How much difference does a 2x teleconverter make?

When I was contemplating getting a teleconverter I wanted to know how much difference it would make. Sure, I knew it would effectively double the focal length of the lens, but what does that look like? Here’s a demonstration for my past self, and maybe for you, too. Click on the gallery below for a closer view.

at 200mm

at 2x200mm

This is the same lion as in an earlier shot - he got ribs for breakfast for the second week in a row, and he was not complaining.

The first image was shot about a minute before the second one - it takes a while to insert the teleconverter between the lens and the camera - but these are consecutive shots. Taken from the same spot, in the same light.

The first was shot at f/4, 1/1000, ISO 125 at 200mm on the 70-200mm GM II.

The second was shot as f/5.6, 1/1000, ISO 250, at 200mm physically on the lens (metadata in the image says 400mm) - so one stop smaller aperture, one stop more ISO. If I had planned this as a comparison (I didn’t!), I’d have shot the first one at f/5.6, too.

Both images were cropped from 8640 pixels wide to 8240 pixels wide to make them better suited for printing.

My past self would have found this fairly compelling evidence of why he’d like to get a teleconverter - he might even have bought one earlier than he did. My current self is enjoying it now, but is impatiently waiting for the 1.4x to become available again. Photographers can suffer from terrible GAS…