EF 100mm macro + Kenko Pro 300 dg 2x extender

[ooo]

I will confirm that auto focus works on my 100mm macro lens, strangely it works for my 17-40L as well. I will test my other lenses and the IQ after this post. Edit >> I realized my 30d does not recognize that there is a teleconverter attached. I can focus with all my lenses but focusing is slower, with my sigma lens it keeps going back and forth as expected.

Anyways, there is a big difference in IQ when I shot with the 2x tube on my 100mm macro. Tripod test, shot at f/2.8 and f/11. I tried to get them in the frame the same. These shots are all straight out of camera, no sharpening.

"Duck Shots Below"
2x f/2.8
http://rlcstudio.com/images/potn/20080402/1.jpg

no extender f/2.8
http://rlcstudio.com/images/potn/20080402/2.jpg

2x f/11
http://rlcstudio.com/images/potn/20080402/3.jpg

no extender f/11
http://rlcstudio.com/images/potn/20080402/4.jpg

Here is a 17-40L manual focus, no tripod test, 2x extender, wide open at 40mm f/4.
http://rlcstudio.com/images/potn/20080402/5.jpg

[gasrocks]

Macro shot at 2.8? Comparison of 100 macro to 17-40? I guess I don't understand.

[ooo]

I was just testing out my 2x extender and the IQ of it. There are no questions with this thread. The first shot is with an extender at f/2.8 and the next is without, then I did a f/4 test. I also tested the extender on my 17-40L and it came out really sharp.

[nicksan]

Strange that the Kenko Pro 300 2x would AF with the 17-40L. Do you have the pins taped? Hey, if it's working...it's working.

Don't know why you would use a 2x TC on the 17-40L but I'm guessing you were just messing around.:D

I can see the IQ loss, but I would imagine stopping it down even more would produce decent results.

I used to use a Canon 2x with the 70-200 f2.8 IS and I got pretty decent results. Obviously my 100-400L produces superior results as expected.

[ooo]

I didn't tape the pins, I don't know if its a good thing or a bad thing that I can use my AF with any of my lenses. The results with 2x isn't that bad because cropping it down would probably produce similar results. I plan on using this with my sigma 70-200 f/2.8, when I get it =D.

[Jaetie]

I don't know if its a good thing or a bad thing that I can use my AF with any of my lenses.

i believe its just illogical cause an f/4 with a 2x teleconverter would yield a maximum working aperture of f/8. and non-1d series bodies should not be able to AF with lenses that have a maximum aperture of f/8.

[ooo]

i believe its just illogical cause an f/4 with a 2x teleconverter would yield a maximum working aperture of f/8. and non-1d series bodies should not be able to AF with lenses that have a maximum aperture of f/8.

I agree, especially since I was using my 2x on a f/5.6 aperture lens (2 stops making it f/11) and it was still able to auto focus. My only conclusion is that my camera is not reading my extender. I didn't tape the pins either, it just works. I guess its nice that its working without me taping, though the autofocusing isn't really worth it because it takes forever to find, I can manually focus my subject faster.