Canon EF mount has a register distance which lets us use Olympus OM, Pentax M42 and K-mounts, Leica R, and Contax mounts with proper adapter rings. These are vastly available on the net for purchase (ebay). However, Canon EOS auto-focus system needs a lens to speak to itself to work. The lens communicates its focal length and aperture values and the camera activates AF after confirming these. Some clever chaps cracked the code and embedded it in a tiny PIC chip and slapped those on Canon EF adapters for manual lenses.
In this hack we'll permanently embed one of these PIC chips in the camera. This hack requires some disassembling and soldering skills. I can rate it at medium hardness.
- One AF confirm activating chip for Canon EF mount (ebay keywords: Canon AF confirm chip)
- A tiny switch (if you want disabling functionality)
- Thin wires
- Epoxy (optional)
- Philips 0 and flat screwdriver
- Soldering iron and solder
- Self adhesive tape/ribbon
Do not put the battery in the camera when it is disassembled, even if you have it in off position. There are live circuitry in it and you may accidentally short it - burning out some fuses (I'll write another instructable about fixing those, later). AF confirm chip is a tiny pic chip and can be affected from static discharge easily, so be careful while you are working with it.
DISCLAIMER: Like all other hacks, this will void your warranty (I don't know if there are any 300D left with warranty anyway). Also involves exposing flash circuitry, if you are careless you may experience a high-voltage electric shock even when the battery is out (which I did briefly). This hack may render your camera totally useless, so if you brick it don't blame me, but put it on ebay for parts (others will like this). I am not responsible for any of these above if you experience a problem.
REFERENCE: There are few places where I borrowed wording from Gary Honis's excellent instructions on Canon EOS 300D IR filter removal. Check out his site for an alternative take on disassembling. However, we don't have to deal with the mainboard, so don't strip your camera to barebones like he did.
Step 1: Prepare the AF Confirm Chip to Fit in the Camera.
I had to soak it in acetone to soften the epoxy. After a few minutes I could shave it off the metal adapter easily (Photos 1-3).
However, during the process I damaged the chip/board assembly and got the chip de-soldered off the board (Photo 4).
I then soldered thin wires to the tiny PIC chip and mapped its pins on a paper (Photo 5).
I finally embedded the wired chip in a drop of clear epoxy. Now the chip is ready to be soldered on the camera.
If you just bought the chip separately (not like me), I advise you to solder thin wires on the pins of the board, and map them to the ones on the camera (and solder them permanently following my next steps).
Step 2: Disassemble the Rear Cover!
1- Take out the strap, battery, rubber eye cup and CF card, put a body cap on to keep your mirror box clean.
Now remove the rear panel by doing the rest:
2- Remove grey plug on back of camera that covers a screw and remove the screw (Photo 1)
3- Remove three screws at bottom of camera (Photo 2)
4- Remove two screws under CF compartment cover (Photo 3)
5- Remove two screws on the black rubber panel (where you have ports - Photo 4)
6- Remove the black rubbery black panel and rubber port cover by popping it out from the bottom edge using a sharp knife (Photo 5)
7- Now you can gently take the rear cover out but be careful there is a flat ribbon cable connecting the LCD and the buttons on it to the mainboard. You have to remove that from the mainboard. The ribbon cable does not just pull out of its connector. Instead, the connector is a "hinged type". The connector is color white and its hinge is black. There are two small black hinge tabs at each end of the connector. Lift these two tabs upward with a small flathead jewelers screwdriver and the black hinge will rotate upwards into a vertical position. This releases pressure on the ribbon cable and the cable can be pulled out with the rubber tipped pliers. (Photo 6)
Now you exposed the mainboard of your camera. But that's not enough. We need to access the front face of the camera where we need few soldering job to do. We'll do that in the next step.
Step 3: Remove the Front Panel!
1. Remove four screws at the base (one is different don't mix them) (Photo 1)
2. Remove two screws near the grip (Photo 2)
3. Remove the battery door by pulling the springy hinge connector (Photo 3)
4. Remove the battery door hinge by unscrewing two screws (Photo 4)
5. Remove the plastic cover to expose holes to access grip screws (Photo 5-6)
6. Remove two screws connecting the grip on the body (Photo 7)
7. Remove two screws from front (Photo 8)
8. Pop out the flash by forcing it, or do it in advance (Photo 9)
9. Pry the front casing out, off the tripod connector. Be gentle (Photo 10)
10. Check out your work area now (Photo 11)
Step 4: Solder the AF Confirm Chip Permanently on the Camera!
I may be wrong on the pin-out below, so please test it with a multimeter.
Put your camera back together, put the battery in and see if the tiny chip is reporting a lens. In my case it reports a 50mm f/2.0 lens. This varies to what you have on the chip. You can ask the seller of the chip to program a specific number for you, too.
Step 5: Some Final Thoughts...
Now I can put many gorgeous manual focus lenses on my camera and still have AF confirmation (like this superb Olympus Zuiko 35/2 - Photo 1). AF confirmation chip simulates a 50mm f/2.0 lens as seen on Photo 2. The tiny switch enables/disables the built in AF confirmation chip. It is nicely hidden in battery compartment.
Well I guess I should say: I modified it, because I can. :-) It was fun.