Extension Tube Snafu?

The other day, I experienced something really strange when using my macro extension tubes with my 50mm lens.

When I attached my 50mm lens to the 12mm extension tube on my camera, the first shot worked fine. The light meter registered as expected and all looked normal.

After the first shot, the view through the lens suddenly got dim. There’s a blue circle of distortion in the center of the viewfinder that does not record when I click the shutter. The light meter reflects a need for a longer exposure however the image recorded does not reflect this dimmer view.

Really weird! It is incredibly hard to shoot this way! The shots worked out fine, but figuring out my exposure without a light meter and trying to see my subject through such a dim view was too difficult to keep up.

I took the whole shebang apart several times. You need to attach the tubes to the camera before you put the lens on so that the senors will register correctly. I thought maybe something went wrong with that process. But each time I attached the 12mm tube and then the 50mm lens on top of it I experienced this problem. I did not try the 12mm tube with my 18-105mm lens.

When I added the 20mm extension tube on top of the 12mm, it worked perfectly. So 12mm extension tube + 50mm lens = WTF!? and 12mm+20mm extension tubes + 50mm lens = A-Okay.

My lenses seem to be working just fine otherwise!

Drawbacks of Extension Tubes

Aside from this strange experience, I’m still deeply in love with my extension tubes. Their limitations are becoming clearer, however. This may ring true with an actual macro lens also, but I’ve never worked with one so I can’t say.

• Less light gets into the camera requiring a longer shutter speed.
• Depth of field is crazy-insane. The aperture needs to be set at f/5-f/10 to get an entire medium sized flower in focus. (Forget about huge flowers).
• The two factors above practically necessitate a tripod, but I continue to be stubborn in my attempts to capture these shots hand-held.
• I wonder how much dust and crap I’m getting on my image sensor every time I change out extension tubes? (This would be true of any lens changes though.)
• They fit very tightly on my lenses. I am frequently afraid I’m going to break my lens during attachment or detachment, though I’m not sure if that fear has any basis in reality.

Example of Extension Tube Capabilities

Working with my 50mm, I notice I don’t get much along the way of magnification using 32mm worth of extension. I do get the ability to focus much much closer, which I suppose is the true purpose of the tubes.

The first shot below is taken with my 50mm lens of these beautiful purple flowers in my mother-in-law’s garden. The second shot is taken with the 12mm+20mm tubes (for a total of 32mm between my camera and lens) and my 50mm lens.

Would I Buy Them Again?

I’d absolutely buy the extension tubes again! I still think they’re a great and affordable method to get close-up shots. I’ve used the tubes in various combination on both my 50mm and 18-105mm lens and I’ve been happy with the results, even without using a tripod.

I need to test out just the 12mm on the 18-105mm lens to see if it gives me the same problems, but I think perhaps 12mm is just too short a distance to extend a 50mm and expect a big difference in results.