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# photography nerdity: (federate.social)
submitted 1 year ago by to c/photography@fedia.io
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#photography nerdity:For much of my architectural work especially, I often create high resolution "stitched" composites made of multiple captures of different parts of the subject.Modern image software (like Capture One and Photoshop) make this fairly easy and seamless, but the technique and equipment you use to create the individual captures can have a significant impact on the quality of the result. The main idea is require the software do as little geometric work as possible.1/

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[–] [S] 1 point 1 year ago (30 children)

Basically, the more the perspective changes among the components, the more geometric transformation the software has to do in order to line up the edges to tile them together. Any transformation comes at the expense of resolution and distortion of other parts of the final image.So the first thing you want is a tripod placed in a single position to make the component captures. That's essential - but still not completely sufficient - for maintaining a fixed perspective3/

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  • [–] [S] 1 point 1 year ago (29 children)

    Once you've selected where the tripod goes, the simplest thing to do is pan and tilt the camera on the tripod head between captures, pointing it at different areas of the subject such that there's some overlap between captures.For best results, this must be done with the camera mounted on the tripod head in a way that the tilting and panning pivots around the central "nodal point" of the lens. Otherwise, the camera is effectively moving its position, even if the tripod itself isn't.4/

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  • [–] 1 point 1 year ago (1 child)

    @mattblaze Is the nodal point where all the light converges before hitting the mirror/sensor on the other side as an inverted image? It's hard to describe with words what I mean, but that's kind of what mentally makes sense to me as the point to choose to rotate around.

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  • [–] [S] 1 point 1 year ago (26 children)

    Finding the nodal point can be tricky. There are special rigs for this that move the camera on the tripod head to make this easier and more systematic and repeatable.But even with the panning and tilting done at the exact nodal point, the software still has to do considerable, resolution eating, transformation. To create a rectangular final image, each component has to be stretched at one edge or squeezed at the other, murdering pixels in the process. But results can still be pretty good.5/

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  • [–] [S] 1 point 1 year ago (25 children)

    To avoid having to do any transforms at all, you need to capture the component images without moving the camera AT ALL. No panning, no tilting.But with most cameras, that would mean every component would be of exactly the same image. There'd be nothing to stitch together!Enter the "technical camera", which is what I generally use for making stitched images.6/

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  • [–] [S] 1 point 1 year ago (24 children)

    A technical camera provides internal "shift" movements that move the sensor (or film) with respect to the lens. That is, the lens (which is what determines perspective) stays in one place, but the sensor (or film) can be moved left, right, up, or down.This effectively moves where the center of the captured image is. So if you make one photo, then shift the sensor to the left and make a second, the two photos together capture a "wide" view of the subject but with no change in perspective.7/

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  • [–] 1 point 1 year ago (2 children)

    @mattblaze I was going to ask why not moving the camera in a plane, I guess this is easier (for values of “easy” that are not easy at all)

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  • [–] [S] 1 point 1 year ago (19 children)

    Technical cameras are specialized devices, and they need special lenses that can "cover" - project an image onto - an area larger than the sensor (to allow the shifting). All this is makes everything bigger, heavier, and more expensive. But they allow for making stitched composites without reducing the resolution or distorting geometry the way you'd have to when you capture the components by panning or tilting the whole camera.8/

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  • [–] 1 point 1 year ago

    @mattblaze Layman question. I understand the idea, my first thought was, why not "just" make the sensor bigger, filling the space that the smaller sensor could move/shift to and then "just" not use the whole sensor for all the captures? Or are bigger sensors more expensive the a smaller one with some motors to move it?

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  • [–] [S] 1 point 1 year ago (17 children)

    I generally use a Phase One (medium format) digital back on a Cambo "WRS" camera for making my stitched images. This system provides a fair amount of room for movements.But there are less expensive and cumbersome alternatives. For 35mm-format, both Canon and Nikon make a few "perspective control" (sometimes called "Tilt/Shift") lenses that can be used for this technique on an existing DSLR or mirrorless camera.9/

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  • [–] 1 point 1 year ago (2 children)

    @mattblaze I've noticed that most (all?) of your images are monochrome. Do you do anything special with filters or image sensors for this, or are you just capturing raw full-color images and flattening to monochrome in post?

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  • [–] [S] 1 point 1 year ago (1 child)

    @wordshaper I have a monochrome sensor, but I hardly ever use it except for special circumstances. Mostly I use a color sensor and filter in post.A monochrome sensor has some benefits. The lack of a color Bayer filter means the images can be a bit sharper, and it's easier to make captures in the IR spectrum. But using a color sensor lets you do all the color contrast filtering in post rather than optically with colored filters at the time of capture.

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  • [–] [S] 1 point 1 year ago (13 children)

    The 35mm shifting lenses aren't absolutely theoretically ideal for this, because they generally shift the lens rather than the sensor when the camera mounted on a tripod. But the change of perspective between captures is very small, and barely an issue in the final result. And they provide a much less expensive alternative to a full technical camera system.If this sounds fun, I suggest renting a shifting lens and playing around with the technique.10/10

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  • [–] 1 point 1 year ago (6 children)

    @mattblaze On a technical camera can’t you also move the plane of the lens as well as the back, to effect the shift. Are there advantages or disadvantages to moving, one or the other or both?

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  • [–] [S] 1 point 1 year ago (5 children)

    @Sc0tty generally you want to move the back to avoid disturbing the perspective. But, depending on the camera, you can move either, often in opposite directions, to achieve a greater amount of shift.

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  • [–] 1 point 1 year ago (4 children)

    @mattblaze Thanks now you’ve said it, that makes sense. Otherwise could get very ‘slinky’ !

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  • [–] [S] 1 point 1 year ago (3 children)

    @Sc0tty now, I should also mention tilt, another movement in which you move the lens and the sensor planes out of parallel alignment, to control focus. There, the general rule is to shift at the rear, and tilt at the front.

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  • [–] 1 point 1 year ago (2 children)

    @mattblaze Presumably then that would allow for ‘corrections’ to compensate for non optimal camera position

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  • [–] [S] 1 point 1 year ago (2 children)

    Related: Shift is also (more often) used to maintain geometric accuracy in certain subjects even in non-stitched images. It's the secret weapon of architectural photography. Here's a little thread I did on it a while back.federate.social/@mattblaze/112

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  • [–] [S] 1 point 1 year ago

    Also, whenI use the term “quality” here, I’m using it a strictly technical sense to refer to the fidelity of the image, not the aesthetic qualities of the image. I very much dislike this usage, but it’s fairly standard in discussing this stuff.

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  • [–] 1 point 1 year ago

    @mattblaze Thanks for the great thread!During my conscription (in 1980) I learned by myself how to use the Linhof 8×10" of the military school, without any clue, just making experiments.But since film was expensive, I often had to resort to thin tracing paper :blobfacepalm: on the film plate to make correct drawings of devices for manuals (to make them was my "official" duty).

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