Brightness and Contrast

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JerrysTib

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Joined 2003
#1
Hello, I am going to explain my set-up, and then ask for any help possible with my problems.

I have a Proxima Ovation 820 LCD Panel, a quite old overhead projector that uses DYS bulbs, which I believe run at like 17,000 lumens, and a screen made from blackout cloth. Anyways, I am having trouble with the brightness of the image. I can turn the contrast up on the panel, but then colors start to bleed and skin tones and other like colors start to look orange and crappy. I think my problem is in the bulb my OHP uses, but I'm not sure. The picture becomes very washed out and bland, and you can barely see anything sometimes, especially with dark scenes. I hope someone can help me.:scratch:
 
#2
The only solution is to turn down the contrast and beef up the lumens sort of speak. You projector is not 17,000 lumens... I would say it is 4000 (just a guess. That seems to be the avearge). You need to retrofit metal halide or buy a brighter ohp. Anything around 10,000 lumens will be more than enough. That will be about a 1000 ansi lumen picture you will have on the wall.

http://members.cox.net/rolm/update is a good site about retrofittiing, but it would be harder for you becuse you projector is a DYS style bulb that has the reflector built in.

Hope this helps.
 
#3
verbose mustafa said:
The only solution is to turn down the contrast and beef up the lumens sort of speak. You projector is not 17,000 lumens... I would say it is 4000 (just a guess. That seems to be the avearge). You need to retrofit metal halide or buy a brighter ohp. Anything around 10,000 lumens will be more than enough. That will be about a 1000 ansi lumen picture you will have on the wall.

http://members.cox.net/rolm/update is a good site about retrofittiing, but it would be harder for you becuse you projector is a DYS style bulb that has the reflector built in.

Hope this helps.
Click to expand...

Lamp Number DYS/DYV/BHC
Bulb Audio Visual / Photographic
Base GZ9.5
Volts 120
Watts (Amps) 600
MOL in/mm 2.50/63.5
MOD in/mm 0.87/22.0
LCL in/mm 1.44/36.5
Filament CC-6
Base GZ9.5
Special Desc
Lumens 17000
Color Temperature 3200
Average Life 75

I didn't mean to say that my projector was 17,000 lumens, but that is what the bulb is rated at. Also, the bulb does not have a reflector built in, it's part of the projector itself. I figured the color temperature may have been part of the problem.

An externally hosted image should be here but it was not working when we last tested it.



http://www.bulb-source.com/dyspict.htm
 
#4
Oh man im sorry... I must be loosing it! 🙁 I should know... I have a dys bulb in my projector... Well, your all set to retrofit then. I have the exact same bulb in my ai-1000. It seems wer are in the exact same shoes... I have had the same problems as you with my spectra c panel. Lowering the constrast makes for more detail, but less brighess. I will definitly retro fit like rolm did. What kind of projector do you have by the way... Im looking to replace my ai-1000 becuse it has a bit of shipping damage, and it is not the type on lens i want. I want to research ohps a little.

Im glad you know your bulb types... lol 🙁
 
#5
verbose mustafa said:
Oh man im sorry... I must be loosing it! 🙁 I should know... I have a dys bulb in my projector... Well, your all set to retrofit then. I have the exact same bulb in my ai-1000. It seems wer are in the exact same shoes... I have had the same problems as you with my spectra c panel. Lowering the constrast makes for more detail, but less brighess. I will definitly retro fit like rolm did. What kind of projector do you have by the way... Im looking to replace my ai-1000 becuse it has a bit of shipping damage, and it is not the type on lens i want. I want to research ohps a little.

Im glad you know your bulb types... lol 🙁
Click to expand...

I have a Beseler Porta-Scribe...I just want a better picture:bawling: It looks pretty good with the cartoons, but when I come to dark scenes in movies and what have you, I just loose all definition...it bugs the hell outta me. So if I retro-fit a MH set-up in my projector, should I see a major improvement?
 
#6
Well, you will have a brighter, whiter light, so i say yes... Rolm is really the expert on this one though, if you can figure out how to contact him. I do not think his light source is much brighter than 17,000 lumens. I am thinking it is about 28,000??? That would still be a good boost though and last 10,000 hours... Think about the cost of buying 10,000 hours worth of dys bulbs... Ouch!:dead:
 
#7
I think part of your problem could be the low contrast ratio of these older projection panels. I have a sharp qa-1650 and I am having the exact same problems. But I am useing an overhead projector with a HMI575 watt bulb. Something like 49,000 lumens
at the bulb and 6000k on the color temp. Dont get me wrong, its definatly a big improvement over my halogen projector, but dark seenes still suck, and the bright seenes seem washed when I fiddle with the contrast and brightness. I am currently working on upgradeing to a 14 or 15 lcd monitor. I think 300:1 or better contrast would help considerably.
 
#8
Yeah, I have a proxima oviation + 944 and am running into the same problem. I have basically concluded that it is the contrast ratio in these older panels. I find it decent for watching tv and doing computer stuff but movies give it problems sometimes. I also am eventually going to upgrade to a monitor screen. Hopefully when I do some of those old 14" that are easily taken apart will still be floating around e-bay.
 
#9
I agree with the comments about the older panels. I went from a Spectra C on a 3M 1750 OHP (4000 lumens) which gave a just about acceptable picture to an Ask Impact 24 on the same OHP which looks absolutely fantastic. Much better colours, contrast ratio and greater detail. I really can't praise the Ask Impact 24 enough actually - it's got a very small footprint and even a very quiet fan.
 
#10
I have the saem problem as all of you, not very visible dark scenes and whites arent too white. I dont think its the contrast ratio, sharp Qa-1200 150:1 ratio i think thats pretty good. I think there are many things to blame,
1)The DYS bulb (which i also have 🙂 ) this bulb burns at 3200K and its a bit yellow,
2) The screen, I have a custom vinyl and bedsheet screen....not very good.. but i like it.
3)The enclosure, there is ALOT of light coming out the OHP and through the sides of LCD panel, my 1st movie i watch was scarface andi watched it without any enclosure,the next day i tried to blockout the light and it LOOKED WAAAY BETTER!!!
try somethng like RYDAD, his pj is amazing!
I also plan to retrofit with MH, but i heard that RASPAC tried it and faild or was it GOLDMOTH, one of them used a reduced jacket 400 watt MH, thats wat i want to get since its smaller...

well i hope that helps 🙂


-JimmY-
 
#11
I agree with your comments about light leakage. I have a light guard on top of my OHP - made by nView but easy enough to make one yourself. It's a piece of opaque plastic with a an LCD sized hole cut in the middle.

On top of that (literally!) I have built an enclosure around the LCD that goes all the way up to the triplet optics to prevent any light leakage. It's made from matt black mount board (available from art shops). It's like a tall pyramid with the top cut off. The top is shaped with guides so the optics can still move up and down inside for focussing.

The whole thing is mounted on a trolley (along with progressive scan DVD player) with extra mount board light baffles on the side to prevent light leakage from the OHP vents (but not interfere with airflow). The net effect of all this work has been a noticeable improvement in contrast and detail.

N.b. mounting on a trolley means it can be used in study or living room. TV and VHS are sent from video via 2.4 GHZ wireless sender in living room. DVDs are watched from built in player for clarity (direct VGA out from Arianet PDVD2255 DVD player to Ask Impact 24 = FANTASTIC quality). Sound is via plumbed in cables to stereos in each room (via flying phono lead from trolley for DVD). Screen is portable slide projector screen which is very good actually. It looks a bit like a dalek but it's great having it so portable 🙂
 
#12
I too have done some baffeling to block the excess light. It has helped a bit.
Jimmy, I think your QA-1200 is newer than my 1650. Yours came
out when the QA-2500 did I belive. Mine has a typical contast of about 60:1 and some where around 100:1 full/off. Its just not enough.
I have noticed that most of the projection panels and lcd projector specs I have looked at list contast ratios at "full on/off."
Most of the lcd monitors I looked at list the contrast as "Typical".
I wonder if there is a significant difference.
I read a review of an infocus X1 projector and the contast ratio on that one is 2000:1 full on/off. The review mesured the actual ANSI contrast at slightly less than 400:1.
Dunno, Just thinking out loud.
Here is that review if anyone is interested.
http://www.pcmag.com/article2/0,4149,887370,00.asp
 
#13
my Proxima is rated at 100:1 for contrast ratio and for that time it is often listed as "Typical" I have a glass beaded DaLite screen and have no problems with whites (using 400W MH). My only problem seems to be dark scences (hard to tell what's happening). If I adjust the contrast to compensate for this, then the light scences start to get washed out, which isn't to bad since their seems to be more dark scences than light ones in most movies. Anyhow just my experiences...
 
#15
One of the DVD's I find contrast to be a problem for me on is Star Wars Episode II ATOC. Especially in the beginnig when they are on Courosant. The buldings in the background are super bright, and very washed out and the forground of the sceen at the same time is very dark, and hard to make out the detail. Thats really what got me thinking about getting a higher contrast panel.
 
#17
IMHO, i think gettin an LCD monitor would be better since it has higher ratio and reolution for about 250-300+ i see 2500's for 400-500+ the ONLY projection panel i would pay 600 for is the proxima 9XX which has 12XX 10XX res but i dont knwo about ratio. IMHO
 
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