Canon CP-E4 – Endless Power For Your Flash

Canon CP-E4 battery pack

I’ve added a new gadget to my equipment: Canon’s compact battery pack for the Speedlite 580EX, acting as external power supply for the flash.

Why now? Well, I have been shooting with high-end re-chargable batteries (e.g. Ansmann 2850) for a long time, but I still felt that sometimes, just sometimes, the flash succession would not be fast enough. The other day I shot a wedding ceremony in a rather dark location, and I ended up with a sequence of images where I could clearly see the flash being “too slow” to recycle: Image with flash, image without flash, with flash, without… You get the idea. While this is not a big issue, it was bugging me, and I was looking around for external batteries. The obvious choice was Canon’s original equipment, the CP-E4.

Here’s a quick review for those facing the same problems, wondering whether the CP-E4 might be the solution.

The first impression is very, very good. In the pack you get a robust bag for the battery pack, a tripod mount, and a huge instruction leaflet in 8 languages. The battery pack itself is a sturdy plastic case with a flexible spiral cable (which connects to the flash) and a battery magazine (the CPM-E4) designed to carry eight AA-sized batteries.

A lot of thought seems to have gone into the bag: it can be fixed to a belt, but you can still change the magazine and also remove the entire pack if you need it. The magazine, however, does not confirm this impression. While it seems to be quite robust, I think that the small “noses” (that add stability to the batteries) can break off when you have to change batteries quickly on location. Well, time will tell.

Canon CPM-E4 battery magazine

You can mount the battery pack to any camera body using the tripod mount. But before doing so you should take note of the following section in the instruction leaflet (highlighting by me):

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 an EOS-1D series camera. When using an EOS DIGITAL camera other than an EOS-1D series camera, attach an optional battery grip to the camera’s tripod socket, the attach the Compact Battery Pack CP-E4 to the tripod socket on the battery grip.

So I should be lucky because I am using 1D mark IV bodies. But when I tried using the camera with the battery attached to the tripod mount, it did not work very well.  The camera became unmanagable with that “thing” attached. The battery pack not only adds considerable weight (which is already quite high with the camera and the lens and the flash); it also prevents an easy and secure grip to controls I use often (e.g. the vertical shutter release). So for me this is not a good solution. For me, the only way to use the battery pack is at the belt.

Also, when mounting the CP-E4 to the tripod mount you actually can not mount the camera to a tripod any longer! The geniuses at Canon just forgot to add a tripod mount to the battery pack!

But does the battery pack work? Does it help with shooting? Oh yes, absolutely! It works like a charm. Where in the past a flash powered by weak batteries would be available after, say, two or three seconds, sometimes even longer, it now is available right away, shot after shot after shot. When shooting in a quick succession (which happens often at weddings), every shot now gets a flash. Jee-Ha!

But before getting too excited, please watch out to not shoot continously. The instructions say:

During continous shooting, avoid taking more than 20 sequential shots using the flash. If you do take 20 sequential shots using the flash, take 10 minutes intermission before taking another shot.

This warning is in line with the warnings of the Speedlite 580EX instructions, so it seems to be a real risk for your flash.

Finally, you need to make a decision whether to use the custom function 07 of your Speedlite 580EX. This setting controls the way the power (from both the internal and external batteries) is used. By setting C.Fn-07 to “0″ the recycle will use power from both the Speedlite’s internal batteries AND the CP-E4 external battery. This is the default setting. While this gives you the maximum power available for your flash, you should be aware that this drains all the batteries in a uniform fashion. But the Speedlite 580EX needs some power for controlling the flash. So if you drain both internal and external batteries, you may end up being unable to use the flash at all. All 12 batteries need to be replaced then, and this may take some time. This will be avoided by setting C.Fn-07 to “1″. This setting uses the external batteries (if connected) as single source for the flash and the internal batteries as single source for controlling the flash. If your external batteries are empty, you just have to exchange them (e.g. by using a pre-filled CPM-E4) and you can continue to shoot shortly after.

The price for both pieces is just a bad joke. The CP-E4 (including bag and CPM-E4) cost me 140 Euros net, the additional CPM-E4 came in at 39 Euros net. Wholy moly! 39 Euros for a flimsy piece of plastic with no intelligence whatsoever? Canon surely knows how to charge extra for just their brand name! I admit, that I am quite reluctant to use unbranded components since I want to keep the warranty of my bodies. (There are cheaper knock-offs of the CP-E4 and the CPM-E4 available on the Internet.)

:: Pro’s

  • Endless power for your Speedlite 580EX flash
  • Robust product with a cleverly designed bag
  • Easy to handle in all situations

:: Con’s

  • Unsuitable for attaching to camera body
  • No tripod mount if you attach the pack to the camera body
  • CPM-E4 magazine is not as solid as the CP-E4 housing
  • Way too expensive for just a few pieces of plastic
  • No power level indicator (just a red light)

:: Summary

The CP-E4 is the external battery of choice for your Speedlite 580EX, and it will give you the power you need to survive exhausting shootings. Be prepared to pay a huge price for using original Canon equipment, and do not get too excited about mounting the external battery to your camera (it won’t work in practice).

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