Panomundo

3D Photography by Brian Greenstone, Austin TX

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HOW TO: The Process of Making a Pano

Section 3: Shooting the Panorama

Setting the Camera Mode

To shoot good panos you must use a camera that can save in RAW (digital negative) format. JPEG compression artifacts get amplified during the pano morphing process, so you need to use a lossless RAW format. Additionally, RAW images have not been modified with white balance, saturation, sharpness, etc. This is critical to ensure that each shot in your pano was exposed the same. Even if your camera can save as TIFF, this won't work well because the TIFF images will be white balanced independently which will cause you problems when you stitch. We'll cover this in further detail in the next section, but for now be sure to set your camera to RAW mode.

So, set the camera into full Manual Mode. Manual aperture, manual shutter speed, manual focus, etc., and be sure you're saving as RAW.


Setting the F-Stop

You should run tests with your lens to determine which f-stop gives you the sharpest images. While higher f-stops will theoretically give you the best depth-of-field (keep more of the image in focus), higher f-stops can also have some unwanted side effects with fisheye lenses. Light coming in through a tiny aperature (high f-stop) on a fisheye lens tends to have trouble due to the steep angles that the light is coming in at. This varies from lens to lens, and on some lenses f10 might be the sharpest, while on other f4.5 may be the sharpest. Most people I've talked with tell me that f4.0 to f5.5 is the best range for their lenses, but in some tests I've done with my Sigma 8mm, f8-f10 gives the sharpest results. See what works best for you.


Setting the Focus

Always use manual focus. Fisheye lenses have a huge depth of field which means that you really don't have to do much focusing to keep the entire scene in focus at just about any f-stop. There is a great web site here which lets you calculate the depth of field of any lens at any f-stop:

The bottom line is that if you set your focus to anywhere from 3ft. to infinity your entire scene will be in focus. On the Sigma 8mm, the focus ring shows 3ft. and Infinity with no sub-markings between them, so I usually set my focus right in between there:


Setting the Shutter Speed / Exposure

When shooting RAW, you have the ability to adjust the exposure later in Photoshop without losing any image fidelity, so this gives you some latitude in the choice of exposures. What I typically do is to set the shutter speed such that the camera reports an exposure value of +/-0EV for most of the shots around the scene. Some shots may be -0.3EV and some may be +0.3EV or even more. But so long as the average is around 0.0 then this can be tweaked in Photoshop later if it isn't quite right. Just be sure that the exposure is the same for all of the shots in the scene!

Sometimes, however, exposure isn't a constant. This happens when you're shooting outside and there are fast moving clouds. You might shoot your first shot when there is direct sun, but then by the time you shoot the 3rd shot a cloud has made everything darker. If you're patient you can just wait for the sun to come back out, but if you're in a hurry then you can still take your shots since most of these exposure discrepancies will be worked out during the stitching process later. It's always best to have constant lighting, but your pano won't be destroyed if it isn't. For example, take a look at this pano that I shot:

In the above equirectangular image, the clouds were not cooperating for me, and you can tell that at least one of the shots was taken when a cloud blocked the sun because it shows up as a dark smudge in the pano (that dark area in the middle on the bricks). You probably wouldn't have noticed anything wrong if I hadn't pointed it out, and in the actual VR pano it's almost impossible to notice it unless you're looking for it. This is typically what happens with inconsistent lighting, so as you can see, it's not the end of the world. However, in some cases the sun casts shadows and if a shadow disappears when the sun goes behind a cloud that can cause a major stitching problem later. Just one of the many joys of shooting panoramas!


Taking the Shots

In scenes where there isn't much of anything moving in the background I typically shoot 4 shots around with my Sigma 8mm. That gives me ~20% overlap from shot-to-shot which is adequate for aligning control points. However, if there are lots of people or other things moving around then I'll sometimes shoot 6 or even 8 horizontal shots which gives me a more overlap so that I have more data to work with to fix areas where people moved across seams in the pano.

The Zenith shot is easy - just tilt the camera up 90º, duck down, and shoot it.

The Nadir or down shot is not necessary with an 8mm lens. An 8mm fisheye lens is wide enough to even capture the tripod in the horizontal shots. You only need to shoot the nadir shots if you're using the Nikkor 10.5mm or a longer lens. Tilt the camera straight down and shoot the shot. Then spin it 180º and take another nadir shot. Two nadir shots allows you to cover the area of the floor where you were standing when you shot it.


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©2005-2009 Brian Greenstone