Ive been wondering about this for a while now, but today I had my first real chance to test it out. Ive carried a Kenko 2x Extender for a while. Ive never purchased Canon’s version for 2 reasons, Price and Fit (it doesnt fit all lenses). After todays test, Im considering it.

Take a look at this nice Bay shot. This was taken with my Canon 5DII with a 16-35mm wide angle lens. Its hard to see, but there is a seal right where the red box is marked, and I wanted to get a closer look.

I typically use my longer lenses on smaller sensor bodies. In this case, my 70-200 on the T1i, is the equivalent of a 320mm focal length. (1.6 magnification factor x 200mm = 320mm)-

Adding a single 2x Extender will turn this into the equivalent of 640mm. I was fairly happy with the result, the camera’s auto focusing system worked absolutely fine, even though we lose 2 stops. I do notice more of a softness, and what seems a very small amount of haze- but otherwise this is pretty amazing, and easily cleaned up in Photoshop if we have to.

These shots are straight out of the camera:I slapped a second 2x Kenko extender, because….well, I was just curious as to see how it would perform.

This should give the equivalent of a 1280mm which as you may realize is ridiculous.
I think Sigma has some tank of a lens that runs $32,000 –
The 2x extenders are pretty cheap $75 each. When double stacked, you are losing 4 stops, or 8 times the amount of light. I was still shooting at 1/640 (on a tripod) at f 6.3 and an ISO of 1600. It was extremely windy, so its possible camera shake did play into this. I also noticed that I lost my auto-focus completely, so I had to focus on manual. Still…you can see what’s going on. Makes me wonder if there is a way to get cleaner images when double stacking.

Something to consider….Finally, I cropped out and added some contrast (just a little) in PS otherwise you can see how image quality is degraded when double stacking.

I think the lesson learned here, is yes, you can double stack 2 – 2x Kenko Extenders, just do it on a very bright day and dont expect the image to be anything very quality…but maybe if you are spying on someone. 🙂

Im Michael Andrew, and thats your tip for the day!

(yes, Ill be making a little video on this when I do more tests).