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Fresnel lens for Ianabeam Blonde?

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Harry Bromley-Davenport
Fresnel lens for Ianabeam Blonde?
on Mar 6, 2012 at 9:14:19 pm

Hi -

I own 3 Blondes (2k) and am wondering if there is some clever way of buying fresnel lenses and converting them.

Am I insane?

Has anyone ever done this?

I'd appreciate any ideas.

Many thanks,

Harry.



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Todd Terry
Re: Fresnel lens for Ianabeam Blonde?
on Mar 6, 2012 at 9:26:47 pm

I think you could.

I was making a homemade 150w HMI once, and I put a 5" fresnel lens on a little cheapo PAR can. Worked like a charm. Of course it's a fixed-focus fresnel, but that was fine in my application.

I'd say the biggest thing would be to make sure it's not all sealed up too tight, so that plenty of air can still get to the globe to avoid overheating.

T2

__________________________________
Todd Terry
Creative Director
Fantastic Plastic Entertainment, Inc.
fantasticplastic.com



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Harry Bromley-Davenport
Re: Fresnel lens for Ianabeam Blonde?
on Mar 7, 2012 at 12:50:38 am

Thanks so much for the encouraging reply. Heat will be a problem, I can see. There's very little space between the (imagined) fresnel lens and the globe - There is one slot for filtration and one slot for barn doors. I might have to make some sort of extension to push the whole front forwards, if you see what I mean.

Do you have any ideas about a place to buy the fresnel lens? I've done some internet searching but if you have a recommendation, that would be great.

In any case, thanks for the reply.

Best wishes,

Harry.



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Dennis Size
Re: Fresnel lens for Ianabeam Blonde?
on Mar 7, 2012 at 12:43:25 am

Ignoring the intense heat of an Ianabeam -- which will most assuredly crack the lens -- you will not be able to get the proper focal length needed for a lens of such a diameter that would be required. The optics would require that the lens would need to be further away from the lamp than the fixture will allow it to be mounted. You won't be able to get the full range of spot to flood -- one of the main attributes of a fresnel fixture.
Unless you're a real "do-it-yourselfer" who loves to tinker with arts and crafts projects I would suggest buying fresnels.
Open faced fixtures are designed a specific way for a specific purpose. If you're just looking to soften the beam use diffusion on the doors, or a chimera lightbank.

DS



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Harry Bromley-Davenport
Re: Fresnel lens for Ianabeam Blonde?
on Mar 7, 2012 at 1:08:44 am

Thank you for the reply to my cry for help. I thought that these fresnels were made of the same stuff as those glass oven dishes and were indestructable. So you reckon it will crack? Hmmm. That's not exactly what I had in mind - red hot glass flying across the set and lodging in the actors' faces.

I have chimeras already, and agree that I can throw some diffusion on the front of the Blonde - and I take your warning about exploding shards of glass very seriously. What I want is something relatively powerful, light and focus-able - and I don't want to pay $800 for an Arri 2k Junior.

I do have a couple of friends who absolutely love projects like this (car nutcases) and, perhaps, with a little research as to the best distance from globe to lens, I could get at least one unit test-converted and see how it goes.

Do you think that this is out of the question because of the heat issue? Suppose I can have a sort of extension made - like rods on a camera - that might serve the dual purpose of allowing air to circulate and the ability to focus.

Maybe this is all too silly for words and I should go out and buy a 2k fresnel. Still, I'm tempted.

Thank you again for your thoughtful reply.

Harry.



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john sharaf
Re: Fresnel lens for Ianabeam Blonde?
on Mar 7, 2012 at 1:43:02 am

Harry,

Sorry, but I have to jump in here and tell you this is crazy talk!

A Fresnel light has an interior design diametrically opposed to an open faced quartz; namely a small reflector creating a pin spot light source that is then "focused" by the fresnel (available from any manufacturer who makes such lights as a spare part) into a smooth spot to flood pattern (that you crave!).

The open faced light has a large reflector that maximizes the output (and heat). If you were to enclose the front, even with a baffled extension that would put the lens at the proper focal length to work you'll essentially be creating a heat bomb, and by virtue of the large source itself, you'd need a gigantic lens (like a 10K which would cost about a $1K)

The simple solution is to buy a used Junior on ebay, you'll be much happier and safer!

The only other thing that comes to mind is a Fresnel based "science project" that my friends at K5600 have in their catalog. It's called a big eye. It's not cheap, but check out the concept, I know you'll appreciate it:

http://www.k5600.com/products/bigeye/index.html

Sorry to bust your bubble, but if you really want to turn this into a hobby project, start from scratch and don't burn up and/or damage your precious Blond!

Cheers,

JS



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Harry Bromley-Davenport
Re: Fresnel lens for Ianabeam Blonde?
on Mar 7, 2012 at 1:56:51 am

Ah. OK. Bubble burst. People like me with tiny little brains have to be protected from themselves.

Thanks very much for preventing me from blowing everyone up.

Best

Harry.



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Dennis Size
Re: Fresnel lens for Ianabeam Blonde?
on Mar 7, 2012 at 5:02:51 am

Harry ..... If you really want to learn why what you wanted to do was not a great idea, you should go ahead and do it. You'll probably learn a lot about optics, heat, fixture ventilation, etc.
John, as usual, has hit the nail on the head as to how crazy/dangerous what you were planning to do was, however.

As I said before, if your goal was merely to have a fresnel then just buy one ...it's a lot easier, far less hassle, and you won't risk hurting anyone while wasting time trying to figure out why your plan wouldn't work.
Incidentally there's no way on earth that you could have created anything that would match the optics of the Arri Fresnel you desire; but you can own a fresnel -- or several -- for far less than $800.
I just did a quick check on USEDLIGHTING.com and in 2 minutes,without checking the entire website, I found:
+ a 10" Mole Richardson Junior 2kw fresnel with accessories for $240 (a steal)
+ a 6" Strand Bambino 2kw fresnel for $200
+ an 8" Colortran 2kw fresnel for $100
+ an Altman 2kw Fresnel for $550
+ an Altman 750w Fresnel for $89
and, if you really want to fry something, a 10kw Fresnel for $200.

DS



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Harry Bromley-Davenport
Re: Fresnel lens for Ianabeam Blonde?
on Mar 7, 2012 at 5:10:52 am

Thank you so much, Dennis (love your portrait) for responding.

And the same goes to one and all.

I promise I will not attempt to carry out my plan. Your wiser minds have prevailed.

Many thanks for the guidance and wisdom,

Best

Harry.



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