How to scan 4x5 film, in one shot or stitched
To scan 4x5 film with a camera, you either photograph the whole sheet in one frame, at about 0.23x on a full-frame sensor, or you shoot it closer in overlapping tiles and stitch them. One shot is fast and gives about 20 megapixels with a 24-megapixel camera. Four or nine tiles give about three to six times that. Either way, stitch the RAW tiles first and convert the stitched file once.
What you need
The basic setup is the one in how to scan film with a camera. For sheet film, check these points:
- A light larger than the sheet, even from edge to edge, with a high CRI. Negative Supply, for example, makes 4x5 light sources rated at CRI 97 and 99.
- A holder for 4x5, with glass, anti-Newton-ring (ANR) glass, or no glass. More on this below.
- A macro lens that focuses to at least 0.25x for one shot, or close to 0.5x for tiles. A 1:1 macro lens does both.
- A tall enough stand. At 0.23x the lens sits much farther from the film than for 35mm. A shorter macro lens (50 or 60mm) needs less height than a 100mm one.
- Stitching software if you shoot tiles. See the list further down.
Each tile overlaps its neighbours by about a third, and the outer tiles reach past the edges of the sheet. Keep the camera fixed and slide the holder between tiles, row by row, in the same order every time.
One shot or stitched tiles
A 4x5 sheet is 4 × 5 inches, about 102 × 127 mm. The picture is a little smaller, because the film holder covers the edges of the sheet. To fit the short side onto the 24 mm short side of a full-frame sensor, you need about 0.23x.
More tiles mean more magnification, and more pixels on the film. This table shows the sums for a 24-megapixel full-frame camera (6,000 × 4,000 pixels), with about 30% overlap between tiles. With a higher-resolution camera, the results grow in proportion.
| Tiles | Magnification | Stitched size | Pixels per inch of film |
|---|---|---|---|
| 1 | about 0.23x | about 20 MP | about 1,000 |
| 2 × 2 | about 0.4x | about 57 MP | about 1,700 |
| 3 × 3 | about 0.55x | about 115 MP | about 2,400 |
These are upper limits from the sensor. The real detail also depends on the film, the lens, the focus and how flat the sheet is. Past a point, more pixels only show bigger grain.
One shot is fast and simple. There are no seams, and you convert the file directly. It suits contact-print-sized output, the web, and a first look at a box of sheets.
Tiles take longer and need a stitcher, but they give you large prints from a camera you already own. Higher magnification also means less depth of field, so a sheet that bows in the middle shows it more.
Hold the sheet flat
A 4x5 sheet is large and can bow, especially in a holder that only grips the edges. You have three choices.
- Plain glass. A sheet of glass on top, or the film between two sheets, holds it very flat. But each glass surface is one more place for dust, and where the shiny base touches smooth glass you can get rainbow patterns called Newton rings.
- ANR glass. Anti-Newton-ring glass has a finely etched surface that stops the rings. Put the etched side against the film. Negative Supply’s 4x5 carriers use ANR glass, and its basic 4x5 kit comes with either ANR glass or micro-etched acrylic. At high magnification, check that the etched texture does not show in the picture.
- No glass. A glassless holder grips the sheet by its edges, so there are no rings and fewer dusty surfaces. The pixl-latr, for example, takes 4x5 sheets without add-ons. The middle of the sheet can sag, so focus on the centre and stop down to f/8. For badly bowed sheets, see how to flatten curly film.
Put the shiny base side toward the camera, so the picture reads the right way round.
Shoot the tiles
- Fix the settings. Manual mode, RAW, base ISO, f/8, and a fixed white balance. Set the exposure once for the whole sheet, from the clear film edge, and use it for every tile. Auto exposure gives each tile a different brightness, and the seams show.
- Fix the focus. Focus on the grain in the middle of the sheet. Check it at the corners, and refocus for a tile only if that tile is soft.
- Move the film, not the camera. Keep the camera and the light fixed and slide the holder between shots. The lens then always sees the same patch of light, so each tile is lit the same way. If you move the camera instead, keep its height and angle exactly the same.
- Overlap by about a third. The stitcher matches detail that two tiles share. Plain areas such as sky give it little to match, so give those tiles more overlap.
- Shoot in a fixed order, row by row, so you can see at a glance if a tile is missing.
- Include the edges of the sheet in the outer tiles. You crop later.
Stitch first, then convert
Stitch the RAW tiles into one file, then convert that file once. If you convert each tile on its own, the converter sets its own black and white points for each tile, and every seam shows as a step in brightness or colour. A single conversion of the whole stitched sheet treats every part of it the same.
Process all tiles with exactly the same RAW settings before or during the stitch: the same white balance, the same exposure, no automatic adjustments.
Apps that stitch
- Adobe Lightroom Classic. Select the tiles and choose Photo > Photo Merge > Panorama. It merges RAW files into a DNG. Then export that DNG as a 16-bit TIFF with no added contrast, for apps that need a TIFF.
- Adobe Photoshop. Develop the tiles to 16-bit TIFFs with identical settings, then use File > Automate > Photomerge. The Reposition layout aligns the tiles without stretching them, which suits flat copies.
- PTGui. It runs on macOS, reads many RAW formats, and writes 8- or 16-bit TIFF and DNG. Its help explains how to stitch flat mosaics: set a rectilinear lens with a very long focal length so it does not warp the tiles. Viewpoint correction, which helps when the camera moved, is only in PTGui Pro. The trial is complete but adds a watermark.
- Hugin. It is free and open source and has a mosaic mode for flat subjects. The Hugin site says its official Mac build does not run on Apple silicon Macs.
Each of these apps does the job well. Lightroom Classic is the simplest if you already use it. PTGui gives you the most control over difficult stitches.
How I do it. I shoot nine tiles per sheet, three by three. For me, it is the best compromise between time and quality. When I really like a picture, I go up to 16 or 25 tiles. I stitch them in Affinity Photo.
Common problems
- Seams with a step in brightness or colour. The tiles had different exposures or white balance, or you converted them one by one. Reshoot with manual settings and convert after the stitch.
- Bands of light falloff in a grid pattern. The light is smaller than the area the lens sees, or the lens is wide open. Use a larger light and stop down. After conversion, falloff shows up even more.
- The stitch fails or bends. The camera moved in height or angle between tiles, or the overlap is too small. Keep the camera fixed, overlap more, and use a flat-mosaic setting.
- A soft centre. The sheet sags in a glassless holder. Use glass, or flatten the sheet first.
- Rainbow rings. The base touches plain glass. Switch to ANR glass or a glassless holder.
- Specks of dust. Four glass surfaces collect a lot. Clean them and the sheet just before you shoot, and see dust on film scans.