Slide and film scanning tip: Which side do you scan to make sure your digital images aren’t upside down?

If you don’t know how to correctly load your slides or negatives into your scanner, you’re wasting your time.. Here are three simple tips to quickly determine which side is which:

1. Slides and negatives are two-sided.

Did you know that a 35mm slide or 35mm negative film strip has a positive and a negative side? When the film was developed, one side was coated with what is called a “matt emulsion”. This side with the matte emulsion is the negative side, the other side is positive. I know, a negative strip also has a negative side. But don’t worry about the terminology, just know that slides and negatives are two-sided. What you need to determine is which side is the positive side.

2. How to determine the “positive” or negative side of a slide

I want you to take out a slide and bring it to a light source, like a lamp or a window. Move the slide back and forth and you will notice a subtle difference. One side will have little grooves, you will see lines that form a shape, and it will be a bit dull or opaque. The other side will be shiny, smooth, and there will be no lines.

The smooth and shiny side is the positive side. The other side, the rough side, is where the matte emulsion was applied. This side is the negative. If your dad has cheapened and bought lower quality slides in the past, he will have a hard time determining which side is positive or negative. But he keeps moving the slide back and forth, and eventually you’ll see a smooth side versus a rough side. Remember, smooth equals positive, rough equals negative.

Finding the positive/negative side of a negative movie is much easier. You can use the same technique, or you can look closely at the numbers and letters printed directly on the negative. If the letters and numbers are backwards, then that is the negative side. If the letters and numbers are in front of you correctly, that’s the bright side.

Another quick tip: after scanning over 500,000 slides and negatives, I know instantly which side is which. The negative side of a negative slide or film will be concave, which means it will sit up like a bowl. The positive side will be convex, which means it will bubble. But be careful with this method, sometimes the cheapest film will be the other way around. And you’ll see, maybe after 100 scans, you’ll get used to it.

3. How to load your slides and negatives correctly in your scanner

Now that you know a bit more about the positive and negative side of the movie, I can now tell you which side goes where.

If you have a flatbed scanner, you want the positive side DOWN, facing the window. So when you load your slides, you’ll want to make sure the rough side is facing you and the clear side is facing the glass. It’s the same with negatives: make sure the letters or numbers on the negative are upside down when you look at them. Just think, “shine down, dirty.”

For film scanners, like the Nikon Coolscan, the method is reversed. Load your slides with the smooth side up and the rough side down. With negative film, make sure the letters/numbers are upside down.

Improve your scans: Get more free tips for converting slides, movies and photos: