If you have a choice, which would you buy ? 3M 9700 or 3M 9800 ?
Which one is easier to convert to MH bulb ?
Thanks.
Which one is easier to convert to MH bulb ?
Thanks.
Converting 9700
I am using the parts from 2 3M 9700's and believe me you'll have a hard time converting them to MH. The first problem you will have is the fact that the fresnel is a plastic one, not glass. This means that at the distance involved in a OHP you will diffinately melt a plastic fresnel with the room involved. Also, the halogen lights are pointed down towards an angled mirror on the bottom of the OHP which then reflects the light up through the fresnel and the stage. The projection lens is top quality and has impressed me so far.
I am using the parts from 2 3M 9700's and believe me you'll have a hard time converting them to MH. The first problem you will have is the fact that the fresnel is a plastic one, not glass. This means that at the distance involved in a OHP you will diffinately melt a plastic fresnel with the room involved. Also, the halogen lights are pointed down towards an angled mirror on the bottom of the OHP which then reflects the light up through the fresnel and the stage. The projection lens is top quality and has impressed me so far.
Glass Fresnel
The only one I know off the top of my head is the Dukane 680. I recently contacted a parts supplier and discovered that to order the fresnel used on this projector would cost $70 US. You're better off trying to find a whole projector on E-bay. A warning to those outside the US though. I have heard rumors that very few OHP make it across the boarder with thier glass intact no matter how well packed (happened to both of mine and one was in a professional shipping case).
The only one I know off the top of my head is the Dukane 680. I recently contacted a parts supplier and discovered that to order the fresnel used on this projector would cost $70 US. You're better off trying to find a whole projector on E-bay. A warning to those outside the US though. I have heard rumors that very few OHP make it across the boarder with thier glass intact no matter how well packed (happened to both of mine and one was in a professional shipping case).
Re: Converting 9700
melt??? perhaps a 1000 or 1500w MH bulb would melt a plastic fresnel, but aren't halogen bulbs hotter than MH? so why would a 250 or 400w MH bulb melt a plastic fresnel if these fresnels can handle 250, 360, 410 watt halogen bulbs?
bitbyter said:
melt??? perhaps a 1000 or 1500w MH bulb would melt a plastic fresnel, but aren't halogen bulbs hotter than MH? so why would a 250 or 400w MH bulb melt a plastic fresnel if these fresnels can handle 250, 360, 410 watt halogen bulbs?
As far as I know
A 400W Metal Halide is hotter than a 400W Halogen but produces more light vs. heat. The Metal Halide lights are more efficient in the light to heat ratio but not neccessarly in a direct Wattage to Heat comparison. Speaking from experience MH bulb get very hot and at the F2 point will burn through cardboard in seconds (melt plastic is minutes). Although your fresnel won't be at the F2 point you do not have a lot of room to maneuver in a OHP case. The distances are just to close for safety in my opinion. If you're going to be using the larger single ended MH bulbs then you will most likely have to build your own enclosure. If you are using the smaller double ended bulbs (much more expensive) I wish you luck and wish I had your buget.😀
A 400W Metal Halide is hotter than a 400W Halogen but produces more light vs. heat. The Metal Halide lights are more efficient in the light to heat ratio but not neccessarly in a direct Wattage to Heat comparison. Speaking from experience MH bulb get very hot and at the F2 point will burn through cardboard in seconds (melt plastic is minutes). Although your fresnel won't be at the F2 point you do not have a lot of room to maneuver in a OHP case. The distances are just to close for safety in my opinion. If you're going to be using the larger single ended MH bulbs then you will most likely have to build your own enclosure. If you are using the smaller double ended bulbs (much more expensive) I wish you luck and wish I had your buget.😀
Re: As far as I know
hmm, what is the F2 point? my OHP has an EHJ (24v/250w halogen) lamp assembly with a separate convex-concave diffuser(?)/condenser(?) lens which appears to spread out the light before it hits the (plastic) fresnel? would it be possible to use this lens with a metal halide bulb?
should i instead opt for a 175w or 250w MH setup to reduce heat to avoid melting the plastic fresnel or should i hunt for an 11.25 in^2 glass fresnel to fit my elmo HP-A305LV?
thanks
bitbyter said:
hmm, what is the F2 point? my OHP has an EHJ (24v/250w halogen) lamp assembly with a separate convex-concave diffuser(?)/condenser(?) lens which appears to spread out the light before it hits the (plastic) fresnel? would it be possible to use this lens with a metal halide bulb?
should i instead opt for a 175w or 250w MH setup to reduce heat to avoid melting the plastic fresnel or should i hunt for an 11.25 in^2 glass fresnel to fit my elmo HP-A305LV?
thanks
Research optics
Do some research on F (focus points) on this forum. The F1 point is where you place the light in your reflector, the F2 point is where the reflector focuses the light to it's maximum intensity.
Do some research on F (focus points) on this forum. The F1 point is where you place the light in your reflector, the F2 point is where the reflector focuses the light to it's maximum intensity.
How about the 3M 9800
I would assume the 9800 would have plastice fresnel as well, but the enclosure is a bit larger.
I would assume the 9800 would have plastice fresnel as well, but the enclosure is a bit larger.
We have some info on F1 and F2 in ellipsoidal reflector on this thread. Hope this may help.
http://www.diyaudio.com/forums/showthread.php?threadid=7864&perpage=15&pagenumber=4
http://www.diyaudio.com/forums/showthread.php?threadid=7864&perpage=15&pagenumber=4
the 9200 model has FXL lamp, similar to the 9700 model, but smaller stage area than the 9700.
I wonder, with the 82volt FXL lamp wouldn't it be better to use these models to mod into MH light source ?
I wonder, with the 82volt FXL lamp wouldn't it be better to use these models to mod into MH light source ?
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