Thursday, September 18, 2008

Meet My Friend Bo

I've been working with a new panorama tool this past month or so, and I'm liking it a lot.

It's the Bo Bracket, a simple, light, accurate panorama bracket made by Bo Lorentzen, a photographer and computer graphics artist. The bracket is made of model aircraft birch plywood, cut with a precision laser and laminated.

The bracket is designed for specific lenses.  I ordered mine to fit my Sigma 8mm f/4 fisheye.  It's also available for the Sigma 8mm f/3.5, the AF Fisheye-Nikkor 10.5mm f/2.8, and several point-and-shoot fisheyes. 

Its construction is simple - the base with 3/8" tripod mount socket, the lens bracket, and a long screw with wingnut to hold it all together. It clamps around the lens, allowing it to be rotated around its no-parallax point (NPP), or "nodal point". 

Bo recommends using a Manfrotto 259B tripod extension column as a rotator, since the base of his bracket is too small to allow attachment to a regular size tripod head.

I'm using mine atop a short metal post that originally was part of a Forscher Polaroid back for a 35mm film SLR. (Moral of this story - never throw any piece of photo gear away, no matter how obsolete).

The post and Bo Bracket go atop a monopod, and I rotate that, being careful to keep it as vertical as possible. This is very similar to how I used the Nodal Ninja 3 on the campaign trail earlier in 2008. It's very helpful to use a hot-shoe two-axis bubble level
or a surveyor's rod level to keep the monopod vertical. 

I use the monopod from both ground level and holding the monopod up as high as I can. In the picture at left, I'm using my credential holder to hold up the monopod. A flag holder like you might see in a parade would work very well for this. And of course, you'll need a wired remote release.

There are a couple of things to be aware of. In my early testing, I was using the bracket with a Nikon D200. The overhang of the D200's prism cover contacts the bracket, but I was able to turn the lens 90 degrees and mount the camera. Depending on the camera model, this may prevent getting the lens fully into the bracket, thus missing the NPP.

Also, the instructions included with the bracket caution that it's very sensitive to moisture. It's recommended to coat it with epoxy if it's going to be used in wet environments.

The one thing the bracket can't do is to swing up and down to shoot zenith and nadir precisely from the NPP. In the tests I shot (not shooting up or down, but just around), the zenith hole was minimal and could easily be patched by editing the top cube face. The footprint of the bracket is quite small, making a nadir patch easier. The nadir can be shot handheld away from the NPP if necessary. PTGui's viewpoint correction feature makes stitching these off-NPP images much easier.

I put the rig to the test this past weekend at the new zMax Dragway @ Concord. Check out the three panoramas on this page of, our motorsports website. These panos were all shot with the Nikon D700 full-frame sensor camera and my trusty Sigma 8mm f/4 fisheye. I've wanted the three-frame advantage of a full circular image, and I wasn't disappointed. I'll post my impressions of shooting and stitching circular images in the next few days.