Quick disclaimer: This assumes that you have basic knowledge of After Effects. There are many youtube tutorials that can take you through the basics of the program, this post will just show you the steps I took to create this specific animation.
In order to make this animation, I needed to make separate layers from a photo that I took of Seth. But first, I went into Adobe Lightroom and made adjustments on the photo to look more appealing. Below is the RAW unedited photo on the left and the final edited photo on the right.
I then brought the photo into Adobe After Effects. Stay tuned to the end of this post to download a free flicker effect that may help you make spooky stuff like this.
After importing the photo into After Effects, I duplicated the photo; one for the cutout of Seth, and one for the background.
In order to create a blank canvas for a background, you would need to use the clone stamp tool. This allows you to copy a spot on the photo (by holding ALT + clicking) and brushing away the foreground subject.
After you have separated your layers, you can start animating the subject up and down or wherever you would like them to go. If you would like to get a really believable animation, cut out the shadow of the subject in the same way and animate that along with the subject.
Assuming you know how to keyframe the position of your subject, you can now move onto the dust particles. For this, I used an effect called CC Particle Systems II within After Effects. You will need to apply this effect onto a solid layer, so create a solid of any color by clicking Layer > New > Solid. After applying the effect, it will look something like this:
You will need to play with this effect a little bit to get it to your desired look, but to start for the dust effect, make sure your Birth Rate is below about 0.5. This affects how quickly new particles appear on screen. Next, adjust the Radius X & Y under the Producer section to make the particles fill the frame. Under Physics, change the velocity to around 0.1 and the Gravity to 0 so that there are no spastic particles flying around. You can change the color to your liking. After messing around with the parameters, this was the final setup of my effect.
Now for the flicker effect. I used a wiggle expression that is pretty simple to use, but just to make it a little easier for you, I exported my specific flicker effect for you use.
In order to install it, first download it using the button below. Then in After Effects, click on the layer that you want to add flicker to (in this case, I pre-composed the composition in order to apply the flicker to everything), and then at the top bar, click Animation > Apply Animation Preset... then open the ffx. file that you downloaded. The download link is below:
Don't worry about adding your credit card information, just leave that blank and fill in the location forms and you will be able to click through to a link for your free preset download!
Well that was a lot of stuff, sorry I didn't get into the nitty gritty of using After Effects and the specific steps that I took. Hopefully this helps a bit. If it's super confusing and doesn't make any sense at all, just dm me on Instagram and we can try to figure it out.
Remember to follow me on instagram and tag three friends in the stranger things post for a possible shoutout on my story.