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Canon CP-E4 battery pack causes image noise (?)

David Marat , Apr 04, 2008; 12:42 p.m.

I found some info stating that when using Canon Battery Pack attached directly to EOS DIGITAL camera, images may contain noise due to electromagnetic interference. May a battery grip (on 40D) resolve the problem? Any experience?




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Charles Webster , Apr 04, 2008; 01:06 p.m.

Can you cite the source of that info, please?


David Marat , Apr 04, 2008; 01:44 p.m.

As I remember the original source was the battery pack's manual.


Jason Hall , Apr 04, 2008; 04:52 p.m.

EMI requires magnetic fields to move and fluctuate thus induceing voltage in place it should not be. That is normally not a function of a DC power supply. So I don't know if this is a valid claim.

On top of that the battery pack is made to power a flash not the camera. The battery grip powers the camera not the flash. So no a battery grip will not replace a CP-E4 battery pack.


Jim Strutz - Anchorage, AK , Apr 04, 2008; 04:55 p.m.

There have been some complaints on forums about it too. Usually happens with certain cameras when using high ISO. Not sure about the 40D though. I haven't had any issues with my 40D, 550EX and CP-E3 up to 800 ISO. I seldom go higher with flash.

Jason Hall , Apr 04, 2008; 05:02 p.m.

The EMI must be coming from the flash due to the faster cycle rates. Ineresting.


David Marat , Apr 04, 2008; 05:18 p.m.

Ok, this is what I found on the Canon CP-E4 battery pack's manual at retail store:

"When using an EOS DIGITAL camera with the Compact Battery Pack CP-E4, images may contain noise due to electromagnetic interference. Therefore, be sure to keep the battery pack at least 5 cm/2 inches away from the camera body. Also, do not directly attach the Compact Battery Pack CP-E4 to the tripod socket on an EOS DIGITAL camera other than as EOS-1D series camera. When using an EOS DIGITAL camera other than as EOS-1D series Camera, attach an optional battery grip to the camera's tripod socket, then attach the Compact Battery Pack CP-E4 to the tripod socket on the battery grip."

Well, I new that a distance between a camera body and the batery pack matters swomehow and now it is clear somehow. That's why I mentioned about a battery grip - increasing the distance. Anyway, this is just theory. I wander how it works in the field.


Rajarajan Rajamani , Apr 04, 2008; 07:36 p.m.

Coming to think of this, there might be some explanation. My shot at it is as follows - The output of the CP-E3/E4 is to the order of 300V to 320V in order to do a rapid charge of the flash. The 8 cells it holds internally would only amount to 12V DC and this has to be stepped up (i.e. inverted) using a circuit. This inverter circuit has an oscillator which generates AC as output (which may or may not be converted to DC) before it feeds the flash. It is this oscillator that is the most likely cause of EMI/EMC which can affect the performance of the digital camera.

Coming back to the original poster, the CPE3/4 powers only the flash and not the camera. The OP says 'attached'. It cannot be attached to the camera electrically, if placed next to the camera, then maybe it might affect if the camera is not adequately shielded against electrical noise, which is likely in the case of plastic bodies. Metal camera bodies would be less susceptible.

Lee Smith , Apr 05, 2008; 01:28 p.m.

Hi David, The 5D is sensitive to EMI. I have a Quantum Compact that I used to attach to the underside of the camera to power a 580EX and I got a lot of banding. After I moved it off the camera to the flash bracket, the problem cleared up. The Quantum site posts a warning only for the 5D. Lee Smith

Jason Hall , Apr 05, 2008; 01:52 p.m.

I did not realize that the pack steped up the voltage from the 12v. That being the case it make perfect sense that is causes EMI. Learn something new every day. Glade I know now, I may get one of these suckers.


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