jmdh Posted February 28, 2012 Share Posted February 28, 2012 Hello, I'm considering hiring in a moving light for a specific effect requested: a narrow beam (would need to be a couple of degrees) illuminating just the face, expanding to a whole body. The Robe Colorspot 575e has been offered to me and has an iris, but I'm having trouble finding its minimum setting, to figure out whether the effect would be workable. Can anyone let me know? Thanks! Link to comment Share on other sites More sharing options...
mac.calder Posted February 29, 2012 Share Posted February 29, 2012 Minimum setting on 99% of iris' is almost completely closed - it is literally a shutter with a lot of blades that restricts the light output in a fairly circular manner - the downside is you loose a lot of the brightness of the fixture. According to Robe, the 575 has adjustable zoom in stage (I assume using a lens wheel or something) with 15, 18 and 22 degree beam angles which are remotely adjustable. Link to comment Share on other sites More sharing options...
jmdh Posted February 29, 2012 Author Share Posted February 29, 2012 Minimum setting on 99% of iris' is almost completely closed - it is literally a shutter with a lot of blades that restricts the light output in a fairly circular manner - the downside is you loose a lot of the brightness of the fixture. According to Robe, the 575 has adjustable zoom in stage (I assume using a lens wheel or something) with 15, 18 and 22 degree beam angles which are remotely adjustable. Great, thanks for that. I wasn't sure what was "normal" for this type of units, and thought I'd read something about some units only going down to 15% diameter. Should give us plenty of flexibility. Loss of brightness shouldn't be an issue in our setting. Link to comment Share on other sites More sharing options...
jmdh Posted March 10, 2012 Author Share Posted March 10, 2012 In the end, this wasn't quite enough; partly this was because we needed to site the unit further away from the area than planned. Since it ended up being sat next to the operation area I was able to improvise by placing a black folder in front of the beam a few inches away. Of course this ended up with horrible fringing and loss of light output, and wasn't very stable, but it actually sort of suited the act (mouth miming). I estimate that the minimum beam angle (with the 15 degree zoom selected) on this unit is around 1.5 degrees - we would have wanted to end up with around 0.5 degrees. One to chalk up to experience :) Out of interest, what other equipment would people recommend for this sort of effect (allowing for an expanding beam)? Link to comment Share on other sites More sharing options...
smalljoshua Posted March 10, 2012 Share Posted March 10, 2012 If you want such a tiny divergence, the devil's advocate in me says a laser might be appropriate. Provided all the risks are assessed. Failing that, a Sharpy has a beam angle of 0-3.8deg but also happens to have a 12m minimum distance to the nearest illuminated object. Something to consider is that even though the diameter of the spot hitting a surface is reduced, an iris doesn't alter the beam angle so when you're calculating the beam diameter at a given distance, you have to take that into account. Also, you loose an awful amount of light output from using the iris. Josh Link to comment Share on other sites More sharing options...
hadyn.williams Posted March 10, 2012 Share Posted March 10, 2012 Out of interest, what other equipment would people recommend for this sort of effect (allowing for an expanding beam)? If you want such a tiny divergence, the devil's advocate in me says a laser might be appropriate. Provided all the risks are assessed. hmm, can you open out lasers to create the expanding beam though? I wonder if a projector would be a good solution? Or maybe a followspot as they iris down all the way to close. Link to comment Share on other sites More sharing options...
smalljoshua Posted March 10, 2012 Share Posted March 10, 2012 If you scanned it to create a cone, that'd allow you to create a circle instead of a solid beam at least. Josh Link to comment Share on other sites More sharing options...
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