willp Posted March 19, 2014 Share Posted March 19, 2014 Is it possible to buy a PC lens and swap the fresnel lens out of an selecon acclaim to make a PC fixture? (And then back again) If so any idea who sells these? Edit: Just spotted they may use different reflectors, this may be harder than I thought Link to comment Share on other sites More sharing options...
Peter18 Posted March 19, 2014 Share Posted March 19, 2014 Is it possible to buy a PC lens and swap the fresnel lens out of an selecon acclaim to make a PC fixture? (And then back again) If so any idea who sells these? Edit: Just spotted they may use different reflectors, this may be harder than I thought I had to do almost exactly this on a collection of Selecon Acclaims that I purchased recently - the lenses on a pair of lanterns had been reversed (no idea why, and I did not try them out before I did the swap back). It turned out that it was much easier to exchange the entire front assembly to achieve this (remove all the self tapping screws at the front). I also found that the lens support in the casting seemed to be designed to accommodate a different thickness of glass in the two lanterns. This was for 'mark 1' Acclaims - it may be that the later version (larger, more plastic) has a different arrangement.So to do what you suggest for the Mk 1 you would need both the lens and the front casting. The last time I looked the cost of a lens was about half what I was prepared to pay for a complete used lantern so the economics of this are not encouraging! Link to comment Share on other sites More sharing options...
Ashley R Posted March 19, 2014 Share Posted March 19, 2014 Honestly I dont understand exactly why you would want to do this. THe cost of a new lens and the labour would just make its uneconomical. Vs the cost of picking up a 2nd hand one. I do not understand also why you would go to all that trouble, over the slight difference in the edge of the beam, for the type of shows that acclaim fresnels/ PC's are normally used for. Link to comment Share on other sites More sharing options...
vinntec Posted March 19, 2014 Share Posted March 19, 2014 The Mk 1 ones we have, the cases are different lengths so the reflector must also be different (unlike the Strand Quartet where it is the same). They aren't any use as "classic" conversions so should be quite easy to pickup second hand, although a look around the usual suspects doesn't show any at the moment! However, the question is why? Yes the fresnel has slightly less range than a PC (6-60 v 4-64) and a slightly softer edge but I would have thought it would be hard for Joe Public to see the difference - unless you are trying to use a PC as a "spotlight" when you really need a profile? Link to comment Share on other sites More sharing options...
Marineboy63 Posted March 19, 2014 Share Posted March 19, 2014 I'm with Ashley R and Vinntec on this. I would be interested to know why.The difference in beam width is mainly a function of the different length of the lantern body so the only difference would be the very slight beam edge variation. Link to comment Share on other sites More sharing options...
delicolor Posted March 21, 2014 Share Posted March 21, 2014 I'm curious about there being different reflectors between the Fresnel and the PC as a focus lantern optical system generally requires the reflector to be spherical with the lamp at the radius point so that light falling on the reflector is sent back through the gaps in the filament. (If it doesn't have neutral magnification then it would impact on the beam quality and range). Of course, you don't want a silvered mirror reflector in such a lantern as you may get striation. It could well be that the two different reflectors just have different grades of stippling to suit the lens performance? Link to comment Share on other sites More sharing options...
Bryson Posted March 21, 2014 Share Posted March 21, 2014 I don't see the advantage. The only real reason to buy Fresnels over PCs is the cost saving. If you can afford the PC, just get the PC. Link to comment Share on other sites More sharing options...
Roderick Posted March 21, 2014 Share Posted March 21, 2014 I don't see the advantage. The only real reason to buy Fresnels over PCs is the cost saving. If you can afford the PC, just get the PC.Going slightly off-topic, but why is a PC more expensive than a fresnel? Link to comment Share on other sites More sharing options...
Bryson Posted March 21, 2014 Share Posted March 21, 2014 I don't see the advantage. The only real reason to buy Fresnels over PCs is the cost saving. If you can afford the PC, just get the PC.Going slightly off-topic, but why is a PC more expensive than a fresnel? Short answer: More glass = more expense. Fresnel lenses are a way of achieving approximately the same result while using a lot less glass. (Admittedly, the fresnel beam is a little softer than the PC one, but judicious use of diffusion seems much easier than changing the whole damn lens. I thought that maybe the Fresnel went wider, but the PC is 4-64 degrees and the Fresnel is 6-60) Link to comment Share on other sites More sharing options...
Ashley R Posted March 23, 2014 Share Posted March 23, 2014 Also economies of scale - Selecon makes more Fresnels than PC's, and they make more Black fixtures than white. Link to comment Share on other sites More sharing options...
Graham NZ Posted March 24, 2014 Share Posted March 24, 2014 The reflectors are exactly the same, the difference in length is to allow for the different optical qualities of the lenses and to allow for the beam angles. If you want to swap the lenses you can, if you put a PC lens in the Frensel then you will limit the range of beam angles. Cost of lenses, different quantities of glass, different manufacturing processes, different economies of scale. Fresnel lenses are used in many applications outside of performing arts, PC lenses more performing arts and theater biased. Graham Link to comment Share on other sites More sharing options...
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