lens

95 Articles

A Fresnel Lens Without The Pain

June 3, 2023 by 21 Comments

Making a traditional glass lens requires a lot of experience, skill, and patience grinding a piece of glass to the required shape, and is not for the casual experimenter. Making a glass Fresnel lens with its concentric rings requires even more work, but as the ever-resourceful [Robert Murray-Smith] shows us, a Fresnel lens can be made from far more mundane materials. He shows us a working lens made from transparent plastic tube, and even successfully smoulders a piece of paper with it under the anaemic British sun.

His lens, with its circular profile tube filled with water, is not perhaps the most efficient lens in terms of light focused per unit area of lens. From dredging up our highschool physics lessons we are guessing that half the light is diffracted outwards rather than inwards by the cylindrical profile of the coil, but for the cost of the whole device we’re not sure that matters. Next time we’re shipwrecked on a desolate island with a handy supply of clear plastic tube and fresh water, we know we can always raise a fire.

If Fresnel lenses interest you, we’ve taken a look in the past at their history.

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IR Camera Is Excellent Hacking Platform

June 1, 2023 by 14 Comments

While there have been hiccups here and there, the general trend of electronics is to decrease in cost or increase in performance. This can be seen in fairly obvious ways like more powerful and affordable computers but it also often means that more powerful software can be used in other devices without needing expensive hardware to support it. [Manawyrm] and [Toble_Miner] found this was true of a particular inexpensive thermal camera that ships with Linux installed on it, and found that this platform was nearly perfect for tinkering with and adding plenty of other features to turn it into a much more capable tool.

The duo have been working on a SC240N variant of the InfiRay C200 infrared camera, which ships with a Hisilicon SoC. The display is capable of displaying 25 frames per second, making this platform an excellent candidate for modifying. A few ports were added to the device, including USB and MicroSD, and which also allows the internal serial port to be accessed easily. From there the device can be equipped with the uboot bootloader in order to run essentially anything that could be found on any other Linux machine such as supporting a webcam interface (and including a port of DOOM, of course). The duo doesn’t stop at software modifications though. They also equipped the camera with a lens, attached magnetically, which changes the camera’s focal length to give it improved imaging capabilities at closer ranges.

While the internal machinations of this device are interesting, it actually turns out to be a fairly capable infrared camera on its own as well. The hardware and software requirements for these devices certainly don’t need a full Linux environment to work, and while we have seen thermal cameras that easily fit in a pocket that are based on nothing any more powerful than an ESP32, it does tend to simplify the development process dramatically to include Linux and a little more processing power if you can.

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AI And Savvy Marketing Create Dubious Moon Photos

March 13, 2023 by 48 Comments

Taking a high-resolution photo of the moon is a surprisingly difficult task. Not only is a long enough lens required, but the camera typically needs to be mounted on a tracking system of some kind, as the moon moves too fast for the long exposure times needed. That’s why plenty were skeptical of Samsung’s claims that their latest smart phone cameras could actually photograph this celestial body with any degree of detail. It turns out that this skepticism might be warranted.

Samsung’s marketing department is claiming that this phone is using artificial intelligence to improve photos, which should quickly raise a red flag for anyone technically minded. [ibreakphotos] wanted to put this to the test rather than speculate, so a high-resolution image of the moon was modified in such a way that most of the fine detail of the image was lost. Displaying this image on a monitor, standing across the room, and using the smartphone in question reveals details in the image that can’t possibly be there.

The image that accompanies this post shows the two images side-by-side for those skeptical of these claims, but from what we can tell it looks like this is essentially an AI system copy-pasting the moon into images it thinks are of the moon itself. The AI also seems to need something more moon-like than a ping pong ball to trigger the detail overlay too, as other tests appear to debunk a more simplified overlay theory. It seems like using this system, though, is doing about the same thing that this AI camera does to take pictures of various common objects.

Interesting Optical Journey Results In Hybrid Viewfinder For Smartphones

December 12, 2022 by 5 Comments

Fair warning: if you ever thought there was nothing particularly interesting with optical viewfinders, prepare to have your misconception corrected by [volzo] with this deep-dive into camera-aiming aids that leads to an interesting hybrid smartphone viewfinder.

For most of us, the traditional optical viewfinder is very much a thing of the past, having been supplanted by digital cameras and LCD displays. But some people still want to frame a photograph the old-fashioned way, and the optical principles that make that possible are actually a lot more complicated than they seem. [volzo]’s blog post and video go into a great deal of detail on viewfinder optics, so feel free to fall down that rabbit hole — it’s worth the trip. But if you’d rather cut to the chase, the actual viewfinder build starts at about the 23:00 mark in the video.

The design is an interesting combination of lenses and beamsplitters that live in a 3D-printed enclosure. The whole thing slips over one end of a smartphone and combines an optical view of the scene that corresponds to the camera’s field of view with a small digital overlay from the phone’s screen. The overlay is quite simple: just some framing gridlines and a tilt indicator that’s generated by a little Android app. But it’s clear that much more information could be added now that [volzo] has all the optical issues sorted out.

We appreciate this deep dive into something that appears to be mundane and outdated, which actually proves to be non-obvious and pretty interesting. And if you have any doubt about the extreme cleverness of the camera engineers of yore, look no further than this sort-of solar-powered camera from the 1960s.

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Trinocular Lens Makes Digital Wigglegrams Easier To Take

October 30, 2022 by 13 Comments

Everyone likes a good animated GIF, except for some Hackaday commenters who apparently prefer to live a joyless existence. And we can’t think of a better way to celebrate moving pictures than with a 3D printed trinocular camera that makes digital Wigglegrams a snap to create.

What’s a Wigglegram, you say? We’ve seen them before, but the basic idea is to take three separate photographs through three different lenses at the same time, so that the parallax error from each lens results in three slightly different perspectives. Stringing the three frames together as a GIF later results in an interesting illusion of depth and motion. According to [scealux], the inspiration for building this camera came from photographer [Kirby Gladstein]’s work, which we have to admit is pretty cool.

While [Kirby] uses a special lenticular film camera for her images, [scealux] decided to start his build with a Sony a6300 mirrorless digital camera. A 3D printed lens body with a focusing mechanism holds three small lenses which were harvested from disposable 35 mm film cameras — are those still a thing? Each lens sits in front of a set of baffles to control the light and ensure each of the three images falls on a distinct part of the camera’s image sensor.

The resulting trio of images shows significant vignetting, but that only adds to the charm of the finished GIF, which is created in Photoshop. That’s a manual and somewhat tedious process, but [scealux] says he has some macros to speed things up. Grainy though they may be, we like these Wigglegrams; we don’t even hate the vertical format. What we’d really like to see, though, is to see everything done in-camera. We’ve seen a GIF camera before, and while automating the post-processing would be a challenge, it seems feasible.

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Telephoto Lens Without The Fiscal Pain

August 24, 2022 by 20 Comments

If you’re in the market for a telephoto lens, the available range of optics for your camera is limited only by the size of your bank account. So when [Pixels and Prisms] promises a telephoto for $13 USD it has to be worth a second look, right? Where’s the catch.

The lens has a 3D printed shell containing the optics, with associated focusing and aperture, and has a mount designed for Canon cameras to give a result with 163 mm focal length and f/2.5 . When a Canon lens costs many times more it’s evident that there is some compromise involved, and it comes in the lens system being very simple and comprised of off-the-shelf surplus lenses without the great effort put in by the manufacturer to correct distortion. The result is nonetheless a very creditable lens even if not the first choice for a paparazzo in pursuit of an errant politician.

The real interest for us in this open source project comes in it being something of an experimenter’s test bed for lenses. There’s no need to use the combination shown and the design can be readily adapted for other lenses, so spinning one’s own lens system becomes a real possibility. Plus it’s achieved the all-too-easy task of engaging a Hackaday writer’s time browsing the stock of the Surplus Shed.

We’ve featured a lot of lens projects over the years, but they more often take an existing camera lens as a starting point.

Ultimate Bokeh With A Projector Lens

August 2, 2022 by 22 Comments

Bokeh is a photography term that’s a bit difficult to define but is basically soft, aesthetically pleasing background blur, often used to make a subject stand out. Also called “background separation” or “subject isolation”, achieving it optically requires a fast lens with an aperture below 2.8 or preferably lower. These lenses can get very expensive, but in the video after the break [Matt] from [DIY Perks] blows all the commercially available options out of the water. Using an old episcope projector, he built a photography rig with background separation equivalent to that of a non-existent 35mm f0.4 lens.

Unlike most conventional projectors used to project a prerecorded image, episcopes were used to project an image of physical objects, like books. To use this lens directly in a camera is impossible, due to the size of the imaging circle projected out the back of the lens. At a diameter of 500mm, there is simply no imaging sensor available to capture it. Instead, [Matt] built a projection screen for the image and photographed it from the opposite side with a normal camera.

The projection screen was made by sandwiching a sheet of diffuser film between two sheets of clear acrylic held in a frame of aluminum extrusions. To block out all other light, [Matt] added aluminum shrouds on either side of the screen, which also serves to mount the lens and a camera. The shroud on the lens’ side is mounted on a separate aluminum frame, enabling the image to be focused by adjusting the distance between the screen and lens. Linear rods and bearings on 3D printed mounts allow smooth motion, while a motor-driven lead screw connected to a wired remote does the actual adjustment. The gap between the two halves was covered with bellows made from black paper. Continue reading “Ultimate Bokeh With A Projector Lens” →