For 3D, spacing between the lenses really does matter

I have been shooting 3D mostly using two GH-2 DSLR type cameras. Due to the width of these cameras, my interaxial lens spacing (the distance between the centers of the lens) is almost six inches.

This spacing turns out to be much too wide (which I expected) for most subjects and is definitely too wide for anything closer than 15-20 feet from the camera. Using the wide spacing causes the left and right eye images to be separated by too much. While they can be brought closer together in the editor, this tends to cause problems on more distant items in the scene.

Last weekend, I went to a park and using a set of trees spaced in front of me, I shot 3D on both two Kodak Playsport Zx3 cameras with about 3 inch spacing and the same scenes with the GH-2s with 6″ inch spacing. Without question, the 3″ spacing was better looking than the 6″ inch spacing and when the distance to the first tree was reduced to about ten feet, the Playsport 3D combo did a nice job but the with the GH-2, I had to severely reposition the tree in depth to avoid hurting my eyes. But that really messed up the more distant trees. This little test confirmed the importance of working with closer lens spacing.

That said the GH-2s, of course, have great image quality, low light capability, and better dynamic range and compression. They remain a great tool for shooting scenes with longer depth, such as my Civil War battle re-enactment video. And the GH-2s did a great job when I was testing at about 30 feet from the first tree.

But for close in subjects – and generally that means most indoor shooting where space is limited – close lens spacing is essential.

I am starting to test using two Canon HF M301 video cameras that I picked up for $200. So far, the results look to be extremely good. With the M301, I get a high 24 Mbps AVCHD encoded video data rate for good image quality, plus using my custom 3D mount, the lens spacing is just 2 3/4 inches. And if I really wanted to, I could reduce that to 2 5/8″ for sure.

The M301s are quite a deal, albeit, their lenses, at the widest, are about the same as a 40mm lens on a full frame camera. In other words, very close to a “normal” lens. 3D likes wide angle. I tested my 43mm filter ring Canon wide angle adapter using a 43 to 37mm adapter, and this lens produced very good quality wide HD on the M301. But alas, 3D requires two lenses, I only have one wide angle adapter and do not plan to buy another any time soon (unless I get lucky and find one for sale really cheap!)

My goal is to find good 3D video solutions that do not cost a fortune. That rules out using beam splitter rigs for sure! Plus, I usually shoot while “portable”, meaning I am on my feet a lot, and sometimes even running with my cameras, so small size and light weight are important. I typically shoot using a monopod since its lighter than a tripod, very fast to set up, and I often use it to lift my cameras high over head for an aerial view. Anyway, I will continue to work on finding simple, affordable solutions and will post what I learn on this blog.

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