Kinect and Raspberry Pi Add Focus Pulling to DSLR

Prosumer DSLRs have been a boon to the democratization of digital media. Gear that once commanded professional prices is now available to those on more modest budgets. Not only has this unleashed a torrent of online content, it has also started a wave of camera hacks and accessories, like this automatic focus puller based on a Kinect and a Raspberry Pi.

For [Tom Piessens], the Canon EOS 5D has been a solid platform but suffers from a problem. The narrow depth of field possible with DSLRs makes it difficult to maintain focus on subjects that are moving relative to the camera, making follow-focus scenes like this classic hard to reproduce. Aiming for a better system than the stock autofocus, [Tom] grafted a Kinect sensor and a stepper motor actuator to a Raspberry Pi, and used the Kinect’s depth map to drive the focus ring. Parts are laser-cut, including a nice enclosure for the Pi and display that makes the whole thing reasonably portable. The video below shows the focus remaining locked on a selected region of interest. It seems like movement along only one axis is allowed; we’d love to see this system expanded to follow a designated object no matter where it moves in the frame.

If you’re in need of a follow-focus rig but don’t have a geared lens, check out these 3D-printed lens gears. They’d be a great complement to this backwoods focus-puller.

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Building a Full-Spectrum Digital Camera on the Cheap

The sensor on your digital camera picks up a lot more than just the light that’s visible to the human eye. Camera manufacturers go out of their way to reduce this to just the visible spectrum in order to produce photos that look right to us. But, what if you want your camera to take photos of the full light spectrum? This is particularly useful for astrophotography, where infrared light dramatically adds to the effect.

Generally, accomplishing this is just a matter of removing the internal IR-blocking filter from your camera. However, most of us are a little squeamish about tearing into our expensive DSLRs. This was the dilemma that [Gavin] faced until a couple of years ago when he discovered the Canon EOS-M.

Now, it’s important to point out that one could do a similar conversion with just about any cheap digital camera and save themselves a lot of money (the practically give those things away now). But, as any photography enthusiast knows, lenses are just as important as the camera itself (maybe even more so).

photo-31So, if you’re interested in taking nice pictures, you’ve got to have a camera with an interchangeable lens. Of course, if you’re already into photography, you probably already have a DSLR with some lenses. This was the case for [Gavin], and so he needed a cheap digital camera that used Canon interchangeable lenses like the ones he already had. After finding the EOS-M, the teardown and IR-blocking filter removal was straightforward with just a couple of hiccups.

When [Gavin] wrote his post in 2014, the EOS-M was about $350. Now you can buy them for less than $150 used, so a conversion like this is definitely into the “cheap enough to tinker” realm. Have a Nikon camera? The Nikon 1 J3 is roughly equivalent to the original EOS-M, and is about the same price. Want to save even more money, and aren’t concerned with fancy lenses? You can do a full-spectrum camera build with a Raspberry Pi, with the added benefit of being able to adjust what light is let in.

3D Printed lens Gears for Pro-grade Focus Pulling

Key Grip, Gaffer, Best Boy – any of us who’ve sat through every last minute of a Marvel movie to get to the post-credits scene – mmm, schawarma! – have seen the obscure titles of folks involved in movie making. But “Focus Puller”? How hard can it be to focus a camera?

Turns out there’s a lot to the job, and in a many cases it makes sense to mechanize the task. Pro cinematic cameras have geared rings for just that reason, and now your DSLR lens can have them too with customized, 3D printed follow-focus gears.

Gear_Selection_01_full_render_preview_featuredUnwilling to permanently modify his DSLR camera lens and dissatisfied with after-market lens gearing solutions, [Jaymis Loveday] learned enough OpenSCAD to generate gears from 50mm to 100mm in diameter in 0.5mm increments for a snug friction fit. Teamed up with commercially available focus pulling equipment, these lens gears should really help [Jaymis] get professional results from consumer lenses. 

Unfortunately, [Jaymis] doesn’t include any video of the gears in action, but the demo footage shown below presumably has some shots that were enabled by his custom gears. And even if it doesn’t, there are some really cool shots in it worth watching.

And for the budding cinematographers out there without access to a 3D printer, there’s always this hardware store solution to focus pulling.

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Vintage Lens On A Modern Camera

Sometimes you get plain lucky in multiple ways, enabling you to complete a hack that would otherwise have seemed improbable. [Mario Nagano] managed to attach a vintage 1950’s lens to a modern mirrorless camera (translated from Portuguese).

Photographers tend to collect a lot of gear and [Mario] is no exception. At a local fair in Sao Paolo, he managed to pick up a Voigtlander Bessa I – a bellows camera (or folding camera). It came cheap, and the seller warned him as much, commenting on the bad external shape it was in. But [Mario] had a sharp eye, and noticed that this was a camera that would have remained closed most of the time, due to its construction.

Inspection showed that the bellows was intact. What excited and surprised him was the excellent Color-Skopar objective mounted on a Prontor-S trigger, which is considered premium compared to the entry level Vaskar lens. His plan was to pick up another Voigtlander Bessa-I with a better preserved body, but the cheaper lens and do a simple swap. He never did find another replacement though. Instead, he decided to fix the excellent vintage lens to a DSLR body.

He’d read about a few other similar hacks, but they all involved a lot of complicated adapters which was beyond his skills. Removing the lens from the vintage camera was straightforward. It was held to the body by a simple threaded ring nut and could not only be removed easily, but the operation was reversible and didn’t cause any damage to the old camera body. The vintage lens has a 31.5mm mounting thread while his Olympus DSLR body had a standard 42mm thread. Fabricating a custom adapter from scratch would have cost him a lot in terms of time and money. That’s when he got lucky again. He had recently purchased a Fotodiox Spotmatic camera body cap. It’s made of aluminium and just needed a hole bored through its center to match the vintage lens. There’s no dearth of machine shops in Sao Paolo and it took him a few bucks to get it accurately machined. The new adapter could now be easily fixed to the old lens using the original 31.5mm ring nut.

The lens has a 105mm focal length, so the final assembly must ensure that this distance is maintained. And he got lucky once again. He managed to dig up a VEB Pentacom M42 macro bellows from an old damaged camera. Was it worth all the effort ? Take a look at these pictures here, here and here.

Automated Weatherproof Timelapse System with DSLR and Raspberry Pi

[madis] has been working on time lapse rigs for a while now, and has gotten to the point where he has very specific requirements to fill that can’t be done with just any hardware. Recently, he was asked to take time lapse footage of a construction site and, due to the specifics of this project, used a Raspberry Pi and a DSLR camera to take high quality time lapse photography of a construction site during very specific times.

One of his earlier rigs involved using a GoPro, but he found that while the weatherproofing built into the camera was nice, the picture quality wasn’t very good and the GoPro had a wide-angle lens that wouldn’t suit him for this project. Luckily he had a DSLR sitting around, so he was able to wire it up to a Raspberry Pi and put it all into a weatherproof case.

thumbOnce the Pi was outfitted with a 3G modem, [madis] can log in and change the camera settings from anywhere. It’s normally set up to take a picture once every fifteen minutes, but ONLY during working hours. Presumably this saves a bunch of video editing later whereas a normal timelapse camera would require cutting out a bunch of nights and weekends.

The project is very well constructed as well, and [madis] goes into great detail on his project site about how he was able to build everything and configure the software, and even goes as far as to linking to the sites that helped him figure out how to do everything. If you’ve ever wanted to build a time lapse rig, this is probably the guide to follow. It might even be a good start for building a year-long time lapse video. If you want to take it a step further and add motion to it, check out this time lapse motion rig too!

Reach Out and Touch Someone with WiFi Photo Booth

[kitesurfer1404] put together a nice looking vintage photobooth with WiFi capability. He’s using an arduino to monitor the state of the buttons, LED lighting control, seven segment display AND the DSLR camera. He then uses a Raspberry Pi to control imagine processing and to provide scaling and other effects, which can take up to 20 seconds per image. The Pi runs in WiFi Access Point mode, so anyone with a WiFi capable device can connect to the photo booth and view the images.

We’ve seen some interesting twists on photo booths before. But [kitesurfer1404’s] vintage style makes his stand out all on its own. He designed the graphics with Inkscape and printed them on thick paper. He then soaked the graphics in tea for several hours and dried then for several more days to get that nice rustic look.

Be sure to check out [kitesurfer1404’s] site for full details and an assortment of high resolution images of his project.

Astrophotography and Data-Analysis Sense Exoplanets

[David Schneider] was reading about recent discoveries of exoplanets. Simply put these are planets orbiting stars other than the sun. The rigs used by the research scientists include massive telescopes, but the fact that they’re using CCD sensors led [David] to wonder if a version of this could be done on the cheap in the backyard. The answer is yes. By capturing and processing data from a barn door tracker he was able to verify a known exoplanet.

Barn Door trackers are devices used to move a camera to compensate for the turning of the earth. This is necessary when taking images throughout the night, as the stars will not remain “stationary” to the camera’s frame without it. The good news is that they’re simple to build, we’ve seen a few over the years.

Other than having to wait until his part of the earth was pointed in the correct direction (on a clear night) at the same time as an exoplanet transit, [David] was ready to harvest all the data he needed. This part gets interesting really quickly. The camera needed to catch the planet passing in between the earth and the star it revolves around (called a transit). The data to prove this happened is really subtle. To uncover it [David] needed to control the data set for atmospheric changes by referencing several other stars. From there he focused on the data for the transit target and compared points across the entire set of captured images. The result is a dip in brightness that matches the specifications of the original discovery.

[David] explains the entire process in the clip after the break.

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