AF Light for the E-PL1

Started Aug 7, 2010 | Discussions
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ZappB Regular Member • Posts: 132
AF Light for the E-PL1

You might remember sometime back, I posted about an AF light I made for my E-PL1.
http://forums.dpreview.com/forums/readflat.asp?forum=1041&message=35425623

It is supposed to be used in dark environments to focus, and then it turns off automatically for the shutter and flash actuation. It also has a mode for continuous light, which is less impressive but handy for video or a poor man's flash. It runs on two 3V watch batteries and makes it 1000% easier to get an AF lock indoors in dim lighting. At the same time, it doesn't effect the image because it turns off automatically while the exposure is happening. I use it on my E-PL1, but it should work on ANY camera that triggers its flash shoe before an exposure.

After some research, I've determined that the market is just not big enough to make any substantial money off of the development of such a product. It would have to be marketed to people with small dslr cameras that have flash but don't have an AF light and have a flash shoe. With upfront costs in the tens of thousands, it's too risky of a venture for myself for very little reward.

That means I'm going to release the plans like I promised to you guys. Bellow is the circuit diagram of the device and an image of the components before I encase them in epoxy.

SW1 and SW2 are actually encompassed by a single three position switch (off,auto, always on). The device mounts in the flash shoe of your camera and connects to the center pin and the ground (the side of the flash shoe). I'm not 100% sure, but the trigger (tr) may have to be wired to the opposite side of the battery than to what is shown (it varies between 555 timers, I think). You can have one or more LED's connected in parallel for the light source, but I hit the maximum current the batteries could deliver at three 3mm super-bright LEDs. You may think that 6V is too much for the LED's but the voltage actually drops during operation.

So the circuit is epoxied to a flash shoe cover with the appropriate electrical connections going through the center of the cover and connecting on the side using springs and exposed wires. The circuit in the epoxy make a coin shaped disk slightly larger in diameter than the batteries. Battery terminals are then made out of strips of flat metal on top. I then cap the entire device with a rubber 3/4" pipe cap that has been cut to length with notches cut out for the LED's and the switch. You can use a set screw to keep the cap connected to the circular epoxy base on top of the flash shoe cover. Depending on your 555 timer, you can get away with using one 3V battery, but the current it can output will be limited. You can get the parts for this from almost any electronics store.

Let me know if you have any question. Have fun building!

everythingsablur Regular Member • Posts: 287
Re: AF Light for the E-PL1

Very cool ZappB!

What's the approximate cost of parts if someone was to make this themselves as a one-off?

ZappB OP Regular Member • Posts: 132
Re: AF Light for the E-PL1

Most of the parts come in packs of at least 10. It came out to $5 for all the electronics for 10 units not including the LED's, the cap, or the flash shoe cover.

10 circuits = $5
3 LED's = $1
100 Pipe caps = $5
Flash shoe cover = $5

If you make one, you'll spend about $16. The next unit would only cost you $6

When I priced out how much it would cost to develop these professionally, it came out to $5-10 per unit based on the volume I bought (min volume 10,000).

This is not including epoxy, solder, dremel,...etc

everythingsablur wrote:

Very cool ZappB!

What's the approximate cost of parts if someone was to make this themselves as a one-off?

ljf5000 New Member • Posts: 13
Re: AF Light for the E-PL1

Thank you for posting a circuit diagram! I thought about using this:

Note: I grabbed this off the internet from http://talkingelectronics.com/projects/200TrCcts/200TrCcts.html#16

ZappB OP Regular Member • Posts: 132
Re: AF Light for the E-PL1

ljf5000 wrote:

Thank you for posting a circuit diagram! I thought about using this:

Note: I grabbed this off the internet from http://talkingelectronics.com/projects/200TrCcts/200TrCcts.html#16

Thanks for posting this. This would work just fine too. One difference I see is that this design would turn the light off for the image to be taken, but it would have to be turned on again manually for a second picture.

In my design, there is a one second period where the light is off, but then it turns back on again (great for parties). That time spent off can be controlled with the 100k Ohm resistor in the circuit. If replaced with a 200k Ohm resistor, it would give you two seconds of exposure time. A 50k Ohm resistor would give you half a second of exposure time, and so on.

There are literally a million ways you can implement this concept. You could use two of the circuits you just referenced. The first circuit delivers power to the LED, while the second circuit turns the first circuit back on after a trigger event.

sudirdjo Senior Member • Posts: 1,238
Re: AF Light for the E-PL1

Thanks much for sharing your design ! Very useful for this lowlight capable cam.

My knowledge in electronics is very limited and would appreciate if you can inform the type of transistor that's used to switch the led (in line with led).

kev777zero
kev777zero Senior Member • Posts: 1,556
Re: AF Light for the E-PL1

you should make some more and starting auctioning them off Ebay. I'd be ur first customer!

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redfoxdogs Contributing Member • Posts: 837
Re: AF Light for the E-PL1

Seems like a useful little gadget.

ASR45
ASR45 Forum Pro • Posts: 35,085
Re: AF Light for the E-PL1

Interesting stuff great.

Regards Alan.

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rpm40 Senior Member • Posts: 2,202
Re: AF Light for the E-PL1

kev777zero wrote:

you should make some more and starting auctioning them off Ebay. I'd be ur first customer!

Agreed!

PhotoMED Regular Member • Posts: 338
Re: AF Light for the E-PL1

Anyone else have luck with this? I struggled and tried, in vain.

im10er New Member • Posts: 6
Re: AF Light for the E-PL1

Would it be possible to create a circuit that would split the hot shoe signal between two devices? I bought a flash that of course is triggered and communicates by the hotshoes contacts but I would love to have that LED lighting to shoot a quick flash to allow the camera to focus before the shutter is pressed.

I've seen some little devices that screw into the tripod mount area. Been looking for a way to secure this thing down there and trigger while focusing.

Any ideas?

im10er New Member • Posts: 6
Re: AF Light for the E-PL1

Would it be possible to create a circuit that would split the hot shoe signal between two devices?

I bought a flash that of course is triggered and communicates by the hotshoes contacts but I would love to have that LED lighting to shoot a quick flash to allow the camera to focus before the shutter is pressed.

I've seen some little devices that screw into the tripod mount area. Been looking for a way to secure this thing down there and trigger while focusing.

Any ideas?

ZappB wrote:

Most of the parts come in packs of at least 10. It came out to $5 for all the electronics for 10 units not including the LED's, the cap, or the flash shoe cover.

10 circuits = $5
3 LED's = $1
100 Pipe caps = $5
Flash shoe cover = $5

If you make one, you'll spend about $16. The next unit would only cost you $6

When I priced out how much it would cost to develop these professionally, it came out to $5-10 per unit based on the volume I bought (min volume 10,000).

This is not including epoxy, solder, dremel,...etc

everythingsablur wrote:

Very cool ZappB!

What's the approximate cost of parts if someone was to make this themselves as a one-off?

phrenicthenub Regular Member • Posts: 109
Re: AF Light for the E-PL1

If only there were some enterprising electronics tinkerers in china that could produce these and sell them on eBay, I'd pick open up for under 20$.
--
-Trevor

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