Extension tubes, a macro alternative

I just posted a piece with photos on my blog discussing extension tubes as an alternative to macro lenses. This came about as I was considering yet another macro lens purchase and a someone suggested using extension tubes instead. I listened to him, picked up a used set of Kenko tubes and gave them a work out this morning.

To summarize the article -

The advantages to using extension tubes in place of a macro lens.

Small size and weight
Ability to use on more than one lens
Ability to stack tubes to increase magnification ratios
A helluva lot cheaper than another lens

Disadvantage in comparison to macro lens:

Macro use only
Very limited focal range, close-in use only
AF function has a tendency to hunt
More cumbersome, slower to use
Light loss increases with each tube size increment

If you have interest in this subject, I invite you to visit the blog: www.foto-gizmo.blogspot.com

aboudd wrote in post #16862455
Disadvantage in comparison to macro lens:

AF function has a tendency to hunt

I have both macro lens (Canon 100mm) and extension tubes. I wouldn't ever attempt to use AF with extension tubes.

My extension tubes arrived today. Xit XTETC Auto Focus Macro Extension Tube Set. Fifty bucks.

They work well so far. Autofocus works.

I'm sure a crop sensor gives a much better experience with the tubes and macro lenses. But today is my first day, so I have a lot of learning ahead.

GJim wrote in post #16863137
I have both macro lens (Canon 100mm) and extension tubes. I wouldn't ever attempt to use AF with extension tubes.

I actually did use AF on this shot of the orchids. I think it only worked due to the length of the lens, a Canon 200MM 2.8L . I used 32MM of extension. Shot on a tripod, 1/13th sec @F10. No post process except for resizing for web display.

I got the Neewer with AF enabled but I didn't bother either as once the tripod is set and the right distance it was easier to just focus manually.

Is it normal to have more distortions like this? 70-200 f/4L directly over the motherboard set at f4. It seems like every photo I took still had these distortions all away from the center. The lens was fairly close to the board (I forget how many rings I used).

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