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Before we start

This particluar post is from my old blog. Back then it ran on Wordpress, but since I swapped my hosting provider from a Linux based one to a Windows based on, all the old posts were lost. Most of it didn't matter, but it appears that one particular post were fairly popular elsewhere since several sites were linking to it. Because of this I've decided to repost it so others might benifit from the information. I'm afraid the full size images were lost in the process as well, but small pictures are better than no pictures at all. Here goes...

Let's get started

Want to improve your macro photography just a little? Then you simply need better light. Unfortunately the different ring flashes for macro work is quite expensive. That’s why I came up with this design for a DIY macro ring light. Now, I can’t take credit for this idea at all. There are plenty of great DIY ring flashes and lights out there, some made with LEDs as I have done here. Still I thought it would be fun to share my experience with all of you. I added the capability to variable control the light output from each half of the ring. Before you spend time and money on this, remember that LED’s let out a smaller range of wavelengths than flash or ordinary light. This can affect the quality of your macro pictures. I ended up using around 90 dollars or so. Also make sure you use a correct white balance when using this ring light as the LEDs have a cold light to them (or shot in RAW and fix it later). Before we get to the part about how I built it, take a look at the final product and some sample photos.

The ring light it self (the small black clamp with the orange head in the picture is only there to keep the ring light upright while the pictures were taken)

The ring light turned on

Sample pictures (from the left: ring light at full power, right side turned down, left side turned down, ring light off). The ring light ment the difference in shutter speed between 1/10 and 1/100 (that's about 3 1/3 stop)

I’m afraid that I was without my camera when I made this right light, which is why I can’t show you the process in pictures. I’ve tried to make up for this flaw by creating some drawings for you to follow instead. Enjoy!

Please note that this design is for a Canon 100mm 2.8 USM Macro lens. You might have to adapt the design to your macro lens.

What you need

• 20 LEDs. The higher the power, the better. Remember that some LEDs have a wide angle beam, but outputs less mcd (millicandela - which stands for “luminous intensity”), while others create a narrow beam, but output more mcd. Try to find LEDs that are in between. I used Ultra bright White Super-flux LEDs with a 50 degree angle beam and 16,000 mcd. Take a look at this page for more info on calculating angle and mcd into lumen, which is an actual measure of the light being put out: http://www.gizmology.net/LEDs.htm. You need a reasonable angle; otherwise you will end up with a ring of light with a darker center showing in your pictures. The LEDs I used are a bit funny since they don’t have two pins as most do, but four instead. Don’t be alarmed, you still only need to connect two of the pins and it doesn’t matter which pair you select. I got my LEDs here: http://www.dotlight.de/shop/product_info.php/cPath/36_50/products_id/742/language/en?osCsid=49ae481480d51360c61a82654ce253bc My LED’s has a suggested supply voltage of 3.5 volts. Since rechargeable AA batteries each supply 1.2 volts, 3 batteries would supply 3.6 volts which is close enough. Do not use ordinary AA batteries as these supply 1.5 volts which will sum up to 4.5 volts and ruin your LEDs.
• A white rain water pipe, 75mm across, you won’t need more than 20 cm in length at most, unless you’re really clumsy when you cut it.
• Some sort of extension tube for the rain water pipe. I’m not sure what it is called, but it is used to extend the rain water pipes. This means that part of the extender tube has a bit narrower width on the bottom half of the tube. This slightly narrower tube fits almost perfectly on my Canon 100mm 2.8 macro USM lens.
• 1 battery box for 3 x AA batteries. You can get these in any electronic store
• Some PVC covered wire, with a square of only 0,14mm. We’re talking very thing wires. Get a few meters and you’re all set for a few mistakes as well.
• 2 x potentiometers (a variable resistor). You don’t need more than 1 watt at most. Potentiometers come with different resistor capabilities usually noted with the value “R” (at least here in Europe). I got two with an R-value of 22, which proved to be reasonable. I suggest getting asking in an electronic store if they can recommend something else. Mine didn’t completely cut power down to zero, so perhaps you need another R-value. If you can, then get potentiometers which can also shut off the power completely (like with a “click”). That way you won’t need the power switch I added to the design.
• A small box that can hold the two potentiometers (and perhaps the power button, depending on your own whishes and design.) You can get this at an electronic store as well.
• 2 knobs for the potentiometers. Again go to the electronic store.
• An on/off switch (the type that goes “click” and stays on or off)
• A hot glue gun with glue
• Black gaffers tape
• Double sided tape
• Some sort of rubber with adhesive on one side. Draught proofing strips for windows and doors works ok. Mine is about 3 mm high, which is a bit too much. I have to force the ring light onto the lens. Go for 1-2 mm in height instead.

• Last, make sure you have a decent soldering iron.

The process

Cut the rain water pipe. I cut the extender for the rain water pipe into a ring around 2 cm wide. You only need one of these, let’s call it the inner ring. Next, cut the ordinary 75mm rain water pipe into a ring approx. 4.2 cm wide and cut it in half as shown in figure 1. We’ll call this the outer ring.

Calculate the exact position of the 20 LEDs so they will be evenly distributed. I used my favorite DTP program to create a template I could use on the inner ring. See figure 2.

Use a narrow piece of double sided tape (used for securing carpets and stuff) approx. 0.5 cm wide all around the one of the edged of the inner ring. See figure 3.

Attach the first 10 LEDs evenly onto the tape according to the template. Make sure the legs are pointing down along the side of the ring (the outside of the ring that is). See figure 4. Important: Make sure the LED’s are turned properly. Even though it doesn’t matter which of legs of the two pairs you use, you must make sure that the two legs that end up pointing upwards each belong to a different pair. You can always test the LED to make sure it is positioned the right way. If you supply power to the wrong legs, or supply + or - to the wrong legs, the LED will not light up. Test before fixing the LEDs in the next step.

Use hot glue to fix the two inner legs of each LED to the inner ring.

Take a piece of wire approx 17-20 cm longs. Carefully strip a little bit of the plastic from the wire 10 places along the wire. Use the same spacing between these “holes” as each “left” leg on the LEDs has on the ring. Make sure you leave some extra wire at each end of the 17 cm wire for later soldering. See figure 5.

Cut out small pieces of wire, each around 1.5 cm long. Strip each end and solder one end of the small wires to the longer wire. You end up with a wire that looks like figure 6.

Now solder the other end of the small wires carefully to one of the legs on each LED.

Repeat the process once more, but this time use 2.5 cm wires instead of the 1.5 cm ones. Solder these onto the other leg of each LED. Se figure 7 for details (note, the layout of the LEDs in the drawing have been stretched, they are still supposed to be attached and glued to the inner ring).

Test that all 10 LEDs light up when you attach power to the two wires. Use 3 rechargeable batteries in the battery box, attach the +wire to one of your wires on the ring, and the -wire to the other wire on your ring. If the LEDs don’t light up, try and reverse the wires from the battery box. If it still doesn’t work, you have made some mistake earlier on. Go back and try to fix it.

Repeat all of the above for the other 10 LEDs on the other side of the ring.

Now you have to solder the battery box, the potentiometers and the on/off button to the LED’s. Below you will find the complete wiring diagram (figure 8). As you can see each side of the ring light can share the same -wire, while they have to have separate access to the +wire. This is because the potentiometers have to regulate the power output to each side of the ring. The potentiometers have 3 connectors. You usually use left for the power (+wire) and the middle one for the regulated output. The right one is for passing on the same power as you put in, but we don’t need that. Test before soldering!

Once you have verified that everything works as expected, you can begin to cover it all up (at least so people can’t see your poor soldering skills  Use the two halves of the outer ring, carefully holding one tightly into the LED’s while using plenty of hot glue between each LED. Continue to do so with the other half as well, thereby creating a protective shell around your delicate wiring and LEDs. Se figure 9 and the close up pictures of the ring flash.

 Strap the wires along the outside of the shell to the top. Use the black gaffers tape to secure the wires and also create a sleeker look to your ring light.

Make sure that your “top” is where the two individually controlled LED-arrays are split. At this top mount the battery box with double sided tape. Mount the small box with the potentiometers on top of that. As you can see I chose a box too small for both the potentiometers and the power button, but you could choose a larger box or go for the potentiometers with the off-capability. For a more solid mount you could go for self-cutting screws. I think I’ll try that option out soon as the double sided tape is not perfect for long term use.

Fill up the inside of the ring light with lots of hot glue to keep it together and fix the wires into place. Se the picture below for more detail.

Last, apply some sort of rubber ring on the inside of the inner ring, closest to the back, like the fore mentioned draught proofing.

The ring light took me around 2½ hours to make.

That’s it. I hope you have enjoyed this little presentation and find it useful.