Need Help focusing a bulb...

[ShineOnYouCrazyDiamond]

I would like to focus the bulb in my M6 a little off to obtain a bit more flood.

I've been trying to search the net to see if there was an app out there which could graph the effect of changing the focal point of the light bulb within the parabola of the reflector, but to no avail. It's been a long time since I took geometry and calculus and I don't have the time to relearn everything right now.

My question is would it be better to go above or below the ideal point of focus to obtain more flood?

Just sketching it out it would seem that going below the point of focus would result in slightly more disperse reflections OTF. Going above the point of focus could results in more internal reflections losing the light and reflections OTF going much more the side and being lost.

Anyone with more experience in focusing have any better idea?

 

[cernobila]

I would like to focus the bulb in my M6 a little off to obtain a bit more flood.

I've been trying to search the net to see if there was an app out there which could graph the effect of changing the focal point of the light bulb within the parabola of the reflector, but to no avail. It's been a long time since I took geometry and calculus and I don't have the time to relearn everything right now.

My question is would it be better to go above or below the ideal point of focus to obtain more flood?

Just sketching it out it would seem that going below the point of focus would result in slightly more disperse reflections OTF. Going above the point of focus could results in more internal reflections losing the light and reflections OTF going much more the side and being lost.

Anyone with more experience in focusing have any better idea?

Well, I don't know the theoretical mathematical answer.......I look at the practical options, can you push the bulb further in to the reflector or is it easier to pull it slightly out by using a washer or something similar?

 

[ShineOnYouCrazyDiamond]

Well, I don't know the theoretical mathematical answer.......I look at the practical options, can you push the bulb further in to the reflector or is it easier to pull it slightly out by using a washer or something similar?

Practically speaking it's a WA1185 in a FM MN bi-pin - so the perfect focus point gives me about 1.5mm movement in either direction.

Playing around with it seems to be very close. When I go below focus I get a bigger circle with a hole which starts to form in the middle at a certain point. As I go above I start to get a more football shaped spot, but at a certain point I feel like I lose some brightness.

 

[donn_]

It's nearly impossible to de-focus the KT4 to a flood condition. The reflector is a thrower. You can try frosting the lamp, putting diffusion film on the lens, or using a SF diffuser to spread out the beam, but all those methods reduce total lumens out.

 

[cernobila]

Practically speaking it's a WA1185 in a FM MN bi-pin - so the perfect focus point gives me about 1.5mm movement in either direction.

Not a factory lamp, I understand. You can go in both directions.....with my 1111, 1185's it may take me 30 minutes of experimentation before I am happy with the result, depending on the reflector....sorry its the best I can offer you.