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JMS

POLARIZED LENS: WILL THEY HELP camera over light?

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I've been flying lately and I noticed that my videos are very dark in image. That's before I fooled around with the brightness, contrast, gamma etc.. but that's just simply cheating!

I remember seeing a military UAV and noticed the glass covering the sensitive camera was almost mirror like. Are those polarized lens?

I thought about cutting out the bottom of my black camera lens cover and sliding it back partially to make my own lens hood. Or even buying the lightest tinted sunglasses with polarized lens and use it ( a lens) to cover the camera, hoping it would deflect the bright sun light from shutting the cameras' iris. Would this work? I know most of you pick and choose the time of day to fly like noon, when the sun is at it's highest point. But for a guy like me who works most of the time, I can't work around the sun. The sun has to work around me B) . So would a lens hood or a lens hood with a polarized lens work? Just a thought that popped into my head this morning. :D

JMS

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The way polarizing filters work, it can be a bit of a challenge to keep the filter at the best orientation with aerial photography. Polarizing filters work best when the sun is at a 90 degree angle to the object you are attempting to photograph. In other words, if a giant photographer stood in the Atlantic Ocean pointing his camera at the United States to the west, he would get the best results around noon when the sun is at a 90 degree angle to his position. If you were to use a filter on a camera that is pointing downwards towards the ground, you would have to fly parallel to the sun, (not towards it or away from it) after sunrise and before sunset to achieve the maximum effect of the filter.

You can get a decent quality one for about $20. The ones made by Tiffen are a good start.

Here’s one for example: http://www.bhphotovideo.com/bnh/controller...oughType=search

This should give you an idea of what to expect with a polarizing filter

http://www.naturalhighs.net/waterfalls/fal...2/taugh-p9.htm# (click on the camera to the right)

Edited by s2e3s2z2

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Thanks s2e3s2z2

For filling in that question void in my head! ;) I had a hunch that it was possible since when I fly fish, the water ripple reflects sunlight causing loads of glare. Put the polarized sun glasses on and bingo, I see fish! But I had no idea about the angle part but it makes sense since the lens are made up in layers.

I might toy with this. I found some camera polarized filters (fairly transparent, fairly cheap) on Ebay. I don't know if it's good or not? I have a friend in the eye ware business and I will ask him if he can shave them down to fit a lens hood I will fabricate on my buddy's lathe. I play with angle lens thing before I hack it up..... I could use a set for my digital camera if this idea doesn't work.

Thanks again for the input! :D

Edited by JMS

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I tried a few weeks ago to cut a piece from my kids sunglasses, and taped it in front of my kx131 cam, it really helped alot.

since the cam is ultra light sensitive and can not handle the dynamic range.

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Maybe it's just the camera. What are you using?

I'm using a KX 131. But I tried it on a KT&C 520tvl bullet cam and same results. Too much light for the sensors to handle so the video goes dark. :angry:

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I tried a few weeks ago to cut a piece from my kids sunglasses, and taped it in front of my kx131 cam, it really helped alot.

since the cam is ultra light sensitive and can not handle the dynamic range.

Yes Thomas, I was thinking of that too! But with my own sunglasses :D

I think I will give your idea a shot since it's easy to do and available at my disposal. :D

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Well I'm not too educated on this subject, but I checked out my "polarized" fishing sunglasses. I tilted it in all the angles I could think while looking through it. I didn't noticed any disruptions of vision as told about polarized lens. So does it mean there are various grade of "polarized lens"? Anyhow here is the picture of the lens I talked about.

BTW, my friend at the eyeglass shop said it's possible for him to custom carve out a lens whether curved (like sunglasses) or flat (like camera filter lens) to the right size I want to fit over my CCD camera. :lol:

post-5-1178163398_thumb.jpg

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another pic..

To come to think about it. These cheap sunglass lens are fairly soft. I can bend them so perhaps I could use a heat gun and flatten them out? Perhaps trim them myself carefully with a Xacto/hobby knife? Anyways the tint is too dark and I have seen really light yellow aviation version at Walmart or similar. I'll have to look into this more.

post-5-1178163487_thumb.jpg

Edited by JMS

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Cheap & cheerful solution, just some pins covered in wire insulation. No image distortion or edge flare I've noticed (even when it's not seated quite right!).

I've convinced myself it helps a little on bright days; a bit less glare from clouds. Perhaps. I ought to submit a 'with-without' comparison and see if anyone on the forum can tell which is which...

post-5-1178552649_thumb.jpg

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Hi Doofer :)

Wow .... I had a feeling if someone who would of tried this, you seem to come to my mind since you are one of the pioneers in FPV. I bet you tried many, many things out to improve this hobby over your years of experience! So it would be nice if you could post a "with-with out" lens to see the difference. I have another answer as well, but more costly from RCG. http://www.rcgroups.com/forums/showthread.php?t=680128 Read the comments on a really nice guy, (CAMSHIP). He's using camera IR filter over a high resolution camera. Interesting! ;)

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Thanks JMS, were it not for the coming week's forecast of 'rain rain rain' I'd get right onto it - ahh, this island weather...

The PF filter, from Kaya's description, sounds like a glorified 'skylight filter' i.e. a piece of glass, which filters out the UV end but leaves the Infra-red, popular with landscape photographers as it supposedly differentially cuts down contrast (sky - lots of UV, ground - less). What I've never been able to understand is why these filters have an effect when the camera front element is already, er, glass. However, if there's one thing FPV has taught me it is that you really won't know what effect something has until you've tried it in practice. Their product still has the problem of how to mount the d*mn things onto a board camera (hence my string 'n spit solution).

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Just a quick tip for those who don't know.

If you want to find out if your cheap sunglasses are polarised or not, hold them infront of an LCD screen (eg. wristwatch). If you can see the numbers on the display then rotate the sunglasses by 90 degrees. If they are polarised lenses then the display will no longer be readable.

Si. :)

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What I've never been able to understand is why these filters have an effect when the camera front element is already, er, glass.

Because the filters are not only glass, they also have a coating that has the desired effect. The glass is only there to support it...

If you look a bit into specialized optics (lasers for example) you'll find there are countless treatments (anti-reflective, highly reflective, absorbing, polarising, ...) for about any wavelength range you'd expect to use in your application. To the naked eye they're just glass filters, but they're actually much more than this.

However, if there's one thing FPV has taught me it is that you really won't know what effect something has until you've tried it in practice.

Exact!

ahh, this island weather...

Be reassured, it's the same here ;)

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Their product still has the problem of how to mount the d*mn things onto a board camera (hence my string 'n spit solution).

Sounds a lot like me! :lol:

As for island life.... yes I can relate since my island is much the same as yours! RAIN, RAIN and MORE RAIN!

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Kirah - I must admit, the effects of skylight, neutral density and other filters I've tried seem very subtle (= nothing much at all - sorry, Thomas!) - of relevance to professional photographers perhaps. Nothing like the magnitude of effect needed to address the contrast problems so much in evidence while FPV flying.

Perhaps we'll start believing filters will help when RC-Tech start selling them :rolleyes:

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Meh ;)

With a neutral density one it's normal you see nothing, its purpose is only to attenuate light as uniformly as possible (i.e all colors the same) so that you can use longer times/bigger apertures in a given condition ;)

I'm no photo expert at all so it's pretty much all I know of :P

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Ok Kilrah.... I keep seing you use the words "MEH". So what does MEH means? :lol:

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Ahhhhh ... thank you Kilrah for guiding the light into my face :lol::lol::lol::lol: I finally know what MEH means now! :lol::lol::lol: hee hee

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Another way to see if a lense is polarized is to look at it through a known polarized glass. When one is turned 90 deg to the other, it will appear black and opaque.

Also, to the fellow that posted a pic of the lense in front of the camera lense, if there is a space between the two lenses, you will get a visible reflection of the sun when it shines between them. It will only be noticable sporadically. Or depending on where on the plane it is located, you may end up with a reflection of part of the plane that will appear like a water mark throughout your video.

I tried the polarizing filter using cut up sunglasses and a kokam(sp?) photography filter. To my suprise, there really was not much difference. The camera (kc-121) auto compensates the brightness. I flyfish as well (for bonefish, permit, snook and tarpon) and was expecting to see a dramatic difference as when I put on my Costas, REVOs, or Ocean Wave sunglasses.

-dave

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Thanks for the valuable input Dave! :D I'm getting more and more similar messages regarding this, but it is great for others who are reading this thread to now know the results. It adds more to the FPV Encyclopedia :D

BTW I just received a new Airwave A/V RX and to my surprise, the video from my KX131 is suddenly brighter with more resolution compared to the old one I was using. Mind you, this is only a bench test under florescent lighting. I guess my old (unknown make) RX must have loads of internal noise thus the poor results. Oh well, when I bought the silly thing, I wasn't a member of RC-CAM at the time. I have so much to learn and as long I am here, I know I am in good company because of people like you! :D

John

Edited by JMS

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you could possibly attach the lense with carbon filled epoxy. Would create a very well light sealed enclosure. Would have to make sure the lense works first though.

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