Can I just give you guys a breif question to see if I am on track please?
I have a panel, and a light source but no lense. When i use the light source on the panel and put a piece of paper behind the panel, you can clearly see the image if its less then 1 inch away, any more than this and I loose the clarity of the image.
Is this normal without a lense?
Will a lense fix the problem?
Or is the light source not directed enough?
Thanks
I have a panel, and a light source but no lense. When i use the light source on the panel and put a piece of paper behind the panel, you can clearly see the image if its less then 1 inch away, any more than this and I loose the clarity of the image.
Is this normal without a lense?
Will a lense fix the problem?
Or is the light source not directed enough?
Thanks
Can some1 please explain focal length to me or link me to a site that explains it. And also, what significance does the focal length of a lens play in a projector?
My proector(once built) will be a MAXIMUM of 5 metres from the wall.It will most likely be 3-4 metres, so what focal length is good for this(if it has anything to do with distance from the projector to the projected image).
I am looking for an image size that is bigger than 1 meter diagonal.
Jeroth
My proector(once built) will be a MAXIMUM of 5 metres from the wall.It will most likely be 3-4 metres, so what focal length is good for this(if it has anything to do with distance from the projector to the projected image).
I am looking for an image size that is bigger than 1 meter diagonal.
Jeroth
jeroth: somewhere in the thread is a post explaining focal length, and i think gunwan(??) has a spreadsheet on his site 4 calculating it....search back through the threads and it'll be in there somewhere..
jackson ho: in my understanding u need 2 lenses......you need a point light source, then a "fresnel" type lens atached closely to the panel to direct the lightwaves to a point, then at this point u need another lens to then project and enlarge the picture...a real quick play around is to buy 2 $3 plastic sheet magnifyers and use them....wont be a perfect picture but will be enuf to whet your appetite....
to all newbies (not saying i'm an elder or know what i'm on about 🙂 ) go to the bottom of the page, click on "show printable version" and use the edit,find button and type in "http" this will list every link, alot are ebay so u can ignore them, but most of the others will bring u up to speed.....have fun 🙂
jackson ho: in my understanding u need 2 lenses......you need a point light source, then a "fresnel" type lens atached closely to the panel to direct the lightwaves to a point, then at this point u need another lens to then project and enlarge the picture...a real quick play around is to buy 2 $3 plastic sheet magnifyers and use them....wont be a perfect picture but will be enuf to whet your appetite....
to all newbies (not saying i'm an elder or know what i'm on about 🙂 ) go to the bottom of the page, click on "show printable version" and use the edit,find button and type in "http" this will list every link, alot are ebay so u can ignore them, but most of the others will bring u up to speed.....have fun 🙂
UK suppliers
Does anyone know where suitable lenses can be bought in the UK or europe cause i can't find anything. Or even an American one that ships worldwide. Cheers
Does anyone know where suitable lenses can be bought in the UK or europe cause i can't find anything. Or even an American one that ships worldwide. Cheers
Curious about panels etc
I have been reading this thread over the weeks from start to end and I notice all the trouble people have with the actual display panel/screen. This is seems is due mainly to the nature of the display to block light, hence requiring massive light sources.
Just looking around at display technology it appears to me that the manufacturing desire is to have light dispersed from the display at a maximum angle, to increase viewing angle. This would of course mean that light is non linear and diffuse. Either you then again concentrate this or try obtain a display with as narrow as possible viewing angle.
I would guess data-projectors that sit atop overhead projectors would be like this, but not much else that is small. Apart from that is the actual displays used in the projectors themselves.
It appears people could be exacerbating the issue rather than applying to the source. It could be tested by getting hold of an old narrow angle LCD screen.
I have been reading this thread over the weeks from start to end and I notice all the trouble people have with the actual display panel/screen. This is seems is due mainly to the nature of the display to block light, hence requiring massive light sources.
Just looking around at display technology it appears to me that the manufacturing desire is to have light dispersed from the display at a maximum angle, to increase viewing angle. This would of course mean that light is non linear and diffuse. Either you then again concentrate this or try obtain a display with as narrow as possible viewing angle.
I would guess data-projectors that sit atop overhead projectors would be like this, but not much else that is small. Apart from that is the actual displays used in the projectors themselves.
It appears people could be exacerbating the issue rather than applying to the source. It could be tested by getting hold of an old narrow angle LCD screen.
rex,
i am somewhat confused about your post... the idea is not to have light dispersed from the panel at a high angle. a straight shot light beam would be ideal. that is why LED or even laser would be awesome.
as far as viewing, most screens make up for that. my glass-bead screen has a viewing angle of 45 degrees off-axis. which, in a medium sized room would be more than adequate.
i do however agree that our problem is not with light, but with the panel itslelf. panels stop a considerable amount of light from passing through, and that is where our problem ultimately lies. BUT, if you apply logic, the high contrast, and better shartper colors will come from a panel stopping MORE light. to get deep rich coloring, the panel has to produce such color, not dull watercolors. just by the nature of "projection" the panels must block a significant amount of light.
thus, we need a panel that is giving us the best efficiency. one that will produce a great image while still allowing light to come through. this is achievable through a correct size, matched to our light source. if we use an OHP, we want it to be in the brightest part of the stage. the ideal is for the panel to be as large as possible, while still being as small as the light source. (for quality reasons, not convenience).
maybe i misread your post, could you rephrase maybe?
i am somewhat confused about your post... the idea is not to have light dispersed from the panel at a high angle. a straight shot light beam would be ideal. that is why LED or even laser would be awesome.
as far as viewing, most screens make up for that. my glass-bead screen has a viewing angle of 45 degrees off-axis. which, in a medium sized room would be more than adequate.
i do however agree that our problem is not with light, but with the panel itslelf. panels stop a considerable amount of light from passing through, and that is where our problem ultimately lies. BUT, if you apply logic, the high contrast, and better shartper colors will come from a panel stopping MORE light. to get deep rich coloring, the panel has to produce such color, not dull watercolors. just by the nature of "projection" the panels must block a significant amount of light.
thus, we need a panel that is giving us the best efficiency. one that will produce a great image while still allowing light to come through. this is achievable through a correct size, matched to our light source. if we use an OHP, we want it to be in the brightest part of the stage. the ideal is for the panel to be as large as possible, while still being as small as the light source. (for quality reasons, not convenience).
maybe i misread your post, could you rephrase maybe?
Listen Here.
You know how when you get the panel, you wanna see if it works, so you put it agains the window, lower the contrast, and see the picture.
but...i did not believe it, but my friend's friend works at nome depot and he let me borrow the industrial lamp they have hanging from the ceiling. it is High Pressure sudium.
the funny thing was that it was TOO bright. even when i turned the full contrast on, i did not see anything.
conclusion: there is no right bulb that will serve us all. i need a weaker bulb for the best performance, when Undream-just for example needs a brighter bulb. If i will use undream's bulb, i won't see anything because it will be too bright, when Undream will have the opposite. we each need to use the bulb that is right for our particular panel in order to achieve best results. why do you think commercial projectors use so many different bulbs- different LCDs and different contrast ratios. ...something to think about....
ok, hope this will get the thoughts in your heads going.
aleksey🙂
You know how when you get the panel, you wanna see if it works, so you put it agains the window, lower the contrast, and see the picture.
but...i did not believe it, but my friend's friend works at nome depot and he let me borrow the industrial lamp they have hanging from the ceiling. it is High Pressure sudium.
the funny thing was that it was TOO bright. even when i turned the full contrast on, i did not see anything.
conclusion: there is no right bulb that will serve us all. i need a weaker bulb for the best performance, when Undream-just for example needs a brighter bulb. If i will use undream's bulb, i won't see anything because it will be too bright, when Undream will have the opposite. we each need to use the bulb that is right for our particular panel in order to achieve best results. why do you think commercial projectors use so many different bulbs- different LCDs and different contrast ratios. ...something to think about....
ok, hope this will get the thoughts in your heads going.
aleksey🙂
damn, I havent even messed with the contrast yet on my panel. I need to get the darn thing put together so I can go crazy with it. I cant wait to be done. taking a trip to colorado this weekend, leaving tonight, getting back next tuesday, so, project is on hold. doh!
Undream said:
HEY, cool. you are gonna be in my neck of the woods! where in colorado you planning to visit?
Re: Listen Here.
no. the bulb isnt too bright, you just need a lens of SOME sort to focus the light, and produce and image. of course if you put a bright light behind anything transparent, it will wash the image away. try using at least a fresnel between the light and the LCD. trust me, "too bright" isnt something i think we could achieve...
prjctr_builder said:
no. the bulb isnt too bright, you just need a lens of SOME sort to focus the light, and produce and image. of course if you put a bright light behind anything transparent, it will wash the image away. try using at least a fresnel between the light and the LCD. trust me, "too bright" isnt something i think we could achieve...
cowanrg,
everyone here seems to believe, the brighter the better! But this isn't completely true! Brightness level has to be set in relation to the light blocking capability of the panel. A too bright light can make bad blacklevels of a projected image, if the contrast ratio is low. So a 400 ANSI lumen image with good blacklevels looks better than a 1000 ANSI image with bad contrast, which have only grey blacks!
xblocker
everyone here seems to believe, the brighter the better! But this isn't completely true! Brightness level has to be set in relation to the light blocking capability of the panel. A too bright light can make bad blacklevels of a projected image, if the contrast ratio is low. So a 400 ANSI lumen image with good blacklevels looks better than a 1000 ANSI image with bad contrast, which have only grey blacks!
xblocker
i agree. this is why i am trying to get a higher contrast panel. i have realized the limitations of traditional "projection panels". these have low contrast ratios, so with appropriate light, NO ambient light can exist, and with enough light so you can see with ambient light, the image appears washed out and too bright.
but in the case of prjct_builder, it's really difficult to test a panel with just a light behind it. you really can't tell anything from that.
but in the case of prjct_builder, it's really difficult to test a panel with just a light behind it. you really can't tell anything from that.
hehe
dude, i said the SAME thing in my previous post, but cowanrg said it was wrong. now xblocker says the SAME this and cowanrg says it is right. when i used the halogen bulb behind my panel, i could see the colors and graphics and stuff, but when i placed it on the HPS industrial lamp, it got washed away. So, there IS such thing as TOO BRIGHT. you need to find the EXACT bulb that will match YOUR panel...get it?
aleksey
xblocker said:
dude, i said the SAME thing in my previous post, but cowanrg said it was wrong. now xblocker says the SAME this and cowanrg says it is right. when i used the halogen bulb behind my panel, i could see the colors and graphics and stuff, but when i placed it on the HPS industrial lamp, it got washed away. So, there IS such thing as TOO BRIGHT. you need to find the EXACT bulb that will match YOUR panel...get it?
aleksey
when I had mine setup with with the 400W MH i looked at the lcd screen and it looked ****ed up like the colors were wrong it was all blue looking and it was very washed out put on the screen it looked fine. if you want to test it tape a peice of white printer paper to the back and use like a 100w incadesent bulb and it will atleast let you know it works ok.
that is what i was saying.... when i was testing mine with the LOA, it was REALLY washed out and looked bad, but it turns out it wasnt NEARLY enough light...
just saying its really hard to tell just by holding a light behind it. sorry aleksey, didnt mean to act like i was telling you that you were wrong, just saying it can be deceiving.
just saying its really hard to tell just by holding a light behind it. sorry aleksey, didnt mean to act like i was telling you that you were wrong, just saying it can be deceiving.
Sorry if this is just a re-run of earlier posts:
It is also important to remember that lumen ratings of bulbs more than likely represent the dominant part of the spectrum produced by the bulb. In the case of most MH bulbs, fortunately, the full visible spectrum is produced fairly evenly, whereas high pressure sodium bulbs produce nearly all of their lumens in the red/orange spectrum. A MH bulb with the same rated lumens as a HPS bulb will be much brighter when using it with an LCD. This is because any pixels that are not red will filter out most of the output of the HPS bulb. For example, if you place a blue tinted lens in front of a red "party" bulb, you will not get much light output through the lens.
This goes back to CRI, or color rendering index. MH bulbs are very good in this respect. HPS bulbs have very low CRI because of their narrow red spectrum output.
This is true with any low CRI bulb (like a mercury vapor), so I'm not picking on anyone with an HPS bulb. I do believe, however, that you can overdo it with a too powerful MH bulb (you lose contrast).
Good discussion, everyone!
-f4
It is also important to remember that lumen ratings of bulbs more than likely represent the dominant part of the spectrum produced by the bulb. In the case of most MH bulbs, fortunately, the full visible spectrum is produced fairly evenly, whereas high pressure sodium bulbs produce nearly all of their lumens in the red/orange spectrum. A MH bulb with the same rated lumens as a HPS bulb will be much brighter when using it with an LCD. This is because any pixels that are not red will filter out most of the output of the HPS bulb. For example, if you place a blue tinted lens in front of a red "party" bulb, you will not get much light output through the lens.
This goes back to CRI, or color rendering index. MH bulbs are very good in this respect. HPS bulbs have very low CRI because of their narrow red spectrum output.
This is true with any low CRI bulb (like a mercury vapor), so I'm not picking on anyone with an HPS bulb. I do believe, however, that you can overdo it with a too powerful MH bulb (you lose contrast).
Good discussion, everyone!
-f4
I got my Apollo AI-1000 OHP in today.
The Good:
major wattage; 600w!!!
OVER 8'x10' projection; Not sure how this will need tweaking for the light to be focused.
The Bad:
kinda old.. I'm afraid that they'll stop selling lamps for this 🙁 .
bulky... just like
I should be able to test this out with the Spectra C within the next couple days.
The Good:
major wattage; 600w!!!
OVER 8'x10' projection; Not sure how this will need tweaking for the light to be focused.
The Bad:
kinda old.. I'm afraid that they'll stop selling lamps for this 🙁 .
bulky... just like
An externally hosted image should be here but it was not working when we last tested it.
I should be able to test this out with the Spectra C within the next couple days.
Ok,ok.
one thing is to judge a projected image and the other side is to judge a backlighted panel. If some one looks directly into the bulb direction of a slide p.e., this is to bright for your eyes, they can't discriminate brightness levels in such an overkill of light. Reference should be projected image quality !
xblocker
one thing is to judge a projected image and the other side is to judge a backlighted panel. If some one looks directly into the bulb direction of a slide p.e., this is to bright for your eyes, they can't discriminate brightness levels in such an overkill of light. Reference should be projected image quality !
xblocker
noodles,
Is the bulb for your OHP a "DYS"? That's what my old OHP uses (600 watts), and although that bulb has been around for a long time, I think it is still stocked in many areas. I just bought a replacement bulb from Office Depot. It was one of the three or four types they sold.
Everyone:
I have noticed some "smearing" when projecting with my Spectra C. I thought it was my fresnels, but I replaced them, and it is still occurring.
It appears with motion or still frames where a group of bright pixels next to an area of dark will "smear" to the left and up of the bright pixels. It makes me feel like my contact lenses are dirty, but they are not. Has anyone noticed this? This affect happens with DVD or computer source. Any ideas?
-f4
Is the bulb for your OHP a "DYS"? That's what my old OHP uses (600 watts), and although that bulb has been around for a long time, I think it is still stocked in many areas. I just bought a replacement bulb from Office Depot. It was one of the three or four types they sold.
Everyone:
I have noticed some "smearing" when projecting with my Spectra C. I thought it was my fresnels, but I replaced them, and it is still occurring.
It appears with motion or still frames where a group of bright pixels next to an area of dark will "smear" to the left and up of the bright pixels. It makes me feel like my contact lenses are dirty, but they are not. Has anyone noticed this? This affect happens with DVD or computer source. Any ideas?
-f4
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