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BugEZ
Joined: 26 Mar 2011
Posts: 292
Location: Loves Park Illinois
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 Posted: Sat Jan 21, 2012 8:59 pm Post subject: Big Bucket Light |
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Several weeks ago I was trying to photograph a large specimen (Dobsonfly) and get a good photo of the eyes. Several folks suggested I use polarized light to reduce the reflected glare on the eye. (http://www.photomacrography.net/forum/viewtopic.php?t=15693)
I was having a difficult time setting up to use a lighting scheme with polarizers on the lens and on the source. The difficulty was compounded by the size of the specimen. Basically, I needed a bigger light ring. At the same time I was admiring canonian's Octo-lite. (http://www.photomacrography.net/forum/viewtopic.php?t=15612)
So... I decided to bite the bullet and make a bigger and brighter light. I constructed a "bucket light" that will allow me to photograph a larger specimen with the illumination enveloping the subject.
Here are some photos of the project.
I'll post some photos taken using the light soon.
For now... Here is posting showing the construction of the light.
http://youtu.be/qzjLifFfYZE
Keith |
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rjlittlefield
Site Admin
Joined: 01 Aug 2006
Posts: 12553
Location: Richland, Washington State, USA
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| Posted: Sun Jan 22, 2012 1:03 am Post subject: |
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Truly excellent -- I cheered and laughed several times while watching the video, and bear in mind, I am alone in the house tonight. 
Looking forward to seeing pictures made with the BBL.
--Rik |
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Harold Gough
Joined: 09 Mar 2008
Posts: 5707
Location: Reading, Berkshire, England
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elf
Joined: 18 Nov 2007
Posts: 1104
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| Posted: Sun Jan 22, 2012 11:57 am Post subject: |
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The movie was great. I was continually amazed by how things appeared on the desk just when they were needed  |
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DQE
Joined: 08 Jul 2008
Posts: 1433
Location: near Portland, Maine, USA
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| Posted: Sun Jan 22, 2012 5:18 pm Post subject: |
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Can't wait to see some photos using your amazing creation!
I really enjoyed your movie, too!!
------------------
Compared to my 1-LED, 3-watt, 2 AA cell flashlight, (I think 80 lumens), can an estimate be made of your light's relative output?
_________________
-Phil
"Diffraction never sleeps" |
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BugEZ
Joined: 26 Mar 2011
Posts: 292
Location: Loves Park Illinois
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| Posted: Sun Jan 22, 2012 6:13 pm Post subject: some photos |
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Here are some photos using the new light. The light allowed me to orient the Dobsonfly in front of my 50mm lens and polarizer without resorting to dissection. I am still waiting for some large polarizing sheet film to allow me to polarize the illumination, but that is another topic...
DQE wrote : | Quote: | | can an estimate be made of your light's relative output? |
I'll take some accurate measurements of the load resistor resistance and operating voltage. I designed it to drive the 140 LEDs at the continous rating of 30mA, but I don't think I hit the target exactly. I think I am a bit lower. Were I on target, the output would be .31 lumens each for about 43 lumen. Realistically, the light must bounce to reach the subject. So the subject lighting is well below this... A large fraction "leaks" out or is absorbed by the walls/diffuser.
Keith |
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Harold Gough
Joined: 09 Mar 2008
Posts: 5707
Location: Reading, Berkshire, England
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| Posted: Mon Jan 23, 2012 12:32 am Post subject: |
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Interesting project. Of course, when you mix diffusers and polarisers, the situation can get quite complex, the diffuser possibly polarising some of the light.
Harold
_________________
Happiness is having the right adapter.
My manual flash setup for high magnification:
http://www.photomacrography.net/forum/viewtopic.php?p=117843#117843 |
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ChrisR
Joined: 14 Mar 2009
Posts: 3035
Location: Near London, UK
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| Posted: Wed Jan 25, 2012 3:23 pm Post subject: |
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What exposure are you getting, Keith?
I have visions of a second popcorn bucket slipped inside the first one, to act as a diffuser. Is that perhaps why, even when diffused, we can still count the leds in the fly's eye? The reflections are a bit misleading because it looks like a structure.
Perhaps bucket #2 could be spaced out/further away from the leds to increase the diffusion?
I wonder how much difference it would make to the exposure time if you wrapped a reflector round outside the bucket. Maybe not aluminium foil - try a glass mirror one side first? |
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BugEZ
Joined: 26 Mar 2011
Posts: 292
Location: Loves Park Illinois
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| Posted: Thu Jan 26, 2012 7:42 pm Post subject: Diffuser |
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ChrisR asked : | Quote: | | What exposure are you getting? |
My exposures before I made the light bucket using 4” of extension tubes and my F4, 50mm lens set to F5.6 and ISO 200 were usually around 2 seconds long. With the same f stop, ISO setting and the light bucket I had to reduce the exposure to 1/6th of a second. So that is about 12X more light. With relatively modest magnification, I don’t have a “shake” problem so I can get by with the shorter exposure. Were I using my 10X objective and tube lens, I would probably have to dim the lights a bit to allow a longer exposure to combat the shutter bounce.
ChrisR also mentioned/asked: | Quote: | | I have visions of a second popcorn bucket slipped inside the first one, to act as a diffuser. Is that perhaps why, even when diffused, we can still count the leds in the fly's eye? The reflections are a bit misleading because it looks like a structure. |
Conceptually, that describes the diffuser quite well. The diffuser I used in the test photos was a quickly made paper cone, loosely rolled and shoved in the bucket. I then taped the seam of the cone to lock in the taper and crudely trimmed it with sissors. The paper was in contact in many places with the LEDs producing bright spots. Here is a photo.
As can be seen, there is one area where the paper cone does not contact the LEDs and stands off approximately ¼ inch. That appears to be a somewhat proper distance to avoid the highlights. The dilemma is that pulling the diffuser inward reduces the working diameter of the bucket. Sadly, I find myself wishing for a bigger bucket! I will work on the diffuser and make a better fitting one. I'll make it stiffer and removable and with a proper gap.
ChrisR also wondered: | Quote: | | I wonder how much difference it would make to the exposure time if you wrapped a reflector round outside the bucket. Maybe not aluminium foil - try a glass mirror one side first? |
On some of my smaller LED ring lights I have used aluminum foil to reflect light from the camera side of the objective lens toward the paper diffuser (see sketch).
If my bucket turned out to be too dim, I was contemplating some strips of foil glued between the rows of lights to reduce losses through the plastic bucket. As I have an ok exposure time, I don’t think that will be needed.
Here is a comparison of the previous lights and the current light:
The bucket is quite bright.
As you can see from these photos I took this morning, I am tending to over expose the subject a bit and will have to adjust things downward.
Keith
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BugEZ
Joined: 26 Mar 2011
Posts: 292
Location: Loves Park Illinois
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| Posted: Thu Jan 26, 2012 7:54 pm Post subject: Oops... |
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One additional comment... The comparison photos above of the bucket light with the tube and objective light were with the bucket light at 2/3 power.
K |
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abpho
Joined: 17 Aug 2011
Posts: 691
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| Posted: Sun Jun 03, 2012 11:03 am Post subject: |
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| Looking good. Thanks for the link. |
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