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I wish to take wide-angle shots (e.g. of a large building or the inside of a small room) but don't have a wide-angle lens.

What differences will I get if I shoot the scene with a narrow-angle lens (from the same position as I would have done with the wide lens) and stitch the images with Hugin or Autostitch, e.g. in terms of relative proportions of near and far objects and depth of field?

What stitching mode (e.g. spherical, cylindrical or rectilinear) should I use to best simulate a wide-angle lens?

Thanks!

  • Of course, excluding effects of changes in the scene (e.g. people moving and changing light conditions) and that the stitched image has much higher resolution. – Gnubie Jan 27 '15 at 12:24
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What differences will I get if I shoot the scene with a narrow-angle lens (from the same position as I would have done with the wide lens) and stitch the images with Hugin or Autostitch, e.g. in terms of relative proportions of near and far objects and depth of field?

The differences are those dictated by the lens. A stitched panorama typically won't have the "feel" of a wide angle lens, because it won't have the barrel distortion such a lens typically exhibits, and the DoF will be determined by the lens/aperture setting/subject distance you're using. For landscape usage, in the f/8-f/16 arena, chances are that depth of field won't be noticeably different, but stitching will sometimes create more background blur with longer lenses at wider apertures, which is why portrait photographers sometimes go Brenizer Method.

For my tastes, ultrawide and wide angle lenses tend to exhibit more "funk", while a stitched panorama (assuming a not super-wide typical landscape pano) exhibits greater "calm." One isn't necessarily better than the other but they do taste a little different.

And, of course, there's the issue of ghosts/clones with moving subjects with any post-processing method that involves combining multiple images.

What stitching mode (e.g. spherical, cylindrical or rectilinear) should I use to best simulate a wide-angle lens?

It depends on how much distortion you like, what kind of distortion you like, and the angle of view of the final panorama. Cylindrical is most likely to be your go-to if you're shooting not-super-wide landscape panoramas that are a handful of member images. Equirectangular/spherical works better if you're doing 360x180s spherical panos, but stereographic is a good place to go if you're going so wide that cylindrical and rectilinear are causing issues. Rectilinear, oddly, may be the worst choice of all for very wide panoramas, because of the extreme distortion and shape that will result (the image gets pulled into an X-like shape), and is probably only going to be good if you're shooting a small number of images with a normalish lens or using a telephoto lens. However, none of these projections is particularly good at simulating an ultrawide, because in most stitching programs lens distortion is corrected for prior to stitching, and then mapped out along one of these projections, none of which really simulate an ultrawide lens with barrel distortion. Fisheye can simulate a fisheye's equisolid mapping pretty well, but that's far more extreme than an ultrawide lens will give you.

If what you really really really want is the effect of shooting with an ultrawide lens, I'd say go get an ultrawide lens, and don't bother with panorama stitching. OTOH, you may find that panorama stitching is its own reward, rather than a mere ultrawide substitute.

  • Thanks for the detailed answer, inkista. Just a comment about "Equirectangular ... works better if you're doing 360x180s spherical panos ...": Doesn't equirectangular distort towards the edges to keep straight lines straight, so even a 180° view would be infinitely wide? – Gnubie Jan 29 '15 at 10:14
  • @Gnubie Equirectangular only keeps vertical lines and the horizon straight. Horizontal lines bend. And it isn't infinitely wide; That's the point: for 360x180s it's one of the few projections that can contain the full spherical image in a single image where you can still perceive what's what vs., say six cube faces. Most other projections, you'll lose some of the information, because the data will map out to infinity (e.g., stereographic). – inkista Jan 29 '15 at 19:19
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What you get with stitching is increased resolution, more control over the projection used, and possibly some artifacts if something moves or the light changes.

If you want to simulate what you'd get with a wider lens then you should use the rectilinear projection. You will get the same proportions of near and far objects. You will get reduced depth of field for the same f-stop (entrance pupil will be larger as you have a larger focal length), so you might need to stop down a bit more. Don't worry about diffraction, it's format independent.

If you go really wide much better results can often be obtained from a spherical, cylindrical or piecewise rectilinear projections.

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More of a comment than a proper answer but it may be insightful:

In "tight space", it can be hard to stitch photos well (distortion, leaning tower effect), a wide angle lens becomes thus easier to use a wide angle lens, which will also show the same effects (e.g. leaning towers) but give you a continuous image (no bad stitching). Panoramas can be shot in small enclosed spaces - but I recommend a lot of photos with a lot of overlap.

Once the motif is further away, for example a landscape, you have less of an issue with a "leaning tower effect" and also less distortion. Stitching well becomes a lot easier too. Here the panorama has the huge benefit of providing a higher resolution and thus more detail.

  • Actually, in smaller enclosed spaces, parallax error is the big bugaboo; a tripod and panohead (as well as a wider lens) are typically called for. – inkista Jan 27 '15 at 23:28
  • @inkista you might want to add that link into your answe – DetlevCM Jan 28 '15 at 8:45
  • Well, I don't talk about indoor panos at all, so there's kinda no place for it. :) I've got plenty of that stuff on my answer on taking virtual tour panos, though. – inkista Jan 28 '15 at 20:03
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First, it's important to note that you can get the same effect as a wide angle lens with stitched images, if you use the correct distortion (rectilinear) model. The problem with this approach is that if the images to be stitched were shot with a longer lens, the projection to rectilinear coordinates will significantly stretch the image, leaving you with lower resolution and sharpness along the corners.

To remedy this, you may have to shoot tens of photos with small angular area to ensure you have the covering you need.

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