Macro Extension Tube

I tried to remedy the depth of field problem the best I could. For one, I did not shoot with the 50mm f/1.8 portrait lens. I shot with the 18-135mm zoom lens at its longest focal length, ensuring that the widest aperture was f/5.6 (instead of f/3.5). This was the smallest aperture I could get with the equipment I had. Still, the photos had a pretty shallow depth of field.  

As you can see from the photo above, the grass was still green with I shot these photos.  It wasn't until this fall that I learned that f-stops are constant only in exposure and not it terms of depth of field.  What I mean is this:  if you meter a scene and it reads an exposure of 1/30s at f/5.6, no matter what camera or what lens you use, your exposure will be the same.  But depth of field at f/5.6 might not be same from lens to lens.  The reason that cheap zoom lenses have a variable maximum aperture, like f/3.5-5.6, is because the meter has to compensate for the changing distance between the lens and the sensor or negative.  As you zoom further out, the distance becomes greater and less light can reach its destination.  So, when your zoom lens is fully extended and you're shooting at f/5.6 instead of f/3.5, your aperture is not closing down, indeed it is actually the same.  It is merely compensating for the difference in light.  Your depth of field will remain the same.

All in all, I suppose the depth of field gives the photos a unique flavor.

And heck, for 10 bucks its worth toying around with.

You can check out the rest of the macro tube photos here.