Very Dull Image, Not Bright At All

[jazzbee]

Hi Guys,

Man could I use some help...

I have just retrofitted my OHP and the results are very sad indeed

The picture is not bright and is misarable, very faint.

I am using:

400w MH Ballast
400w Metal halide Lamp
Highly polished reflector (good ol' soup ladle)
Crappy Leisegang OHP (made from plastic which is nearly melting)

I have attached a pic of the insides, any tips to improve the brightness would be greatly appreciated.

 

[ancorp]

better optics?

 

[ace3000_1]

Is the bulbs arc in the center of the ohp? also at the frensels focal?

Trev

 

[jazzbee]

The bulb is where it was placed before,
but the halogen light this OHP used before had another lens directly on top of the halogen, please take a look at the below picture.

I am slightly baffled....

Maybe i need to use that lens or get a better fresnel....


DIY is a real pain...

 

[brianuk]

looks like a condenser to me, though im no expert!
try temporarily mounting it in front of ur new bulb to see the effect OR you could try moving the fresnel further away from the bulb, i suspect its now too close together without the condenser though others may advise a little better ace?

Dont give up, the fun is just starting!

 

[tetutigre]

Hi,

I am really interested in this thread. I've been thinking recently on trying some sort of non-invasive retrofit to my OHP because I need a brighter and clearer projection for my classes. I've thought about going the MH way, since it seems kinda cheaper than a $200 HQI set.... I might be wrong though.

I've seen some 400w MH bulbs on Ebay, and some @ Home Depot...(I can't find the base though)... the OHP it's an Apollo Concept 2210, which is supposed to put out 3000 lm with a 360w 82v ENX bulb.... I use it in my classroom with the blinds down and the front light out, but it looks blurry.... I can have the back lights out, but then the students might fall asleep LOL....

So, what do you think? I've seen this bulbs

http://www.homedepot.com/prel80/HDU...ID=ccccadcmflelgddcgelceffdfgidgjk.0&MID=9876

this is a 1000w one

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=3860&item=3834291023&rd=1


But now I found this thread.... and I'm afraid I might have the same results.... what do you recommend? Should I look more into it, or is it just a waste of time? Even better: If someone has a HQI setup that is not being used, let me know

 

[brianuk]

Is there an easy way to stop the light you must have on for having a direct path to the screen, ie block them on the screen side. Might be an easy fix.

Not having direct light reflecting off where your image is will brighten it up in comparison. You cant beat a completely dark room though.

Can you dim the lights?

 

[tetutigre]

Would a condenser lens in front of the ENX bulb in my OHP help any? Also, I found out it has a singlet lens.... would a triplet lens help as well? thanks in advance

 

[tetutigre]

You mean doing a pyramid-like structure from the LCD panel to the OHP lens?

 

[tonydean]

it does not look like your lamp is centered in the ohp?

i can believe that your going to melt the plastic. i see no
heat shield at all behind that relector. that piece of metal
is going to get super hot. also why give up the original
blower fan? i will be much better than the muffin fan
with proper ducting.

i have several Leisegang ohp's, i rather like them. mine
have nice triplets and nice focus racks. i would use the condenser
from the original light box also.

 

[brianuk]

No i dont mean that, but having that pyramid (and blacked out painted internally does help stop light eascape).

No i meant if you have to have lights on at the back of the room is there an easy way to stop them having direct view of the screen as they will be brightning it making the contrast of your projection less than it might be. IE the screen would be shaded from those lights, but they will still add light to the rear of the room.

Condensers dont always work well, they can put more heat on the fresnel/panel. If you can find one to try easily it might be worth a go.

what are u using for the projection screen?

 

[tetutigre]

The lights in my room are fluoresent ones, very diffuse and thus no way of blocking them from the screen. For the screen I am using blackout cloth - I had found this really nice projection screen that is silver, and I thought it would help, but it doesn't seem to help - specially at an angle.

I use Word and prject it for my class notes... I could have the lights off, but then complains arise that can't see their notebook, books, etc... LOL

 

[brianuk]

Its always going to be hard with that amount of light on.
I went to see spdiy II last week, i was early and the guy had the projector on with the lights running some adverts. I could hardly make out the image! Goes to show.

If there are a strip of flourescents some sort of block in front of them would still help the screen - you would only get reflected light onto it, much less intense.

Screen....................block......flourescent
                                  |          | |
|     >                         |
|                  >             
|                               >PJ
|                  >
|    >                                          :confused:

try it, nothing to lose, might just help enough.
Obviously the scale of my diagram is bad, hope u get the idea!
note the confused student in my bad diagram.

 

[tetutigre]

FL FL FL


FL FL FL


FL FL FL
OHP

FL FL FL



__SCREEN__

This is kinda the arrangement of the room FL=fluoresent lights -arrangement is crappy but you get the idea

With the first 2 rows off, the image is viewable and readable(at least word is) but not crispy, kinda blurry.

All lights out, looks better of course, but not a desireable educational environment (can't see, fall asleep, etc etc -just go back to our years in school LOL)

And as for the student , try

x 30

I teach Foreign Language

 

[Tiarb]

jazzbee, I am not very experienced with OHP retrofits because my own project does not involve one, but I checked the photos you sent and noticed two things about them. Firstly, that reflector might be something that's not doing any good, but I dont know. It's a ladle. Not even a spherical or round ladle but some weird soup ladle. I'd try the reflector that your projector initially had.

The bigger problem you have is that the lamp is not in the same position as the original lamp was. I combined your photos to make sure of it (resized and so that the images matched) and the lamp and also the reflector is quite a lot of their place. I dont know how that works with OHPs but with my project if the flame is few centimeters in a wrong place I might not get image at all, so I'd guess that that might also make a difference with OHP's too. I attached the image I made to this post.

Try to get the flame on the right position and also try the original reflector that the OHP came with. Also, if you attach the original relflector just the way it was, it might be easier to get that flame on the right position.

Regards
HB

 

[Tiarb]

I'm sorry I gotta add that this whole problem seems like a joke... I just checked the images again and the original reflector of the OHP looks like something that is much better then what is in the retrofitted image... how the heck would some one seriously use a small soup ladle if the original reflector is such a big and perfect thingy... Even if its not possible to get the MH at the same position as the original halogen, that reflector still seems to be much better choice then the ladle

 

[raquibul]

Safty first

I have watched his MH setup inside one thing that it is very risky to blow cold air directly to a MH bulb
I have seen it because the fan u useing is for air intake not hot air out.
Original setup with helozen and infront of it is a condensor lense.
Why dont u use it with its original shape?
another thing of your MH setup I think the light path and the freslense should be changed.

 

[jazzbee]

Thanks for the tips guys,

I am using the old reflector (even though it is much smaller than the ladle) and have also adjusted the lamp position.

It has made a huge difference but I still have a bit more adjusing to do as the image is still dull. The old fan in the liesegang was really crap, it hardly moved any air out of the unit, even with the old set-up the plastic inside was melting.

I have attached 2 fans now, heat control seems ok now, but I will probably end up making a new case, as I don't feel comfortable with the amount of heat that lamp produces, it is SERIOUSLY HOT!

Special thanks to TIARB for merging both my photos to illustrate the lamp displacement

Now for some more diy... Back to the garage

 

[ace3000_1]

I'm sorry I gotta add that this whole problem seems like a joke... I just checked the images again and the original reflector of the OHP looks like something that is much better then what is in the retrofitted image... how the heck would some one seriously use a small soup ladle if the original reflector is such a big and perfect thingy...

Heya Tiarb, can you please calm down abit?, we dont want to go and affend other members on their projects.

As for Jazzbee using the original reflector well its no good unless you know the focal point of a reflector, having the lamps arc not at the reflectors focal point will either cause problems or not work.

There is obviously an issue here with this ohp retrofit, from my experience its the frensels focal, having a reflector wont do too much unless all of your optics are lined up perfectly. The image should be bright with that bulb with or without a reflector and to me in this case, it is simply a miss alignment in the optics.

Trev

 

[tetutigre]

Hi

I've been working around my problem.... couple things I found is that, at a 640x480 resolution the image is a little bit better.... also, the silver screen that I have works fine with lights out, but not too good with back light on... and it also works better with movies, gives you more contrast and stuff.

I've been reading about MH and looked around on Ebay and all, but I am not sure what to do about that.... I am no electrician, and am afraid of electrocuting myself.... LOL ... and also, I wonder if the MH would be a cheaper way than shelling out $200 in a Hqi setup... any thoughts?

Ace, could you help me out with my problem with the OHP and all that? can I improve the performance I have with my current setup, or do I need to think MH ? Thanks in advance.