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

AF problem? Adjust the zoom-brush!

A lot of used (and repaired) zoom lenses have autofocus problems, front focus or back focus. Case the lens has been disassembled before, the problem can be caused by the non-adjusted zoom-brush.

What does the zoom-brush have to do with auto-focus? The answer is in the working principle of the AF measuring of the DSLR-s.

Read the whole article – but for us at the moment is enough to know:

1. The autofocus is a secondary optical system – so, case the AF determines the correct focal position, the photo will be sharp ONLY if the primary optical system, the lens/CMOS  is correct adjusted to the AF system. This can be done in some cameras through the camera menu too (fine adjustment)

2. In the AF system we take two light-beams coming from the same point: one which goes through the right side of the front lens, and another one, which goes on the symmetrical opposite point (red and blue on the picture). Case the object is focalized, the two images will fall on the same point on the AF sensor. case out of focus, they will be physically separated. As more out of focus, as bigger the distance. This distance can be measured electronically by the AF chip..


Case you know this distance (the error), with simple geometry the camera can calculate the correct AF sensor/lens distance.

But for this, you will need one mode data: the focal distance of the used lens. This is no problem in case of a prime (fix focus) lens. But what about zoom lenses?

Yes, in this case the camera needs the momentary value of the zoom position.This i captured with a simple conductive flex cable with some lanes, connected through a metal brush. Normally this is a 5+1 lane flex, in this way you can make a 5 bit number (32 discrete values)  which gives the position of the zoom lens.

The cable must be clean, the brush must be aligned with the lanes – and HAS TO BE adjusted in position – to give the correct lens focal distance in any position.



Case the lens gives wrong focal distance value to the camera, the calculation will be wrong – the camera will give you the green dot in the viewfinder, as picture is in focus – but this will not be true!

How to adjust it?

There is a probably not very precise, but very simple method: use the external system strobe to display the zoom position. the method is good even to determine (without disassembly!!!) if the brush has contact problems).

  NewImage_800_451_90(18)   NewImage_800_451_90(17)

So mount the strobe, put on auto-zoom, and follow it’s display and the real lens position.

Case there is a difference, just readjust the brush.


Try it!

(the individual lens data are stored in the EEPROM of the lens, and they are also used to make the correct calculations.  This is the explanation, why you cannot change the electronic board from one lens to the other. But that is another story …)

Posted in 17-55 F2.8 IS, lens | 10 Comments

Nikon SB-24 flash repair

I have bought a Nikon SB-24 for a bargain price. I checked it, worked well.


…excepting the fact, that after 30 seconds the flash always went sleep.  From this mode was easy to wake up: just a short impulse on the middle pin in the hot shoe.

On the net you can find the repair manual

This flash has some settings in the inside: you can set the security voltage (the maximum after which it will shut off to protect the capacitor and the circuits)), the monitor voltage, which is that threshold, on which the ready light  goes on, and others, for example the light quantity for a Manual or an Auto flash.

On my flash the ready light on the back  was NEVER on – and for this flash is a normal behaviour, that case he can not observe the ready light (better to say, the capacitor can not reach a predefined voltage (ca. 330 Volts) after 30 seconds goes to sleep.

 So, be careful: a flash is not a joke. Works on 300-350 volts, can KILL YOU.

Before repairing it, always CHECK the capacitor, case it is charged, discharge it through  a small power 230 volt lamp, or a 1 kohm /5 W resistor.


This is the normal behaviour after 5-10 seconds



And this is mine, with NO ready light. The flash worked – but disconnected after 30 sec.


Case you open the body, begin with the bottom, then the red front cover. More is not necessary for this operation..

WP_20171005_22_21_07_Pro  WP_20171005_22_21_22_Pro

Under that cover you will find the measuring point of the capacitor voltage (deep under the plastic, so you will need a long multimeter probe), GND is on the front, in a 3 pin socket, under a cover, and the 5 different potentiometers. VR2 is the right one, if you watch it from the front (see the picture with the screwdriver).

Turn it clockwise (CW), and the monitor voltage limit is lower. Conterclockwise (CCW) – will be higher.

And worked. Imade a setting fo 320 volts. Lower,  than official (so will have a little bit less power) – but I will use it only as an auxliary flash with a radio remote control in Manual mode. 

2017-10-06_001644  2017-10-06_001748


For the whole description see the link

By the way: the hot shoe middle pin voltage is +4,50 volt, with the GND on the side pin of the hot shoe.

Posted in flash/strobe | 6 Comments