Today, movie effects are mostly done in CGI, especially if they’re of the death-defying type. [Tyler Bell] shows us how they shot actors with arrows before CGI.

Almost every medieval movie has someone getting shot with an arrow, but how do you do that non-destructively? [Bell] shows us two primary methods that were used, the pop up rig and steel pronged arrows. The pop up rig is a spring loaded device with one end of an arrow attached that pops up when a mechanism is triggered. [Bell] 3D printed his own version of the mechanism and shows us how it can be used to great effect on shots from the side or rear of the victim.

But what about straight on shots where the rig would be blatantly obvious? That’s when you get to actually shoot the actor (or their stunt double anyway). To do this safely, actors would wear wooden body armor under their costumes and arrows with two small prongs would be shot along a wire into the desired impact site. We appreciate [Bell] using a mannequin for testing before letting his brother shoot him with an arrow. That’s definitely the next level above a trust fall.

We even get a look at using air cannons to launch arrow storms at the end which is particularly epic. Looking for more movie magic? How about the effects from King Kong or Flight of the Navigator?

Thanks to [Xerxes3rd] on Discord for the tip!

Have you ever scanned old negatives or print photographs? Then you’ve probably wondered about the resolution of your scanner, versus the resolution of what you’re actually scanning. Or maybe, you’ve looked at digital cameras, and wondered how many megapixels make up that 35mm film shot. Well [ShyStudios] has been pondering these very questions, and they’ve shared some answers.

The truth is that film doesn’t really have a specific equivalent resolution to a digital image, as it’s an analog medium that has no pixels. Instead, color is represented by photoreactive chemicals. Still, there are ways to measure its resolution—normally done in lines/mm, in the simplest sense.

[ShyStudios] provides a full explanation of what this means, as well as more complicated ways of interpreting analog film resolution. Translating this into pixel equivalents is messy, but [ShyStudios] does some calculations to put a 35mm FujiColor 200 print around the 54 megapixel level. Fancier films can go much higher.

Of course, there are limitations to film, and you have to use it properly. But still, it gives properly impressive resolution even compared to modern cameras. As it turns out, we’ve been talking about film a lot lately! Video after the break.

Thanks to [Stephen Walters] for the tip!

For all the advances in digital photography, there remains a mystique for photographers and filmmakers about chemical film. Using it presents an artistic and technical challenge, and it lends an aesthetic to your work which is difficult to find in other ways. But particularly when it comes to moving pictures, how many of us have ever ventured beyond the Super 8 cartridge? If you’re not lucky enough to have a Spielberg budget, [Stand-Up Maths] is here with a video taking the viewer through the various movie film formats. He claims it’s the first video shot for YouTube in 35mm, and given that his first point is about the costs involved, we can see why.

In particular it serves as an introduction to the various film terms and aspect ratios. We all know what full frame and IMAX are, but do many of us know what they really mean in camera terms. A particularly neat demonstration comes when he has two cameras side by side with the same stock as a split screen, one 35mm and the other 16mm. The cheaper smaller framed format is good quality, but using a profession resolution chart you can see some of the differences clearly. The full film is below the break, and we’d suggest you watch it in the full 4K resolution if you are able to.

Meanwhile, some of us have been known to dabble in 8mm film, and even sometimes shoot footage with it.

Thanks [Jurjen] for the tip.

[The Thought Emporium] has been fascinated by holograms for a long time, and in all sorts of different ways. His ultimate goal right now is to work up to creating holograms using chocolate, but along the way he’s found another interesting way to manipulate light. Using specialized diffraction gratings, a laser, and a few lines of code, he explores a unique way of projecting hologram-like images on his path to the chocolate hologram.

There’s a lot of background that [The Thought Emporium] has to go through before explaining how this project actually works. Briefly, this is a type of “transmission hologram” that doesn’t use a physical object as a model. Instead, it uses diffraction gratings, which are materials which are shaped to light apart in specific ways. After some discussion he demonstrates creating diffraction gratings using film. Certain diffraction patterns, including blocking all of the light source, can actually be used as a lens as the light bends around the blockage into the center of the shadow where there can be focal points. From there, a special diffraction lens can be built.

The diffraction lens can be shaped into any pattern with a small amount of computer code to compute the diffraction pattern for a given image. Then it’s transferred to film and when a laser is pointed at it, the image appears on the projected surface. Diffraction gratings like these have a number of other uses as well; the video also shows a specific pattern being used to focus a telescope for astrophotography, and a few others in the past have used them to create the illusive holographic chocolate that [The Thought Emporium] is working towards.

It isn’t just a spy movie trope: secret messages often show up as microdots. [The Thought Emporium] explores the history of microdots and even made a few, which turned out to be — to quote the video you can see below — “both easier than you might think, and yet also harder in other ways.”

If you want to hide a secret message, you really have two problems. The first is actually encoding the message so only the recipient can read it. However, in many cases, you also want the existence of the message to be secret. After all, if an enemy spy sees you with a folder of encrypted documents, your cover is blown even if they don’t know what the documents say.

Today, steganography techniques let you hide messages in innocent-looking images or data files. However, for many years, microdots were the gold standard for hiding secret messages and clandestine photographs. The microdots are typically no bigger than a millimeter to make them easy to hide in plain sight.

The idea behind microdots is simple. They are essentially tiny pieces of film that require magnification to read. After all, you can take a picture of the beach and shrink it down to a relatively small negative, so why not a document?

The example microdots use ISO 50 film to ensure a fine grain pattern, although microfilm made for the task might have been a better choice. Apparently, real spies used special film that uses aniline dyes to avoid problems with film grain.

However you do it, you need a way to take high-resolution images, put them on film, and then trim the film down, ready to hide. While microdots were put on pigeons as early as 1870, it was 1925 before technology allowed microdots to hold a page in only ten square microns  in a 10×10 micron square. This was a two-step process, so between the film and the single-step processing, these homemade microdots won’t be that dense.

If all this is too much trouble, there’s always invisible ink. Or use a more modern technique.

We’re now somewhere over two decades since the mass adoption of digital photography made chemical film obsolete in a very short time, but the older technology remains in use by artists and enthusiasts. There’s no longer a speedy developing service at you local mall though, so unless you don’t mind waiting for one of the few remaining professional labs you’ll be doing it yourself. Black-and-white is relatively straightforward, but colour is another matter. [Jason Koebler] has set up his own colour processing lab, and takes us through the difficult and sometimes frustrating process.

From an exhaustive list of everything required, to a description of the ups and downs of loading a Patterson tank and the vagiuaries of developer chemicals, we certainly recognise quite a bit of his efforts from the Hackaday black-and-white lab. But this is 2024 so there’s a step from days past that’s missing. We no longer print our photos, instead we scan the negatives and process then digitally, and it’s here that some of the good advice lies.

What this piece shows us is that colour developing is certainly achievable even if the results in a home lab can be variable. If you’re up for trying it, you can always automate some of the process.

In the same way that a doctor often needs to take a non-destructive look inside a patient to diagnose a problem, those who seek to reverse engineer electronic systems can greatly benefit from the power of X-ray vision. The trouble is that X-ray cabinets designed for electronics are hideously expensive, even on the secondary market. Unless, of course, their sensors are kaput, in which case they’re not of much use. Or are they?

[Aleksandar Nikolic] and [Travis Goodspeed] strongly disagree, to the point that they dedicated a lot of work documenting how they capture X-ray images on plain old analog film. Of course, this is nothing new — [Wilhelm Konrad Roentgen] showed that photographic emulsions are sensitive to “X-light” all the way back in the 1890s, and film was the de facto image sensor for radiography up until the turn of this century. But CMOS sensors have muscled their way into film’s turf, to the point where traditional silver nitrate emulsions and wet processing of radiographic films, clinical and otherwise, are nearly things of the past.

Luckily, though, [Aleksandar] and [Travis] happened upon a small X-ray cabinet whose sensor had given up the ghost, forcing them to improvise. The first pass was with plain black-and-white film, Ilford Ortho Plus to be precise. The 4×5 format film was just the right size to substitute for the wonky image sensor, and at ISO 80 was fine-grained enough to capture the details needed for reverse engineering. After 3D-printing some film holders — PETG proved to be more radiolucent than PLA for some reason — they took some long exposures of various devices in their X-ray cabinet.

The film was processed with the standard chemicals, and the results were pretty fantastic. For those opposed to the wet work, they also tried using instant film packs like those used in Polaroid and Fuji Instax cameras. After removing a single piece of film from a pack inside a dark bag and sensitizing it with a quick flash of visible light, they were able to expose the film and re-insert it into an empty film pack. Slapping the pack back in the instant camera ejects the film, squeezing out the chemical and developing the picture. Et voilà, instant X-rays.

We’ve got to say that this is pretty fantastic work, and we love that this perhaps makes a valuable reverse engineering tool a little more accessible to the average hacker. [Aleksandar] and [Travis] presented this work at Schmoocon a couple of weeks back; the entire track of talks was streamed live, but luckily their talk is at the very beginning of the long video below.

Thanks to [FuzzyAleks] for the tip