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LGSutekh
(0-9 posts) Newbie
Joined: 18 Oct 2005
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 Posted: Tue Oct 18, 2005 7:19 pm Post subject: SOUP LADLE REFLECTOR question |
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| I have purchased the- 1023 S400DD Lamp-from Lumenlabs. Sorry DIY. But I did start off with a purchase of the soup ladle reflector here at DIY. This lamp has a diameter of 1.8 inches so it will fit the soup ladle reflector. My question is, how do you position and fit the reflector? I know the centers on the reflector and bulb should be lined up, but how is the reflector positioned? Wont the uncut half block placement of the bulb? Thanks in advance |
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blackmichael
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| Posted: Tue Oct 18, 2005 9:39 pm Post subject: |
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I've got the Ushio and the ladle reflector. I don't remember how the reflector was cut when it came, but I needed cutouts on both sides which I made / deepened with tin snips. It wasn't easy, and I could see that the process was warping the ladle. I bent the ladle back into shape as best I could. The lamp just fit into the new notches, and the center of the lamp arc seemed to be at the center of the sphere (which the ladle is half of). My lamp position isn't adjustable, and neither is the reflector's position relative to the lamp. Looking back, I don't think relying on measurements (from theory) was the best decision, and I intend to make both tunable in my next box.
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msk1hc
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| Posted: Wed Oct 19, 2005 1:20 am Post subject: Re: SOUP LADLE REFLECTOR question |
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| LGSutekh wrote: | | S400DD Lamp- This lamp has a diameter of 1.8 inches |
The s400dd is at T-15, so it is 15/8 inches diameter, or 2 1/8 inch diameter. It would [as commented on above] require bigger holes in the sides of the reflector.
As I understand it, if the ladel is a hemisphere, you want the arc [the center globe] centered upon the front lip of the ladel. |
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LGSutekh
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Joined: 18 Oct 2005
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| Posted: Wed Oct 19, 2005 2:04 am Post subject: |
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| The spec on the lamp says 1.8 in diameter, not 2 1/8. It would be nice if the company mentioned you have to drill another cut-out. What would be a good tool to cut that part out? Hi speed jigsaw-bandsaw.....???Anyone else have these experiences.? |
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blackmichael
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| Posted: Wed Oct 19, 2005 3:45 am Post subject: |
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Which company would tell you what to do with a random soup ladle and random lamp? I don't think anyone could anticipate your exact needs 
I hear good things about using a dremel with a cutoff wheel.
Also, if I've read correctly, you can use the IKEA napkin reflector (~4 USD) and the Ushio without cutting.
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Asdasl
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| Posted: Wed Oct 19, 2005 2:18 pm Post subject: |
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| How big is that IKEA dish? I've seen some things at Target that have a perfect half sphere and are mirror finished. |
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blackmichael
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| Posted: Wed Oct 19, 2005 3:02 pm Post subject: |
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IKEA:
Diameter 110mm
Focal length 64mm
It's only part of a hemisphere, but apparently it reflects as much as your panel would see anyway, and being shallow (I think) Ushio users don't have to cut it.
Here is a link to one place that sells it, and also a good diagram.
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LGSutekh
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| Posted: Thu Oct 20, 2005 2:49 am Post subject: |
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| Thanks for that info. I just ordered one from that link you placed. How do you align the reflector's focal length with that of the lamp? I purchased the napkin reflector. Maybe I could find out about that somewhere here... |
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blackmichael
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| Posted: Thu Oct 20, 2005 2:59 am Post subject: |
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In theory you want the center of the light to be one radius from the surface of a spherical reflector. However, some things I've been reading make me think that it's not so easy, so as I mentioned I will be building in more adjustability next time.
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LGSutekh
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| Posted: Thu Oct 20, 2005 4:50 am Post subject: |
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Kinda vague. Can you elaborate with some numbers? If the lamp arc is 27mm and the focal length of the reflector is 65mm, how are they positioned?
The numbers I give are exactly the ones for both the lamp and reflector. |
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blackmichael
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| Posted: Thu Oct 20, 2005 5:15 am Post subject: |
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I didn't want to be too specific because not everyone has the same setup. But if your particular reflector has a radius of 64.08mm, put the lamp arc 64.08mm from the bottom of the reflector. Simple!
However, you might have noticed the diagram on the IKEA page linked to showing the lamp arc slightly ahead of the focal point (64.08mm). Apparently this works better in real life. Also, the light producing area could be different places in the arc tube, depending on burn position, etc, etc... That's why I keep talking about wiggle room.
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LGSutekh
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| Posted: Thu Oct 20, 2005 7:03 am Post subject: |
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| ah, that makes sense. Thanks. But the arc of 27mm. Where is this distance being measured from? I'm just hazy when you say: "put the lamp arc 64.08mm from the bottom of the reflector" Is the lamp arc the center of the illuminating element and then the measurement is done from that point? |
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Asdasl
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| Posted: Thu Oct 20, 2005 2:15 pm Post subject: |
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| Quote: | | Where is this distance being measured from? |
If you lay the ikea on it's bottom (like a soup bowl), the bottom of bowl. Imagine that this bowl was part of a complete sphere (hollow). The center of that sphere is the focal point because it's an even distance in all directions from the surface of the sphere. The center of the sphere is also the radius. If you kept that point at the radius (or the center of the sphere) and removed most of the sphere leaving only the bowl left, that would be the focal point of the bowl.
The radius stays the same. There are equations you can use to find the radius based on the arc (curvature) of the circle. Or you can measure the diameter of the bowl and take half of that (radius = diameter / 2).
So in your example, you take the center of the arc (27mm / 2 = 13.5mm) and measure from there to the bowl (reflector). |
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LGSutekh
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| Posted: Thu Oct 20, 2005 9:34 pm Post subject: |
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| hey,thanks alot. The diagram is nice. But the lamp arc? Is that on the edge of the bulb as measured from the center of the filament, 15.5mm outward from there? Could you diagram me the lamp with the reflector and where the positioning is to occur? Does the arc and focal point match up somewhere? As you propably are aware I'm just a little bit confugsed. |
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Asdasl
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| Posted: Fri Oct 21, 2005 5:45 pm Post subject: |
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Here is a diagram that should help you out. The yellow is the arc. The red line is the radius. The black arc is the reflector.
Last edited by Asdasl on Sun Jan 15, 2006 5:32 pm; edited 1 time in total |
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