This is not a post about the aesthetics of the image set up, or a post production tutorial, but it is a shooting stage checklist to help ensure the images stitch successfully.
- Exposure. Do multiple meter readings, across the entirety of your sweep and decide on the best combination given the scene you are about to capture. When doing multiple frame stitches there is often a large dynamic range present across your scene. Shoot in manual so that your exposures remain consistent through out. Not only does this help with the stitching, but it also makes the image look uniformly better- no alternating light and dark washes across the image.
- White Balance. Get out of Auto White Balance (AWB). Either dial in your own preset or pre determined WB setting or choose one that will work for you. White balance assumes that neutral white light is best and so tries to eliminate all other conflicting colour casts. As you sweep across your scene taking a number of images, the light changes, as does its colour temperature. Leaving your camera set to an AWB setting will mean variations in colour casts will be evident across some/many/all of your frames. Similar to above, but with colour washes instead.
- Image Stabilization. This is not necessarily specific to doing stitched panoramics, but any time you are shooting off a tripod make sure that your lens IS/VR/VC/OC (image stabilization/ vibration reduction/ vibration compensation/ optical stabilizer) is switched off. Leaving it on will induce camera shake and resultant blurred images.
- Fix your focus. Keep your focus constant. Make use of your hyperfocal distance to maximise depth of field if necessary. Allowing your camera to refocus between shots may alter the area covered by depth of field and if it doesn't cause your stitch to be thrown out by the editing software altogether, it will cause ugly blurry areas in certain areas of your image.
- Fix your focal length. Whilst some image editing software can still stitch or compensate for lens distortion it is often easier, if you have the room, to minimize distortion at the capture stage. This means shooting at 50mm if you have a full frame sensor, or its equivalent if you don't (normally around 35mm for most sensors). Shooting for a 'non-distorted' series also minimzes undulating horizons which are suspicious and a giveaway for poor shooting and therefore stitching. Fixed focal length has the added benefit of more accurate composition. You can also correct for lens distortion at the post production stage too.
- Overlap each frame by about 1/3rd. Stitching software works best with an overlap on each frame of about 1/3rd. If you are careful, about a 1/4 is sometimes better. The overlap gives the algorithms something to chew on and will help ensure they spit out a decent stitch.
- Shoot portrait, not landscape. The algorithms used to correctly match pixels work best when they can build up a bit of a stride. The long axis of the frame helps with this and gives the stitch a greater and more importantly, longer surface area to work along.
- Keep your horizon level. It goes without saying that shooting off a tripod is very preferable, not only because it helps by keeping the camera steady, therefore minimizing camera shake, but also because skew horizons are even less forgiving on a stitch.
- Make global adjustments across all of your images at the post production stage prior to stitching. This way you will not reintroduce colour and/or exposure changes between images that you have worked so hard to avoid by sticking to the above points. Rather stitch the image then make localised adjustments.
- Previsualise and be methodical. Look with both eyes and 'see' the completed image. Don't just shoot a bunch of frames and think you will decide on the exact composition later by doing a post production crop. You will neaten the image up with a post production crop anyway but invariably what would have been your 'perfect frame' has a chunk of sky missing or not enough tree on the left etc. Think through the dominant elements in your frame and compose them. You'll avoid awkward central dominance and visual imbalance.
So to sum up: BE CONSISTANT! Be consistent in the taking of the images and be consistent in how the images are captured. Consistency is king when it comes to stitching!