Arca Budgie Sony A7-series Shift-and-Stitch Adapter

prusaprinters

<p>Use your full-frame Sony E-mount (FE) body to capture images up to 48x36mm -- generously larger than the 44x33mm sensors people are often calling medium format. I argue that's really best considered as <i>multi-aspect 135 film (35mm)</i> format for getting the largest possible coverage sampling using a designed-for-full-frame lens.</p><p>Budgie is an adapter for Leica M to Sony FE -- except it does offset shifting and, unlike the original version, includes an <strong>Arca-Swiss compatible</strong> mount as well as 1/4-20 threaded mounting holes. The Budgie name comes from the idea that the camera can be budged +/-12mm relative to the mounted lens to capture multiple images for stitching. The diagonal of a 36x24mm full frame is approximately 43.27mm. However, that's with the standard 3:2 aspect ratio. In 1:1 (square) format, <strong>a lens that can cover that diagonal also should be able to cover a square with approximately the same diagonal, which would be 30.59x30.59mm</strong>. In infinity:1 (the limit on panoramic aspect ratio), <strong>a lens covering that diagonal should be able to cover 43.27x0mm</strong>. In other words, all aspect ratios are contained within a 43.27x30.59mm capture rectangle -- which easily fits inside Budgie's 48x36mm space. Very few full-frame lenses will produce high-quality coverage of the full 48x36mm capture space, but quite a few will cover more than one would expect; for example, most lenses I've tried can cover a 36x36mm square image. In any case, using a 42MP body, such as the A7R II, stitching two (or better, three) shots will get you an approximately 48x36mm stitched image with about 84MP effective resolution. If you have a body like the Sony A7R IV, combining this with the camera's "pixel shift" will give up to 482MP of image detail! Of course, the image stitching software might give you any number of pixels, but the point is that you can get that medium-format look using your existing full-frame camera and lenses.</p><p>Why Leica M? For the same reason the TechArt Pro LM-EA7 uses it: nearly all old lens mounts can be adapted to Leica M, so this adapter is reasonably universal. For example, to use a Canon FD lens, simply mount a Canon FD to Leica M adapter on this and then mount your FD lens on the front. Not only are lots of adapters commercially available, but I've also designed and posted free 3D-printable M adapters for: <a href="https://www.thingiverse.com/thing:3095199">Argus C3</a>, <a href="https://www.thingiverse.com/thing:1730319">Minolta/Konica-Minolta AF / SonyA</a>, <a href="https://www.thingiverse.com/thing:1727361">Canon FL/FD/FDn</a>, <a href="https://www.thingiverse.com/thing:1719685">Minolta SR/MC/MD</a>, <a href="https://www.thingiverse.com/thing:1708739">M42</a>, and <a href="https://www.thingiverse.com/thing:1706976">Kiev 10/15</a>.</p><p><strong>Notes:</strong> This is the sixth major version of the Budgie adapter. There are really just two new features: (1) the addition of an Arca-Swiss compatible mounting foot and (2) a move away from metal-screw sliders to fully 3D-printed ones that get welded in place after printing. The welding is quick and easy using a soldering iron, and it actually works better than screws because the screws tend to loosen with use.</p><p>Also note that, although you could use Budgie with an APS-C E-mount body, the result couldn't be larger than about 39.6x23.6mm. Thus, for APS_C, it's probably more interesting to use <a href="https://www.thingiverse.com/thing:4880226/">APSC2</a>, which also uses full-frame lenses with an M mount, but captures four offset-rotated shots, giving an image of approximately 30.6x30.6mm.</p><h3>Printing</h3><p>There are actually five parts in Budgie:</p><ul><li>20220730me.stl -- the E-mount part</li><li>20220730mm.stl -- the M mount (and most of the adapter, including Arca base)</li><li>20220730mwtop.stl -- the top connector to weld into place</li><li>20220730mwbot.stl -- the bottom connector to weld into place</li><li>20220730screw.stl -- the M mount locking screw</li></ul><p>Unlike earlier designs, there are no metal parts; everything is 3D printed. These are precision parts, so pick appropriate settings for your printer. However, there is nothing tricky about printing them. The touchiest part by far is the set screw, which is a 1/4-20 thread part with a screwdriver slot; it is used to lock the M adapter in place. The screw is potentially subject to deformation over time and use, so you might want to print a spare or two.</p><p>It is strongly recommended that the E and M mount parts be made of opaque material to prevent stray light leaking in.</p><h3>Using Budgie</h3><p>Before assembly and use, clean-up any threads or bumps on the printed parts. If you filed any parts, it's probably a good idea to lightly wash them to remove any plastic dust. If you wish, it's also a good time to paint the bird logo as I did.</p><p>The Budgie parts need to be assembled for use, but it's pretty simple:</p><p>Put the E and M parts together with the sides that were on the bed facing each other. Push the top and bottom connectors through to lock the E part into the slots on the M part. While pushing the assembly tightly together, use a soldering iron to melt the ends of the connectors into the rings around them in the E part. You want as little gap as possible between the welded E part and the M part; having a gap will still work, but less precisely and potentially with minor light leak issues.</p><p>Mount your M lens (or adapter from the lens mount to M) on Budgie. To do this, align the red dot on the M lens (or adapter) with the screw-threaded hole, push it into Budgie, and then turn it clockwise so that the M locking slot shows in the screw hole.</p><p>On the other side of the adapter, slide the E part so you can access the screw hole and screw-in the locking screw. This should prevent the M adapter or lens from rotating. Note that you can't change an M-mount lens while Budgie is mounted on the camera, but if you're using an M-mount adapter to, for example, Minolta MC, you can trivially change the Minolta MC lens while Budgie is on the camera.</p><p>Line-up Budgie's E flange (with Budgie's tripod foot hanging off the non-grip side of the body, insert it, and turn clockwise to lock it (as you would an E-mount lens). There is very little clearance of the E-mount release button as you mount the E adapter, but it should clear. After mounting, the Budgie symbol should be on the front side of the camera (opposite of earlier versions) and the camera's grip should be on the opposite side of the lens from the Arca foot.</p><ol><li>Mount the Arca-Swiss-style foot on any compatible device or pick any one of the six 1/4-20 threaded holes in the tripod mount, and mount it on your tripod normally. The camera's grip should be on the top as it is mounted on your tripod. Note that Budgie can be used with the tripod holding the camera horizontal, but Budgie was <strong>not</strong> designed for that.</li></ol><p>To use Budgie, you'll need a suitable lens. A Minolta MD 50mm f/1.7 and commercial MD-to-M adapter are shown, but I've used lots of different lenses. Some vignette more than others, but most lenses seem to work with surprisingly minor vignetting. I recommend starting to frame the shot by sliding the lens to the center, focusing, and then checking/tweaking composition by sliding the lens back and forth. In theory, you only need two shots to get 48x36mm, but perfect alignment of shots is unlikely, so I recommend shooting one in the center, one left, and one right. It's fast and easy. However, if your tripod isn't very good (mine non-Arca-compatible ones aren't) I'd suggest setting the camera to use electronic shutter and either remotely trigger it or use the self timer -- that will minimize misalignments due to vibration -- and also brace the tripod while you're sliding the camera so the tripod doesn't move.</p><p>For stitching, I recommend <a href="http://hugin.sourceforge.net/">Hugin</a>. It's free, runs on most computers, and produces very high-quality results. The key trick to know is that, unlike stitching a sequence of photos taken by moving the camera and lens, your images shouldn't really have any lens motion. Thus, you'll want to tell Hugin that you used a lens with a relatively long focal length, so that it doesn't try to undistort captures that were not distorted in the first place. For example, I find 5 degree view angle an effective lie. Keep in mind that the stitched images will vary slightly in pixel count and even in aspect ratio due to minor misalignments. I recommend letting Hugin pick the render resolution and then cropping and (down) scaling to the appropriate image: stitching three images from my A7R II nominally produces a result with around 10600x7952 pixels. The generous overlaps mean that Hugin could do a bit of HDR, super-resolution, and/or noise reduction processing, so each pixel should be of slightly higher quality than a single shot delivers -- provided nothing has moved between captures.</p><p>The second image posted here is a scaled-down stitch result. The MD lens used does vignette, but surprisingly little considering it was designed for a 43mm diameter coverage circle and the stitched captures have a 60mm diagonal.</p><p>&nbsp;</p>