marknorton

You knew it was coming, you just didn’t know when. Well, “When?” is “Now”.

Last year, I showed you a dismantled Leica Digilux 2 (“Anatomy of the Leica Digilux 2”) and like an itch needing to be scratched, I’ve been waiting to do the same for the Leica M8. My dealer’s web-site told me M8s were in stock and that was the catalyst to buy another M8 to take one apart.

As befits the stature of the camera, I am going into rather more detail to show you how it is built and how it works.

I’m walking a thin line between giving you enough of an insight to make this a worthwhile exercise and reverse engineering the product which is a serious infringement of Leica’s IP. So, I’m restricting what I show and tell you to what I can glean by simple observation and interpretation of what I see based on my own experience. I’ve used just normal camera maintenance tools, no test instruments, no circuit tracing, no data analysers, no de-compiling of firmware.

Of course, it goes without saying that you should NOT do this to your own cameras. The warranty will be voided and Leica could justifiably refuse to fix a camera which has been tampered with.

So, join me to take a look at a Leica M8, serial 3105477.

__________________
Mark

marknorton

To start, here are some images of the camera with the top cover and lens mount removed.

Camera Top Rear.jpg

From the back, you can see the Digital Signal Processing board protruding up into the top of the camera including the Analog Devices Black Fin DSP and 4 of the 5 Samsung memory chips which form the RAW data buffer.

Running along the top of the camera is the main control board of the camera. This is part of the camera which meters the scene, detects the lens in use and fires the shutter. It’s an M16C processor from Renesas, formerly Mitsubishi, who are the world’s largest supplier of microcontrollers. This processor, type M30624FGPGP, has 256k of Flash EPROM program memory and 20k bytes of RAM.

Because this circuit board runs right underneath the top cover of the camera you can see why there is not enough space for a larger LCD.

The connector to the immediate right of the processor is to the LEDs in the viewfinder, an astonishingly small connector with 30 pins. The circuit board changes level via the red flex print to make space for the shutter speed dial and shutter release and you can see three white connectors at the lower level. These connect to the light metering circuitry, the circuitry in the top cover and to the shutter/motor-wind controller.

Camera Front.jpg

Viewed from the front, you can see the familiar Leica M rangefinder and the vertical adjustment which is accessible through the Red Dot. The adjustment tool locates in the hole and the cam on the tool adjusts the slider up or down.

Sensor Vertical Alignment 2.jpg

The inverted U flex print at the back is the only connection between the “camera” electronics and the image processing electronics, more on this later.

The flex print at the left of the picture connects to the shutter and motor-wind controller and this is used both to supply power (notice the thicker tracks to handle the current required) and control signals to fire the shutter and monitor the wind-on process.

There are some thicker tracks in the DSP flex print as well. Those are probably for the backup battery because, as we’ll see, the DSP gets its own power directly from the battery.

The lens mount is shown removed here. A slot in the lens mount engages with the top cover front edge so it is intended to remove the top cover before removing the lens mount. The lens mount is screwed directly to the front machined face of the casting without using shims.

You can see the lens code detector which appears to be a small circuit board with IR LEDs and photo-diodes mounted on it. It fits into a recess milled into the back of the lens mount. This recess is also painted black to minimise stray reflections.

You can also see here the three metering cells in the floor of the lens throat, the central light metering cell and the flash metering cells (actually photo-diodes) either side.

Camera Top 2.jpg

Viewed from the top, you can see the centre white connector is vacant. This is where the electronics in the top cover of the camera connect.

To the right, you can see the tubular “blue dot” light sensor which appears to be a simple photo-diode behind a light pipe/lens.

M16C.jpg

Here’s a close up of the M16C processor. You can see that the LEDs in the viewfinder are connected directly to the microprocessor. Also interesting is the empty connector at the bottom which connects to at least 4 pins on the microprocessor. These pins are one of the M16C’s UARTS, meaning it would be possible to connect a PC serial port (via a suitable level shifting circuit – NOT directly which will cook the chip). It’s likely this connection is used for diagnosis and calibration during manufacture and repair.

Here’s the complete circuit removed from the camera and shown flattened:

M16C Circuit - Flat.jpg

So this is how this core part of the camera connects to the rest of the camera:

- Left-hand flex: Power, Lens Code detector, Frame Selector detector
- On-board Connector 1: Diagnostic Port
- On-board Connector 2: Viewfinder LEDs
- White Connector 1: Light Metering
- White Connector 2: Top Plate
- White Connector 3: Shutter/Motor Wind
- Right-hand flex: DSP Board

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Mark

marknorton

Looking now at the top…

LCD Driver Chip.jpg

What’s immediately striking is the weight of the top cover, fully 20% of the total camera weight. It’s a very impressive piece of machining.

This picture is with the LCD display removed, the shutter speed dial dismantled, the power switch partially dismantled, the shutter release switch removed and the circuit board unsoldered from the hot shoe connections.

There are three screws underneath the circuit board securing the hot shoe. It is also glued in with silicone sealant which may be to improve weather proofing, provide additional insulation from possible high voltages on the hot shoe contact or discourage tampering with the serial number.

The circuit board is actually soldered to the 4 hot-shoe contacts and the fourth mounting screw (top right) makes for a direct ground connection which will help avoid any ill-effects of using a flash with a high voltage trigger.

Shutter Speed Dial 1.jpg

Looking at the circuit board you can see:

A contact pattern for the shutter speed dial, the power switch is similar. There are 33 possible positions of the shutter speed dial and a rotating contact connects one or more of the patches to ground at each position. By looking at which contacts are connected to ground, the microprocessor can figure out the selected shutter speed.

The board uses a Philips (now NXP) technology called I-squared C (I2C) which uses a serial interface to connect the circuitry to the microprocessor. Here, there’s an I2C LCD display driver (bottom right) and an 8 bit port expander (bottom left).

The shutter speed dial requires 6 data bits to specify its 33 possible positions, the power switch 2 bits and the shutter release 2 bits. If, for example, the 8 bit port expander was used for the power switch and the shutter speed dial, a single pair of serial data and clock lines could provide the complete interface to read the power switch and shutter speed dial and support the LCD display.

The port expander used can also interrupt the micro when an input changes which avoids the need to have the software repeatedly scanning for data change. This may also be used as part of the wake-up sequence when the camera is turned on or the shutter release pressed.

A high voltage transistor (the black component to the left of the hot shoe connections) connects directly to the hot shoe centre contact. It’s this which fires the flash under control of the microprocessor, not the old fashioned electrical contact linked to the physical shutter.

The flex print, bottom left connects the top to the rest of the camera and its 13 connections provide the following interface:

- Power for the top of the camera
- Flash trigger
- Flash SCA bi-directional communications
- LCD functionality
- Status of the Shutter Speed Dial, Power Switch and Shutter Release
- Wake-Up Interrupt

To be clear, the power switch here is not actually interrupting power to the camera, it’s signalling instead to the microprocessor to start up/shutdown the camera.

Here’s a picture with the Shutter Speed dial and Power Switches re-assembled. The metal “ears” serve to limit the motion of the Power Switch.

Shutter Speed Dial 2.jpg

I haven’t yet at this point re-soldered the flash hot shoe connections…

The detent for the Shutter Speed dial is provided by a pair of ball bearings on the outside of the camera. A metal block has two holes carrying a spring and ball bearing. These are at different distances from the centre line and each engages in one of the two circles of detents on the underside of the shutter speed dial. The outer ring handles the main shutter speeds, B and A and the inner ring handles the half-stop speeds.

Shutter Speed Dial Detents.jpg
Shutter Speed Dial Detents 2.jpg

The top flex print has 4 contacts which screw to the sides of the shutter release switch. Here is it in pieces:

Shutter Release Components.jpg

There are 3 black screws to screw into onto the back of the power switch and the gold plunger makes the required connections as it is pressed. The contacts are made of very small springs and gold ball bearings. The screws, springs and plungers (only one shown here) are used to set the strength of the detents for the shutter release.

Tiny components, one sneeze and you’d be in trouble…

__________________
Mark

marknorton

Splitting the Clam-Shell

This is pretty much all you can see without splitting the front and back castings. This involves peeling back the synthetic leather to expose 3 screws at each end. Remove them and the front and back halves of the camera separate.

Here’s a picture of the back half:

Clamshell Rear Internal.jpg

So this is the front of the DSP board which you saw in the first image. Things to note, starting top left and moving anti-clockwise:

- The interface to the M16C processor, the “camera” electronics.
- The infamous standby battery
- “Power Supply Central”. There are 6 separate power supplies from a MAXIM MAX1567 chip on the other side of the board. This is a highly efficient chip for generating the various supply voltages (which may be more than the nominal 3.7 volts of the Li-Ion battery) required by digital cameras in general and CCD sensors in particular. Each of the supplies uses an inductor (black) and a low impedance decoupling capacitor (brown).
- The SD card holder.
- The 30 way connector to the sensor board.
- The white power connector which connects directly to the battery.
- The white connector to the left hand push buttons (play, info, etc).
- The switch to detect if the base-plate is on.
- The white connector to the LCD display which of course sits behind this board.
- The USB connector.
- The white connector to the Menu button, the thumb wheel and the red LED.

In effect, this board is a self-contained computer with its own processors, user interface (Buttons/LED/LCD Display), dynamic RAM and non-volatile storage (SD card), USB interface and image capture interface.

This board shows how the camera’s electronics are split into two. The main camera electronics is all about initiating the taking of the picture, this part is all about either capturing the image from the sensor, processing it and storing it.

The interface between the two will allow a two-way exchange of information. Commands and data from the M16C will be about initiating image capture, sending data to the DSP board on lens type, light and exposure for inclusion in the EXIF; information back from the DSP will include a Ready/Not Ready status showing whether or not more images can be taken, information on the space available on the SD card and so on. There will also be support for sharing the settings of the main and set menus.

Remove the DSP board and we can now see the full back of the board:

DSP Board Rear.jpg

Here, you can see the main DSP used, the Analog Devices Black Fin processor along with 5 64Mb dynamic RAMS, each organised into 4 * 4Mb * 32 bits. Top left is the MAXIM MAX1567 power supply chip; centre top is the Intel PXA270C which is used for the user interface and a Xilinx FPGA (Field Programmable Gate Array) which effectively is a custom logic chip to tie everything together. A firmware upgrade changes the firmware in the Black Fin, the Xilinx, the PXA270C as well as the M16C.

Notice too the spare lands on the board which suggests the possibility of alternative parts being used or some, as yet undefined, future expansion. The white square is a bit of a mystery, I think it’s the audible “clicker”.

Looking at the edge of the board, I can see as least 6 imbedded layers in addition to the copper on each side, making 8 layers in all. It’s a very impressive piece of digital electronic design.

Removing the DSP board and this is what you see:

Clamshell Rear without DSP.jpg

You can see the three flex prints to the DSP board and the back of the thumb-wheel. The spring plate on the left is used to provide the detent for the thumb wheel.

I removed the right hand button panel to show you the buttons but left it at that because I did not want to get dust in the LCD panel. You can see that to get at the LCD panel to either remove dust or replace a scratched LCD screen is quire a lot of work, but even this is a walk in the park compared to what’s needed if the Lens Code sensor fails.

Button Switches.jpg

__________________
Mark

marknorton

Turning our attention to the other side of the clam-shell, this is what we see.

Clamshell Front Internal.jpg

So, from the left:

- The battery case with the two flying red/black wires to supply power to the back of the camera
- The sensor board which is actually the aluminium plate secured in three locations – look for the green locking lacquer, top left, top right, bottom centre.
- The sensor circuit board is soldered directly on the back of the sensor which is mounted on the aluminium plate, apparently using epoxy. The flex print at the bottom connects to the DSP board on the back of the camera.
- To the right, there is the shutter/motor-wind controller which is run under control from the M16C processor, removed in this picture.

Here’s a close up of the battery connections.

Battery Connections 2.jpg

The red/black wires feed the DSP board and power is fed to the M16C processor through the flex print – check out the wide connections which make use of more than one contact on the connector. Interestingly, all the brass contacts from the battery holder apparently make it through to the microprocessor for monitoring purposes, even though the current battery doesn’t use them all. This may allow for different batteries in the future.

Here’s a close-up of the Sensor Board.

Sensor Board.jpg

This was the board that was supposedly replaced by the hardware recall and we understood at the time that the sensor was not being replaced. However, the sensor is soldered to this board, you can see the rows of soldered connections (4 * 15 pins), so it’s not clear exactly what was done.

This is a later camera and did not need to the hardware recall. If I was to open my M8 which did go back (which I’m not about to do, one M8 in bits is enough), I might find some more specific information on what was done.

In any event, this is the electronics which interfaces to and drives the sensor. Look at the board and you can see a certain symmetry which matches the dual output architecture.

Look also here at the bottom fixing. You can see the shims which fit underneath to precisely position the sensor relative to the lens mount. Because the sensor is mounted at three points (like a tripod), it can be adjusted to be square to the lens axis in all directions by fitting shims of different thicknesses under each mounting point.

When I removed the sensor, I was very careful to keep the shims from each mounting point separate so that when I put the camera back together again, the sensor alignment will not be disturbed.

Leica does this very precisely. The thinnest shim of any there is 0.01mm. I’ve measured the thickness of the shims and they are as follows:

Left: 0.61mm
Right: 0.49mm
Bottom: 0.34mm

So, deep breath, remove the sensor.

Sensor Front.jpg

With the sensor removed, you can see the back of the shutter:

Shutter Rear View.jpg

__________________
Mark

marknorton

The Shutter

The shutter is of course made by Copal. It’s operated by two small electro-magnets and a mechanical cocking lever. There’s also a contact in there which may be used to indicate back to the microprocessor whether it’s cocked or not or else it might be used for flash purposes.

Before we remove the shutter, let’s look at the bottom of the camera….

Camera Base.jpg

Here, you can see the shutter cocking lever (to the top and left of the large flat screw). The shutter is cocked by pulling the lever to the right. That’s done by the copper coloured arm which is connected to a lever which is in turn moved by the rotating cam.

Shutter Wind 2.jpg

When the shutter needs to be cocked, the cam does a single rotation, the arm moves first to the right and then the left to cock the shutter. There’s an optical position sensor so that the microprocessor can monitor the motion of the cocking level in case something gets jammed. At rest the sensor is blocked. Early in the motion, the sensor becomes unblocked until the shutter is cocked.

Shutter Wind Sensor 2.jpg

Shutter Wind Sensor 1.jpg

The firmware in the M16C can monitor the status returned by the sensor and also perform a reasonableness test by measuring the time the shutter cocking action takes.

__________________
Mark

marknorton

Shutter Lock

When the shutter is fully cocked, a lever is actually which “sticks” in the actuated position using a permanent magnet solenoid. These use a pulse of power to release them, not actuate them.

Here is it in “unlocked” position:

Shutter Lock - Unlocked.jpg

Here is it in “locked” position:

Shutter Lock - Locked.jpg

You can see the armature – the bit that moves - has been filled with silicone, presumably to stop it rattling and making a noise. There’s another position sensor on the reverse side so that the micro can tell if the shutter is locked or not.

In operation, as the shutter is cocked, the armature moves towards to solenoid and sticks because the core is a permanent magnet. Under microprocessor control, a current is passed through the solenoid to release it.

It was said the that the change to the shutter noise in V1.092 firmware was because this lock is released earlier in the shutter release cycle and becomes audible as a separate event.

The shutter is cocked using a small motor made by a Japanese manufacturer, Namiki, and a finely engineered gear train which turns the cam. The profile of the cam has, apparently been tailored to provide the best action with the shutter.

In this picture, you can see the complete shutter cocking motor, shutter lock and control electronics.

Shutter Wind 3.jpg

With some unsoldering, I’ve removed the circuit and unfolded it:

Shutter Controller.jpg

I tried running the motor directly from a 3v battery and, outside the camera, it is much quieter than when inside. I think at least some of the excessive shutter noise comes from vibrations from the motor being amplified because it is directly mounted on the camera body. A compliant mounting to reduce transmission might reduce the noise.

__________________
Mark

marknorton

Shutter Removal

The shutter is held in by 3 screws and a single flex-print to the shutter/motor-wind controller. One oddity is the bottom right mounting where instead of a screw, the corner of the shutter is secured by a plate:

Shutter Mounting 1.jpg

Originally I thought that this was because the mounting hole ended up in the wrong position but no, if you remove the plate, the hole for the screw is perfectly aligned, so it’s a mystery why they didn’t use it.

Shutter Mounting 2.jpg

Once removed, the shutter is fine, almost watch-like device. No, I didn’t take it apart!

Shutter 0.jpg

Shutter 1.jpg

Shutter 2.jpg

Shutter 3.jpg

__________________
Mark

marknorton

With the shutter removed, there’s not much left, especially once the shutter/motor wind controller is also removed.

Rear without Shutteer.jpg

There is an additional circuit board, connected to the three sensors at the bottom of the lens throat and held in place by the aluminium bar. From there, a folded circuit board and a flex print to the M16C board and the “blue spot” sensor. This circuit then is the light metering circuit – the ambient sensor, the main light meter and the twin flash metering cells.

Here’s a picture of the circuit board:

Photo Diode Circuit - Flat.jpg

The final surprises come when you remove the battery case. The front of the battery case and the lens throat are a single plastic moulding and underneath the battery case is the circuit for the lens coding detector.

Frame Selector.jpg

In this picture, the lens code sensor connects bottom right and there are six (black) transistors, presumably to amplify the signals from the photodiodes in the sensor. There is also a pair of tiny toggle switches which are activated by the frame selection lever.

Clearly, repairing this part of the camera if it should fail is complex, involving as it does almost complete dismantling of the camera.

Frame Selector Closeup.jpg

In this case, the upper switch is activated. When the lever is in the centre position, neither switch is activated. In the lower position, the lower switch is activated. These switches are used to determine the selected focal length when the Normal Tri-Elmar is mounted on the camera.

That’s it. I hope you’ve enjoyed this tour of the Anatomy of the Leica M8.

__________________
Mark

stnami

Brilliant, just plain brilliant,..............

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http://www.etrouko.com.au/

eronald

Zat eeet waz exercise 1.
Exercise 2 is putting eet together again !


When I was 13 I was given a broken Leica II. It took me 20 hours to fix it, and one part (tensioning the shutter) I had to ask some profesionals to help me do.

Edmund

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jaapv

Do you think you will be actually be able to assemble it again?

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Jaap

WWW.JAAPVPHOTOGRAPHY.EU

Skype: JAAPVPHOTOGRAPHY

John Maio

Amazing

Will you try to reassemble it?

marknorton

Of course!

__________________
Mark

eronald

Is this just my impression or does this thing lack electronics integration ?

Separate circuit boards for separate functions is a nice mantra in practice, yielding an easier development and update process, but even nicer is simplification and a reduction of component count.

Edmund

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marknorton

No, I think they've done a spectacular job keeping in mind the production volumes. If it were a mass-market Canon, you'd see more integration using custom chips but in a way, it makes the Leica more interesting, it's built from more standard parts.

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Mark

sm23221

Excellent. Thank you for the anatomy. In your opinion, do the components look like they are top grade?

marknorton

The component quality is fine and the board quality - the accuracy of component placement and soldering quality - is excellent. If you compare these pictures to my ones of the battery charger, there's a world of difference.

I'd also mention the use of gold for the shutter speed dial and shutter release, all of which show the camera is designed for a long life.

__________________
Mark

earleygallery

Thats nuts! but fascinating. You're very brave, I hope you can put it all back together again!

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Regards,
James

croydonconfidential.blogspot.com

dugby

Are you going to try and fit these parts into an MP.....?