It’s time to cover another frequent question that I get: How large can I print from a film scan? This question is most often asked by those who are curious about having me drum scan their film, but it also comes from many folks who are just asking about scanning in general. It is most often phrased as such, “How big can I print from a drum scan of 35mm film?” Today I want to explain how complicated that seemingly straightforward question is, and what factors come into play when considering the print sizes possible from different film formats.

Film Size

This is one of the more obvious elements when it comes to print size; larger film will generally allow you to create larger, clearer prints. I remember reading years ago that some photographers consider print detail to be excellent if the film is magnified no more than 10 times its original size when printing. Using that guideline, here’s the maximum print size for some common film formats with some minor adjustment to consider more common print sizes:

35mm film: 10x15 inch print
645 film: 16x20 or 16x24 inch print, depending on crop
6x6cm film: 24x24 inch print
6x7cm film: 24x30 inch print
6x17cm film: 24x72 inch print
4x5 inch film: 40x50 inch print
8x10 inch film: 80x100 inch print, if you can find a printer that size

If you were to stop reading this article right now, you would have a decent answer to the question from the above list. This really isn’t a bad starting point for determining possible print clarity, but I do think there’s more leeway especially in the small film sizes. The smaller format camera systems often have some impressively sharp lenses, and they are typically used at a smaller f number which results in less diffraction than larger formats where f22 or beyond is the norm. In my experience, it’s quite possible to make prints much larger than 10 times the size of the film if you keep a few things in mind that we will cover in greater detail in this article.

“Gannett Glacier” - Wind River Range, Wyoming - August 2021. 6x7cm Ektar, 75mm lens. How big of a print can we make from this format that is smaller than my normal 4x5 sheet?

Print Viewing Distance

When the print is framed and hung up on the wall, how close do you plan on viewing the print from? This is the point where we could throw in some math, as there is an often cited guideline that the ideal viewing distance for a print is 1.5 times the diagonal of the print. Using the Pythagorean Theorem (a^2 + b^2 = c^2), let’s work this out for a 16x20” print:

16^2 + 20^2 = 656

√656 = 25.6 (this is our diagonal in inches)

25.6 x 1.5 = 39.75 inch viewing distance

This means that a 16x20” print would ideally be viewed from about 40” or 1 meter away. Does this really mean anything? I have my doubts. While that may be a pleasant distance to take in the entire image, I often walk much closer to prints of that size to enjoy the details. 16x20” prints have always been that size that’s small enough to hold, yet large enough to enjoy the details - especially if it was photographed using a larger film format. The viewing distance math for a 40x50” print comes to 8 feet or 2.5 meters. When I put down a tape measure and stand 8 feet away from a 40x50” print in my home, that distance feels about right for a quick glance at the entire image but begs me to move forward for a closer inspection.

“Sneffels Meadow Sunrise” - Ektar 100 4x5, 90mm lens, 20 seconds at f22, 2 stop soft GND filter. This is one of those images where it’s great to view the entire large print at a distance, and then walk up close to enjoy all the fine details in the forest and meadow. **Prints available.**

It really depends on the environment that the print will be displayed. A book, while it won’t likely contain very large prints, will be inspected quite closely as we hold them in our hands while viewing. It would be important to maintain at least 300 dpi for prints in a book, and we will cover the subject of dpi shortly. For mid size prints (think 16x20 and 24x30”) hung in a normal living space it can be fun to walk up to the images to see finer details but it starts to get less important. For much larger prints (40x50 and up or huge panoramas) hung in a grand room, the sharpness is often not as critical because most viewers will be standing back quite a ways to take in the entire image. This is especially true if it’s being hung on a wall that people can’t walk up to, such as over a fireplace mantle or beyond a piece of furniture. Additionally, I’ve had businesses license my images for gigantic wall murals (20 feet long and more!) and there’s no way you’re going to be able to maintain crystal clarity at those sizes when viewed up close, but the purpose of a wall mural is to be viewed from all the way across the lobby. I’m glad I used large format film to create my images, but even with that resolution these murals still need to be enjoyed from an appropriate distance.

“Aspen in the Fog” - Velvia 50 6x17cm, 1 minute at f45. I like to print this image at 30x90 inches, it’s one that often gets hung high on walls or beyond furniture so a large print helps immerse the viewer. **Prints available.**

Don’t get me wrong, it can really be a pleasure to really inspect a large print up close. If it’s a panorama of aspen trees hung in a long hallway that people walk by, it’s nice to see all the individual leaves and texture of each tree. However, for most situations it’s ok to let the close up sharpness slide a little when it comes to really big prints. It’s just important to curb your expectations when it comes to making big prints from smaller film sizes, no matter how the film is scanned you’re going to see obvious grain and less overall detail if you’re blowing it up way more than 10 times its original size.

Subject Matter

This leads us to the point where things start to get extremely, well, subjective. The subject matter of the image itself can play a role. Some images are much more about light, emotion, and mood than critical details. Smaller film is often used for its ability to work on the fly, to capture the perfect moment with less-than-perfect image quality. If the feeling of the image is more important than sharpness, don’t hesitate to print that image big! The image below is a good example of one that works at really large sizes, even though it was only shot on 6x6cm film. The fine details of the sandstone aren’t really all that important, what matters is the beam of light illuminating the frame.

“Canyon Light Beams” - Velvia 50 6x6cm, 75mm lens, 1 second at f11, no filters. **Prints available.**

Other times the image may be more abstract or about color over texture, such as the blue waves pictured below. There really isn’t any sort of texture that needs to be enlarged; it’s just smooth colors and blurry waves from a longer exposure. The sky's the limit when it comes to enlarging images like this, though it can be a good idea to consider the graininess of the film being used as you will start to see it as the prints get large.

“Blue Waves” - E100 6x7, 165mm lens with 2x converter, 1/30th at f8, no filters. A good example of an image where fine detail doesn’t really matter very much. Prints available.

Film Grain

When making big enlargements, the shape, color variation, and size of film grain starts to come into play. With slower ISO 100 speed films it’s not generally much of an issue, but it quickly becomes noticeable with 400 speed and faster films and smaller formats. How much the grain bothers you at big print sizes is purely subjective, but it will take away from apparent sharpness. Some people are completely satisfied with a large print with visible grain to show that the image was captured with film, others may want to minimize grain as much as possible by using slow films and larger formats.

A comparison of grain in the sky of several different film types that I use. I find Provia to be the smoothest grain, Velvia and Ektar have some of the finest grain, and Portra gets pretty grainy even in the 160 variety.

As a general rule, slide film tends to have smoother, less visible grain than color negatives. Negative film can have a lot of different colored grains - especially in the shadows - that can be seen in a big enlargement. Black and white grain can vary greatly depending on the film type, speed, and developing process. I’ve always found B&W grain to be less distracting in a big print even with higher speed film, but that’s just a personal opinion. Grain will also get much more noticeable for all film types if a lot of contrast is added to the scan during digital post processing.

Image Sharpness

Another huge factor that affects print clarity is if the image itself is actually sharp. Did wind blur vegetation during the exposure? Was the camera on a tripod and was the scene focused correctly? These are completely unknown factors to me when someone emails asking how big they can print from a certain film size. When sending film for a drum scan, it can be a good idea to inspect them closely with a loupe to make sure there was no camera movement, wind blur, or poor focus. Things like lens diffraction from stopping down too much or just poor lens quality may be a little harder to pick out by looking at the film with a loupe, but may reduce the sharpness of a scan.

“Service Road in the Fog” - Provia 100f 4x5, 90mm lens, 2 second at f32, 2 stop soft GND filter. Very calm air allowed me to capture a sharp image of wheat at sunrise. A touch of lens tilt also ensured sharpness from near to far. **Prints available.**

Scanning DPI vs Print DPI

When scanning film, the software will allow you to choose a DPI setting. This stands for “dots per inch” and refers to how many pixels the scanner will resolve per inch of film. On the drum scanner, I scan 4x5” film at 4000 DPI, which means that each inch of film will have 4000 pixels. To figure out how much resolution a film size/resolution combination will have, just multiply the DPI number by the size of the film in inches. The result from 4x5” film is a file that is roughly 16000 x 20000 pixels (320 megapixels!!).

For smaller films, the scanner allows me to crank up the resolution. This is due to a physical limitation in the hardware, the scanner can only pick up 16000 pixels per rotation of the drum. This is where I get the 2000 DPI resolution for 8x10 film (16000 pixels divided by 8 inches) and the 4000 DPI resolution for 4x5 film. On a small format like 35mm I go up to 8000 DPI. The image area of 35mm film is close to 1 x 1.5 inches in size, so the scanned file has a resolution of 8000 x 12000 pixels.

“Hilltop Hut” - Portra 160 4x5, 125mm lens, 1 second at f32, no filters. The drum scanner with 4x5 film gives me a file that allows for a 300 DPI print at 48x60 inches, it’s a lot of resolution to work with! **Prints available.**

Most scanners - especially flatbeds - will have trouble resolving much more than 2000 DPI, even though the scanner may make ridiculous claims of resolutions up to 6400 DPI. The drum scanner actually does work up to these high resolutions, and on the smaller formats it seems to help create just a little more image detail to work with. 8000 dpi is well beyond the actual resolution of the film’s grain, but it is nice to have each individual grain represented by several pixels so that it is very smooth and an accurate representation of the physical film.

When it comes to printing, DPI refers to the number of dots per inch that will be resolved on the paper. Because prints are just viewed with the naked eye and there’s no need to magnify further, the DPI numbers are much lower. We usually use 300 DPI as the gold standard for prints that need to be viewed closely. Some people may argue that for smaller prints such as 8x10 or those in a book that will be handheld could even be printed higher, but I’m not sure that I’m able to see any more clarity beyond 300 DPI. 16x20 is an excellent size to print at this resolution, and from the drum scanner you’ll be able to easily get a scan that will make a 300 DPI print at 16x20” from any film size 35mm and up. To make a print this size and resolution, you would need a file that is 4800 x 6000 pixels (16x20 multiplied by 300).

As the prints get larger, the viewer stands further back to soak in the image. For this reason, the printing DPI can get much lower as the prints get big. By the time we get to 40x50” it’s completely acceptable to print at only 150 DPI (this would require a file that is 6000 x 7500), and for huge wall murals 75 DPI would be a good target but it’s alright to go even lower. Is higher DPI better? Generally yes, a huge print from a sharp image with tons of resolution will look better if the viewer walks up to it. But don’t sweat this too much. If the image itself is good and you want to show it big, it can absolutely be enjoyed from an appropriate distance.

To preview how your image will look in a large print size, you can always zoom into the image using PhotoShop. Resize the image to your actual planned printing size at 300DPI, or lower if you don’t have the resolution in your scan. The above screenshot shows how to set up an image to an actual print size. Then you can use the rulers (View>Rulers if you don’t have them enabled) and zoom in until one inch on the rulers is one inch on your monitor, for this you will use a real physical ruler to verify. Once you have it zoomed in to this point, you’ll only be able to see part of the image, but you can stand back to a reasonable viewing distance and decide if what you’re seeing on the monitor looks sharp enough to make a good print. You can make judgments standing at various distances to see if the image is satisfactory.

Types of scanners

There are a few different types of scanners that people will be using these days. In all reality, the most common one that new film photographers will have access to is a DSLR. Many photographers already own one of these, so getting a light table and setting up a system for using a digital camera as a scanner can be quite cost effective and easy. If this is your route, there won’t be any sort of DPI settings to adjust when “scanning.” You’ll just be getting a file that is the same size as the normal digital file from your camera. You could also stitch multiple digital files together to increase the resolution with larger film formats. Since I don’t even own a quality DSLR, this is not a process where I can provide a ton of advice but I can assure you that there is plenty to be found on the rest of the internet.

Consumer/Prosumer scanners are another option, and come in a few different flavors. Flatbed scanners like the Epson v700 and v800 are common for people using large format film, and they do a fine job at scanning sheets. These scanners make claims of 6400 DPI optical resolutions, but really struggle to pull out much more detail beyond 2000 DPI. No matter what DPI setting is used, they often don’t really pick up the grain detail of slower speed film. There are also dedicated film scanners that often take up to medium format or even just 35mm film. Nikon Coolscan and Plustek OpticFilm are just a couple of scanner names that come to mind. These often perform a bit better than a flatbed for smaller film formats and you may even find them capable of getting true 3200 or 4000 DPI resolution that is reasonably sharp.

“Alpenglow over Two Rivers Lake” - Ektar 100 4x5, 75mm lens, 2 seconds at f32, 2 stop soft GND filter. I still haven’t gotten around to rescanning some of my older work on the drum scanner, so this one is from the flatbed. It can be satisfactory with larger film formats, though it doesn’t quite have the color rendition of a higher end scanner and can’t begin to compare when it comes to sharpness.

Lab Grade Scanners also come in many varieties, ranging from Noritsu scanners that are meant to scan an entire roll of film rather quickly to high end drum scanners that are much slower to operate. These are far less common to have in your own home and are made to cater to very specific uses. The rapid scanners that labs use can tackle a lot of film very quickly, but often rely on software sharpening or automatic color corrections that cause sharpening artifacts or clip important highlight and shadow details. Some skilled operators will offer services where they work through each scan individually to give you a much better file. These services are often geared towards getting your film photos online efficiently or making small to medium sized prints.

And of course I can’t mention drum scanners without a plug for my film scanning service. You can read more about these scanners here, but essentially I’m able to provide a very high resolution scan with excellent color accuracy with this specialized equipment. Even the slowest, finest grain films will be fully resolved without any software sharpening. The real film grain is what you get in the file, and this is an excellent way to ensure that the print will look just like the film you started with. This type of scan would be the absolute best if the end goal is a large, high quality print no matter what film size you’re shooting with.

Aspect Ratio and Cropping

One final consideration when it comes to print size is aspect ratio, and if the scan will need to be cropped before a print is made. I’m only adding this section because many folks ask me if they can make a 40x50” print from 35mm film, or perhaps they will even ask if they can make a square format print such as 30x30. It’s certainly possible, but just keep in mind that you’ll have to throw away some data to crop the image and make such a print anytime your print aspect ratio is not the same as the film aspect ratio.

“Tombstone Sunset” - Ektar 100 4x5, 75mm lens, ¼ second at f32, no filters. I create my panoramas by just cropping from full sheets of 4x5 film after scanning. My preferred aspect ratio is 5:2, exactly half the height of a 4x5 sheet. Even though I’m throwing out half the data, there’s so much detail in sheet film that these images make excellent panoramic prints. Prints available.

Aspect ratio refers to the ratio between the width and height of an image. 4x5” film uses a 5:4 aspect ratio, and so does 6x7cm film with its actual size of 56x70mm. This aspect ratio is very useful for traditional print sizes such as 16x20 or 40x50. 35mm film uses a 3:2 aspect ratio as the film size is about 24x36mm. This works for prints like 8x12, 16x24, or 30x45 inches. 6x4.5cm is one of the weirdest sizes. With an actual film area of 41x56mm, it’s going to need cropping for any of the standard print sizes as it is somewhere in between 5:4 and 3:2. Just keep in mind that if you have a print size that doesn’t match the aspect ratio of the film, you’ll be losing resolution by cropping out a portion of the image. This doesn’t matter a whole lot for small changes, but if you’re trying to make a square print from 35mm film you’ll be throwing out nearly ⅓ of the scan when making that crop!

Conclusion

Hopefully this article helped understand why the question of maximum print size is almost impossible to answer without asking an additional dozen questions. And even after all that, it’s entirely subjective and up to your personal goals. More resolution and bigger film will alway help make a sharper print, but subject matter, emotion, viewing distance, and the overall intention of your print matter much more.