Pano-Vision, Part 1

“Whatever story you want to tell, tell it at the right size.”
  -Richard Linklater

Making infinitely large prints with infinite detail is one of photography's holy grails. My 2007-vintage DSLR has a 12.8 megapixel sensor, not large by early 2011 standards. It's a “full-size” sensor, the same size as a frame of 35mm film. With my printer and the resize/resample tool in Photoshop® I've been able to make high-quality prints as large as I've wanted, typically in the 17 x 25-30 inch range. With other specialized software for “up-rezzing” digital files, I could certainly print larger with acceptable results. My printer is limited to 17 inch wide paper, but I could farm out larger print jobs or (more likely) replace my printer with a 24 inch model, something I'd like to do next year anyway.

Cameras newer than mine have much higher pixel counts, improved processing power, and more capable noise reduction software and circuitry. Assuming these are quality pixels and good shooting technique is used, larger, high-quality prints are possible. With medium-format film or digital capture, one can print ridiculously large with stunning detail. Of course, digital MF equipment prices are breathtakingly high and beyond the reach of many of us.

Not all pictures should be printed large. Some subjects seem to look more natural when printed at smaller sizes. An entomologist might enjoy a six-foot wide print of a green lacewing larva; it's not something I'd be comfortable exhibiting on my walls. But shooting for a large print opens new areas for experimentation, new ways to be creative. This is true for the grand scenic, but it can also be true for more intimate scenes and even macro work. One way to do this is to shoot mulitple frames while panning across the scene or subject, and then “stitch” those frames into a single image in the tens or hundreds of megapixels range. Although my printer is limited to 17 inch wide paper, it can print very long images from roll paper.

Part one of this article focuses on the hardware I use when capturing frames to assemble into large images. In part two I present some images and relate the stories behind them.

Big on a Budget

Shooting multiple frames for stitching can be done very simply by hand-holding the camera and sweeping it across the scene while making overlapping exposures. Some digital cameras have a panorama mode intended to be used in exactly this way. Better results are likely if a tripod is used, along with a panning head or base (many tripod heads have an integrated panning base). The tripod would be set up and the camera made level so the horizon, or other elements in the image, remain straight and level as the camera is panned. This arrangement puts the axis of the pan at the film/sensor plane, which will, with many lenses, introduce parallax error. The stitching software will attempt to correct this. The photo below was made this way.

Parallax error can be minimized by using a nodal point slide, an adjustable rail installed on a panning base or tripod head. The slide rail allows adjusting the position of the camera so the entrance pupil of the lens (often called the nodal point), rather than the camera's focal plane, is centered over the rotational axis (the tripod head). When shooting, the pan is centered on the nodal point, reducing parallax problems. This is a good set-up for single-row panoramas.

For multi-row panoramas the rig requires additional components so the camera can be tilted upward and downward. With this, the complexity (and weight!) of the rig increases, and the cost of the system may begin to strain the budget. But with a little practice one can get excellent results fairly easily.

One can push the limits, and increase the cost, by using tilt-shift lenses. In a sense, such a set-up makes a digital SLR into a medium- or large-format digital camera.

If money is no object, one can also consider equipment in the Gigapan® category. These are heavy-duty panning systems, sometimes motorized and partially automated, for multi-row panning for very large, often “full surround” images.

Descriptions of all these options can be found on the Web, along with instructions for properly setting things up. I've included some links at the end of this article.

Dad Solves Another Problem

I've made the occasional panorama either by ignoring parallax error, using no specialized equipment and hoping the software would deal with it, or by shooting single-row panoramas using a nodal point slide. I made this slide from part of an old Topcon® bellows I'd owned since the 1970s. Since I no longer have the Topcon cameras and lenses, this seemed a good way to get some use from and old piece of kit that had been packed away for a couple of decades. It worked well enough, and the price was right. Because I didn't have a quick-release clamp on the rail I could only mount the camera in the landscape, or horizontal, orientation. This resulted in panoramas that were wide but with minimal height. I was never very happy with those; I felt limited by the equipment, unable to capture some of the scenes I envisioned.

To remove that limit I'd need more complex gear. I don't shoot a lot of panoramas; I can't justify the substantial investment for commercial equipment. Instead I made some sketches of the parts needed to build a multi-row panorama rig. It would incorporate the Topcon rail, and use a quick-release clamp so I could mount the camera body, which has an L bracket, in either landscape or portrait orientation. My Acratech® Ultimate Ballhead has a panning base, so it would not be necessary to build one of those.

I sent those sketches to my dad, a retired machinist who keeps a nice shop in his home in Ohio. Always happy to take on a challenge if it involves cutting metal, Dad set to work. He's very good at taking my terrible sketches and half-baked ideas and turning them into workable designs, documented well enough so they can be produced. He then makes the necessary parts, machining aluminum, steel, and plastics per the specifications in his drawings.

As usual, Dad did a terrific job. Shown here is the completed panorama setup, including the leveling base and ball head, quick-release clamps, Topcon rail, and the parts Dad made. The clamp immediately to the right of the camera body, and the L bracket on the camera, allow attaching the camera either vertically or horizontally.

As of spring, 2011, we are working on a minor modification, but the rig is perfectly usable as-is, and I've been having a good time with it. When the revision is done I will polish the aluminum parts and send them off to be anodized (black). This is a coating that looks nice, but more importantly is extremely hard, making the aluminum parts more durable and cleaner to handle.

A Brief Customer Service Story

I've used my Acratech Ultimate Ballhead since 2002 and have been delighted with its light weight, durability, and impressive design. My gear doesn't come close to the head's published weight capacity, so I've never stressed it. The quick release clamp included with the head is a nice, compact design; I wanted to use it on the pano rig, but I was unable to remove it from the head's ball stem. Rather than risk damaging the head, I contacted Acratech for help and had an e-mail exchange with Chrys. I was told to send the head to Acratech; the clamp would be removed, and the head would be cleaned and repaired to make it “almost like new”. I take pretty good care of my gear; as far as I could determine, the head needed no repair. But I wanted the clamp removed, so I sent in the head. Eight days later it was returned. The clamp had been removed as expected. Because of a slight difference in finish it was clear every part had been replaced except the main "frame", or body, indeed making the head like new. There was no charge for this. They even included some brass bushings to adapt the 1/4-20 screw used by the new clamp I'd chosen (from an Acratech competitor, no less) to the 3/8-16 thread in the stem of the head's ball.

I'm not sure what this is, but it's something well beyond customer service. Thank you, Acratech!

Level Headed

Setting up the pano rig is fairly simple. When I determined the nodal point for my short zoom lens at various focal lengths, I printed a chart. I refer to this when setting up, and adjust the Topcon rail as needed. I've found the most difficult aspect of setting up is getting the tripod perfectly level. The setup must keep the camera level as it is panned through the entire scene. Uneven or rocky terrain, sand, ice, or snow can make an ordeal of leveling the tripod. I have a level on the camera and also on the quick-release clamp. At times it's maddening—the wind is blowing, my fingers are freezing, and I'm screwing around adjusting tripod legs to get the camera level. Even in friendlier conditions getting things level can be frustrating. A leveling base, installed between the tripod and the ballhead, is the solution to this problem. The tripod can be set up in any stable arrangement; no need to be concerned with getting it level. The leveling base is then adjusted to center its bubble level. This takes seconds. Several companies make leveling bases. I liked the design of Acratech's, in part because of its light weight.

I mentioned this to Dad as I was describing my use of the pano rig and the frustration of trying to level the setup. I said I planned to get the Acratech leveling base someday. About a week later UPS left a little box on my front porch. Inside was, of course, the Acratech base, with a note from Dad. He simply wanted my rig to be perfect, and figured this would help. It was a wonderful surprise and a bit of a shock. Months later I still smile when I think about it. I leave the leveling base on the tripod. It's weight is not significant, and it's quite useful whether I'm using the pano rig or not.

The Proof is in the Panning

In part two I present some large images, mostly wide panoramas, and describe the shooting setup for each.

More Information

Below is a list of links to articles about shooting panoramas, finding the entrance pupil of a lens, and links to equipment-makers' sites. As always with a list of links, these sites may change or disappear over time, breaking the links. If you find a broken link, please let me know. You can always use your favorite search site to find more information.

March, 2011

All products and brand names mentioned are trademarks or registered trademarks of their respective owners. I've done my best to get all the ® amd ™ symbols in the right places, but I can't guarantee the correctness or completeness of this effort.