Videoing laser (specifically beam) shows?

[LtKernelPanic]

Ok so I bought one of those Reke 500RGB projectors from DD and I have to say for a cheap projector it's pretty damned nice. Getting video of graphics is easy but I'm not sure about how to capture beam shows. This PJ isn't the the most powerful beast with a theoretical max power of 560mw which is still enough to damage your eyes. I've looked at a handful of videos of beam shows here and on youtube and mot seem to have the camera off center and below the projector's aperture. Ideally you'd want to be father away to capture the spread of the beam and to let the power dissipate with distance but in a small house that's not really an option. Is there a rule of thumb that's best to follow? Since this is my first (and *definitely* not my last!) projector I want to do this the safest way I can and still get nice results.

 

[ARG]

Check your camera first and make sure it's not sensitive to lasers, I tried to take a video of a 5mW laser (the beam didn't get close to the lens at all) and my video camera was damaged (some hardly noticeable red lines in the bottom comer)

Try it out with a 5mW laser before you start recording a 500mW projector, just so you don't kill your camera badly. (If this is your first time recording a laser with your video camera)

 

[Cyparagon]

I prefer them inside the projection zone, but you need a beam attenuation map to blank the center where the camera will be. A cheap projector like that probably didn't come with appropriate software for this, though.

You could try what SOHO does. "Block the sun to see the corona" becomes "block the aperture to see the beams"

 

[LtKernelPanic]

Thanks for the tips. This PJ doesn't have any software other than the basic built in controllable by the dip switches. I'll try the "block the corona" method sometime soon as I've done that in the past by hand when looking towards the aperture of a laser. I plan on getting a basic DAC (thinking Audiolase) and some software (undecided maybe Spaghetti or drlava's?) to make some better shows. I realize this cheap PJ isn't going to make the mind blowing shows like some of the awesome builds here but it'll tide me over until I eventually get something better. I did do a test using my D90 in video mode last night shooting it from outside the cone (not gonna even chance frying my DSLR!) and it came out decent. One other thing I need to do soon regardless is get better fog juice for my fogger. The stuff it came with sucks!

 

[Benm]

I prefer them inside the projection zone, but you need a beam attenuation map to blank the center where the camera will be. A cheap projector like that probably didn't come with appropriate software for this, though.

You could try what SOHO does. "Block the sun to see the corona" becomes "block the aperture to see the beams"

There is a potential simple alternative for this: You can test-run the entire show, with the camera in position and the lens cap on. The trick is to find a spot that is never hit during the entire show, which is sometimes possible.

As long as you don't move things around, you can safely remove the lens cap and run the exact same show again to record it.

Blocking with some object in between does have the advantage of masking stray light from the projector output splashing the image, but you will see whatever you use to block the light in the video, as well as whatever you need to use to keep the blocker in position.

 

[LtKernelPanic]

There is a potential simple alternative for this: You can test-run the entire show, with the camera in position and the lens cap on. The trick is to find a spot that is never hit during the entire show, which is sometimes possible.

Now why the hell didn't I think of that? The only problem is without a DAC it just cycles through the build in images which means the output is all over the place. I'm still debating an audiolase DAC and either spaghetti or drlava's software. Need to check compatibility though.

 

[Benm]

You can build a souncard dac too, right? Afaik this projector has ilda input, so it should not be that hard to just construct the correction amp and run a show in spaghetti, lfi or whatever you prefer?

 

[Guyfromhe]

I'm still trying to convince my Audiolase to work with this projector (or at all?)

 

[LtKernelPanic]

Yeah I could build a sound card based DAC but I suck at soldering which is why I was thinking of being a lazy bum and spending the $150 on a complete sound card + DAC from Adam over at PL. I'd just need to decide on the software to go with it.

 

[Guyfromhe]

I finally am getting close... I got a blue splotch to appear with the DAC and I can turn it on an off... I a, supposed to have a phone call with Adam to get it working properly in the next few days and I will be doing a detailed write up on getting it working with this projector soon..

I needed to modify the cable to get it to recognize that ILDA was connected...

 

[rocket689]

Yeah I could build a sound card based DAC but I suck at soldering which is why I was thinking of being a lazy bum and spending the $150 on a complete sound card + DAC from Adam over at PL. I'd just need to decide on the software to go with it.

Cfavreau over on PL has designed an Arduino based DAC. I bought one of his beta units this past weekend at SELEM.

I havnt gotten to use it yet, but his demo looked like it works pretty slick. :beer: