# UV filter

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#### mememem

I have a UV / IR filter, same size as the condensor, where's the best place to position the UV filter?

#### Jl2

Right behind the condenser lens. It should fit perfectly as mine.

#### Quin

Pointing out the obvious here, but just in case: make sure it can take the heat, I've seen one guy melt lexan over his bulb - Not a very good thing to do

#### mememem

thanks for replies, by behind, do you mean between condensor and light?

#### Jl2

I think u have the 90mm UV/IR filter among with the same diameter condenser lens from "exclusiv", Germany. If that is the case, u have probably bought the small reflector too. In that case a good distance between lamp and filter/condenser is 1 cm, and the reflector must go 3mm behind the lamp. As Quin said be sure u have proper ventilation there.

By behind I mean use the filter at the back of your condenser, without leaving any space among them.

#### mememem

Yes you're right, it's from exclusiv but on the site it says 1mm to reflector and 2.85 mm to condesnor, where did you get your values from?

#### Jl2

Once you buy something there they give you access to the forum. Inside the forum there is a post dedicated to the setup of the distances with an attached image. I think both values are correct cause of geometry considerations (there is a good post in this diyaudio forum where they teach you how to graphically calculate reflector/condenser setup).

In fact the values I gave you are multiplied by 3 (1,0 mm x 3 / 2,85mm x 3)

Also, I would be worried to put my uv filter/condenser at 2,85mm from a 400w HQI. The reflector is made of alluminium layer but optics are less temperature steady. They could melt at that short distance...

#### mememem

sorry i meant 28.5 mm, would that measurement be from the centre, back or front of the light?

#### Jl2

sorry, and I ment 23,85 divided by 3, so more or less 8mm, as the other distances I gave you.

Both distances are correct, here u can find the image of the post the visualize how to calculate them: http://www.diyaudio.com/forums/attachment.php?s=&postid=576478&stamp=1108523093

the values are from the protective glass of the hqi, alligned at the center of the bulb, where the gas is ignited, supposing that you have an FC2 base lamp.

#### mememem

my reflector is 5cm diameter and condesnor is 9cm, would this explain with exclusiv have given 1mm for light to reflector and 28.5mm to condesnor?

#### Jl2

yes, the main point is to assure that reflected rays hit the condenser lens without falling out of the its diameter, or in the opposite case, that they are to narrow, in comparison of diameter/distance of the lens.

#### mihari

hi there,
where did you get your condenser and reflector and filter again?
are they online?
can i get them in greece?

exclusiv

exclusiv-online

#### mihari

Thanx!

That place has it all (not so cheap though)
I have one main question:
What is the inner diameter of the cold reflector (if you would check it out for me)? Is it spherical? Is it a hemisphere or is it less?

Lesser questions (small talk):
did you put everything together? do they work?
I dont think that exclusiv's fresnels do the job.
I think that their projection lens might be OK.

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