Steve Scherrer said:
Yeah 🙂
I thought it was interesting given that this a completed commercial unit so is relative to prisms alignement. Just from what I have learned about prisms and how they bend light, I would have said firing the beam from the other direction would give the optic stretch.
Mark
morkys said:
I looked into it. Due to the size of the prisms, a special jig would need to be made. In the end, you really need to weigh up the benifts as proper "multi-coating" is expensive...
Mark
Ok, the lucite prisms look to be a non-starter. They are 4" x 4" x 7" and cost $98USD each.
Back to the Internet! I want a bigger angle than what has been used so far.
Ok, back to the Lambda drawing, if light enters at D1 and exits at D2, the prisms are doing HE not HC, according to the drawing. I guess I better get two prisms and stop talking theory!
Back to the Internet! I want a bigger angle than what has been used so far.
Ok, back to the Lambda drawing, if light enters at D1 and exits at D2, the prisms are doing HE not HC, according to the drawing. I guess I better get two prisms and stop talking theory!
Well, it took me almost a week to get through this thread, but I finally did it. Do you guys know if the J series prisms you are using are made from optic crystal or lead crystal?
Mark Techer said:
Yeah, that's the dimensions they gave me but that doesn't quite calculate correctly for a triangle. Since they want $98 I'm not worried about getting the dimensions corrected!
pretty sure they are optical crystal, but there are a few grades, mine are not the J series, but are similar, I think most of these 'crystal wedge trophies' are 1 optical grade below the proper optical crystal used in professional setups, but to my eye's they work perfectly.
stevodude said:
I've been told there are K9 optic crystal where BK7 was used by the French guys...
Mark
Thanks for the clarification on the crystal. I was wondering b/c as I was searching the net for them I came across both lead and optic.
This goes out to Bud Bray.
Could you tell me how you have your HD72 set-up (16x9 screen width and distance from projector to screen)?
Thanks
Could you tell me how you have your HD72 set-up (16x9 screen width and distance from projector to screen)?
Thanks
Larger angled prisms
For anyone in the States looking for prisms with a larger angle, search for the CWD** series. The 4x6 (CWD46) has an approximate angle of 18 degrees and the 5x7 (CWD57) has around a 16 degree angle. Most places I found sell these for $100-$150 a piece, but I did find one place that has them for $60-$75. I am waiting for a reply on a non-engraved price. I will let you know when I find out more.
For anyone in the States looking for prisms with a larger angle, search for the CWD** series. The 4x6 (CWD46) has an approximate angle of 18 degrees and the 5x7 (CWD57) has around a 16 degree angle. Most places I found sell these for $100-$150 a piece, but I did find one place that has them for $60-$75. I am waiting for a reply on a non-engraved price. I will let you know when I find out more.
"I've been told there are K9 optic crystal where BK7 was used by the French guys..."
Is that info certain?
I read that K9 glass is the Chinese equivalent of BK7. BK7 is a widely used optical glass, good homogenity, and low dispersion.
I thought of getting myself a pair of prisms but raytracing programs indicate sensible chromatic abberations. Besides practical reports here say the final brightness is less than the smaller resolution image.
Still, they would be nice to experiment with, if inexpensive. What about these http://www.promopeddler.com/Detail/62984/202-9 9"x5" prisms? Anyone knows their price ungraved and angle?
Is that info certain?
I read that K9 glass is the Chinese equivalent of BK7. BK7 is a widely used optical glass, good homogenity, and low dispersion.
I thought of getting myself a pair of prisms but raytracing programs indicate sensible chromatic abberations. Besides practical reports here say the final brightness is less than the smaller resolution image.
Still, they would be nice to experiment with, if inexpensive. What about these http://www.promopeddler.com/Detail/62984/202-9 9"x5" prisms? Anyone knows their price ungraved and angle?
CWD46 and CWD57 Pricing
Here are the prices for these two prisms from The Crystal Factory
CWD46= $40 non-engraved
CWD57= $60 non-engraved
You will have to either call or e-mail to receive the non-engraved price. My order for two of the CWD57 will be going through shortly.
Here are the prices for these two prisms from The Crystal Factory
CWD46= $40 non-engraved
CWD57= $60 non-engraved
You will have to either call or e-mail to receive the non-engraved price. My order for two of the CWD57 will be going through shortly.
bluesboyjr said:
Actually the screen (painted MDF)itself is 61x130 but I have curtains across the top & hope to have some along the bottom real soon to reduce the screen area to 51x130 and set the width(also with black curtains) to about 51x 121. The PJ is 12 1/2 feet from the screen so I can use the zoom for the size I want. I had the PJ back farther before but thought the picture looked a bit dark so I brought the PJ forward a bit. I'm ALWAYS tweaking. Interesting news about those prisms.might give a set a try. I'm currently back to my 4 prism set, I just like the picture better, the reflections are there but really only on a black background so it's livable.
Bud
I'm thinking, these new prisms with the wider angle, with the coating found a bit back in the discussion might be the trick. $40 per prism & $80 to coat each is $120 each for a coated lens...2 set$240...4 set(not really needed) $480. Not too shabby!
Think a 2 set is in the works for me real soon.
Bud
Think a 2 set is in the works for me real soon.
Bud
Bud Bray said:
Don't you need the 5x7 prisms for the HD72? Those are $60 each. The 4x6 are $40. I have the HD73 and I took a measurement today and at 8" from the lens the image is almost 4x6, so I just went ahead and ordered the 5x7's.
If you contact the Crystal Factory, try talking to Joe Lopez. That is who I dealt with.
I've got a quick question to all those who have measured their prisms at 8 degrees. When I put the measurements in all the right angle triangle calculators I could find I get an approximate ange of 11.77 degrees (side 1=6", side 2=1.25", hyp=6.13" and the angles are 78.23, 90, and 11.77 degrees). Am I missing something? How are you figuring 8 degrees? BTW, when I mentioned the degrees of the CWD series prisms, I used the same method I used to figure the 11.77 degrees for the other prisms. Thanks.