How to measure CMOS position with a dial gauge

Case You want to replace the shutter in a newer Canon camera, you will have to take out at first the sensor. And the sensor is positioned regarding the flange NOT with the help of some adjustment washers, but with springs and adjustment screw.

Please trust me: you will NOT be able to put it back only by marking the original position, or counting the rotations of the screw. We are talking about the precision of 0,01 mm at least.

Somebody told me, that the description of the dial gauge holder was not clear enough – so here You have a more detailed description. Sorry for the photo quality – has been made with a phone)

At first, here is the distance, You should measure. Better to say, only one of them, the other 2 they are not accessible at all. But does it have any sense to be measured with a caliper?


Of course: NOT.

Even the precise calipers are not made for this type of measuring. So, You will need a stand for a dial gauge, and a fixture for the camera, to make possible, to hold it with high repeatability under the gauge.

DPP_0002  DPP_0016

The distance is about 43.0-45.0 mm – o You would need a digital gauge in the 0 – 50 mm range. Not cheap.
I decided to make a cheaper solution, so I used a 0 – 12,5 mm gauge, 0,001 mm resolution (don’t confuse resolution with precision – in this case, the real precision is probably 0,01 mm.

At first, we will set the “0” display using a 40,0 mm steel block – just to make possible a later measurement. I use a steel block made of HSS steel, used as a lathe cutting tool. Important is, that it should be hard and with perfect parallel faces. (I let this made on a grinding machine). You can use for example a 200x20x20 mm bar, cut with an angle grinder to pieces.
2 pieces together give approx 40 mm. The exact size does not count – important is only, to be able to use always the same “etalon”


DPP_0004  DPP_0005

Now put the steel block on the base surface, and set zero on the dial gauge (the base surface is made of a hard steel plate, in my case on the internal part of a Delphi diesel pump)). This is the most important part – it has to be a perfect plane.

DPP_0009  DPP_0006

This is the original displayed value, before zeroing:


And this is after pressing the ZERO button.


Now You can take off the steel block. (Next time You can set the same zero point using the same steel block again.

IMG_20180930_095900_HDR_1538306657817_1  DPP_0001

On the CMOS you have to mark the 3 measuring points with a cross, and letters: A, B, C.

DPP_0016  DPP_0010  DPP_0011

Now you position the measuring tip on the cross and measure the height.


Don’t forget to add the 40,0 mm to this, and write it on a card:

DPP_0013  DPP_0014


Remember, the adjustment screws have TORX head, to help You to rotate them without axial force.

Don’t push or move the CMOS plate during measuring. The case you press it will change its position, and You cannot put it back to the right position. Excepting the case You measured it  before…)

Posted in Canon camera, DIY, tools | 10 Comments

Optical alignment

Cementing a Doublet: Opto-Alignment Technology, Inc.


SmartAlign for lens alignment and assembly processes


Canon EF Lens Plant – Lens Assembly Process


Lens Handler Operations

Posted in lens | Leave a comment

The mystery of NO FOCAL LENGTH on flash

The customer has got a used Tamron 17-50 F2,8 lens, and realized that using with a Canon strobe, there is no change on the strobes display, it shows always 17mm focal length.

I was sure that there has to be something with the zoom position brush, so I disassembled the lens.

IMG_20180219_212016_HDR_1519071773821_5 IMG_20180219_212026_HDR_1519071773459_4 IMG_20180219_212038_HDR_1519071773100_3

When moving the zoom ring, I could feel that the zoom tube does not follow too tight the ring. This happens, when the follower, a casted metal parts sits not strong enough on the ring, loosen screws.

But what I have found in the inside, was more over my expectation….

IMG_20180219_212049_HDR_1519071772782_2 IMG_20180219_212056_HDR_1519071772444_1

In the inside of the lens there was no zoom-brush – and no flex cable at all.

And as flex cables usually dont sublimate… The seller has forgotten to tell, that the lens is a repaired one, better to say, assembled without repair.

Posted in Canon lens, Tamron lens | 7 Comments

Canon 5d MkII – error code 20 : shutter…

… or not the shutter?!?

One of my customers has a 5d MkII. Time to time the camera stopped working with error code 30 after shooting. This is a general error code: “

Err 30
Description: A malfunction with the shutter has been detected.
Resolution: Turn the power off, then remove and re-install the battery. Then turn the power on again.

Normally in an official service you ill get an offer for a shutter exchange. But after 33000 shutter activations?!

Reading out the internal error memory with the SPT software, I have got the following error list:

2017-09-27_221556 err231 

Ok, this looks a little bit better, as I had in the past a similar problem with some 7d bodies. After disassembly, I checked the mirror motor, if it is loose or not, as that can cause a blocking of the motor during activating the mirror. But it was not the case.

Before replacing the shutter unit (150 USD), I decided to check it disassembled. The 5d MkII has a complicated shutter, more reliable than the small cameras.

ATTENTION: this cameras have a CMOS (sensor) with screw adjusted position. Seems to be with shims – but be careful: under the shim you have a rubber-bumper, which modifies it’s hight as you tighten the screw….

cmos_base_0399 cmos_base_0400

Disassemble ONLY after measuring the original position of the CMOS regarding to the body flange, or you will not be able to mount the CMOS in it’s original position anymore (better o say, only very difficult, as you don’t have the equipment of an official service.

Let we see the shutter:

In this case the curtain springs are cocked by the motor, and hold by two small mechanical triggers. In case of exposure, this triggers will be released by two small oscillating motors – I mean, some motor-like mechanisms, which can execute only a 45 degree rotation with a single coil.The motor has a mechanical position sensor (phase sensor with brush), the curtains have opto-couplers.

A few soldered parts on the flex cable – so even the soldering could be a problem (cracked cold soldering points).

WP_20171226_18_25_21_Pro WP_20171226_18_25_36_Pro WP_20171226_22_14_14_Pro

It is very easy to dismantle, but You will have to desolder at first the two coils from the flex cable.

WP_20171226_18_26_17_Pro WP_20171226_18_26_26_Pro

The phase sensor was clean, no oxide spots, no short between the lanes (check always with 20 kohm or 200 kohm setting on the multimeter!) . We are talking about a short to ground for a signal.

 WP_20171226_22_14_41_Pro     WP_20171226_22_14_28_Pro  

I have seen only one strange thing: some sticky grease on the curtains. I washed them submersing in some brake-cleaning fluid ( a kind of light white spirite)

WP_20171226_18_40_47_Pro WP_20171226_18_40_58_Pro WP_20171226_21_49_01_Pro

Be careful by assembling – always make some photos about the order of the blades and springs and washers….

As I could not see any spectacular fault, really nothing unusual, I decided to resolder all parts, the diodes, the capacitors, the optocouplers – and the coils. I observed that the original soldering alloy is not a very soldering-friendly material (probably lead-free) – so I used my own normal, Pb-Sn alloy, and a lot of flux.

I assembled the camera with some doubt about the final results – so I mounted the CMOS without any adjustment, just to check the shutter (but for this, you have to connect all boards, parts, back of the camera.

And NO ERROR anymore. Checked in shot-by-shot,checked in machine gun mode –nothing. Wow.

I disassembled the whole camera again, I adjusted the CMOS, mounted all screws with Loctite 243 (threadlock).

Checked the camera…..


… and ERR 20.


That was the point when I started to think how to give back the camera to the owner unrepaired, and to change my hobby on fishing or solving crossword puzzles… anything excepting repairing Canon cameras.

After 5 minutes of staring to the infinite, I disassembled the bottom of the camera – and I found the missing plug on the bottom PCB – the shutter motor was not connected Mosolygó arc

Remark: this time there was ERR 20, not ERR30!

WP_20171226_23_59_28_Pro WP_20171227_00_02_53_Pro

I checked the the camera a few times again, I glued the rubber covers, and I went sleep. (2 o’clock in the morning.)

Today I will have to adjust the AF sensor of the same camera, as the central AF point has a bad factory (!) adjustment: on vertical and horizontal lines gives different focal distance, ca. 1 cm on 1 meter. For the owner this means ca. 50% of the photos out of focus, as the owner never knows, which sensor will be finally used.

I  hope, the shutter will be still alive.

Posted in 5d2, Canon camera, shutter | 2 Comments

Solvent for the cemented lens (not with canada balsam)

Case You want to dismantle a glued (cemented) lens, try to use this:

70% dichlor-methane
20% methanol and
10% ammonia solution (I think 40%).

Be carefull, dont swallow them, they all are dangerous..

After ca 1-2 days of soaking, you will be able to separate the parts. If not, apply a 10-20 mbar vacuum for a few minutes, then let back the air pressure – will help.


Posted in General topics | 2 Comments

Canon 40dcmos – with no Bayer-filter!

After long trials yesterday I managed to eliminate the complete Bayer-mask from a Canon 40d sensor. No scratches, no damage – just a beautiful golden mirror.

Not very simple – and definitely NOT only by scratching it with a piece of wood. There is a special mixture of solvents, a lot of patience, and some mechanical tricks too.

Next days I will have to mount it in a camera. Does anybody know, if the RAW files does contain the pixel images separately (so the native R G G B pixel information), and the softare does only the reconstruction of the RGB values of each pixel, or in the RAW there is the interpolated information already?

This is the real part after eliminating everything from the silicone chip surface.

I have got this info:



Posted in General topics | 5 Comments

Canon 7d – ERR20 – again and again

This 7d has been repaired a few months ago with an ERR20 error code after each shooting. ERR20 could mean many different problems, here is he internal ode:

Interesting is, that, the internal error 215 is Mirror position problem, as possible case you find here the mirror OR the shutter phase switch.

I disassembled the mirror mechanism, the phase switch or brush was OK. I put some grease on the wheels, assembled – ERR20.

OK, let’s see the shutter,. On that unit they were no signs of any damage, but I ordered the ne shutter. Replaced – and ERR20 was over.

I made a few test shots, and gave back the camera to the owner.

After 2 months he called me: ERR20 again…

OK, I read out the error codes: ERR215

I disassembled the whole thing 3 times. Checked each socket and cable  – NOTHING. no corrosion, no damaged wires.

But: ERR20.

After a new disassembly of the  mirror mechanism, I observed, that the motor has –given by construction a relative big play, it is mounted on some rubber bumpers. When pushed in a certain direction, the gears were slightly blocked. Ouuups. I checked a disassembled 40d. That on has no bumpers, the motor is mounted on the plastic chassis.

The small “O”-rings are really very weak. So, I took some other screws, and I mounted the motor without any rubber rings (just the rubber base on motor side). Motor stands now rigid on the plastic base. To be safe, that the motor ill not get loose, I put some 2k glue on one side too (Poxipol)

Mounted it, checked: no error. 50 shoots: no error.

Wow, repaired!


And after this, i remembered, that in the past this happened me once. I checked on my blog …. Yes , it was exactly my own 7d – exactly the same failure, the same repair. (see below)

I think, this is a constructive given problem. Could happen by any other camera having the rubber dampers.

I should read more internet, before working a lot.


Canon 40d motor revival in the body of a 7d

This is a story about my own 7d, which has been flooded with water, before I have purchased it “as it is”, practically not working. I repaired it in a few hours -worked well after.
After a certain time stopped working, message was Exposure not possible, ERR20. Mirror moved up, but the curtain not. Other lots of hours of repair, disassembly-assembly. Normally I should change the shutter, but is really expensive. So i have rather bought the SPT software for the 7d.
I have read out the fault memory. And it was a problem regarding – the mirror motor position.!!!
Disassembled again – no sign of anything unusual.
Assembly – works. Second day in the morning – NOT working.
I resoldered MANY times a damaged cable socket, which was not so easy, as the former corrosion has damaged the contact surfaces.
Then I realized, that touching the motor, the camera works. Pushing it in another direction, the fault appeared immediately. Wow. The motor here is fixed to it’s frame only through 2 flexible points – 2 screws and two rubber collars. I disassembled a 99% similar motor from an old 40d – this has no flex joint, just two screws. No problem – I had no other solution anyway. So, i made both operations (out and in). And even after 3 days the camera is working perfect.
So, never give up!

7d h  7d-2h

Canon 7d – ERR20

After exposure, ERR20 – shooting is not possible message. This means some mechanical failure.

Official Canon advice:

“Err 20

Description: A malfunction with the mechanical mechanism has been detected.

Resolution: Turn the power off, then remove and re-install the battery. Then turn the power on again.”

Or say a prayer, whatever.

Reading out with SPT software:

2016-11-19_120133-err240_thumb  2016-11-19_120152-err216_thumb

This means, the mirror position sensor is not working. I disassembled the camera, and on the flex cable which comes from the sensor, I have found a tiny oxide dot (or what).

DPP_0001_thumb  DPP_0003_thumb  DPP_0004_thumb

I washed it away with normal water, then I treated it with some methanol, to take away the water.

And now it works, and no error code!


Posted in 7d, Canon camera | Leave a comment