Tuesday, April 29, 2008

Hacking a Canon off-shoe flash cord part 5 (final)

This is an initial shot taken by my 20D at F8.0 (the lowest my lens will focus at right now :) ) - in manual mode with the shutter speed at 1/100s. The flash is held at point-blank range so any E-TTL mishaps should be disastrous. Seems like it worked, though! - This is of course my trusty fujifilm F30 camera that most of the photos are from on this blog...

Here is one taken at 1/1000 sec - I am using the high sync speed feature of this flash to achieve this. Aperture still at F8.0. This would certainly not work without E-TTL functioning!

But if there were any questions left, here's one taken at 1/8000 - my max shutter speed. Its interesting to see how the ambient light has totally dropped out in these last two photos :) and the subtle difference between the two as well.

Posted by Picasa

Hacking a Canon off-shoe flash cord part 4

Ok - here are the last photos of construction. I am having to blog these four at a time because I am using Picasa's "blog this" feature - for some reason the web interface is down on blogger and I can't sign in that way.

I was lucky to have the network jack fit so nicely. I had to cut the metal "frame" that used to clamp the cord (see previous post photos) in order to fit the jack, but after that and careful cutting out of the pen marked area the jack fit nicely and its inbuilt clips hold it in place when the cover is closed - no glue involved, though I had it ready :)

Other installation notes: I used a small jeweller's saw to make the cuts, but a coping saw or fretsaw or even a saw blade attachment on a dremel would work. Also notice in a previous post how I re-wound the wires (flash shoe end) around the little metal "choke" before punching them down on the network jack - this is important because it stops any spikes of HV electricity from travelling the wires.

You can see the wiring inside the camera module. I used a piece of network cord for the wires since the jack is made for that kind of wire anyway. I did use a "real" punchdown tool but you can buy a package of these jacks that has a little plastic punchdown tool in with them. I have also used a small screwdriver in the past but it is hard to do properly.

I tested the setup with a multimeter the first time - I plugged in a network cord and tested for continuity between the pins of the camera module to the flash shoe and also to see if there were shorts between any pins... had a bit of a heart palpitation as the blue wire (trigger) had no continuity... I checked my connections and found nothing wrong, then disassembled the flash shoe end to find a small component inline (see pic). I thought perhaps a diode to stop backfeed? At any rate then I felt secure enough to test on camera. Results follow in the next post...

The inside of the camera module finished

The inline component

The finished setup

Hacking a Canon off-shoe flash cord part 4

Here are a couple of assembled pics:

Flash shoe end, taped. I used linerless rubber splicing tape to wrap the cord/flash end because I like it better than plain electrician's tape.

Camera module
Posted by Picasa

Hacking a Canon off-shoe flash cord part 3

Wires re-wrapped around "choke" (flash shoe end)

Wires punched down (flash shoe end)

I sent the ground shield down two wires. 1stly the w/blue to be a pair with the blue (see previous post) and secondly just another free wire since there were two spare and the shield was too fat to fit in one punchdown space...
Posted by Picasa

Hacking a Canon off-shoe flash cord part 2

The thing to notice in this post, apart from the photos, is the way the copper shield is wrapped not only around the main bundle of wires but specifically around the red wire. This means a "delicate" signal is coming down that - either that or a really strong one that would interfere with signals on other wires. The twisting of the wires in an ethernet cord also works as shielding: it is important to route the red and ground shield together as a twisted pair though. I chose the blue-wh/blue pair.

The plastic shield (bottom right) kept the wires out of the locking assembly (silver bit). It is no longer needed and also in the way.

Marking where to cut

The shield - note the red wire
Posted by Picasa

Hacking a Canon off-shoe flash cord part 1

In this post and a follow-up I will show how I modified a Canon off-shoe flash cord to use a standard ethernet / network patch cord. Why? Well, the length of cord that the item had to begin with was really unusable except for handheld flash. See the first photo for this. I want to use my new 420EX flash more remotely than that. A quick look at the cord told me I had 6 wires to deal with and what could be more perfect than a network cord, given the general availability - and I can easily make custom lengths using crimp-on ends. Or I could even use a building's built in network... :) The connectors are nice also in that they have a latch and so won't pull out.

I found a couple of jacks and quickly saw that the project would work, given some careful hacking. See photos for more details.

The cord before (much) hacking took place

A record of which wires went where...

A network jack taken apart. (Note from afterwards - I didn';t have to take it aprt in order for it to fit. So I glued it back together...)

Showing everything taken apart more.
Posted by Picasa

Tuesday, April 15, 2008



It is supposed to be springtime here but continues cold with occasional snow. I've just finished processing the last of my wedding photos and so hopefully will have a bit more spare time! This does not necessarily follow though since I have started a new exercise regime that effectively knows about an hour off each day. Nice. Thought I should post a photo after so long though... In other news I have sold enough stuff to buy a camera - though my lens remains unobtained so far. It is not here yet but is in the mail. A 20D - part of me wished for a 40D but I would only have been able to afford the body - and you can't do much with that now, can you? :)

I am trying out Picasa's "blog this" button for this post. I like it except it is really slow and blanks out Picasa while the blogging is happening. Not good. But maybe better than the web page approach anyway.

I will hopefully post some wedding pics - want to get permission from the "models" first - showing the final results from my softbox quest.
Posted by Picasa