Canon EF (body-lens data) protocol

Case You want to see, what happens between the camera and the lens, You will need n oscilloscope, or, better a logic analyser. This is a cheap chinese one – but for our purposes will be ok.

Works for example with the
Saleae software: https://www.saleae.com/pages/downloads , or the
Pulseview software: https://sigrok.org/wiki/Downloads .

Case you need an USB driver, you can use the
zadig: https://zadig.akeo.ie/ driver finder (I can not guarantee, if is virusfree or not – but worked for me.

This is the lens pinout:

You can find some interesting material here:

https://gist.github.com/marcan/858c242db2fc595da1e0bb70a05192fc#file-canon-ef-protocol-notes-md

https://pickandplace.wordpress.com/2011/10/05/canon-ef-s-protocol-and-electronic-follow-focus/

Be careful: the Canon SPI is NON-standard, for ex uses 9 bits, but only the first 8 belong to the data.
Use these parameters:
CPOL=1
CPHA=1
no CS signal

I can not write Python programs – so I hade to solve the conversion in an external Excel sheet, see below.

Good luck.

Button cell battery in Canon

The older cameras use a CR1616 or similar non-rechargable battery, which has to be replaced after a certain time, without opening the camera. These batteries have to supply the internal clock.

In a Canon 2000d, or for ex. in a 6d you will fing an INTERNAL, and RECHARGEBLE battery cell, in my case is a MS614SE.

This battery ha a 3V nominal voltage. But what to do, if the camera has not been used for a long time, and stored without the normal battery? The small cell will discharge. Now the question is: can i leave in, or should I replace it?

The voltage in this case was 0.6 volt. From the datasheet we know, it has the following parameters:

capacity of  3.4 mAh

discharge current 0.015 mA (!!!)

Charging voltage/current: 3.1V/0.1 mA

If you want to test it, you have to charge at first. I desoldered a battery holder from an old 6d board, put a resistor in serial (case we start from 0.6 volt, then with 3.1V charging voltage we have 2.5V on the battery – so we need 25kohm (!) for 0.1 mA.

Let we use 3.2V and 10 kohms, less gentle but quicker.

And it works!

The chinese selector wheel and the good old soviet lathe

As you know from my previous post, the chinese replacement wheel has a geometrical issue, so can not be used.

As I have no time to wait for a new original part (and as the customer would not pay for it….), i decided to take off the outer conical surface on a lathe, and to modify an another old (300d?!) wheel on the inner side, and mounted them together by pressing.

The result is PERFECT. Only 15 minutes of work!

And the two wasted hours for the disassembly/assembly, of course.

Here is the original post: https://canonrepair.wordpress.com/2024/01/29/be-careful-with-replacement-parts/

Separating lens doublets

https://www.norlandprod.com/techrpts/separating.html

And here is as a text:

Separating Lenses Bonded
With Norland Optical Adhesive

The simplest method for separating a lens bonded with Norland Optical Adhesive is to immerse the lens in a solvent combination made up of the following: methylene chloride, 100 parts by weight -methanol, 15 parts – concentrated ammonia (26 Baumé or 29% NH ), 2 parts. The methylene chloride is the active solvent and the other solvents increase its activity.

A typical 1 inch diameter lens will separate easily before the full cure by an overnight soak in these solvents. A fully cured lens requires a longer soak because the adhesive is more crosslinked and slows the solvent penetrations. Some lenses may start to separate but the solvent does not penetrate to the center even after a long soak. This is due to a very thin layer of adhesive in the center. To separate these lenses a slight thermoshock is necessary. Warm the lens up to 150°F and immerse it in the solvent combination while still warm. The sudden contraction will allow the solvent to penetrate to the center. Repeat if necessary.

Heating in hot mineral oil is another method that is commonly used. Usually it will take 20 to 40 minutes at 400 degrees F for the lens to separate. An alternate heating method is to place lenses in a vacuum coater and heating them under vacuum until they separate. Remove adhesive from glass surfaces now by immersing in the solvent combination.

Large lenses may require even higher temperatures to separate them. One method that has been successful is a heated sand bath at a temperature of 800°F. A fine sand or emery is heated in a pan on a hot plate. When it is up to temperature the lens is placed on the surface and will separate as it heats up.

Paint strippers containing methylene chloride are usually available from local hardware stores and will work as well or better than the solvent combination given. A liquid formula will work better than the gel-type.

Brulin’s Safety Strip HT and AZ 300T photo resist strippers also can be used to debond our adhesives.  You can get further information on these products at the links below.

Brulin’s Safety Strip HT:  http://www.brulin.com/productdetails.aspx?pid=142&cid=44   

AZ 300T(Electronic Materials):  http://imicromaterials.com/products/photoresist-removers

Protective goggles and gloves should be used when handling chemicals.

Be careful with replacement parts!!!

As everybody else, I have to use chinese replacement parts. Flex cables for exaample a lot – and 99% they are ok.

And sometimes I have to use replacement wheels – as Canon has invented the plastic/rubber wheels, where the rubber is mounted on a conical (!!!) surface. After a certain time this rubber ring will separate from the plastic – and no way to put it back.

The chinese replacement uses the old method: the rubber ring is mounted in a double conical groove. Perfect. Ok – I always glue it with a 2k glue to the plastic. Will held till the end of the world.

Last time I have got back a repaired 6d. Sympthom: the wheel sometimes does not move the cursor, and swiches only after the second movement (jump). ?!?!?!

After disassembly I have found the problem: they made the radial channel for the indexing ball in a bad direction, see the photos.

Now I have to order from another source, and wayt for it, if will be similar or not.

Shit.

I ordered an another one, from other seller.

The same problem……

3D holder for a vise

The base is an aluminium ring. The hemisphere is a plastic Christmas decoration. The filling: steel balls of 1 mm (could be sand). The plate is 3mm thick steel sheet, with a nut soldered on the middle.

The vise has 2 magnets on the base surface.

I use this for soldering, and for the stereo microscope etc.

Canon 24-70 f4 IS – replacing the aperture flex

This time I have no time for a post.

Just here you have the photos, case you need some help during reassembly.

Please mark how I replaced the flex: the old flex was NOT desoldered, just cutted, and the soldering has only been sucked more or less from the soldering pads. This is because the thin wires are much too sensitive, and could happen to tear them during separating. (Happened to me….)

The aperture or the board? This is the question…

I had to repair a canon 17-55 f2.8 is.

Simple case: error 01, broken aperture cable.

Or not. After replacing the flex, assebly – does not work, just struggles to move the aperture. Shit.

Disassebly. Inspecting the board under microscope. Nothing. Studying the aperture. Nothing.

I dont have a full storehouse of parts.

So, i decided to make a trial with an another, similar aperture, from a 17-85 mm.

Othr flex, other pinout. I made a small breakout-box. Yes, took a lot of time. But till now i will be able to test more or less any board from this point of view, just need to sacrify a flax, and solder the necessary 8 wires.

By the way: defective was the board!

***************

After checking the IS module: flex broken! (Thanks Victor!)

How to… take out a stucked ROLLER

I had to repair a Tamron lens – and the 6 rollers (in fact, just plastic positioning washer are stucked in the barrel.

Take a BIGGER self-tapping screw. Screw it in the plastic part. Grab it with a tweezers or pliers. Pull it ot.

Easy, and will not damage the parts.

Stuck screws in the lens

Sometimes you have to disassemble lenses or cameras with stucked screws inside. In fact, you have only one trial: case the screw will not move with the first rotation, the phillips slot will be damaged – and you will get a conus in the head – no more chance, to open with a srewdriver. Last time happened to me repairing a Tamron.

To avoid this, I have a BIG screwdriver for 1/4″ bits, and some 1/4″” bits for PH00 slot.

By using this, you have to push with the maximum POSSIBLE axial force on the tool, otherwise the tool will start to rotate against the screw.

Yes, you need experience to find a good balance, not to damage the lens.

Owner may never see you, during the operation….

Case the screwhead is over, there is onle one more possibility: drill the head with a cobalt drill bit. The diameter should be a little bit more, the the thread. For ex 2mm for a M1.7 screw. Before drilling, pack the lens, use some 2-side tape to, to catch the metal bits.