can someone design an ellipsoidal reflector to use with either a t15(ushio) or ED28 400 watt MH bulb and to work with the standard 220mm rear fresnel? I'm going to have some extra cash after the first of the year and I'm thinking this would be a fun thing, figure I will have it spun from aluminum(and yes, I'm pretty aware of all the caveats...) just for the heck of it.... I can draw an ellipse, but I'm just not sure of the minimum size (like the ikea is not a full hemisphere but it intercepts the maximum angle of light... and big enough that it won't overheat the bulb..with forced air cooling of the reflector) and what the focal lengths would need to be.... found a couple of spinning places that do reflectors...
edit:
if you can give me dimensions I think I can get it into whatever format might be needed

I did an analysis a while back on it, and I found that what you're asking for is difficult at best. The sheer size of our bulb (the ushio) pretty much screws us over. Don't know about the ED28. I used to have some autocad drawings of it laying around, I'll see if I can dig them up.

well, it can't hurt to try it I figure.... even if it isn't a perfect ellipsoid still theres a lot of room for error .... imagine if you could get a reflector to even make 40% of the total lumens from the bulb available.... heck, even 30% would be good I figure....

Youre saying you want to use this with the 220mm frez? This would add like and extra foot on the back of your box just to line up the focal points!...
...but damn that would be a bright picture!

yep..... honestly, if you put it in a vertical, you wouldn't even notice....

Well I can't find my drawings (made them at work, must not have survived me quitting my job ). The problem I was running into was the length of the bulb. Even up to the size of the fresnel as a diameter, the bulb was halfway sticking out of the back of the reflector and the focal point (where the center of the arc should be) was very very very close to the back edge of the reflector. So I would have had a lot of light loss out of the back alone.

Another nice fun factor to consider is the fact that your "point source" is about a half an inch in diameter or so....good luck!

It can be done I have some on the way. The basic testing is done. If you make one from scratch you still have the bulb in the middle problem [like the parabolic dish but not as bad] which has to be diffused some how. So you will have to cut groves or make a compound curve. If you want to start from scrach here is a good patent to look at #4417300. Most good ellipsoidal have some kind of facets cut in them to over lap and wash out the lamp image. There is many off the shelf ellipsoidal reflector around that may be had at somewhat low cost.
There is a trick to make this work, you are close.
Here is a link to a cool math site on ellipse

http://www.jimloy.com/geometry/ellipse.htm

and the patent link
http://patft.uspto.gov/netacgi/nph-Parser?...0&RS=PN/4417300

let us know how the testing comes out.

what exactly is the trick? I haven't seen any ellipsoidal reflectors that can take the 400 watt bulbs we use...
edit: what do you have on the way? ellipsoidal reflectors?

well...lets be a bit more specific I guess.... right now, with the spherical reflector we are delivering at most 5000 lumens to the first fresnel .... thats a little more than 15% of the lumens from the ushio.... given all the problems with an ellipsoidal reflector with our bulbs,all the glass/reflections in the bulb, size of the arc, the size of the bulb...yadda,yadda yadda.....
still.... I find it hard to believe(but admit it could be possible) that ther is NO configuration of an ellipsoidal that wouldn't be able to at least match that 15% and probably surpass that..... I'm not looking for something that will recover 75% of the lumens the ushio puts out...... if it could do 20% even...thats still more than we have now...so put on your thinking caps and take off your skeptic ones ;-)

edit: and it doesn't matter what size it is or how much it will add to the length of the box.....

would 80% be OK?

Click to view attachment

well, I don't think an ellipsoidal by itself will even hit 80%...whats that ring to the left? does that go on the front of the ellipsoidal? I've read about things like that on stage lighting websites...... they use a secondary reflector in the front of the setup ...what are you showing us and where did you get it? ...but look at the size of the hole in the reflector..no way you're getting a mogul base in there!

The ring is the light recycler. It is for a Altman 360 pro light. No I don't think the lamp we use now will work in this [unless you crack the shell] and I don't know the beam spread but other lamps will fit. The 80% figure is one I found on the web comparing different reflector systems used on pro lights. There number was without a light recycler.

There is still the magic trick that must be done to make any of these reflectors work.

If some one want to try this reflector from china it may be good.

Link
http://jieneng.en.alibaba.com/product/5010...m_/showimg.html

Click to view attachment

Do you actually have one of those Altman reflectors? I thought they were made of aluminum and
the second smaller piece was just an extension to the ellipsoidal shape to collect more light.
Member pjgibbs has one like it.

It looks like I may get 4 of them I don't have any right now. Made a post of the fix for using almost any ellipsoidal reflector. This will change everything if you don't mind a larger box. Time to play.

I personally won't mind a longer box, so play away!

I have already posted this pic in a couple of forums already, but do you think the BD-17 would fit inside one of those reflectors?
I found this bulb, which is a BD-17, its 175w but if you claim 80% reflection then you won't need as many lumens. http://store.peclamp.com/40009c.html