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Pete, Electronic Engineer
Category: Camera and Video
Satisfied Customers: 17677
Experience:  Over 16 years of experience installing and repairing electronics.
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I have a Canon EOS 7D DSLR Camera - about 5 years old - it

Customer Question

I have a Canon EOS 7D DSLR Camera - about 5 years old - it has an existing Canon Zoom Lens EF-S 18-200mm 1:3.5-5.6 IS.
I am go to Africa in July & want a suitable new, more powerful Zoom Lens
A couple of questions -
I looking at a new Canon EF 100-400mm f/4.5-5.6L II USM lens, which from what I am reading is a very suitable & good lens.
What is the difference between the above Lens & an
EF 100-400mm f/4.5-5.6L IS USM lens
I believe both would be totally suitable to my camera?
Also, I want to buy a Canon 2 X Extender - is this compatible with the 2 New Lenses that I am looking at to buy & also, is it compatible with my existing 18-200mm Zoom Lens?
I also have a problem with my Camera.
I have a battery pack on it for 2 Batteries.
When I recharge the Batteries - the Camera does not recognise the batteries & the top right hand battery charge indicator display does not work & the batteries go flat if I do not use the camera for several days to a week. The Camera is fitted with Genuine Canon Batteries.
I look forward to your advice.
Submitted: 1 year ago.
Category: Camera and Video
Expert:  Pete replied 1 year ago.

Hi Richard

Expert:  Pete replied 1 year ago.

The Canon EF 100-400mm f/4.5-5.6L IS II USM lens is the "Mark 2" version, and have 16 years worth of improvements on the older EF 100-400mm f/4.5-5.6L IS USM lens.

Both lenses would indeed suit your camera.


You can use these lenses with the 2X extender, however you may find that performance is limited due to diffraction. It should still be good but don't expect wonders.


The battery problem is common on these Canon cameras.

To resolve the battery problem, try this:

Remove the lens and put a cap on the body.

Turn off the camera but leave a battery in it.

Put the camera in a freezer for 6 minutes.

Then remove the camera and put a room temperature battery in the camera.

Turn on the camera.

The camera should see the battery and display the battery life.