Which led gives out criss-cross pattern to help with camera focus lock?

I need a patterned beam to give my camera's autofocus something to lock onto when I'm shooting pictures in relative darkness. It doesn't have to be bright, or white. In fact the milder the beam the better as I would be pointing the light at my subject's face and would not want to blind them with something too strong. Also, the unit itself would need to be compact, like the smaller Maglites.

Any recommendations?

TIA!

curious, doesnt the camera have an AF-assist light built in if camera focusses using contrast detection (some models use IR range detection i think)? usually one of 4 varieties: either the small popup flash will strobe at low power, or an IR emitter will paint a crosshatch pattern in barely visible red, or a small incandescent or small LED (with light/dark portions quite prominent, like the BMW Roundel logo) will light it up. if i can't get a focus lock, i try to look for some brighter/higher contrast item a similar distance away and let camera focus on that. that said, i'll be using my McHappy to let ME focus manual cameras or let AF get a better lock on the digicam good luck.

I have found that some of the 15mm LEDs have such a very very tight beam that they actually project a copy of the die onto the wall; is this what you are looking for ?

I never trust built in LEDs for a focus lock. I usually "SureFire" the subject's chest with an E2e for the thing to lock.

I think this trick is usually done with special optics.

The Pentax AF module for my Quantaray flash had a red LED shining through some oddball optics to generate this crosshatched pattern. An LED projecting its die pattern probably is not enough.

Hello robbyled,

Low light camera shooting is difficult. The film/media is at its limit to record the image, and as you have observed, focusing is difficult. I agree with AluminumOvercast and would further suggest that you set the camera up with a prefocused area (if you can lock the focus) under higher lighting conditions. Then you can use the prefocused camera under low lighting without having to worry about focus. This will require a change in your shooting proceedure. If your focus is at 4 feet, you will have to take a number of pictures at that setting before raising the lights and resetting to 2 feet, and so on.

Another thing to explore is to shoot in normal light and change the camera settings to look like it was done it low light. This can also be done with post production manipulation (i.e. Photoshop).

Hope this helps.

Tom

Thanks for the responses.

Just to clarify, here's Canon's own version of the AF-assist beam:

http://www.luminous-landscape.com/reviews/st-e2.shtml

It costs $350 in canada, and it allows you to focus in complete darkness by emitting a low-level red pattern. Such a relatively weak (compared to a flashlight) beam is all my camera needs to lock focus. The key is the contrast provided by the criss-cross pattern, not the power of the light.

Unfortunately when the st-e2 is mounted on my camera some of the flash functions are disabled, such as 2nd curtain sync flash, which is why I am looking for another way to create an AF-assist beam that is less expensive and does just as good a job.

The beam looks like this when the unit is 2 ft. from wall. The pattern is 5 inches tall.

I forgot to explain that the above beam comes from the built-in AF beam on my Canon 550ex flash, but it sucks because it only comes on for a second, when you press the AF button, and if you need to see it longer you must press the AF button again and again.

The reason I need the beam for more than a second is because I use the flash with an off-shoe cord, that is, it's not mounted on the camera but is carried separately in my left hand. It is tricky to aim this very small and short-lived beam so that you can see it long enough in the viewfinder in order to place the AF point over it.

The advantages of an LED flashlight would be a constant beam that is easy to track down, and perhaps a beam that is larger and brighter.

And I've changed my search criteria somewhat. I realized that the LED flashlight that I am looking for does not necessarily have to emit a patterned light, as I can supply the pattern myself by sticking a red bicycle reflector lens over it, or doing something similar to that. It'd be great if there is an LED flashlight out there that emits such a pattern, but if not I'll just settle for a AA pen flashlight that has better-than-average bulb life that I can modify.

So...which flashlight should I get? And does anyone know a place in Toronto that carries a good selection?

If you want a good AA flashlight that's LED based, try getting one of dat2zip's BadBoys. (Look for his MadMax/BadBoy thread in homemade/modified)

$35 US for the "pill", drops into a Mini Mag, and is EXTREMELY bright. It uses a Luxeon 1 watt emitter.

Inretech (www.inretech.com) also has some red Luxeon dropins for 2AA minimags I believe.

I went to Canadian Tire today and bought the Dorcy LED flashlight, the only LED flashlight they carry.



I tried to stick various plastic lenses over the Dorcy, a red one from a bicycle reflector, red and orange ones from a box-type flashlight...but the patterns that are cast on the wall when I shine the flashlight through them are too hazy for my camera to lock focus on them.

Now that I have my LED flashlight, my search is now for the lens that will create such a pattern. Of course AF is a snap by just pointing the flashlight at my subject without such a lens, however, blinding ppl with a white light though an effective way to lock focus is not something any self-respecting photographer wants to do, it won't endear you to the ppl you're photographing.

Are there companies that manufacture these lenses that I'm thinking of?

As an aside, remember the Bat-Signal that Commissioner Gordon used in order to hail Batman? That kind of effect can't be created by simply painting the batman logo on a spot light, the result would be an indistinct greyish blob. It's anyone's guess what manner of superhero or supervillian would be conjured up.

I think what I've been sticking infront of my flashlight have been diffusers, when what I need is something that will focus the beam rather than scatter it.

Am I getting close, fellas?

would modding that light with a deep red LED work? since your canon gear already uses the deep red crosshatch pattern, it means the AF sensor is sensitive. all you really need a lightsource that won't blind your subjects but give enough oomph to the af sensor. maybe a etching a the lens with one cross pattern might add some benefit tho i doubt it. let us know how it goes.

You might check the closeout section of Arcflashlight.com to see if they've got a red Arc AAA layind around.

In stage lighting (A distant cousin to falshlighting) you can use GOBOs in the lights--these are paterns cut in wood or a similar medium--but they only work with focused lights. Maybe you need something like a Dr.Aspherlux (Did I spell it right). The Aspherlux is incandessent though, you might also try a normal LED light like, as I have already suggested, an Arc AAA or a Brinkmann Rebel or PALight--both of whihch focus the LED into a somewhat tight beam.

I would have to suggest the PALight because among other thigns it's small and easy to hold, it has 2 brightness settings (The survivor model) under most conditions and it also has what's called "Always on." That is, when the light is off it still emits a very failt glow from the LED that makes it a cinch to find in the dark. If your studio was dark enough you may be able to use this as a third brightness setting. You can get them in the Red LED variaty. If you are going to try the Rebel ($15 US at Wal-mart) I'd suggest you pay the $5 US more and get the PALight.

I totally forgot to explain why PALight or Rebel or even 5mm light over Dorcy. The Dorcy uses a side emitting LED that, even though it comes out in a spot, isn't really focused. The die of a 5mm LED actually provides some focus to the beam, and both the Rebel and PALight actually use a lens to focus the light.

I saw a $3.00 laser pointer at a quicky-mart that had a bunch of different screw in pattern generators I was going to buy one to mod up the power and run time (AA batts or C's). The laser works best because of its highly collimated beam stays nice and sharp. Why make something? Oh and by the way, Edmund makes what your looking for its called a reticle, you project the beam through it. You will need some optics to focus the spot on your subject. The laser pointer would be easier and alot cheaper.

Most AF systems on SLRs are sensitive to horizontal lines. You might get a cheap laser pointer with a "line" projector head (under $10 - try a flea market). This might just do the trick. If you hold it right, you might even be able to have the beam cover all of your AF sensors (assuming that they are in a line).

BTW: The beam picture in robbyled's post above is the same as the emitter built into my Elan-IIe (a very nice camera BTW).

I believe the photographer is photographing living subjects not just flashlights. Didn't want to shine a Surefire in their eyes. Tell me, how would you feel about going to a photographer and having them shine a laser in your eyes?

Sounds like a great idea for non-living subjects though

You don't shine it in their eyes but on their torso!

This may be far from what you are really looking for but I have found that a white L/S bat emitter with the phosphorus and dome removed will give you some linear patterns. The light is blue and if you put a 1/2" or 1" may be better acrylic sphere over the top of it the light will be cast a fair distance. I'll try to get a beam shot up for you.

Huh! the lines just don't show up in the picture that well. I did this with a 1/2" sphere and the L/S was under powered at 3 volt with a couple old AAA's. This was about two to three foot from the door and the camera may have not been set up right. In person there are a lines that run through the center of the light. Give a guy a digital camera, no lessons and this is what happens.