In a previous article, I talked about the physical differences between photography film used for making slides and photography film used for making negatives for prints. I discussed how different chemicals are used to develop the two types of film. These two types of film are intended for entirely different purposes.
But what if you take your photos with slide film, and then decide later on that you actually want to make prints from those slides?
Remember, you don’t have a “negative” from which to create prints. The slide film itself was physically chopped up into squares to make the slides. That slide is the ONLY record you have of the scene.
A negative is the “reverse” of an image. Things are black on the film where they should be light, and so on. That way when light shines through the film to expose the photographic paper, it ends up with everything where it should be.
In comparison, a slide square is the “actual presentation” of an image. That’s because the slide projector is simply going to shine light through the square and onto a screen. You want the dark areas to block the light so it doesn’t shine through. You want the green areas to filter the light green, and so on.
So you can’t just use a slide as a negative, for standard processing. In essence you have to SCAN the tiny little 2-inch by 2-inch bit of film with a HIGH DETAILED scanner so it gets as much information as possible out of that tiny 2-inch square area.
Imagine putting that 2-inch by 2-inch square on a glowing white surface and then pointing your cellphone camera at it. You probably wouldn’t get much detail from that image. Sure, you could probably print a 2-inch by 2-inch print and think it was OK. But if you tried to expand the image out to 8-inch by 8-inch? The quality would quickly degrade.
So you need the highest quality scanner you can possibly get, to minutely record every tiny little detail on that film.
What Is the Resolution of 35mm Film?
There are a wild number of variables in any kind of evaluation of imagery, but just to give a general baseline, most people will go for the 5600 pixels wide by 3620 pixels high guesstimate. Film did NOT have pixels, of course. It had an ability to record light and dark spots. This is just a rough guesstimate, and it varied based on the camera/lens quality, film quality, developer quality, and many other factors.
Still, it’s fair to say that a typical consumer film camera of the 1970s did NOT create images in the 20,000 pixels by 10,000 pixels rage. It just couldn’t manage that level of detail, with the lenses on those cameras. (And we’re not even talking about my darling plastic-case Holga cameras here). So it’s important to set expectations. Film photography was lovely, and I still adore it! But digital photography has surpassed it and continues to improve.
Still, there’s a lot of information packed into that tiny space of a slide. That means, to get the best possible representation, your scanner software should be able to handle that level of detail. You probably can’t use an off-the-shelf all-in-one scanner and expect it to see those tiny details in a 2-by-2 film square. Most people send their slides out to shops with specialized equipment for this reason.
Film is Curved
It’s worth mentioning that a slide is not 100% flat. That is, the film within the slide tends to naturally have a bit of bow / curve to it, because film in a camera is in a roll. You don’t tend to notice this when the slide is being projected, because your eye sorts out those issues on its own. If you went and stood immediately next to the screen you’d see the resulting areas of some sections being more in focus than in others.
But when you scan that film? The scanner is right up against the film, because the film is only a 2-inch square. And that means that even tiny bends in the film can cause the scan to be slightly more or less in focus. The only way to account for that is to strip the slide film out of its case and to manually flatten it down, to ensure it is 100% flat during scanning. That can be a quite pricey proposition heading toward $50 per slide.
If a slide is THAT precious to you – maybe a wedding photo with beloved family members – then certainly do it. But for most people, that’s just too much money to spend for a tiny improvement in focus quality.
How Good will the Slide Scan Be?
Let’s say you scan your slides – and you’re disappointed in the results you get. You were expecting high-quality brilliant-color full-contrast images. Instead, you get something a bit fuzzy.
You might think, well when I show the slide on a screen it is HUGE and it looks awesome – but that’s a trick of the brain filling in details. It’s just like being at a movie theater and seeing crisp images on the distant screen. Our brain fills in all the tiny details. If we were to walk right up to the screen, we’d see just how fuzzy things actually are. But we view those images from a distance.
In comparison, with monitors and prints, we have viewed surface right up against our eyeballs (practically). So we are much more aware of the quality issues. We can see all the fuzzy areas.
If you have a solid-quality film camera with well-exposed high-quality film, the film (whether print or slide) should get a detailed impression of the scene before it. But it is still only a 2-inch by 2-inch square. There’s just only so much “real estate” there to record details. The rule of thumb is generally that you can get an 8×10 print out of that film, in standard situations, before things start to get too fuzzy / grainy to be happy with. Of course, that is very dependent on personal preferences.
It’s also worth mentioning that if you printed an image out at 16×20 you’re probably not going to be standing six inches away from it looking at it. You’ll probably hang it somewhere that you view it from a distance, and now you’re right back to the “eyes filling in the gaps” situation as you have with movies and slide projectors. So it doesn’t matter as much that the image is “imperfect” at that larger size.
Since we’re on my Holga site, I will also comment that the Holga film camera is NOT known for its precision images :). So anything you take with a Holga is going to be (ahem) “Artsy” in the first place, and that will show up in the prints and slides you make. You simply have to embrace that aspect of the image.
So, to summarize, you are always going to have challenges when scanning slides. Unless you were using a top-of-the-line camera with top-of-the-line film, and have been storing the slides in pristine environmental conditions, and then have them all flat-scanned, they’re just not going to create sharp perfect-contrast large prints for you. We have gotten spoiled in our digital age.
Do a test run against a screen. Go up and stand right next to the screen and get a sense for what level of quality really is stored in that 2-inch by 2-inch tiny piece of film. And then, if it is THAT important to you to get top of the line scans of your slides, be prepared to pay for it. The technology is certainly out there to get every last detail out of your slides. It’s just a matter of paying for that equipment, and also understanding that it’s going to have flaws. Most consumer-level older-era film simply was not up to the task of printing large-size prints with precision contrast. They were meant for small snapshots.
I’d love to hear your thoughts on this topic!
Here’s my article on the basic differences between slide film and print film –