| willie |
Hello,
I'm currently designing a small setup and I came across this lens assembly. It's 70mm. The middle lens is heat resistant glass. Can any of you old pros' tell me if this looks like it would be a good condenser? Thanks. |
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| Mr.Kh |
I'm no pro and I don't really have a setup, mainly waiting for a FFC extension I'm constructing, so I've been playing with my optics - sans lcd. BUT I do have that exact condenser lens assembly.
It's quite small. The lense at the front may be 70mm but the hemispherical lens at the back is about half that. I'm having some problems getting the optics setup (mainly due to the bulb size and reflector testing.
With a small enough bulb and a proper reflector this condenser would work quite well. The heat resistant glass is cool **** though (litterally quite hot though). With a 250W MH bulb virtually touching the rear lens and running for 20 mins, I could actually touch the front lens with my fingers, and lift it, the heat resistant glass however was quite roasting. It's quite easy to disassemble, and if I use no part of it other than the heat resistant glass I'll still consider it a good deal. (I just tossed it in with some other stuff I was ordering)
I can take some pics if you want :D But like I said I'm having some problems getting it setup with the rest of my optics. Maybe I'll do some raytraces to follow later, but for now back to studying for finals. |
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| alchemist62 |
| where are these condensor assemblies from? |
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| willie |
| Thanks for the reply. Acutally I'm planning on using a ???w halogen (gasp....I can hear the bashing already....), so I'm glad to hear the heat glass works well, but I haven't totally commited on what type of light I'll use as I'm still getting all the parts together for testing. I'd be great if you could post the pics of your setup. I'm going to be using the same lcd as Ace (7" 800x480), but my setup is going to be totally different. But like I said, I'm still waiting on parts to get here before I can start. Here's where I got it from though, for those who are interested: http://www.surplusshed.com/pages/item/l3092.html |
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| ace3000_1 |
ive made stuff like this in the past, the first lens is the condenser, the second heat glass is a uv filter and the last lens is a field lens, (basically a second condenser) all that is is a condenser setup where it has greater control over the beam, that system u have there would be a spot beam system probally out of a slide projector, a good one i might add, and by using the second condenser feild lens u have a greater control of the light specified to what size of an area u want to light up therfore using more of the usable light out of the condenser to specifically go to the object to be lit up, i made somthing similar to this in my last projector and its one of the reasons why i got it so bright, when testing my new one im building in a quik test that i performed the other week, i tried the same idea and it does make a big difference in brightness over the total area of the lcd.
Trev |
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| dracul |
| What about eveness Ace? Have you noticed the light is much more even on the lcd and the first fresnel? Do you have a light meter you can take readings? |
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| ace3000_1 |
dracul, who is going to be watching your setup? u or your light meter? lol forget the light meter, u dont need it, it is impossible to get the light even to such a degree that u are trying to acheive, u can get it perfectly even to the human eye no problems at all but to your light meter no way, even pro projectors arent perfect with a light meter, there are manny varables that make it not perfect, the bulb for 1 and the lenses for 2 and so on, manny differnt materials arent perfect and unless u want to pay $1000 up u wont ever find a lens thats perfect, even lenses that cost 1000's are not perfect so forget the light meter ****, use your eyes, they are whats going to see the image and nothing is more acurate then your eye, its not hard dracul to get an even image, just with some practical experience and a little reading its not hard at all, now with your frensels i dont know whats going on there, to me the frensels must be shot or its yourself not setting it up right, the light u have forget it and just use the bulb, get a spherical reflector and a condenser, place them 9 inches from your frensels focal and thats it, if that dont work i sujest get new frensels cos its obvious thats the problem.Now i dont use 2 frensels as of yet although in this setup of mine now i may use 2 but behind the lcd and its just to shorten the focal, asoon as i get my new one in ill know for sure what frensel ill be using and how i will have it placed, regarding the 2 frensels vs better then 1 frensel method well its realy upto the designer, u can get better with one or the other, in the 15inch projectors it would be better with the frensels that are available, in the small ones that i make it wont make much difference if u design the light engine right, ive never had a problem spreading light not until now and thats just because of a long focal on a frensel at the moment and thats easily fixed.
Trev |
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| ace3000_1 |
dracul in regards to the experiments i did and the condenser system i made in the last projector the image is very even and very bright, there was no way of seeing if the image was brighter in the center or dimmer on the edge, it looked perfectly even to my eyes but to your light meter i garentee u not as they are never perfect them selfs.
Trev |
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| dracul |
| quote: | | dracul in regards to the experiments i did and the condenser system i made in the last projector the image is very even and very bright, there was no way of seeing if the image was brighter in the center or dimmer on the edge, it looked perfectly even to my eyes |
Thats great. That is all I want to my eyes only would be fine. Also I am not using a 7 inch lcd. But others are doing fine with their 15 inch so its either reflector issue, condenser or my fresnels. |
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| ace3000_1 |
| quote: | | But others are doing fine with their 15 inch so its either reflector issue, condenser or my fresnels. |
ya, i tell u somthing dracul, if u got a candle and placed it at your focal i garentee u that u would see the whole frensel light up, dimly ofcourse but it would prove that your frensel works then, the issues u got are a real; pain in the butt for u im sure, i think probally all of us have been there and learnt where we went wrong, to be honest dracul in my first setup i didnt bother with any focal of the frensel i had, i just put it where it worked and same for the reflector i had, forget the numbers and see what u can get out of that lot u got and try and get it to work, numbers arent always right and neither is science i might add but the reality of somthing working is always right when it works, so right now dracul get the bulb out of its box, put the 2 frensels together and try to see if u can cover those frensels with light with no reflector or any condenser, and its doable without both, ok u get that going , now u have a bearing point or a starting point so to speak, ok then just go from there, split the frensel again and see what u get at that distance ect, its time consuming but u will get there in the end, and at the end of the day after its all going and watching a movie im sure u wont give a dam what number is the focal on what lol as it all works the way u want it.
Trev
P.S when trying to get a even light over the frensel the best way to tell is to use white paper and place that on the top frensel and u will see the light over it, also i might add different lcd's act differently to light. |
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| dracul |
| quote: | | so right now dracul get the bulb out of its box, put the 2 frensels together and try to see if u can cover those frensels with light with no reflector or any condenser, |
Tried this already. What I noticed was the 2 fresnels together(0 space) reduces the back FL of the frensel. When I did the FL test with them together it comes sharp at around 5 or 6 inches. Splitting them seems to be a little better but only slightly.
I just bought a 200 watt large house type bulb to test that is clear and you can see the element burning. Since Brainchild or Cruiser had great results with a 400watt huge single ended this house bulb should work the same only dimmer and yellow right?
Thanks for the candle idea. I will try and see if this solves the uneven problem.
| quote: | | when trying to get a even light over the frensel the best way to tell is to use white paper and place that on the top frensel and u will see the light over it, also i might add different lcd's act differently to light. |
You mean the first or bottom fresnel dont you? Top fresnel narrows the beam much more getting ready to send it to objective. I always only see the center of the 15inch FL fresnel being lit. I would say about a 7 or 8 inch diameter hot spot.
I am not using an lcd to test yet. Just a black and white transparency with 8 point text. |
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| Mr.Kh |
| Hey Ace, how far would you suggest to put this condenser assembly from the bulb arc? |
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| ace3000_1 |
heya buddy hmm well what id do is try it with that front lens in it first to see how wide u get the beam that its designed for, with the condenser about 5-10mm away from the top of the outer bulb glass, if the beam isnt wide enough take the top lens out and try it again at the same distance, it will be alot wider then but probally less bright, but thats normal as the secondary lens is the enhancer, ok if its too wide lift the condenser up from the bulb abit, go 5mm at a time or try 10mm to get a bearing and then do it abit more finley to tune it better and thats about it, make sure u watch your eyes from the light, it does and will damage your eyes, if u are using a 250w mh then try to use some oxy welfding glasses as sun glasses on a 250w or even a 150w does nothing lol, just make sure u have somthing to cover your eyes. Oh by the way the condenser in that thing is the small high rounded lens, the one to the left in the pic.
Trev |
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| ace3000_1 |
| quote: | | Tried this already. What I noticed was the 2 fresnels together(0 space) reduces the back FL of the frensel. When I did the FL test with them together it comes sharp at around 5 or 6 inches. Splitting them seems to be a little better but only slightly. |
ok so what focal with them split did u get a good sharp image at?
| quote: | | I just bought a 200 watt large house type bulb to test that is clear and you can see the element burning. Since Brainchild or Cruiser had great results with a 400watt huge single ended this house bulb should work the same only dimmer and yellow right? |
ya alot more dimmer and yellow but its not a point source, but it will do for testing and its better on your eyes, just use it to get your frensels working, if u get your frensels working with that then all u have to do is put your mh bulbs arc where the element was of the house bulb and bingo! but with minor ajustment to fine tweak it.
| quote: | | You mean the first or bottom fresnel dont you? Top fresnel narrows the beam much more getting ready to send it to objective. I always only see the center of the 15inch FL fresnel being lit. I would say about a 7 or 8 inch diameter hot spot. |
ya what u need to worry about first is to get the best u can out of the first frensel forget the second frensel for now, it may well be that u cant collimate all of the light without the top frensel and this is common but try to get the best u can with the botom first cos that is what sends the light through the lcd, once u have the bottom frensel to the best it can be then we will worry about the top.
Trev |
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| dracul |
| quote: | | ok so what focal with them split did u get a good sharp image at? |
9 inch for the first fresnel. But it was only sharp at the centre 4 feet of a 8 foot wide image. The sides were still soft and dimmer. |
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| dracul |
| quote: | | ya alot more dimmer and yellow but its not a point source |
Why is it not a point source? What is a point source? |
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| ace3000_1 |
| quote: | | 9 inch for the first fresnel. But it was only sharp at the centre 4 feet of a 8 foot wide image. The sides were still soft and dimmer. |
ok thats right bud now what u need in this case is a condenser to spread the light out to the edges so the light is even over the whole frensel, and for a condenser to work u need a reflector aswell, your focal is fine, its just the way u got your light setup bud, try to put a magnifing glass infront of the light and put it close to the bulb, (becarful though dont melt the thing on the lamp or u will have a dead lamp, watch the heat) that will make a difference enough for u too see, if it spreads over the whole frensel that is, anyway try it , it will be good for u to learn.
Trev |
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| ace3000_1 |
| quote: | | Why is it not a point source? What is a point source |
well it is a point source but a darn big one lol and the long filament in normal bulbs dont realy make it a point source, a point sorce is where the light comes from say an arc or a very small fillament, in a house bulb the fillament is large, although still a point source its not ideal for a projection setup, its just ok for testing. |
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| dracul |
| quote: | | its just the way u got your light setup bud, try to put a magnifing glass infront of the light and put it close to the bulb, (becarful though dont melt the thing on the lamp or u will have a dead lamp, watch the heat) that will make a difference enough for u too see, if it spreads over the whole frensel that is, anyway try it , it will be good for u to learn. |
Ace, how do I have my light setup different than anyone else who has a great image? I remember people having great results with bare bulb and 15 inch lcd. Why not me?
Ok. Will try the magnifying glass as well. |
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| ace3000_1 |
not that much differently but with the mh in its enclosure it cant perform in the right manner, now u told me the bulb is out of the enclosure and by its self, well the only other thing why its not working is cos that bulb has a very small burning arc, 11mm from memory and with some of the other guys they tried 400w mh bulbs, the burning arc on those monsters are huge, so with a bigger burning arc they would have had less of an efect your getting, but with a reflector and condenser combination a smaller arc is better for making a point source light.
Trev |
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| dracul |
Ok. Most likely I solved my uneven focus problem so now I am thinking I may need a 250 watt or even a 400 watt MH single ended lamp to use a grey screen.
My question is Ace is , is there a reflector/condenser combo that I can use for the current 150 watt Powerstar Osram Hqi and also for a 400 watt gigantor if I upgrade to that shortly? |
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| ace3000_1 |
ya ill have to order the reflector though as im out of them right now, i can suply the condenser or u could get one from allan, not sure if his would be big enough for a 400w bulb though.
Trev |
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| dracul |
| So I understand FL is a factor also with reflectors and condensers. What do you have that you recommend that will work for 150 hqi and 400w single ended? |
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| dracul |
| How long for you to receive the reflector? |
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| brainchild |
| dracul, if you're using a 1512 why would you need a grey screen? The che mei's have mad contrast... |
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| ace3000_1 |
| quote: | | How long for you to receive the reflector? |
couple of days bud ill have to get onto the guy tomorrow and see how fast he is, i havnt been through him before he isnt far from me so i think about 4 days max |
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| dracul |
| quote: | | dracul, if you're using a 1512 why would you need a grey screen? The che mei's have mad contrast... |
Maybe you are right. I was thinking you cant have too much contrast. The sanyo plv-z2 is claiming 1300:1 |
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| ace3000_1 |
not yet dracul, these things are hard to get for a good price, ive only got one of those left and im keeping it lol, i can get u somthing similar.
Trev |
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| dracul |
| Ok . How long and how much? Will it work with 400 watt single ended giant? |
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