I have been using this string-pano-head for years (since sometime in 1998) however credit for the term "Virtual Panohead" should go to Philippe Hurbain, who not only have created a fantastic tutorial for this process on his website, but also have a tutorial for photographing arial p,anoramas, he is truely a outstanding photographer and creator of technical solutions.
Once you read this text, I suggest taking a look at my video about the same technique, it will help you understand how to do this easy panorama solution. Click to see video.
Naturally process this does not replace products such as the Kaidan panoheads, or my travel bracket for spherical panoramas. But it does allow you to capture a panorama in a pinch. And that is what counts... Right...?
When photographing multible images for stiching later in a software program, the most important part is that the images are all taken the same way, with a level camera, and maybe most important, captured while rotating the camera around the nodal point of the capture lens.
When you use the travle pano barcket, it will fix the camera vertically and lock the rotation around the nodal-point, the result is perfect captures which stich very easy. However while holding a camera by hand this gets a little more tricky. we need to ensure 3 things happens correctly at the same time. first the camera must be perfectly level, then it should be at the same height over the ground as the previous exposure, and finally it should be fixed to a hodal point rotation.
This is how this is done, first you need to get a two way bubble level from your local camera dealer, it is a clear piece of acrylic which ahve two bubble levels inside, you mount this sideways in your cameras hot shooe. By holding the camera at about chest level you can see both levels from above and when both levels are centered the camera is level and ready to capture the image, second we need to have the camera at a fixed height, you do that by tying a string around the lens with a small weight at the end, the weight should barely clear the ground, then you know that you have the same height for all the exposures. Finally to make sure you are actually rotating the camera around the nodal point, you place the string in the appropiate nodal point for the lens you are using, place a coin on the ground and then keep the weight on the string centered over the coin. Now you know that your camera are not drifting sideways, it have the same height for each image captures and it is level both ways for each image so that they will stich easily.
There are two relevant nodal-points on the E-10 & E-20 cameras, the one is if you use the build in zoom lens, set to 35mm (as wide as possible), the other is when using the Olympus add-on lens giving you effectively a 28mm lens. when using the add-on wide angle you place the string right in front of the flange for the lens-hood. When using the 35mm build in lens, you place the string right behind the focus ring.
for the E-10 and E-20 nodal-points.
My panorama from Nui Bay in Thailand was captured using this technique, and it a typical exsample of realizing that I should have brought a tripod and a pano head....
Getting the most out of your frames
Most of us who are interested in panorama photography have at some point shot panoramas "straight handheld", and the results probably came out very nicely. So with that in mind what is the point in going through the hassle of using a bubble level and a plum-bob to level the camera and fix the position of the rotation..?
More vertical field of view. Keeping the camera level at the same angle between each exposure will give you more vertical field of view, this is because final panorama image requires image all along the image, so if one image is out of alignment it will also reduce the vertical field of view. This makes a big difference when printing images where we always like to have them fill the paper as much as possible. also when putting them online as a interactive panorama it allow the viewer to look more up and down in the panorama.
Getting the most from your digital camera
One problem with most digital cameras are the limited wide-angle lenses available, because of that it is critical to keep the camera perfectly level when photographing the panorama, to prevent jumbled frames which will reduce the vertical field of view resulting from a already limited lens. However it is also worth understanding the nature of the stiching software. The pictures are captured "flat" rectalinearly by the camera, and they would not fit together if printed and simply taped together. Because of this the software distort the images by squessing the edges on each side of the images. When stiching the result is kind of the same as if you had jumbled frames, the software will trim the final panorama along the deepest pits and throw away everything outside of that. You can preview what you will really get in your panorama by looking at the corner of the frames, they are going to be the limit to what you can see vertically. I often are excited to see how much I can see in the center, but when I turn the camera I realize that the fov is not as much as I had hoped for.
One way around this Field of View robbing distortion problem is taking more images, instead of over lapping app 1/3 try something like 2/3 or 3/4 overlap, this will add a lot to the top and buttom of the panorama. Normally 12 frames will get your around 360 degrees, however you will get more field of view by photographing 18 or 24 frames. Another advantage is that the stiching software will be able to match the images together better, because there are less distortion in the center of the frame, which means that you will get less problems with things which normally causes problems such as tiles on the floor, brick walls, and branches close to the lens.
Stiching the images into a Panorama
Once you are done photographing you should have a series of images which covers either a partial panorama or a complete panorama. The easiest way to put them together is using a software application created for this purpose. Currently my favorite for web panoramas is "Photo Vista" from MGI Soft, it is VERY easy to use, inexpensive, and delivers great results. The software stiches from left to right, so it is easier to use if you photograph rotating from left to right, this allows you to import the images in one move, however you can also import them one at a time if you photographed the other direction.
Another excelent panorama software is the Panorama Factory created by John Strait. This is shareware and will cost you $35.
Finally one of the most advanced image stichers on the market is Freeware, but it is positively for experts. It is called Pano Tools and are created by Helmut Dersch in Germany, I can highly recomend this tool which allows the user to do much more than just stiching images, it also allows you to unwrap fisheye images into panoramas and many other things.. You can buy a graphical user interface called PTgui which makes it a lot easier to work with Pano Tools.
- Probably the very best stitcher on the market. Highly Recomended
by Bo Lorentzen All Rights Reserved