yes Brain used it with a double ended 400w HQI bulb, pics are in his projector, exact same one to.

I got one and ditched it cause I thought it was too small for my s400dd, dia is 3.5" Polish is great if this small reflector will work go4it.

Click to view attachment Click to view attachment


Would this make a good reflector? I'm pretty sure it's Stainless Steel and it's nice and light.

I found it in a charity shop today for 50p (uk). They've got another 30 or so slightly smaller ones too. I've only spent half an hour polishing it so far. It's 4.25 inches in diameter and 1.34 inches deep. I think these are similar dimensions to those napkin holders people are using except the radius of this is around 1.77 inches.

I plan on buying the LL 240V lighting kit when it comes back in stock and need to know if I should keep polishing this, or get hold of one of the Ikea bowls instead.

Any comments would be good.

I have the venture PS bulb ..... ED28 size ... probably exactly the same size as the Ushio in the ED28 flavor .... Im still building my second pj ... but I have placed the bulb next to the Joe's reflector and it appears that it is exactly the correct length butted as close as it can do ..... maybe .02 of an inch off ... cant get that accurate with my ruler ... (64mm = 2.52 inches) ..... but from what I can see its sitting damn close to 2.5 inches ....

This is with the bulb jacket actually touching the reflector and in as much as it physically can .....

So im not saying it definatly works .. but im near certain .... we will find out in a few weeks when I get my PJ finished ....

so, i wanted to reopen the discussion about different shapes for a more efficient reflector.

The (hemi) spherical reflector works because all the light to the rear of the bulb is reflected back to the focal point (the center of the spere), and the collimator takes that intense point of light and makes the beams go parallel through the lcd.

However, rays not reflected, and not pointing at the collimator are wasted.

Has anyone tried using a full sphere for a reflector? Wouldn't this reflect *all* the radiated light back to the source point?

Of course, you'd have to cut a couple of holes in the sphere: at least two... one for the bulb, and one so that the collimator can 'see' the light source. The good thing is that any light coming out of the hole for the collimator goes to the collimator, and therefore not "waste".

The other thing is, you could cut a rectangular hole for the collimator, further eliminating wasted light.

First problem i can think of is that of finding a sphere. Was someone talking about making a form and then coating the inside with some polishable material?

The second problem i thought about was cooling.

(i tried doing a drawing, but I can't seem to attach it to this post)

This has been discussed before. The problem is that the light does get reflected back to the arc, which is fine, but it goes through the arc, hits the opposite side and gets reflected back to the arc and back to its first reflection point so the light ends up bouncing around but still not getting pointed towards the LCD. Cooling is hard as there is no way to get air in to cool the bulb. So good thought but unfortunely it won't help us.

I have a highly efficient ellipsoidal, but it isn't a "slam-dunk". It definitely reflects MOST of the light to a point, but it obviously is not doing it at the correct angle for the fresnel. I get a bright circle projected with a hole in the middle. Guessing a condenser used to correct the light would do the trick, but I don't know where to start... been sitting on it. Definitely going to need an IR filter. If anyone knows there stuff and thinks there is a solution to my probelem I would love to hear.

Wouldn't you want to move the lamp back as an ellipsoidal converges to a point ahead of it's source? Seems like that would solve the hole in the middle.

I have tested all distance between moving light forward and back in the reflector and moving them together forward and back as a whole. Its easy to find the best position/focal point to place the bulb at.
Best scenario without another lens is a bright circle with a hole so far, unless you have an ellipsoidal that was the right shape to send the light out at the correct path.

Hmmm, that's a shame since an ellipsoidal is the most efficient followed by spherical then parabolic. I doubt a precondensor would solve your dark spot in the middle, but it's worth a try. I was thinking it was an alignment issue.

Click to view attachment

Okay just an idea on pumping the most out of a 400Watt metal hallide without using the reflector.

Just want some ideas or feedback of whether this is possible/practical.


This design is without using the bowl. It basically uses the light from 4 sides of the bulb and reflect it until it goes out the front in the right direction. The only exit path of the light is the front (this is what we want.)

If you look at the diagram you can start from the light source from any direction you will end up exiting at the front fresnel in the right direction. The yellow lines are examples ofthe light path that bulb can take.
Theoretically it should give us around 4X the light output and twice that of a perfect reflector.


This setup needs 4 fresnel lenses (not counting the one on the other side of lcd) and 6 mirrors, and 3 heatshield glass type materials. ( )
$$$


another problem is that the reflected light has to go through many mirror and lenses and each time it passes through itll lose some intensity. Also, having very good alignment of the 6 mirrors and fresnels are going to be crucial.

I don't know how good reflector bowls are but if you compare a mirror to even a polished steel bowl, I think the mirror is better at reflecting light and could make up for all the losses through glass.

Interesting concept, but I believe that the light not only needs to be converging at the focal point of the collimating fresnel, but the light rays also have to be travelling towards the fresnel.

i like the teory behind it. (The light is rotating until it goes to the only exit, lcd)

but wonder if is practical. Isn´t an eliptical reflector a more practical choice?

My head hurts, might work in theory but difficult in practice and I assume you would need same structure above and below, to capture that light as well so it would be huge!!!!

Both the angle and the focal point are going to be right as long as you use the same fresnel front and rear.


The top and bottom I think are not as useful due to the mogul base in the way on one side, and then the other just due to geometry won't get as much light as the 4 sides we are using.

Size wise, iI think you can shrink it in theory ( but you need probably fresnels are hard to get) and u need the right fresnel lenses with the focal length and width ratio as the front.

Otherwise itll take lots of space, and reflector is lots simpler. But would it really work and and give a brighter picture?

I think it could also give u better uniformity with respect to screen brightness since you now have 3 focal point centers along the width of your screen.

It's a good theory, and if we were dealing with ideal components, it would even stand a chance.

We're not dealing with ideal components. The actual light source is too large, and the path length of much of the light provides far too much possibility of error, which would leave too much off axis light hitting the LCD and doing nothing but produce extra heat. The light has to pass through many lenses (Each also requiring a heat shield) which would result in signifigant losses in both the quantity and quality of the result. And even if that weren't enough, the mirror positions would need to be extremely accurate (because of the path length) in order to be close enough to recreating the point source. And last, but not least, it still does nothing about the root cause of the dim corners, and would actually enhance the dim corners, not reduce it, for much the same reasons that photography tends to enhance the problem.

It's an ingenious solution, but impractical.

well, same idea but something smaller;

I got some buffing wheels and compound from home depot to polish the ikea reflector.Heres a picture of 2 ikeas the one on the left is polished, the one on the right is how it comes from ikea.there is a definate increase in brightness after i put the polished one in.
It almost looks chromed after I got done.
I mounted the buffing wheel in my drill press with an arbor, it worked great!

I like the idea :-)

Maybe just for fun, I counted how many fresnels, mirrors and bulb walls the light would encounter on its way to the lcd, for each quadrant of light from the bulb.

Light quadrants named north south east west. What I got is

Babygucci:
N: 1 fresnel, 0 mirrors, 1 bulb wall
S: 5 fresnels, 6 mirrors, 5 bulb walls
E: 4 fresnels, 5 mirrors, 4 bulb walls (average of 3,3,3 and 5,7,5)
W: 4 fresnels, 5 mirrors, 4 bulb walls (ditto)

Rox:
N: 1 fresnel, 0 mirrors, 1 bulb wall
S: 7 fresnels, 7 mirrors, 7 bulb walls
E: 3 fresnels, 3 mirrors, 3 bulb walls
W: 5 fresnels, 4 mirrors, 5 bulb walls

Fun puzzle!

This is assuming the bulb has two walls (if it has 4, I guess just double the numbers)

I have made a flat reflector using retroreflectors. I removed my Norpro and I do have an increase in brightness. Using the retroreflectors offers several advantages.

1. Alignment is simple, mount it vertical behind the bulb and about .50 inches awayfrom the bulb.

2. Captures all relevant light coming out the back side directs it back to the light source where it came from.

For now I have one 4 x 6 inch retro wall behind the bulb. In the next week or so I am making two more, to mount above and below the bulb. This will increase the brightness at the source, but I am unsure of the off axis light effect on output.

John

Very cool. What type of retroreflector is it, do you have a link to a source?

Hey guys. Just wondering, how much does a reflector help?

The guide suggests you can get almost twice the brightness but from what I've heard the light improvement is actually quite small. Less then 50% brighter. Some say only about 20% brighter. Thats not very impressive.

Does it make a really noticable differance? Or does it just look a little better?

Sawtooth,
The retroreflector will be tested against a spherical reflector for light output in the next few weeks. If measurements show a higher output with retro's vs spherical, I will be offering them to the community at a very reasonable price.

Mikau,
I would say that there is a noticeable difference with a reflector. Any increase in light output is a net gain regardless of percent increase. On average a reflector isn't costing more than 15.00, well worth the few bucks and minutes spent.

John

Well about how many extra lumens do you gain? (as if you were using just a brighter bulb)


I had an idea earlier but it looks like somewhat else already thought of it a while ago. Putting a light shield in front of the halide with a very small hole in the middle to let the light through. Keeping the light under control.

But if extra light shines through the lcd and doesn't make it through the triplet, will that wash out the colors of the lcd? Or will it have no effect? Because if it has no effect, the idea above is kind of pointless.

What is a retroreflector?

Sydney,(and all others)-has anyone tried to get bowls from the norpro wholesale site yet? I may be able to work something out if anyone is interested. if just one person knows if it has been attempted or not let me know that way we are not filling this with 50 responses of "ya-try to get some . . . .!!" thanks!!

Ace-hardware here called the manufacturer and the min, order is 100 pieces.

thats why they do not want to stock them either.

[/quote]
What is a retroreflector?

[/quote]

A retroreflector will direct light back to the point from which it came. A corner cube prism is a variant. A corner cube is used in surveying. High quality round glass beads preform the same function. Any light hitting the bead from any direction is directed back to the source.

Therefore, with beads small and round, I emphasize round, they will direct all received light back to the arc.

John

Mikau,

I don'y have equipment to measure output. I am sending a panel to someone that does and they will provide a measured, objective analysis


be sure to allow for angle


It will make it thru the triplet if optics are in allighment. Turn down contrast to avoid washout.


Quite true

John

Check out this reflector unit, its a $199 but it would be cool to find a used one and see how it works.ELLIPSOIDAL REFLECTOR

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Looked for NorPro myself on the internet, found that Kohl's on-line offered a two bowl set. Wanted to see if they had them in the Kohl's near me so I visited the store. Didn't find the NorPro bowls, but found what I think may be better reflectors to use in helping to maximize light usage (point light source). I found what I think are ice cream bowls at Kohl's. They are a double walled 18/8 polished stainless steel. The insides look to be a perfect 1/2 sphere. I don't know if they are deep drawn or spun stainless. Looks like deep drawn as they don't have any marks (striations?) that I have typically seen on spun materials. They measure 2-1/4" overall height with a 4-1/4" ID. These items are made/marketed by SteelTek and were originally priced at $9.99 each. I bought them on sale for 1/2 price, bought 4 of them to experiment with modifying and mounting (They only had about 6 more left). Looks like I can mount them by using sheet metal screws affixed to the flat bottom of the outer shell. Also look to be the right size to use with the condenser lense I have purchased from The Surplus Shed.

Anyone else out there have any thoughts, suggestings, etc. on arrangment using the "Ice Cream Bowl Reflector," LumenLab light kit, and a condenser lense?

Has anyone had any luck using an ikea napkin holder on an EYE bt28 bulb? If not, what would my next best option be?

I am using Ikea Napkin holder from Replica.com with eye B28 from LL. Watched Shark Tale last night. The picture looked awsome. Since I haven't tried with other reflector, I don't know the difference. But for now it seems to work very well for me.

If anyone doubts the IKEA will work with the BT28 EYE I am happy to send one for free just to serve curiosity and you can pay if it does.
So she's workin fine for you Paul3ct04?

Another PJ by this weekend hopefully! The WUXGA. Anyone know of a more powerful realistic and proven light setup than 400w? I really want to blast some light through the WUXGA. i researched quite a bit on using a 1000W (too wide light packet) and xenon (too damn expensive!)

Yes, she's working fine for me, Joe. I'll probablly have the pictures by this weekend.

The Ikea reflector will work with the EYE bulb, I placed it at 62mm from center of arc, and it rest right on the bulb, so if you place it or afix it to the bulb it will be placed correctly.

Joe

Apologies if this has been discussed, but I was wondering if anyone could clarify the statement made by Brain regarding the new parts coming down the pipeline:

http://www.lumenlab.com/forums/index.php?s...pic=2898&st=20#

Here's the quote I'm concerned with:



Does anyone know:

A. What a Pro IR pass reflector is(what it looks like, general description, etc.)

B. If this will be available for us "non-pro" users(there is mention of the S400, which I have in my rig)

C. If there is any idea of the cost?

D. Bonus question What does the entire "pro rig" entail? Is it just a new lens or is it also a new fresnel set/lamp, etc.?

My main concern right now(and if judging by the posts in this thread, this concern is shared by many others), is the light output of my projector. It's good for most pics, but for a "dark" movie like Die Hard, I have to manually bump up brightness which then washes out detail, etc..

thanks for your time,

-Jude

Pure speculation, unfortunately, however, I'd expect that it would be an improved reflector made of a "cold mirror" which will increase light output without increasing heat.

As a separate unit there should be no reason why this reflector should not be usable for a 15" kit. Any reflector suitable for use with the LL design would be usable for either lens set.

You've got me there.

The light kit is either set. The same S400DD lamp and ballast combo is assumed (If using LL parts)

The "Pro rig" basically entails the parts that work with the pro lens. This is a different set of fresnels, which have a different length throw to them (The collimator is the same, but the field lens has a further focal distance to match with the pro lens' focal distance. The other difference is that the pro lenses will accomodate a larger LCD.

[edit]Oh, and for brightness, yes, this is an issue. I personally don't have a problem with dark movies, but I have my projector in a very dark basement. An improved reflector is one potential solution.

Awesome, Supraguy, couldn't have asked for a better set of answers. THANKS!

-J

Speaking of reflectors, I just wonder if someone couldn't design a ellipsoidal reflector and have a "mold" made by one of the guys with a CNC machine.....I imagine it would have to be made in 2 pieces(think joe2000chevy's(maybe?) machine can cut to 4" depth..... then take some metal and form it around the wooden shape.... true it wouldn't be the best, but I know many years ago I used to do similar things with silver in my jewelry making period.... any thoughts? even if it wasn't the best , most accurate ellipsoidal, still according to all posts I've read ellipsoidal would be highly prefferred to spherical....

Metal spinning a shape would be easier. Unfortunately I do not have a lathe available.
John

Has anyone elvaluated exactly how much light the reflector adds to the projected image?

One could guess that the image would double (i.e. 100%) in brightness with a properly adjusted reflector, but I doubt that this is true. I've seen various users indicate that the image brightness increases, but it sounds more like a 20-50% change than a doubling.

Is this becaue stainless steel or aluminum aren't good reflectors or is this due to the non point source of light so that a spherical reflector can't capture all the rays???

Has anyone tried a optical glass coated reflector, I would assume that these would have better reflection characteristics than polished metal?

The brightness doesn't double with a reflector such as a polished steel like the IKEA. The brightness increase is noticable, but a light meter would be necessary to figure what percentage. It is worth your time and money to add a reflector. Polished aluminum is very very efficient and effective. Maybe I should look into getting an aluminum coating on the IKEA's?

I am sure many of us (myself included) have spent countless hours scouring the net for a source of the ultimate reflector like a glass coated you are talking about. The problem is that the ultimate comes at an ultimate price. It depends how important is it to you and how much you are willing to pay.

I did source an optical quality aluminum ellipsoidal reflector that fits our bulbs, but it isn't sending light out on the right path for our fresnels. I am sure a pre-condenser of some sort can correct that, but I no longer have time to do that kind of research. if anyone would like me to send them that refelctor to experiment with I am happy to.

where did u find one? I am interested in experimenting with ellipsoidal reflector

I found one from a lighting manufacturer. I am looking for someone that has a lot of experience with PJ's and optics to send this to for experimenting. It cost me about $45-$50.

Does the size of the reflector make much difference with regards to light transmission?
I've got a perfectly hemispherical reflector that's approx 250mm (~9.8") in diameter, is that too big?

Try using this bulb.

blehhhk... 4k color

Has anyone used the Ikea Napkin holder with a 400W HQI lamp? I really hope to find an answer on this my whole PJ is based on this lamp. If i read correctly in this forum the center of the lamp should be 6cm from the edge of the reflector?

thanks

Hey all

Please redirect me if this has been discussed before, but...I've heard that the magnetic ballasts produce noise where as the electronic versions are silent.

Is there a difference between magnetic and "coil" ballasts?

Do the magnetic and/or "coil" ballasts produce noise?

Thanks,
Mezmer