimbal can accually burn and unbalnce the gimbal ??
    Thank so much for your time and sorry if these as been asked before .....
    Cheers

    Estevan
     
  17. ianwood

    ianwood Taco Wrangler
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    Given the P2 is typically moving quite a bit, the ND is by far the better option compared to a polarizer and doesn't require any orientation. The ND reduces the light entering sensor reducing the shutter speed so that there is less chance of rolling shutter effects and will add some temporal smoothing between frames. If you're filming in broad daylight, it is an essential accessory on the GoPro.
     
  18. Paul K

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    I would agree with you that shutter speed affects the look of your recording ( because GoPro camera has fix aperture only shorter speed controls amount of light entering the sensor ; faster shutter speed = sharper image ,good for still image ,but video looks choppy ,in another hand slower S speed = frames are not to sharp ,but video looks smoother.) Only way to have control over this ,is to darken the lens . The choice is ND filter or Polarizing filter. I personally believe that Pol. filter is better choice ( it is correct that Pol. filter should be oriented for the best effect ,but linear one is not as sensitive for that ,and if I align it just before flight and put it on camera ,effect doesn't change to much even if I would do 360 panning.)As I mentioned in privies posts Pol. filter is only filter which can reduce unwanted reflections and improve colours at the same time. the simple test would be to switch between regular sunglasses and polarizing ones . In case you don't align your polarizer properly it will at least darken the lens and it will work as ND filter.
     
  19. Elfman12

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    I've been testing my Polar Pro Venture 3+ glass Polarizer - I love the way it can turn water into a sheet of glass. Really nice. In this quick video snippet it's not providing enough of an ND effect for the sun (watch sky/sun area on the upper right about 2/3 in), but the reflections on the water are quite nice. I tried it at another angle earlier and it make the sky pretty dull, so it can be hit and miss. Trying to get a "feel" for it.

    http://youtu.be/zoQlBTiUxPU

    Clip is only about 25seconds.
     
  20. Paul K

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    Your clip is pretty good , if you would have ND as well you can try the same shot with it and compare. The problem in the right corner is ,as you know the GOPro's lens/aperture is fully open (can't be controlled) ,and you have to eliminate any burned areas (your right corner) because of missing detail. As photographer in this situation I would compensate to make the picture darker and post process . With GOPro only way to do this would be to add ND along with polarizing filter ,to darken the picture even more (the camera has also spot metering function ,but unless you have it pointed on that light area /sky ;but have it mounted on Phantom it is almost impossible to do it).There are another factors which are effecting quality of the videos; lens hood to eliminate side light hitting front of your lens and antireflection coating on both ends of the lens specially back end of the leans , and I don't thing GOPro would have any coatings. I just ordered 5.4 lens from Rage Camera and I was told by customer service that the lens has antireflection coating on the lens ,and I hope they were right. Go Pro cameras are fairly priced for what you can get out of it, but there should be higher priced model with better control functions ; and lastly every consumer point and shoot camera is sold with lans hood and lens protector (even if is build in ) ,I was told that GOPro has big number of engineers working on the camera ,non of them realized that lens protection cup and lens hood should be primary standard accessories included with the camera.