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Old 11-15-2010, 08:57 PM   #91
wheatgrinder
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yup, Knightly wins the cigar,
I can get closer to a typical standing subject (i.e. Me) therby increasing image detail, more detail, = beter key.
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Old 11-15-2010, 10:17 PM   #92
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I hope it's a good cigar, I'm kinda particular
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Old 11-20-2010, 08:17 PM   #93
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results of experiments using retro-reflective tape

I have done my own experiments using previous information and with the discovery of a very inexpensive material for the backdrop that doesn't require sourcing it from China. I used an old camera for these images so they aren't the greatest quality.


----- Light rings and accessories ---------


Purchased from SuperBrightLeds.com.

In addition to a green and blue ring, I also needed a power supply, dimmer and adapters. If you use the following invoice as a guide, note that it would be best to get two adapters so that you can permanently hook up the green and blue ring each to an adapter eliminating the need to undo the wires. I thought they would plug in to the light ring but the wires are just exposed.



I have only used the green light ring. I measured the diameter of my camcorder's lens then cut a circle in the center of an old plastic yogurt lid. I attached the led ring to the plastic lid and it sits

securely on the front of the lens creating even spacing of the lights.







----- Retro-reflective material -------


An earlier post of mine in this thread noted that there have been two previous attempts at a DIY system documented elsewhere. The frustrating part is that most are unwilling to disclose where they got their material. When they do it's too expensive (3M) or complicated (China). Some have speculated on the use of paint or a projection screen.

A search on Ebay yielded a retro-reflective tape that is ironed on to a fabric. This was convenient because the seller is in Canada (my home country) and offered a full money back guarantee if unsatisfied.
This helped me to take a risk on it and I am very glad I did.

After placing my order, I did a test then created a 5ft X 4.5 ft backdrop. The cost was $50. Add that to the light ring setup and my total cost was about $100. However, I would want to create a larger backdrop so that cost would increase. But it's still a lot less expensive than even the cheapest alternative I have seen.

The retro-reflective tape is available in several different sizes, I chose the 6" width because it would mean less ironing onto the fabric. I had hoped to just tape it on the wall but it is necessary to iron it onto something to successfully pull off the plastic film over the top. Here is the link to the seller's Ebay page, but check my later post below for new information about a less expensive 39" size.

http://myworld.ebay.ca/speedyweboutlet/

This is what it looks like.




------ Video results ------

This is a test video I did today. I just grabbed an image for the keyed backdrop which isn't high resolution.

This certainly isn't broadcast quality but is great for my purposes because it's dirt cheap and very easy. As has previously been posted, you just hang the fabric and turn on the light. I originally had the dimmer too low and had to increase the brightness to get an even green color.

I imported the footage into After Effects CS4 and used KeyLight (1.2) to remove the green. The moment the color was selected the program did a great job eliminating the background with only some minor
changes to the other settings.

I was unable to get the embedded video to work so here's the link: http://www.vimeo.com/17036277


----- I hope this helps. Let me know if you have any questions. -----

Last edited by michaelmanch; 11-21-2010 at 11:55 PM. Reason: embedded video not working
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Old 11-20-2010, 10:04 PM   #94
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awesome job!

Does that dimmer cause flicker?

Thanks
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Old 11-20-2010, 10:32 PM   #95
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for 10'X10' backdrop of that eBay fabric cost is about $230?

I price that link at $2.30 a sq foot.. (3'x6" for $3.50) x2 = $7 for 3 sq ft. divided by 3 gets me $2.30 a square foot. not bad beats $800 for the 3M stuff!
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Old 11-21-2010, 10:40 AM   #96
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Quote:
Originally Posted by wheatgrinder View Post
awesome job!

Does that dimmer cause flicker?

Thanks
Nothing that I can detect. It causes all the leds to brighten and dim evenly.
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Old 11-21-2010, 12:58 PM   #97
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even cheaper price for retro-reflective material

IMPORTANT UPDATE: I sent a message to the Ebay seller and this is his reply:

Quote:
Wow!! That is amazing and so cool!
Actually I have another material that
may serve you better. It's 39 inch wide, slightly cheaper than the 6 inch
wide tape per square feet.
Thanks for your eye opening post.
John

-speedyweboutlet
Identified in the product description as retro-reflective, here's the link for the larger size:

http://cgi.ebay.ca/SILVER-REFLECTIVE...item19bf95d162

Last edited by michaelmanch; 11-21-2010 at 11:49 PM. Reason: new link for product
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Old 11-21-2010, 06:38 PM   #98
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This thread is getting really exciting!
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Old 11-22-2010, 12:42 PM   #99
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Another Update: My Ebay seller sent some more information:

Quote:
The 39" wide retro-reflective sheet is already fabric, so no need to iron
it (you can't iron it as it does not have heat-activated glue).
His Ebay page shows that the 3 ft X 39" fabric is approximately $15. So a 6 ft X 6ft backdrop not requiring any ironing and could be taped to a wall costs about $60. Really wish I had explored this more to save some effort. But there are advantages to creating an ironed on screen that could be hung on supports. What do you do if you arrive at a location with 4 sheets of this fabric. You would still need to bring something to attach it to.

Also, the product description states that "the fabric will be folded and shipped in an envelope because it's very wide." If folded the retro-reflective properties could become damaged and create problems with keying at those spots. Rolled in a tube would be best but I'm not sure about that as an option.

Others with more experience may know how best to approach this.

Again, the link for the 3 ft X 39" retro-reflective fabric:

http://cgi.ebay.ca/SILVER-REFLECTIVE...item19bf95d162

Last edited by michaelmanch; 11-22-2010 at 12:48 PM. Reason: thank goodness for the ability to edit posts
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Old 12-08-2010, 02:53 PM   #100
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thanks for you info, i bouth 4 sheets 1yardx39" from the canadian ebay user (50 euro shipped). I also bought 2 angel eyes 100mm diameter because i will use on reflex lenses that need a bigger size. The ring has 33 led smd. I bought from german ebay shop and i paid 17 euro for 1 green and 1 blue.


Finally i bought a dimmer from hong kong ebay, 8 euro.



When i will have everything in my hands i will setup and test it
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Old 12-08-2010, 05:16 PM   #101
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Originally Posted by onesky View Post
thanks for you info, i bought 4 sheets 1yardx39" from the Canadian ebay user (50 euro shipped). When i will have everything in my hands i will setup and test it
Glad I could help. My Vimeo statistics show a huge number of views of the video from Italy. Any idea as to why there would be such a specific interest from your country? Since you just joined the forum I'm assuming you learned of the project from another source.

I also got some of the 39" fabric and it works pretty much the same. My setup doesn't produce the best results unfortunately. I'm using fluorescent lights in my basement. If my planned Web site about the tests comes to fruition, it would be nice to feature international results as well.

Last edited by michaelmanch; 12-08-2010 at 09:04 PM.
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Old 12-09-2010, 12:32 PM   #102
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about dimmers..

the PWM (pulse width modulation) method of dimming LED's can cause your green screen to oscillate or flicker like a TV screen or Monitor will on camera. The one I have does at any rate. You cant see the flicker with the naked eye, but your camera will pick it up. You can also manipulate this behavior with shutter speed. I don't know if different PWM dimmers work differentially, there may be some method of PWM techniques that allow for dimming without pulsing so slow that it is detectable on camera... any ideas?

michaelmanch, did you FILM your screen as you move the dimmer from off through its range to full on?

Thanks
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Old 12-09-2010, 02:37 PM   #103
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Quote:
Originally Posted by michaelmanch View Post
Glad I could help. My Vimeo statistics show a huge number of views of the video from Italy. Any idea as to why there would be such a specific interest from your country? Since you just joined the forum I'm assuming you learned of the project from another source.
we are talking about the diy-led-setup in the italian video makers forum and i started my kit after reading your post.
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Old 12-11-2010, 08:37 PM   #104
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about dimmers..

michaelmanch, did you FILM your screen as you move the dimmer from off through its range to full on?

Thanks

The idea for the dimmer came from the company's Web site. It proved to be necessary for me. Without the dimmer the led ring is at full brightness. I discovered that as I increased the brightness of the ring, it bled over the lens affecting the exposure of my image. The brighter the light ring made it the darker I became. See the following image showing the changes by increasing the percentage of the led brightness from 25% - 100%.

I am not a technical wizard and fully realize that I could be doing something wrong and welcome any input to improve my situation.



My most baffling experience has been the halo effect that I get. This is not a shadow as some may suspect because I am sitting too far away from the screen and it is consistent all the way around. I visited the Reflecmedia Web site and viewed some of their videos and this doesn't seem to occur with their system. Proper lighting may again be an issue.
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Old 12-11-2010, 10:36 PM   #105
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halo looks like shadow, move your subject away from the screen to help it go away.

as for exposure, auto will adjust to the primary value's brightness... in this case, the green... the brighter the background, the darker the camera goes to make up for it.
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