Photography News issue 24

Technique 30

Photography News Issue 24 absolutephoto.com

Shooting for a perfect stitch

3

It’s important to consider that, unless you’re using a panoramic-format camera, or one with a ‘sweep panorama’ function, you’re recording the raw materials to stitch your pano later. This isn’t a natural feeling when you’re used to perfecting a scene in one go, but you just need to get a series of images that are as level and distortion-free as possible, along with a good amount of overlap in them for the software to work with. Serious panoramic photographers use special tripod heads for their images, but you can usually get away with shooting from a regular tripod. The only time you may run into trouble is when you’re shooting with a very complicated foreground. Don’t shoot with too wide a focal length; it’s natural to want to do this for landscapes,

but if you’re shooting at something like 16mm you’ll add a lot of distortion which becomes obvious in the stitch as bowed, wavy lines. A focal length around 35-50mm is more fitting and although you might shoot more frames that way, the increased quality is worth it. Keeping level is best done by panning from a tripod and using a bubble-level or your camera’s electronic level (if it has one). If you’re hand-holding, an electronic level is useful, but you can use the lines or AF points in the viewfinder too; align one of them with the horizon to make sure you’re following it. Go for around 30-50% overlap of the frame and to help, pick an object at the edge of the first frame and make sure it’s in the middle of the next and so on.

More frames, more quality Shooting at Cwm Idwal in Snowdonia, Kris Williams shot 12 vertical frames for the panorama above. The more overlap there is, the easier the pictures are to stitch and finally a crop can be made to refine the composition.

4

Turning heads for better shots

Each lens has an entrance pupil and once the point of rotation is locked to this everything will align

For the most distortion-free results, especially when dealing with scenes that have complex foregrounds or other close-up details, like architectural interiors, you need to be aware of parallax errors – and how to deal with them. Parallax errors occur when the camera’s line of sight changes in relation to the subject. So, for example in one shot a foreground rock might line up with a part of the scene in the mid-ground or distance, but alter the angle of the camera in the wrong way and it will no longer be aligned, its relative position having changed. Close one eye and hold your thumb up against something in the distance; then look at it through other eye and you’ll see how even a shift of 6-7cm in angle can throw things off. Like other distortions or changes in exposure, this causes problems with the stitching process later. To fix the issue you need to keep the line of sight consistent, and doing that means turning the camera through the sequence of shots on a particular axis based on the ‘entrance pupil’ or ‘no parallax point’ (NPP). Each lens has an entrance pupil and once the point of rotation is locked to that, everything will align. Sticking to the entrance pupil however, is quite tricky, because it differs on each

lens and at each focal length – that’s where panoramic tripod heads come in. These heads make it much easier to lock the camera’s rotation to the entrance pupil, by positioning it on a sliding bar. The entrance pupil is then calculated,

usually by taking a couple of test shots until a foregroundand background element

are aligned. Once you’re used to doing it, it doesn’t take long. Panoramic heads are an additional expense, but one that’s definitely worth it if you’re going to be shooting in this format. Take a look at heads from manufacturers like Nodal Ninja, Panosaurus, and Manfrotto, which cover a wide range of budgets and specifications. Heads youwin If you’re serious about panoramas, investing in a dedicated panoramic (or VR) head can make all the difference, allowing you to shoot more complicated scenes without parallax errors. Pictured here is the excellent Manfrotto MH057A5 Long Head, which you can pick up for around £350.

The no parallax view Changing the camera’s shooting position, as you’ll

naturally do even by a fewmillimetres when turning through a scene, leads to parallax errors. Herein, one shot will see that a close object will line up with a distant one, but in the next shot they will then be misaligned. But by rotating around the lens’s entrance pupil you can make sure that everything lines up perfectly.

www.photographynews.co.uk

Powered by