Louis sullivan NLS Posted October 5, 2012 Share Posted October 5, 2012 Hi everyone, This may sound a bit stupid... I am lighting a dance show soon and have no budget for hiring in some 400w cannons for UV.we have used 4ft tubes in the past at this venue but they upset the camera guy! Is it possible to use 3 or 4 PAR64's on the FOH bar fitted with congo blue or something? Ta Louis Link to comment Share on other sites More sharing options...
maxjones2000 Posted October 5, 2012 Share Posted October 5, 2012 I've found that congo blue works quite well to give a sort-of UV effect... I accidently used it for a carol service (oops...ah the joys of being an innocent 16 year old!).. it didn't last very long though before melting/going clear, and that was in 300W short-nose P56's. Also seen it used several times in fresnels to give a UV sort of effect. Hope this helps,Max Link to comment Share on other sites More sharing options...
indyld Posted October 5, 2012 Share Posted October 5, 2012 Congo Blue or similar can be used to create a deep violet, pretend UV if you will. Common tungsten incandescent light sources produce relatively small amounts of sub-400 nm actual Ultra Violet compared to a black light, this can't be created using a filter. Any glass that gets in the way can reduce what there is created at the filament. I don't think anyone here would suggest that you try to use another UV heavy source and remove any fitted shields that are designed to filter out dangerous UV wavelengths. If Congo non-ultra violet will be suitable for your application depends rather on what you want to achieve for your show. E2A: Couldn't find this earlier, but there is some easy to understand information on UV effects and related issues at: http://www.wildfirefx.com/resources/tutorials/uvtech.aspx Link to comment Share on other sites More sharing options...
Gerry Posted October 5, 2012 Share Posted October 5, 2012 Yes. Congo blue will work and give a UV effect.But very little light is transmitted through a congo blue filter so you need some powerful or many light sources.CheersGerry Link to comment Share on other sites More sharing options...
Brian Posted October 5, 2012 Share Posted October 5, 2012 Yes. Congo blue will work and give a UV effect. Before we get into R.A.T.S. territory can we just agree once and for all that Congo Blue does not give a UV effect but a UV-like effect. Link to comment Share on other sites More sharing options...
timsabre Posted October 5, 2012 Share Posted October 5, 2012 Yes. Congo blue will work and give a UV effect. Before we get into R.A.T.S. territory can we just agree once and for all that Congo Blue does not give a UV effect but a UV-like effect. It does make fluorescent things glow, if that is the desired effect. Link to comment Share on other sites More sharing options...
indyld Posted October 5, 2012 Share Posted October 5, 2012 With filters that cut out pretty much everything apart from a small amount at the lower end of the visible spectrum, there is potential for fluorescence in which invisible light becomes visible again when reflecting from a particular surface. As has been mentioned, all the other colours hefting out of a broad spectrum source such as incandescent get blocked and turn into heat which in practice, burns out the filter PDQ and is extremely inefficient and power hungry for the final light output. If I were going to try to get maximum fluorescence from something like Congo Blue, I would spend quite a bit of time experimenting with hitting the sweet spot in terms of reflective materials and make sure that I was not only getting good reflectance at a particular wavelength but also that I wasn't washing other wavelengths about the place that can lessen the resulting effect. If you look at the relative transmission of L181, you'll notice an uptick at the top end in the visible reds. This might be good to know when looking for materials in that you might try to avoid that end of the spectrum with other things that are supposed to be hidden / less intense. Especially as a tungsten lamp flings out reds like nobodys business and is a bit thin at the other end. Either way, if you need a black light effect that uses fluorescence to glow out, using 181 is making a meal of it IMO. And after all that, I'm not sure your cameraman is going to be any happier. Link to comment Share on other sites More sharing options...
Gerry Posted October 5, 2012 Share Posted October 5, 2012 Yes. Congo blue will work and give a UV effect. Before we get into R.A.T.S. territory can we just agree once and for all that Congo Blue does not give a UV effect but a UV-like effect.OK if you want to be extremely pedantic I should have said UV-like effect.Can we leave it at that and not get into the old FW argument?CheersGerry Link to comment Share on other sites More sharing options...
indyld Posted October 5, 2012 Share Posted October 5, 2012 Just an idea. If you want to use a colour effect that can do show/hide tricks but don't want to get into UV, how about using the principles that the Samoiloff Effect is based on? Careful choice of reflective materials and light colours can make things appear and disappear or glow (basically, be brighter than everything else). It's just coming at the problem from the other end, carefully limiting the colour reflectance of the things on stage, unlike most UV effects that rely on invisible light slowing down when pinging off an, often white, surface. Link to comment Share on other sites More sharing options...
Ian Cunningham Posted October 6, 2012 Share Posted October 6, 2012 Yes. Congo blue will work and give a UV effect. Before we get into R.A.T.S. territory can we just agree once and for all that Congo Blue does not give a UV effect but a UV-like effect. You are Frank Wood AICMFP Link to comment Share on other sites More sharing options...
Jivemaster Posted October 6, 2012 Share Posted October 6, 2012 Tungsten light contains no effective UV so you will NOT get a UV effect from a filter over par cans. What you will get is a very dim light of a specific colour which may be effect enough. Either go for a proper UV or skip the effect. http://www.terralec.co.uk/uv_lamps/100_watt_ultra_violet_lamp_e27/24522_p.html is a compact fluorescent lamp that fits in an E27 (ES) fitting and makes some real UV Maybe your local disco shop will have something similar maybe someone will offer a BC version as well. Link to comment Share on other sites More sharing options...
Ynot Posted October 6, 2012 Share Posted October 6, 2012 I am lighting a dance show soon and have no budget for hiring in some 400w cannons for UV.we have used 4ft tubes in the past at this venue but they upset the camera guy! Is it possible to use 3 or 4 PAR64's on the FOH bar fitted with congo blue or something?Louis, As has been said already, Congo cannot replicate the UV effect, only pick up on anything which can fluoresce. However, the other downside with Congo is that it will also light other areas of the stage that will reflect SOME of the light, even if they don't fully fluoresce. SO if the effect you're after is the age old traditional 'just see the UV whites and colours and nothing else' then you'll be disappointed. But if you actually want something which will pick out the fluorescent bits on costumes whilst still showing the dancers, then maybe Congo is going to suit. Some of the better LED UV fixtures also do this, as they also emit more than just the UV spectrum. However, I'd perhaps take issue with what you say about the cameraman... If this is the guy filming the performance to sell to the parents, then my stance ALWAYS in these cases is that the show is lit for the paying AUDIENCE, not the handful of DVD copies sold in-house. If the 4 ft tubes give him cause to complain, but do what you need for the public show, then I'd politely remind him of this.As it happens, I had a vidiot ask about the haze in use during this week's dress rehearsal for a charity show I was lighting, asking if we could drop it - I gave exactly that answer, though I did point out there was more haze obvious as I'd been programming all day on an empty stage so there was much more than you'd normally expect. After last night's show he came to say that everything was in fact fine after all. :) Link to comment Share on other sites More sharing options...
light-man Posted October 6, 2012 Share Posted October 6, 2012 I once used Congo for a dance show, though I ended up supplementing it with LED cans for the fluorescence effect. We fitted it in 3 500w Prelude Fs and the light output was far from adequate, really, but that's no surprise really since you don't get that much light out of a 1k PAR when using Congo. We have used Congo in 1K PARs on a Panto before to boost the fluorescence of some parts of the set, but that was in addition to 400w UV Cannons. Link to comment Share on other sites More sharing options...
paulears Posted October 6, 2012 Share Posted October 6, 2012 we have used 4ft tubes in the past at this venue but they upset the camera guy I suggest a simple priority issue. What is more important? Three flu tubes will work staggeringly better - and as a camera guy myself, they don't cause any issues at all if a. the operator knows how to use the camera and b. the camera isn't a pile of poo. It really is NOT a problem for cameras - in fact, cameras often show more 'real' colours than the naked eye does. The eye sees bright and white fabric, but the camera can see the difference between white and blue fluorescence. If you want/need UV, then simulating it with a stage load of congo produces a deep blue that has some fluorescent qualities, but 3 real flu tubes might well outshine 12K of PAR64s with 181 in them! Link to comment Share on other sites More sharing options...
J Pearce Posted October 6, 2012 Share Posted October 6, 2012 I did quite a bit of UV work last year with a dance piece we put together. It was filmed on several occasions and we never had any trouble with the 4ft tubes and cameras. Link to comment Share on other sites More sharing options...
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