AF Assistant Laser v3.x

AF Assistant v3.1 on top of my Canon 40D with a wireless flash trigger on top of everything

Have you ever wanted an AF assist light that would work in AI-Servo mode (tracking focus of moving subjects) in the dark?
Have you ever wanted an AF assist light (more then the white light on your camera) that can be used along with a wireless flash transmitter?

Well now you can have both. These are the two key requirements that got me building this tool:

1. When photographing concerts or clubs, or any other venue where light is at a premium, the AF sensor in the camera can only do so much to give accurate focus.This can be remedied by adding a higher end flash to the camera, which will project an AF assist light to help the camera focus in the dark. However, I am using off-camera flashes most of the time now which means on the camera’s hotshoe I only have the wireless flash transmitter, and loose the flash’s AF assist abilities.
The AF Assistant Laser solves this by providing an AF assist light as well as a hotshoe pass-through for any trigger you may want to use.

2. DSLR cameras (that I’ve looked at) don’t do AF assist in AI-Servo mode (when using a flash in the camera’s hotshoe). They don’t allow you to track a subject in the dark, by continuously adding the light from the AF assist lamp on the flashe to help the AF sensor in the camera continuously maintain focus. You get One-Shot focus, which means once focus has been acquired, the AF assist light goes off. But if I want to track a singer as the move on a stage, like one would track a moving person or a race car during the day, you’re stuck. You can’t.
The AF Assistant Laser solves that problem but allowing full control of the AF assist light to be projected as long as you’re focusing (focusing is done by 1/2 pressing the shutter).

How am I addressing those two shortcomings?

What you see through the viewfinder at shutter 1/2 press

1. Moving the wireless flash trigger away from the hotshoe on top of the camera to the end of a ETTL extension solves that problem. The AF assist light sits on top of the Yongnuo ETTL extension block that sits on the camera but does not electrically connect to anything there. In the next revision I plan on removing the extension cord, and adding hotshoes attachment to the AF Assist box to keep everything mounted on top of the camera, with no ETTL extension cords.

2. The connection is made on the side of the camera on the remote-trigger port. The connection there allows for the AF assist light to be on all the time while you’re focusing but 1/2 shutter press. Note, that this AF assist light does not get turned of from the AF-ON button on the back of the camera; only shutter 1/2 press.

The latest version of the AF Assistant Laser is v3.1 Hardware Version B

Work has indeed started on the (near) IR version of this tool. Details on the AF Assistant IR 1.0 (in early development stages) can be found here.

AF Assistant Laser v3.1 is currently in beta testing. If you’d like to help out test the unit, let me know. I currently only have a Canon version available.

Want to buy one?

I have two versions available for sale if you’re interested in buying the unit.
More info available on the Stuff for sale page.
Units will be built as they are requested/bought. I have no ongoing stock of these.

Nikon versions are planned.

Current issues:

– Unit needs a on/off switch so battery power is not wasted when not in use.
When shooting in AI-Servo mode, the last frame frame captures the laser line in about 70% of the images. Issue resolved

Below is a build log which includes all the posts I’ve written in the development of this tool.

List of previous posts leading up to this final build:
AF assistant v3.1
AF assist tool v3.0 – complete
AF Assist tool v3.0 – schematic
Disecting the 550EX AF Assist module
AF Assist tool v3.0 – laser pointer trials 2
AF Assist tool v3.0 – laser pointer trials
AF Assist tool v3.0 – more info
AF Assist tool v3.0 – line laser
AF Assist tool v3.0 – more testing
AF assist tool v3.0 – testing
AS assist v3 project update: The light source
AF Assist tool v3.0

And for referrence, AF Assist tool v2.0 log


4 thoughts on “AF Assistant Laser v3.x

  1. Ignacio Diaz

    Hi, Adrian! I saw your af asistent proyect and i think is the best. I’m tired to lost focus in some low lights. Are you selling this in some place? how can I get one of those?

  2. Brendan Stewart

    Adrian, here is what you need to do.

    1. Build a passthrough hotshoe socket (So one can mount a flash atop of it), on the front of it, point a laser of concentric circles on half press. Have it dimmable for battery life and nuisance control. Make big bucks.


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