Sorry had wax in my ears
Pink mouse I use to be a lighting tech aswell so I know what you are talking about. I had some old berkey colortrans that did that. But I think that by moving the arc in the ellipsoidal is only altering it’s beam angle, not it's distribution. We need the outer edges to be gradually more intence than the center.
DJ
Pink mouse I use to be a lighting tech aswell so I know what you are talking about. I had some old berkey colortrans that did that. But I think that by moving the arc in the ellipsoidal is only altering it’s beam angle, not it's distribution. We need the outer edges to be gradually more intence than the center.
DJ
ok, that's what i got by now.
i started with 220 setup and work out the half angle for 15"
arc=24mm
the angle from the arc corner to the fresnell edge is 37 degrees.
then placed 330 fresnell and worked out this configuration;
real arc at 300mm from fresnell, a precondensor lens (93mm diameter and 60mm focal) at 270mm from fresnell will place a virtual arc at 330mm from fresnell.
the real arc is at 30mm from the pre-condenser lens and the diameter of the pre-condenser is so the half angle is 37degrees (the same 220 setup had).
The placement and the pre-condensor lens are ideal (i don´t know if 93mm diameter/60mm focal is manufacturable either).
Now, the 220/330 setup would project 24mm arc onto 36mm arc.
precond+330/330 setup would project 1:1 arc but the virtual arc is 6/3 times real arc. So 48mm arc would be projected on the triplet in the secon setup.
we have 36mm against 48mm arc. What do you prefer?
i started with 220 setup and work out the half angle for 15"
arc=24mm
the angle from the arc corner to the fresnell edge is 37 degrees.
then placed 330 fresnell and worked out this configuration;
real arc at 300mm from fresnell, a precondensor lens (93mm diameter and 60mm focal) at 270mm from fresnell will place a virtual arc at 330mm from fresnell.
the real arc is at 30mm from the pre-condenser lens and the diameter of the pre-condenser is so the half angle is 37degrees (the same 220 setup had).
The placement and the pre-condensor lens are ideal (i don´t know if 93mm diameter/60mm focal is manufacturable either).
Now, the 220/330 setup would project 24mm arc onto 36mm arc.
precond+330/330 setup would project 1:1 arc but the virtual arc is 6/3 times real arc. So 48mm arc would be projected on the triplet in the secon setup.
we have 36mm against 48mm arc. What do you prefer?
Rox, I don’t think your calculations are correct. I’ve checked my calculation, both mathematical, graphical and a combination of both, and I get an arc length for the 330+330+condenser that is identical to a 220+330 set-up. Here is the method I used:
First I found the angle of the 220mmFL fresnel. = 40.889°.
Then I chose 100mm for the size of the pre-condenser and it intersects the 330mm fresnel’s desired
angle at 86.6mm from the FL
The arc now needs to be placed at 57.7mm from the pre-condenser to match that of the 220mm FL
fresnel (40.889°).
To find the FL of the pre-condenser I used the formula, 1/FL = 1/object distance - 1/virtual image.
=>173.2mm= 1/57.7mm - 1/86.6mm.
To find the virtual arc size I used the formula; Virtual arc size = virtual image distance / object distance
* arc size => 36mm = 86.6mm/57.7mm *24mm
To find the real projected arc image in a 220+330 fresnel combination the formula is;
Real projected arc size= real projected arc image distance/ arc distance* arc size.
=> 36mm = 330mm / 220mm * 24mm
The magnification ratio for a 330+330 fresnel combination is simply 1:1 so with a 36mm virtual arc at 330mm from the 330mmFL fresnel it will project a real 36mm arc. No different from the 220+330 fresnel combination.
DJ
First I found the angle of the 220mmFL fresnel. = 40.889°.
Then I chose 100mm for the size of the pre-condenser and it intersects the 330mm fresnel’s desired
angle at 86.6mm from the FL
The arc now needs to be placed at 57.7mm from the pre-condenser to match that of the 220mm FL
fresnel (40.889°).
To find the FL of the pre-condenser I used the formula, 1/FL = 1/object distance - 1/virtual image.
=>173.2mm= 1/57.7mm - 1/86.6mm.
To find the virtual arc size I used the formula; Virtual arc size = virtual image distance / object distance
* arc size => 36mm = 86.6mm/57.7mm *24mm
To find the real projected arc image in a 220+330 fresnel combination the formula is;
Real projected arc size= real projected arc image distance/ arc distance* arc size.
=> 36mm = 330mm / 220mm * 24mm
The magnification ratio for a 330+330 fresnel combination is simply 1:1 so with a 36mm virtual arc at 330mm from the 330mmFL fresnel it will project a real 36mm arc. No different from the 220+330 fresnel combination.
DJ
the diameter of the pre-cond must be larger than the intersection you used (you need to take care of the arc lengh). In your calcs, you only did the 330/15" triangle, i don´t think it is the best way.
for the virtual arc, the lens will not refract the light, it is like if there was a hole of 100mm aperture, well if you trace the rays of the outer arc, they will never get to the edeges of the lcd, that means dimer corners on image.
thats why i started from the arc end angle. (called "total amount of light")
for the virtual arc, the lens will not refract the light, it is like if there was a hole of 100mm aperture, well if you trace the rays of the outer arc, they will never get to the edeges of the lcd, that means dimer corners on image.
thats why i started from the arc end angle. (called "total amount of light")
jeje, yes, you are not the first one telling me my english offends 
sorry about that (i have other 2 languages that would speak better on)
i mean that if we only consider the virtual arc (mean the one created by the pre-cond lens at the focal of the rear fresnell, then we can forget about the real arc. But now we have a "hole" were the pre-cond is. The pre-cond lens will be something like a window for the virtual arc. (mean there is no refraction, the refraction happens with the real arc, but since we forget the real arc and work with the virtual arc, then there is just a window of 100 mm aperture, you got it?
then considering the virtual arc size and the hole were the pre-conds lens is then you can trace the light rays. Well, there is no way to iluminate the 15" fully trhow the 100mm window. Have a check to my second image 4 post before.
sorry about that (i have other 2 languages that would speak better on)i mean that if we only consider the virtual arc (mean the one created by the pre-cond lens at the focal of the rear fresnell, then we can forget about the real arc. But now we have a "hole" were the pre-cond is. The pre-cond lens will be something like a window for the virtual arc. (mean there is no refraction, the refraction happens with the real arc, but since we forget the real arc and work with the virtual arc, then there is just a window of 100 mm aperture, you got it?
then considering the virtual arc size and the hole were the pre-conds lens is then you can trace the light rays. Well, there is no way to iluminate the 15" fully trhow the 100mm window. Have a check to my second image 4 post before.
yes, but i mean that not all pixels on the lcd will "see" full virtual arc.
your 100mm condensor lens is like a "window" for the virtual arc do you agree?
check this image. The blue pixel sees full virtual arc (full real arc as well)
the green pixel is the last pixel that sees full arc lenght as well.
the magenta pixel sees only a part of the virtual arc because the window is soo too small.
the last corner pixel, will see only the half of the arc. So there is a gradual light losse from the green pixel to the corner. this is only because the lens aperture is too small.
do yo understand what i mean?
your 100mm condensor lens is like a "window" for the virtual arc do you agree?
check this image. The blue pixel sees full virtual arc (full real arc as well)
the green pixel is the last pixel that sees full arc lenght as well.
the magenta pixel sees only a part of the virtual arc because the window is soo too small.
the last corner pixel, will see only the half of the arc. So there is a gradual light losse from the green pixel to the corner. this is only because the lens aperture is too small.
do yo understand what i mean?
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