Halogen spotlights and Bulb types?

[kramer5150]

What difference does the filament orientation make in beam output? I see a lot of different types of halogen bulbs, mainly H1, H4 and H7. Some with the wire filament stretched out horizontal across and some with the filament on-axis with the reflector. The H1, H7 and HID bulbs being examples of the latter.

What difference does the orientation of the filament make? Does a filament that extends on-axis with the reflector throw better than one that extends across?

thanks

 

[danjoo]

An upright filament is better for focusing like a horizontal one in a round reflector, I can not explain the Math but If you compare the spot from a


Osram 90 Watt Starlite 64458(upright)

with a spot from HLX 64657(horizontal)

it is clearly visible that its easyier to have a good spot from the upright filament.

Maybe somebody else explain the math of that..


Daniel

 

[Databyter]

What difference does the filament orientation make in beam output? I see a lot of different types of halogen bulbs, mainly H1, H4 and H7. Some with the wire filament stretched out horizontal across and some with the filament on-axis with the reflector. The H1, H7 and HID bulbs being examples of the latter.

What difference does the orientation of the filament make? Does a filament that extends on-axis with the reflector throw better than one that extends across?

thanks

I'm not an expert, but (with light facing up) it seems to me that the typical cross-ways configuration has a very small point of efficiency within the parabola of the reflector, so focus is more critical, and artifacts are more visable.

The upright filiment such as the 458 bulb is more forgiving in that it's height in the parabola is not as critical, and more of the parabola is used to create the "hot-spot" making it a richer deeper hotspot. The same would apply to artifacts I think. I would guess they would be more blended in to the overall beam. Of course depending on the design and efficiency of the parabola the axial filiment (upright one) would also phase nicely into spill in a more gradual way.

This is just what the picture in my mind is telling me, I am not expert, just surmizing based on the principles involved.

EDIT: Most refelctors seem to be designed with the bulb in mind. This seems like a bulb designed with the reflector in mind.