Lens size

Installed some 11" Ice fixtures in my church a while back, 3 of which are supposed to cover the stage back wall as washes.  Using both Vertical and Horizontal diffusers (I think we have one 60 degree V and one 80 degree H) plus another diffusion gell to get the wall fairly evenly covered.  Pretty soon after the install I noticed a streak of one color on the wall emiting from each of the 3 fixtures (3 streaks to be more precise).  From the floor it appeared there was a gap between the edge of the lenses and the inside edge of the fixture, so just thought the lenses needed to be pushed over more.

Well finally got up there and it appears the lenses are about 3/8 to 1/2 inch narrower than the inside demension of the fixture, so depending on which color is on, the very outside edge led will not have a lense or lenses in front of it and will cause the streak on the wall.  If I slide the lenses over to the other edge then a different color will show because a different color led is on that end.

Any suggestions here?

Also 3 was recommended by our rep to cover the wall but it really needs at least 4.  Can't afford another one at this time so since we are using the max width horizontal lens, what happens when two horizontal lenses are combined - like a 60 and an 80 as an example?  I don't have any to experiment with so don't want to order anything unless I know it might work.  Of course another problem is more spread less output, so having to deal with that as well.

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  • I too have had this issue with my rental inventory of Vivid-R's the lens exposes what i think i remember as a Cyan led? in the corner, yes, no bueno.

    I have full lens sets, I can experiment for you unless someone already knows.

    Are these fixtures pointing AT the wall or skimming it from above? How far away?

    Also what size is the wall?

     

    -Jeff D

  • Hey Jeff.  Glad to hear it's not just me.  It exposes a couple of colors; Cyan or blue and Red.  We get a red streak with yellows and a bluish streak with blues.

    All rough guesses on sizing and distance.  The attached photo is a very long time ago before paint colors changed and before the fixtures but it does show the back wall with the dove that is the issue wall.  That photo shows old Plant Light floresent lamps on at the top and 4 Mini-Ellipsoidals sticking down; two for the Dove and two gelled for the wall.  Plants are now silk, plants lights are now gone and we're just using two Mini-Ellips now for the Dove.  The wall is being lit with the Seladors.

    Fixtures are about 5 or 6 feet from the wall focused at a sharp down angle at the wall.  Obstacles prevent them from being any furthere away.  One fixture in the center and the other two centered between the center fixture and the left and right edges of the wall.  I'd guess it's about 30 feet square.  We also have one 11" ice fixture turned sideways at a down angle on each of the two columns, however the issue doesn't seem to show there because of a completely different application.

    The reason I want to get a wider spread is they still are a bit "spotty" in the middle of each of the 3 areas.  At some point I hope that we can purchase more fixtures but at this point budgeting, board meetings, etc. are a distant item for this so I want to try it with lensing.  Appears the widest is 80 degree and we are using 80H and I believe 60V with the extra diffusion gel.  Cuts way back on output.

  • Called tech support and in a nutshell what I was told is the lenses are manufactured that much smaller to compensate for expansion due to heat.  It's interesting they are only made that much narrower (horizontally) but only a little bit shorter (vertically).  If they were that much shorter vertically they would be too short to slide into the fixture lens slots.

    I was told to position them as centered as possible to cover the led's on each end.  When I asked about building vibration and other factors that can cause lenses to move and fixtures to drop if not tight, I was told to make sure the lenses are inserted into the tighter slots or not to put a thinner lens into a wider slot.

    In discussion I find all this very interesting.  Mainly plastic expands under heat 1/2" - 3/8" one direction and very little in the other direction and that the front of a Selador led fixture can get that hot to cause it to expand in the first place.  Learning new things every day. :-)

  • One more thing, You should use only one horizontal/veritcal filter at a time.. If you try to use multiple of the same type, you would start seeing a prism effect oriented in that direction.  The severity will vary based on the fixture type, lenses used, and distance to the the subject.  

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