 chrisbudny.com - Chris Budny  Contact Chris Budny Chris Budny's Gallery |
Stitched Panoramas using a rail + tilt/shift lens? Hi folks; A very specific question for you -- anyone have experience stitching multiple overlapping images into a wide panaroma under the following conditions: A) the individual images are shot with the camera mounted on a "pano rail" (to produce individual images for stitching which are free of parallax issues that would happen in typical camera/tripod rotation), I explored all of the above this weekend, and ended up with some glaring stitching errors in the final result, and I am wondering what I've missed, or what I've introduced that isn't compatible...
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- Gregory LaGrange Contact Gregory LaGrange Gregory LaGrange's Gallery |
I think your problems are stemming from using such a wide angle lens, from your description, rotating the camera up and down getting the two shots for it sounds like more vertical range. Whenever you stitch photos together, if you need to rotate the camera in any way, it's best to rotate the camera around the focal point instead of the tripod mount. And the focal point is the point that the light intersects as the image is flipped by the lens elements. Doing a stitch job by rotating around the tripod mount, all shots horizontal, is what causes the image to creep up as you try to match up the overlapping photos. And it's best to use a lens at least with the perspective like your eyes are. And the closest focal length to how your eyes are is a 50mm. The closest match would be 55mm, but nobody makes that anymore. A 50mm still has slight barrel distortion on the outer edges in horizontal way, but to shoot so that you overlap the inner 2/3 I'd say is a good place to start. Like, divide the left side and right side of the viewfinder into 3 areas (6 total) and shoot so that the left 3rd of one picture overlaps the right 3rd of the other picture. Longer focal lengths have flatter perspectives, so in that way they are easier to stitch together, but since you're trying to capture a wide scene, you usually can't fit enough in with each shot. So if you try shooting up and down and sliding the camera sideways, or even rotating horizontally, you'll find areas not aligning. And then you'll have to fill in areas or hide things so that lines aren't crooked or start to graduate in one direction. I've done a few stitch jobs using a 50mm and 100mm. I had to use the stamp tool and had to crop them to get the image to come out level enough and to get edges of things line up. But if you want to see some phenomenal, outstanding stitch jobs, look up Jean-Francios Rauzier. You may also still be able to read an interview of him on Digital Photo Pros website archive. He makes massive stitch jobs with a graduated tripod and lenses are mainly telephoto I believe. Like a 200mm. Some of his stuff is composites of real images to make a fantasy type image, but his image "New York Reservoir" is an actual scene that he put together. And he says that he to make sure he shoots everything he sees so that it's easier to fill in spots to get the image to look realistic.
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chrisbudny.com - Chris Budny Contact Chris Budny Chris Budny's Gallery |
Thanks, Gregory; still not getting BP notices when forum replies come in... I'm not actually doing any camera-rotation to achieve the added height, in this example. Just using the Shift Lens' shifting feature, to move the lens vertically (while the camera body stays fixed in place.) I'm only rotating the level camera body itself when it comes time to pan horizontally to the next segment of the scene. And then, that rotation is around a fixed vertical axis (ie, the no-parallax point, achieved with a pano-rail; so, the camera is not situated above the center of the tripod head, as it would be for taking normal shots.) In the interim since posting this, I believe I've figured out the likely cause. The stitching errors that arose, don't "look like normal parallax errors" (such as were a lamppost in the background of several frames, appears to jump and duplicate in the stitched results, relative to the foreground.) When I was shifting the lens element up, for added height via the lens-shift feature, I was not moving the sensor in the appropriate compensating direction -- ie, the step you should normally do say, if you use a Shift Lens to stitch together 2 or 3 frames, captured *only* by lens-shifting, not by body rotation. I believe that because I hadn't accounted for this, my pairs of images (a lower image + an upper image to make 1 tall "slice" of the final wide scene) had between themselves, as individual pairs to stitch to eachother only, parallax-like issues manifested *vertically*, rather than horizontally, because I hadn't in effect shifted my sensor appropriately to a Tilt-Shift lens. It is a hard thing to write out, so I'm not sure if I'm explaining my theory well! Basically, if I stitched all the lower-only images captured from the outing, they stitched very well. If I stitched just the upper-only images from the outing, they stitched fine. BUT, when I stitched each single pair (upper+lower) into a single image -- and then stitched those resulting neighbors together, the errors showed up. Anyway, since I do not yet have proper vertorama hardware in my kit (to mount a body at the no-parallax point for both horizontal and vertical body rotations), I will stick to 1-row panos, with my 17mm TS in Portrait orientation... phew. ;)
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- Gregory LaGrange Contact Gregory LaGrange Gregory LaGrange's Gallery |
Think I get what you're saying after reading up a little on panos done with a tilt and shift lens. The article I read using a t&S lens used a stitching program to put all the photos together instead of doing it by hand. But there were some questions in the comment section about whether it was better to move the lens and keep the body still or keep the lens still and move the body.
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chrisbudny.com - Chris Budny Contact Chris Budny Chris Budny's Gallery |
I use the automated stitching tool built into PS, for my stitched panos so far. It does a fine job (at least, when I'm not trying these doomed-from-the-start double-height tilt-shift combos.) What would be awesome with the tilt-shift lens, is if it had a lens collar with a tripod mount, located up near the front of the lens... like the collars on big telephotos. Then you could mount the lens to the tripod using that collar mount, and when you used the lens-shift knob, you'd actually be moving the camera body (in relation to the fixed front of the lens)... I do get the "perfect" stitching results every time, when making a 1-camera-position pano with the 17mm TSE... Shooting in landscape-orientation I'd take 2 exposures of a single scene (introducing no camera body rotation at the tripod.) The first capture is the left side of the larger image circle available inside the camera, and the second capture is the right side; using just the +/-12mm sideways-shifting available on the lens body. Yet to do that properly and prevent parallax issues in that pair of captures (even though there's no camera rotation) you need to shift the lens left 12mm (using the lens-shift knob) then slide the entire camera body (within the mounting clamp at the tripod head) 12mm to the right -- this brings the front of the lens back to the central starting point, with the end result that the sensor has now moved 12mm from its 'starting point' in order to capture more of the extra large image circle available inside the camera.) Then repeat the pair of movements in the other direction, to capture the "other side" of the image circle. The 2 resulting captures stitch together flawlessly, whether by hand using Layer masking, or using stitching software. But -- I can't do those necessary dual movements in Portrait-mounted camera orientation... yet. ;) Someday my pano gear will include the necessary vertical support bar, second pivot head and what-not, to do multi-row stitched panos...
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- Gregory LaGrange Contact Gregory LaGrange Gregory LaGrange's Gallery |
I guess shifting the lens left and moving the body , and then doing the opposite keeps the focal point of each image at the same spot so the results go together so smoothly. Since it works in landscape but not portrait, maybe the difference is that regardless of what you're shooting landscape, you're shooting from the middle. You shift left, and then shift right, you stay in the middle. But doing a building, to keep the errors from coming up, you'd have to orient yourself to shoot from the middle of the building.
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- Gregory LaGrange Contact Gregory LaGrange Gregory LaGrange's Gallery |
Check out this stitch job https://www.youtube.com/watch?t=177&v=udAL48P5NJU
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