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Prop shadows in video??? Really puzzled :-(
763 16 2016-8-4
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imagesbyjas
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Short video of flight yesterday (segmented to shorten but illustrate).  I never seen this before and don't know if the sun and altitude and angle all played out "wrong"... but watch for lines in the video shortly after take off..  speed up with acceleration on props, fade with gimbal angled down a little.. still showing in later parts until I do a 180 and start coming back where everything was normal..  At a loss, but since the lines sped up with the my acclerating foward, I have to think it had something to do with maybe shadows and just the wrong angle as I said..  Welcome any thoughts..  Whole video is a little over 2 minutes and compress to 1920 x 1080..  Thanks...


P.S.  Hit "Watch on Youtube" for higher res.



2016-8-4
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labroides
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If you fly the Phantom at such an angle to the sun that its light passes through your props and across your lens, this is what happens.
Just be aware of it and arrange your filming to avoid that situation.
2016-8-4
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DJI-Jamie
DJI team
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In addition, you could also be dealing with a lighting issue. Do you use a ND filter?
2016-8-4
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Geebax
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DJI-Jamie Posted at 2016-8-5 08:31
In addition, you could also be dealing with a lighting issue. Do you use a ND filter?

If anything, the images are under-exposed. ND would not help at all.
2016-8-4
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imagesbyjas
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labroides@yahoo Posted at 2016-8-5 06:25
If you fly the Phantom at such an angle to the sun that its light passes through your props andacros ...

Labroides,

I assumed as much, truly had just never seen it.  Makes perfect sense given the frequency resonance with the increased speed as I was accelerating..  Later flights were fine.. just an occurrence I had not encountered but clearly something to be that much more aware of...  Thanks for the reply...
2016-8-4
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imagesbyjas
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DJI-Jamie Posted at 2016-8-5 06:31
In addition, you could also be dealing with a lighting issue. Do you use a ND filter?

Jamie,

Yes I do, but (and also Geebax) this was a "test new setup" more than anything so cinematic excellence was low on the list this time..  just something as I said I'd not seen...  Have both plain ND as well as ND/PL combo (which I love when I can fly at 90 degrees to the sun - incredible difference)..

Thanks for the replies folks..
2016-8-4
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pi-inthesky
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labroides and DJI-Jamie's advice will definitely resolve the problem to a greater degree than Geebax's comment of under exposure that problem is resolved in post editing.Your return flight  with the sun behind you certainly is not under exposed which underpins labroides advice.
2016-8-4
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Geebax
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pi-inthesky@hot Posted at 2016-8-5 10:04
labroides and DJI-Jamie's advice will definitely resolve the problem to a greater degree than Geebax ...

Really? I have no idea where you get the idea that it is best dealt with in post. It is always best to expose rthe camera correctly at the time of shooting. And definitely no to an ND, they are only required where the image is too bright for the cameras to handle, and in the clip posted, it is under-exposed. And finally, an ND filter will not reduce prop shadow.
2016-8-4
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DJI-H.C
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Well, since the shadow speed increase with your prop speed, and the shadow disappears after turn 180 degrees, it's pretty obvious that it's the prop shadow.
2016-8-5
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pi-inthesky
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Geebax Posted at 2016-8-5 10:05
Really? I have no idea where you get the idea that it is best dealt with in post. It is always best ...

Where's the word best in my comment,and the second part of the clip is not under exposed.
2016-8-5
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imagesbyjas
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DJI-H.C Posted at 2016-8-5 16:55
Well, since the shadow speed increase with your prop speed, and the shadow disappears after turn 180 ...

H.C.,

So should I imply that I shouldn't have created a post just to check?  I thought this was the place where we come to help each other no matter if it is something "new" or simple to someone or something many have covered many times, e.g. failures after firmware upgrades, but thanks for the "pretty obvious" tone of the reply.

All,

Thanks for the confirmation of what I suspected but wasn't 100% certain of..  I think we've gotten all the bases covered and again thanks..
2016-8-5
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endotherm
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If flying at that angle to the sun and your subject is unavoidable, and you have time for the correct setup, you can use a lens hood to shade it from the shadows.  It works in the majority of cases.

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2016-8-5
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DJI-Ken
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If you get a ND filter it will take care of that.
2016-8-5
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imagesbyjas
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DJI-Ken Posted at 2016-8-6 00:25
If you get a ND filter it will take care of that.

Ken,

Not sure an ND would have made a difference in this case.  I think this was just a case of the angles just being right so that the shadows of the props were being cast in front of the lens.  Not even sure the lens hood would have helped, but might have..  Might be worth the investment to try..

Thanks for the reply..
2016-8-5
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Geebax
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imagesbyjas Posted at 2016-8-6 03:26
Ken,

Not sure an ND would have made a difference in this case.  I think this was just a case of t ...

You are correxct, an ND filter would not have helped at all, but a lens hood could have helped if the angles were favourable. Just be careful using one though as it unbalances the camera gimbal with the extra weight on the front.
2016-8-5
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DJI-H.C
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imagesbyjas Posted at 2016-8-5 10:02
H.C.,

So should I imply that I shouldn't have created a post just to check?  I thought this was th ...

Hi, I don't mean you shouldn't post it, I was just saying your suspicion is correct and it looks obvious to me
2016-8-5
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imagesbyjas
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DJI-H.C Posted at 2016-8-6 10:27
Hi, I don't mean you shouldn't post it, I was just saying your suspicion is correct and it looks o ...

H.C.,

Thanks for the reply ..  Perhaps just the phrasing?  No problems..

Jay S.
2016-8-6
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