It's all about distance

I'm working a couple projects that will be greatly helped if I can get in tight on faces. Not human faces, animals - horse, dogs, cats, etc. Immediate thought is to use a macro lens, but that means getting up close and VERY personal, which makes most animals VERY nervous. So I have to find another solution if there is one.

Cropping is not desirable because of all the resolution I throw away when I do that. I considered dedicated macro prime lenses, but they are rather costly and if I read the specs correctly, still puts me too close to the animal.

Decided to try a less expensive option and bought an extension tube. The Canon EF25 II to be exact. If it doesn't work out, it's still a good buy as it has uses in several other areas that will benefit from close-ups.

So, I set up a little test where I shot a small subject with a few lenses, then shot it again with the extension tube installed. I also measured the distance from the end of the lens to the subject when I shot the lenses without the tube. Results with the tube were so interesting, I totally spaced out on measuring. Not that it mattered in one case...

I set the camera up on a tripod, set the focus to full closeup, then moved the subject in and out till it was in focus and measured the distance.

The setup:

Mount a Super Clamp on the tripod's ballhead, and my monopod becomes an extension arm for the camera. Yes that's a travel iron being used as a counterweight!

A simple light and reflector setup, this is more about subject distance than light quality stuff.

And here's the results: 

16-35 at 35mm:

Little Bear is only 4" away from the end of the lens.

Add the extension tube you get the above, but LB had to be this close:

16-35 at 16mm:

At 16mm, closest I could get was ~4.5". Interesting, huh? I had to back it up to get it back in focus. But here's the rub: add the extension tube and there's no minimum subject distance. Or, rather, I can't get there, the lens gets in the way. No matter where I put LB or how I cranked the focus ring, no joy, it won't focus at 16mm with the tube. Doesn't matter, wouldn't do close-ups at 16mm anyway - kinda counter productive, don't you think?

135mm F/2 prime:

Without the tube, we go from 4" to 28". That's as close as I could get...

With the tube, and I can pull it in about half that distance, but the magnification impact isn't as big as it is at 35mm.

Decided to try my 24-70 with the tube just to see how it's close-up capability is impacted No joy at 24mm, but I got this at 70mm:

Also, to put this into perspective, Little Bear stands just 5.5" tall...

So, qualitative results imply that the change in magnification is greater as focal length drops into the wide-angle category, but you have to be right up against your subject.

Next test is to actually shoot some dogs and horses. From this initial test, I'll hang out about 35mm. I'm curious to see how my 50mm f/1.4, 85mm f/1.2 and 70-200 f/2.8 does on the extension tube.

And on a side note, image quality does not seem to be impacted by the extension tube... ... 

YAY!!!!!