Flashlight Filter Smartphone

Light filters can be a very nice tool to spice up your pictures. Using purple light you can add some real mysteriousness to your picture, while a more yellowish light might add some joy to your image.

In this Instructable I will share you a 3D-printable model that you can attach to your smartphone, and I will teach you how you can create low-end light filters yourself. If you have access to special light-filter sheets you could use those as well to update the quality / strength of the effect. But none-the-less, all of the pictures you see in this Instructable are made with a 5 year old smartphone, and are using these self-made light filters.

The goal of this project is to create a small tool that you can attach to your smartphone to add some extra spice to your pictures. For this, I have designed a small 3D-printable object, which can hold up to 5 different color filters at the same time and can be attached to any smartphone.

The build is fairly simple and shouldn't take you longer then an hour to make, that includes the time to wait for your 3D printer to finish.

Transparent plastic + Alcohol based markers OR light color filters

Depending on the quality you are looking for and/or the amount of money you'd like to spend on this tool. You could buy real light color filters, but in this project I will guide you through the process of how you could make your own. I made my ones by simply coloring transparent plastic with alcohol based markers. Which has the additional benefit of allowing to experiment with different types of filters.

3D Printer

Required to print the frame of the device.

Glue

Used for gluing the filters as well as for the assembly of the frame.

Clamps*

Where there is glue, there are clamps. But since the used parts are not very large or heavy, you could also just use something heavy as a book or something, in order to put the required pressure onto it.

Double sided tape*

This is required to fasten the device to your smartphone (case). But if you don't want to stick anything to your smartphone, you could also just hold it with your finger. Or if you want to go really fancy, merge the tool with an existing 3D-printable smartphone case so it is embedded in the case.

Ductape*

This might be useful, in case you experience an overexposure when you use the filter in a dark environment. Using a piece of Ductape, you can block the flashlight from immediately reaching the camera lens. More info on this can be found at the endInstructable.

Step 1 - Print the model with your 3D printer

Download the parts from the bottom of the page, and print it via a 3D printer. You can also get the whole Fusion 360 model, so you could make your own modifications to it if you'd like to do so.

Step 2 - Cut light filters to appropriate dimensions

I used a sandwich bag to make my filters with, I just colored the film with different alcohol-based markers. This worked surprisingly well for most of the colors. I cut around one inch (~2cm) of the bag and then colored in small sections. If you have any harder transparent plastic, I would recommend using that, since that would make the filters less floppy, but perhaps the ink will have a harder time to stick.

Step 3 - Glue light filters to wheel (and cut excess foil)

This is a rather self-explanatory step, just make sure that you use the side that does not have the notches on it! The notches are meant to keep the wheel in place, so the wheel does not start rotating by itself when you have selected a filter.

Step 4 - Glue wheel

Not much to say about this step besides I like clamps 😅. Make sure that the sides with the notches in them are facing outside.

Step 5 - Assemble frame & glue case

If you are clumsy, only glue the outer sections. If you decide to glue the center part (which is recommended, since it strengthens the frame) just be careful that you don't glue the wheel to the frame. Since this will make it unable to turn anymore. First glue one part, then put the wheel in (it only fits one way) and then close it with the other part of the frame. If you are using clamps, be careful that you don't apply to much pressure cause that might break the casing.

Step 1 - Attach the device to your smartphone

You can simply use a piece of double sided tape to attach it to your smartphone just make sure that the filter is only covering the flashlight and that the ring does not obstruct the lens (unless you want to use it to experiment with lens filters). If you don't want to use tape, you can also use your finger to place it in front of the flash.

Step 2 - Usage

After you have attached the device to your smartphone, you can rotate it to select 1 of the 5 different filters. Because of the ease of construction, I have made several versions with various filters. I won't be showing all of them over here because some experiments don't show much visual difference, or they simply didn't work out. I have tried different colored alcohol-based markers in my experiments. But I have also used acrylic markers to block some light from the flash in order the create stripes or dots for instance (which didn't really work out). Below you can see some of the effects I have been able to create with this tool!

Selfie (using 5 different color filters)

Indoors with daylight

Capturing reflections (using yellow, green & red filters)

Outdoors in dusk

Red / Blue filter

A filter colored 50% with blue ink, 50% with red ink

Experiments

Multiple versions that hold different filter experiments

I also did some experiments where I used the flash as a genuine flashlight, with the filter on it to emit a colored light. This could be interesting for when you want to accentuate a shot taken with a different camera. Or in an entirely different (non-camera centric) scenario. I also used this tool to cover the lens instead of the led light. Both experiments had various interesting results. Of the first one I unfortunately don't have any pictures. From the second case, I just didn't like the outcomes myself very much. I would describe the results as 'experimental photography', the image becomes very blurry because of the quality of the foil. This might be resolved by using a higher quality filter, but it isn't within my interest to explore this any further.

Lens flare

In an entirely dark environment, where the lens is full dependent on the light coming from the flash. A nasty lens flare can occur (as visible in the picture below). This can be resolved by creating a physical barrier between the lens and the led, so the flash can no longer directly access the lens from the side. I used a piece of duct tape for this, but you could also modify for the 3D model if you'd wish. For the purpose I intended this tool to use, this was not a real practical issue though. So I choose to not modify the model myself, and fixed it temporarily with a piece of ductape 🙂.

Burned filter

When I was using the filter with the flashlight on for a longer period of time, the heat of the LED started to melt the filter. I expect that this is due to do material I have used for the filter. I was using a very thin plastic film that isn't designed for these use cases. I haven't done the experiments, but I expect that using a different type of transparent plastic will resolve this issue. The easiest way to test it is to simply hold a lighter next to it for 5 seconds, and see how the material responds to it. If it immediately start to crumble away, you'll know that it won't withstand the heat of the LED for sure.