Hi Faidzir,
cool thing the 50 Hz flash, but doesn't it create unbearable flicker?
For me, one of the great things about LCDs and projectors is that they don't flicker.
I guess you'd have to push up the frequency to 100 Hz to eliminate visible flicker. OTOH- i dunno. Maybe the "afterglow" time of the flashbulb is long.
What's your experience?
Unfortunately i had no luck getting a service manual for my projector. Hence i don't know about the lamp voltage, start/stop behavior etc. I will not mess with it until the lamp is broken.
I will stay tuned here, and the LEDs are definitely still an option... it would be GREAT to have a silent projector that can be ON always - no big electricity or lamp bills.
Vince, did you try how the light output is without the fresnel lenses? Does the LCD itself eat so much light?
later
Timo
cool thing the 50 Hz flash, but doesn't it create unbearable flicker?
For me, one of the great things about LCDs and projectors is that they don't flicker.
I guess you'd have to push up the frequency to 100 Hz to eliminate visible flicker. OTOH- i dunno. Maybe the "afterglow" time of the flashbulb is long.
What's your experience?
Unfortunately i had no luck getting a service manual for my projector. Hence i don't know about the lamp voltage, start/stop behavior etc. I will not mess with it until the lamp is broken.
I will stay tuned here, and the LEDs are definitely still an option... it would be GREAT to have a silent projector that can be ON always - no big electricity or lamp bills.
Vince, did you try how the light output is without the fresnel lenses? Does the LCD itself eat so much light?
later
Timo
The frensel lenses magnify the light somewhat. The LCD does eat up much of the light. Yet, with the LCD pixels off, there still is light passing through. Good example of black contrast.
The way I see it, the LEDs can be used. We'll probably need more of them and a better condenser system for them.
A method to guide the light would help. Avoiding light scattering into the box. e.g., light leaving the LCD should not mix with the source light. I see it as the equivalent of having ambient light in a room where there is a projected image on a screen. The projected light has to be extremely powerful to compete w/ the ambient light.
Then, there is the issue of the projection lenses. If you look at what dwalls32 wrote, there is definate issues wi the lense system we both are using.
I've seen projectors that are large, but to bulid on that's 4ft long is too much. by using the correct focal length lenses, we should be able to remedy this. The question is how? This needs to be researched some.
What I'd like to know is where are all the people who design/engineer these projectors? Don't they DIY? Is it such a guarded secret?
Timo, can you take a reading of the lamp while it's running?
The way I see it, the LEDs can be used. We'll probably need more of them and a better condenser system for them.
A method to guide the light would help. Avoiding light scattering into the box. e.g., light leaving the LCD should not mix with the source light. I see it as the equivalent of having ambient light in a room where there is a projected image on a screen. The projected light has to be extremely powerful to compete w/ the ambient light.
Then, there is the issue of the projection lenses. If you look at what dwalls32 wrote, there is definate issues wi the lense system we both are using.
I've seen projectors that are large, but to bulid on that's 4ft long is too much. by using the correct focal length lenses, we should be able to remedy this. The question is how? This needs to be researched some.
What I'd like to know is where are all the people who design/engineer these projectors? Don't they DIY? Is it such a guarded secret?
Timo, can you take a reading of the lamp while it's running?
Hi Vince,
i can't take a reading of the lamp while it's running, it sits in a closed box assembly that can only be pulled out as a whole. I hope you understand that i won't pull it before the lamp is gone anyways.
If (i hope!) we can go the LED route, i'll have to make an external power supply anyways and just have to figure out how to trick the protection circuit in case it shuts off the LCD when there is no lamp in the socket...
My projector has three 1.3" panels. It is a bit dusty (red spots), so when i clean it i can try to take some pictures of the internals.
Here's what's printed on the lens:
f=46.5 ~ 74.4 mm
1:3.0 ~ 1:3.8
LCD Projector Power Zoom Lens
BTW; there is a slew of older projectors out there which use 6" LCD panels. While searching for a used unit i was offered a Sayett projector with halogen light and 6" LCD for 280 $. Didn't jump on it because of poor 100:1 contrast (present one has 200:1 and 300ANSI and that's allright).
Timo
i can't take a reading of the lamp while it's running, it sits in a closed box assembly that can only be pulled out as a whole. I hope you understand that i won't pull it before the lamp is gone anyways.
If (i hope!) we can go the LED route, i'll have to make an external power supply anyways and just have to figure out how to trick the protection circuit in case it shuts off the LCD when there is no lamp in the socket...
My projector has three 1.3" panels. It is a bit dusty (red spots), so when i clean it i can try to take some pictures of the internals.
Here's what's printed on the lens:
f=46.5 ~ 74.4 mm
1:3.0 ~ 1:3.8
LCD Projector Power Zoom Lens
BTW; there is a slew of older projectors out there which use 6" LCD panels. While searching for a used unit i was offered a Sayett projector with halogen light and 6" LCD for 280 $. Didn't jump on it because of poor 100:1 contrast (present one has 200:1 and 300ANSI and that's allright).
Timo
Here's some help-
http://perso.club-internet.fr/legault/focal.html
Focal reducer is what interests me the most right now.
http://perso.club-internet.fr/legault/focal.html
Focal reducer is what interests me the most right now.
I have been playing with the parts I have so far...I tried a somewhat compacted overhead layout...I am waiting on another projector lens and more LED's, but I posted a graphic on my webpage that shows the general layout I have been playing with. Maybe the new project lens I ordered will work better than the spare smaller one I have been using...(of course the LED's on the panel aren't arranged like that)
[Edited by dwalls32 on 10-18-2001 at 12:42 AM]
[Edited by dwalls32 on 10-18-2001 at 12:42 AM]
That's the same problem I had. It didn't collect enough of the image. The solution was to use a plano-convex lens after the LCD. Convex side facing the the LCD.
My spacing was all off, so I couldn't get it to project to the screen w/ the plano-convex lense.
from SurplusShed.com
GLASS ASPHERIC CONDENSER LENS
Item No.: L1314
72.5mm diameter with a focal length of 44.46mm. Double convex with a standard spherical curve on one side and an aspherical curve on the other. Center thickness is 27.1mm. Probably designed for use in a high efficiency projector system. Aspherics offer superior aberration correction for light concentration that would normally require several spherical elements.
[Edited by vdi_nenna on 10-18-2001 at 09:31 AM]
My spacing was all off, so I couldn't get it to project to the screen w/ the plano-convex lense.
from SurplusShed.com
GLASS ASPHERIC CONDENSER LENS
Item No.: L1314
72.5mm diameter with a focal length of 44.46mm. Double convex with a standard spherical curve on one side and an aspherical curve on the other. Center thickness is 27.1mm. Probably designed for use in a high efficiency projector system. Aspherics offer superior aberration correction for light concentration that would normally require several spherical elements.
[Edited by vdi_nenna on 10-18-2001 at 09:31 AM]
Hi ive just found this forum and read through it.
I used a 2.2" screen from a casio pocket television in an old kodak slide projector.With the kodak projector you can move the lenses about as they are all just mounted in slides. Works well with video from a distance but its a bit pixelated for a computer.
What i wanted to ask was i was told that you can get glass that dissipates heat better than normal glass. Has anyone heard of this.
I used a 2.2" screen from a casio pocket television in an old kodak slide projector.With the kodak projector you can move the lenses about as they are all just mounted in slides. Works well with video from a distance but its a bit pixelated for a computer.
What i wanted to ask was i was told that you can get glass that dissipates heat better than normal glass. Has anyone heard of this.
epidascope
hi guys,
I am new in this forum, but I 've been reading this thread
from the begining, very interesting indeed.
BTW has anyone know about epidiascope? another type of
projector for projecting an enlarged image of either a
translucent object (such as a slide or transparency) or
an opaque object (such as a photo or printed page) onto
a screen.
Is it possible using this projector with LCD screen?
My thinking is converting cheap OHP to epidiascope and
using it for projecting LCD monitor display without any
changes in monitor.
thank's
hi guys,
I am new in this forum, but I 've been reading this thread
from the begining, very interesting indeed.
BTW has anyone know about epidiascope? another type of
projector for projecting an enlarged image of either a
translucent object (such as a slide or transparency) or
an opaque object (such as a photo or printed page) onto
a screen.
Is it possible using this projector with LCD screen?
My thinking is converting cheap OHP to epidiascope and
using it for projecting LCD monitor display without any
changes in monitor.
thank's
Gunawan W
I tried using an ohp head attached to a television in the same way as it was attched to the ohp it gave reasonable results but possible a little bit dim if you make an enclosure(sort of triangle) from the tv to the ohp head it may help then you wouldnt need to modify the screen if it produces enough light.
eac74
I tried using an ohp head attached to a television in the same way as it was attched to the ohp it gave reasonable results but possible a little bit dim if you make an enclosure(sort of triangle) from the tv to the ohp head it may help then you wouldnt need to modify the screen if it produces enough light.
eac74
Hi all,
I have read all the posts to the forum.
A couple of years ago I saw a laptop for business people where you could flip off the back off the screen and detach the screen from the laptop, all you did then was place it on a OHP. You had a cheap portable projector. The picture looked pretty good. Don't know who made it though.
Ross
I have read all the posts to the forum.
A couple of years ago I saw a laptop for business people where you could flip off the back off the screen and detach the screen from the laptop, all you did then was place it on a OHP. You had a cheap portable projector. The picture looked pretty good. Don't know who made it though.
Ross
Epidiascopes and OHPs
Hello everybody, I'm also new to the forum, but have followed it since some months ago. Congratulations for all the effort and time invested! (not to mention the money, lol).
I wanted to share my experience on epidiascopes or episcopes (also known as "opaque" projectors) and on ohps.
Once I had the chance of using an old opaque projector. It was a big, heavy, hot and clumsy artifact, but it worked out beautifully in optical terms. You could insert any kind of document, book or magazine and project it onto a big screen. As a matter of fact I noticed it could project just about everything; my hand could be clearly seen with every single detail, when I turned the pages or fixed the document in place.
But this projector generated so much heat inside (because of the lamps) that thin pages would bend and tend to wrinkle by themselves under the heat, as was the case with magazines. I also thought of using this kind of technique for video projection before, but I believe the amount of light needed for it to work is too much, and I don't know if you could use LEDs instead, as an equivalent. You're always advised to use this projectors in very dark rooms. The good ones can be a bit pricey, and unless you could find one borrowed to experiment with it, I wouldn't recommend to buy it at first. Here you have two links with different prices:
http://search.shopping.yahoo.com/search?P=all&is=1&p=opaque+projector&did=
and
http://www01.bhphotovideo.com/defau..._Acatalog_html___CatID=1513___SID=E9ECB50DF50
In any case, I believe overhead projectors would behave better, using an LCD panel. I've have tried the ohp's head alone, with TV screens. Not very good results. Many years ago I borrowed the head of an ohp from a friend (although he was pretty nervous about it, lol) and I did precisely what eac74 suggests, I built a sort of triangle which would keep the light inside, with the ohp's head on top. The results weren't very astonishing, light was too dim, it's not what you would like to enjoy or show to an audience. TV screens just aren't that bright. Not to mention that you must be careful for the lens head not to fall down on the TV screen, which could result in serious material and/or human damages.
Please keep posting if you have any other suggestions or experiences with these or other alternate devices.
Cheers,
Mike.
Hello everybody, I'm also new to the forum, but have followed it since some months ago. Congratulations for all the effort and time invested! (not to mention the money, lol).
I wanted to share my experience on epidiascopes or episcopes (also known as "opaque" projectors) and on ohps.
Once I had the chance of using an old opaque projector. It was a big, heavy, hot and clumsy artifact, but it worked out beautifully in optical terms. You could insert any kind of document, book or magazine and project it onto a big screen. As a matter of fact I noticed it could project just about everything; my hand could be clearly seen with every single detail, when I turned the pages or fixed the document in place.
But this projector generated so much heat inside (because of the lamps) that thin pages would bend and tend to wrinkle by themselves under the heat, as was the case with magazines. I also thought of using this kind of technique for video projection before, but I believe the amount of light needed for it to work is too much, and I don't know if you could use LEDs instead, as an equivalent. You're always advised to use this projectors in very dark rooms. The good ones can be a bit pricey, and unless you could find one borrowed to experiment with it, I wouldn't recommend to buy it at first. Here you have two links with different prices:
http://search.shopping.yahoo.com/search?P=all&is=1&p=opaque+projector&did=
and
http://www01.bhphotovideo.com/defau..._Acatalog_html___CatID=1513___SID=E9ECB50DF50
In any case, I believe overhead projectors would behave better, using an LCD panel. I've have tried the ohp's head alone, with TV screens. Not very good results. Many years ago I borrowed the head of an ohp from a friend (although he was pretty nervous about it, lol) and I did precisely what eac74 suggests, I built a sort of triangle which would keep the light inside, with the ohp's head on top. The results weren't very astonishing, light was too dim, it's not what you would like to enjoy or show to an audience. TV screens just aren't that bright. Not to mention that you must be careful for the lens head not to fall down on the TV screen, which could result in serious material and/or human damages.
Please keep posting if you have any other suggestions or experiences with these or other alternate devices.
Cheers,
Mike.
thank's all you guys,
very useful information, for eac74 and Mike,
both of you using OHP with CRT TV,
which is produce light on it's own and
from my understanding you just put the TV behind the
lens and projected it to the screen with light from
the TV itself, am I right?
How about Portable OHP with lamp located near it's lens,
beamed downward to the mirror on it's base
(This type of OHP basically is Epidiascope).
Has anybody ever try projecting LCD display with this
type of OHP?
What was the result? Is it good enough to enjoy the video?
Gunawan.
[Edited by Gunawan W on 10-24-2001 at 01:22 AM]
very useful information, for eac74 and Mike,
both of you using OHP with CRT TV,
which is produce light on it's own and
from my understanding you just put the TV behind the
lens and projected it to the screen with light from
the TV itself, am I right?
How about Portable OHP with lamp located near it's lens,
beamed downward to the mirror on it's base
(This type of OHP basically is Epidiascope).
Has anybody ever try projecting LCD display with this
type of OHP?
What was the result? Is it good enough to enjoy the video?
Gunawan.
[Edited by Gunawan W on 10-24-2001 at 01:22 AM]
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