Friday, August 24, 2012

Panoramic Head - prototype

A friend recently sent me a link to a panoramic photo of Mars, stitched together from a bunch of images from the Curiosity rover that landed last week.  It was as close to I'm likely to get to the experience of really seeing the place, and that got me interested in making panoramic images of my own, of cool places that I have actually been to.

There is free software to stitch images together, but it works a little better if you take all the photos by pivoting the camera around a particular point in space, usually called the nodal point or entrance pupil.  That point is generally near the center of the camera's lens, so a regular tripod doesn't quite cut it because it rotates around the tripod socket under the camera body.  It's also typical to take photos with the camera in portrait orientation (sideways) to capture the vertical dimension as widely as possible.

Enter the panoramic head.  Yeah, sure, you can buy them, but that's not how I roll.  I made a bunch of sketches and here's the first iteration of a working design.  The goal is to have two axes of rotation that intersect at the nodal point of the lens.  This prototype is nothing fancy, just some scraps of plywood and some nuts and bolts from the hardware store.  I tacked it together last night and took a quick set of pano shots of our living room.  They stitched together nearly perfectly, much better than a similar set of shots I took with the tripod alone.  So yay.  Not so yay are some of the details.  The base plate needs to be bigger, and the elevation arm can't swing down to 90˚ to take a shot straight up because of the way the camera is attached to it.  I also didn't take time to rout the groove in the elevation arm that will allow adjustment for different nodal point positions.

Canon 50D with 10-22 zoom on my plywood panoramic head.
The idea is to allow pivoting about the nodal point (white) in two axes: azimuth in red, and elevation in blue.  The green rotational axis is fixed.

Round two of the design will be a lot better.

Tuesday, August 7, 2012

Why I Love Hand Tools

There seems to be a movement going over the past several years toward hand tools, at least for woodworking.  So I'm definitely not the first to try to say this, but there really is a simplicity and elegance to taking care of a job with the simplest and most straightforward tool.  And it's not more work.  It's less.  Less screwing around trying to get the height of your dado blade just right to cut the joint you're working on, and no time or materials wasted making test pieces to run across that dado blade.  Less time is spent worrying about how precisely square your cabinet opening is.  You can cut everything a little fat and shave parts down to perfection with a plane or chisel.  You don't have to figure out how to set your miter saw to that weird acute angle, you just cut to the line with your hand saw.  And on and on.

I wouldn't expect a production line environment to benefit from most hand tools.  Jigs and big powerful machines are the way to go when you have to make lots of copies of anything.  For the artisan or home craftsman, however, you gotta love hand tools.

My first personal example is fitting tenons.  I make a lot of cabinet door frames with bridle or mortise and tenon joints.  I don't worry too much about the width of the tenons.  I cut them a little oversize on the tablesaw (with a tenon jig) or on the band saw, and shave them down to a nice fit in their particular mortise with a rabbetting block plane.  Sort of a block plane / shoulder plane hybrid.  It cuts right to the corner and shaves off a wide swath of the tenon cheek, which helps keep the surface flatter compared to a shoulder plane.

I'm currently working on a table top.  At 7' x 3', very few of us can afford a drum sander or other power tool that would take on the job of flattening a slab this size.  I've seen plans for a track system to run your router on, or I think there are baseplates for handheld belt sanders that help flatten large areas, or maybe you could rent a floor sander,  but with a jointer plane it's a straightforward process to get it extremely, accurately flat.  You may work up a sweat, but that's not a bad thing.