Malowz 7:30pm, 11 November 2010
will try with IR leds also, and a dimmer pot. ;)

www.youtube.com/watch?v=hxEAJ8Gf-9I

sorry for crappy video. later i will post schematics ;)
alohadave 8 years ago
Wouldn't it be easier to use your onboard flash for focus assist?
Malowz Posted 8 years ago. Edited by Malowz (member) 8 years ago
easier? yes. better? no.

with a constant light, focus is faster, don't use cam batteries, and a constant light with this method can be connected together with a trigger, like rf-602. (i may do later)
Kinematic Digit PRO 8 years ago
Definitely interested in how well the IR works. I had theorized for sometime if this would work, however IR might throw off the focus accuracy. I think if the emitter can do a near IR like the ST-E2 emitter at I believe 690-720nm it would work great. This would be less obnoxious in a dark venue and AF would be nice and discrete.
delicate land [deleted] 8 years ago
sign me up!
Malowz 8 years ago
i didn't have noticed that can use this thing on a tripod with a rf-602 receiver to have a off-camera focus assist also ;)
Nick Arora Photo 8 years ago
how exactly did you rig this thing? it looks a bit complicated with all the wires you've shown running off screen.

did you have to open up your DSLR to make it work properly?
dannyt. 8 years ago
No looks like he is triggering off the hotshoe. Would like to see an IR Version too....
Malowz Posted 8 years ago. Edited by Malowz (member) 8 years ago
it's not looking good cause i didn't finish, this is just the first test.

no, don't have to mess with your camera. works using the hot-shoe only.

new test, now together with RF-602 transmitter (and a bit less ugly):

DIY Automatic Focus Assist with RF-602 by Malowz


another crappy video (the "new" version):
www.youtube.com/watch?v=7fy7VC9JR4A
elv0000 8 years ago
This is looking good!!

So you have it switching on at half press and switching off while the shutter goes off?
Malowz 8 years ago
yes.

the signal to "turn off" start a bit late, so if using a very strong light (like me), it may show in the image if close to the subject, or using high iso or wide apertures.

i added a diffuser in front of it, still can focus at about 5 meters on low-contrast subjects. and without light from the led on image.

without diffuser, can focus at 25 meters on pitch black;P
Benjamin Cahill 8 years ago
Does it support E-TTL?

;-)
-DeEsE- 8 years ago
I am interested to know if the IR version works
aperture-priority 8 years ago
IR is going to back focus, you need visible light for this.

Bill.
Benjamin Cahill 8 years ago
Why will IR back focus, something to do with the longer wavelength, or how the AF system responds to IR?
rudy__ 8 years ago
"IR is going to back focus, you need visible light for this."

Yes but how much? If you have enough DOF it may not be a big problem. Maybe having to light emitter (plug in?). One White light, one near-IR.
aperture-priority 8 years ago
Same reason lenses used to have a different manual focus index for IR photography. IR light is refracted more strongly than visible light and hence focuses nearer the lens.

HTH
Bill.
rudy__ Posted 8 years ago. Edited by rudy__ (member) 8 years ago
"Why will IR back focus

Do you have any old manual lenses? Most had a dot or line (if a zoom) to show the correct position for IR focussing.

Notice the red dot to the right of the focus line. With the above lens you could be off focus by more than a couple of feet with a large aperture.
aperture-priority 8 years ago
True and with strobes probably not too much of an issue. But it would be handy if it worked with fast glass in low light too.

Bill.
dannyt. 8 years ago
Thanks Guys! Did not know that about IR.
Happy Tinfoil Cat PRO 8 years ago
Holy crap! Learn something new every day.
elv0000 8 years ago
The red focus assist light on a regular flash is not IR though is it? I read somewhere its just a red filter as the the focus system is more sensitive to the red?

I realise there was a discussion on the IR torches before, and they wouldn't need to be turned off during the exposure, but this one is switching off anyway like a regular flash AF assist.
W.G.W. 8 years ago
Not sure, but ive taken
elv0000 said:
red focus assist light on a regular flash is not IR though is it? I read somewhere its just a red filter as the the focus system is more sensitive to the red?

I realise there was a discussion on the IR torches before, and they wouldn't need to be turned off during th


Ive taken apart the af assist light from a canon flash, the led does shine red in addition to the red filter in front of it. I would imagine that there is IR light being thrown out in addition to the visible red light.
Nick Arora Photo 8 years ago
Really digging this mod. Please post a tutorial once you're further along
Malowz Posted 8 years ago. Edited by Malowz (member) 8 years ago
ive tested with small IR leds, and i wasn't able to focus at all... :(

then tested with a very small (but very directional) red led. focus was good.

will test with a small led with a lens to give a very good trow with small area.

from canon:
"Electronic sensors in general are more sensitive to red light."

i think i will go towards red light ;)
danette5 8 years ago
Someone is a heck of a lot smarter than I am.
Mr. Speedlight Posted 8 years ago. Edited by Mr. Speedlight (member) 8 years ago
I read somewhere its just a red filter as the the focus system is more sensitive to the red? --elv0000

Bring a white flashlight around armature astronomers and you're going to get dirty looks at best. I'm not privy to any inside information by my guess is the AF assist on speedlights is red because red light doesn't mess up night vision (the astronomer thing) and it's not as harsh on people's eyes as white light (a comfort issue).

One can buy red flashlights or LED flashlights with red night vision LED(s) and white general use LED(s). If you have one you could experiment. I got a Mini-Mag flashlight somewhere with a red filter installed.

Now why is the AF assist lamp found on many cameras white? I would think a red light would be used here also.

Dave Hartman

Postscript: the red eye reduction lamp (a white lamp) on my old Fuji E550 worked equally well as an annoyed look enhancement lamp.
Mr. Speedlight 8 years ago
Someone is a heck of a lot smarter than I am. --danette5

You too? I thought I was the only fool posting here today.
Mr. Speedlight 8 years ago
:)
Eric Fialkowski 8 years ago
What about using a timer so on the 1/2 shutter the light will only stay on for a fraction of a second?
Benjamin Cahill 8 years ago
Now why is the AF assist lamp found on many cameras white? I would think a red light would be used here also.

On my P&S (SX110IS), it is red. Interesting!
Daniel W. Laidlow 8 years ago
Got some schematics for us?
Malowz Posted 8 years ago. Edited by Malowz (member) 8 years ago
Automatic focus-assist light circuit by Malowz


im using this AX2002 driver:
www.dealextreme.com/details.dx/sku.26110
with this led:
www.dealextreme.com/details.dx/sku.44305
with this reflector:
www.dealextreme.com/details.dx/sku.5955

need to cut the wiring coming out from EN to make the led driver to turn off by default.

any voltage coming to EN will make the driver work.

so you can get a few volts from the RF-602 half-shutter green led, or the hotshoe itself.

i did also one with a op-amp, will redo later and post here
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