The Medium Formats

For most practical purposes, 'medium format' can be taken as synonymous with 120/220 roll film, though another way to define it is by what it is not: it is bigger than 35mm, and is therefore not 'miniature' but it is smaller than 9x12cm or 4x5 inch, and therefore not 'large format'.

An old saying in boxing, soon borrowed in photography, is that “a good big ‘un will always beat a good little ‘un.” In other words, a bigger negative is a short cut to better quality. This module is about the formats themselves, and why you might choose one over another: there are (or will be) other modules about how to handle 120 (with which there is some overlap); on roll-film backs on 4×5 inch cameras; and on roll-film folding cameras; as well as on building your own 6x17cm ‘Longfellow’. You may also care to look at the module on large formats.


Garden chairs

If you are used only to 35mm, 120 can be a revelation, especially in black and white. Roger used an  ancient Kowa/SIX (6x6cm) and its standard 85/2.8 lens with Maco Cube 400 film, printed on Ilford Multigrade.

The trouble is, of course, that larger formats are also a short cut to bigger cameras, higher running costs and slower lenses: fast lenses for larger formats are huge, heavy and expensive. All formats, large or small, are necessarily a compromise, and the so-called ‘medium formats’ have offered a riot of compromises from approximately 3×4 cm (16-on-127) to approximately 6×24 cm (3-on-120). In this module, we have concentrated on 120/220, though as discussed below under ‘The other medium formats’ there are (or once were) plenty of alternatives.

The 120 format is one of the oldest, introduced in about 1902 to take six pictures, nominally 2-1/4 x 3-1/4 inches or 6×9 cm, on 62mm wide roll film with a paper backing. In the 1920s this was lengthened to take 8 pictures, and it has remained there ever since. Other names include B2, or just 20: the British Standard code was 2.

Sears, California

Frances used her Mamiya 645 for a ‘hard edge’ effect, shooting on Kodak Ektachrome 64 slide film. As this is very desaturated and blue by modern standards, we increased the contrast and saturation selectively in Adobe Photoshop, after scanning. One problem with larger formats than 35mm, of course, is that you need to stop down further in order to get adequate depth of field, because the image is magnified more on the film. The 80/1.9 she used here is roughly equivalent to 50mm on 35mm: precise comparisons are impossible because of variations in image shape.

The original 120 size then spawned 620 (Z20, 62, B.S. code 3), which is the same film and backing paper wound on a narrower spool. This was allegedly to allow for slimmer cameras, but a more cynical interpretation is that it was introduced by Kodak to tie people to Kodak 620 cameras.

The third ’20’ format was 220, a double-length roll of film with just a leader and a trailer instead of backing paper both ends. Obviously, this meant that the traditional ‘red window’ means of counting exposures could not be used, but it gave twice as many pictures per loading: ideal, for example, for weddings where reloading can be a major nuisance. Going in the opposite direction, there has in fact been a half-length ’20’ format, sometimes known as the ‘week-end 120’ but it has rarely been seen outside Japan. For a picture of the different sets of numbers on the backing paper, and the way the film is sandwiched to the paper, look at How do I… Load 120.


Frances used Ilford HP5 Plus in a 6x9cm back on her Alpa 12 S/WA with a 35/5.6 Rodenstock Grandagon, printing on Ilford Multigrade Warrmtone, sepia toned.

The width of the film sets limits to one dimension of the image — about 56-57mm or around 2-1/4 inches — but obviously the other dimension can vary widely, and it has. These dimensions have included 40-45mm (‘six four five’, 15-on or 16-on), 56-57mm (‘six six’ or ‘two and a quarter square’, 12-on or very rarely 11-on), 68-72mm (‘six seven’, 10-on or rarely 9-on), 75-80mm (‘six eight’, 9-on), 78-88mm (‘six nine’ or ‘two and a quarter-three-and-a-quarter’, 8-on, the original format), 110-120mm (‘six twelve’, 6-on), 160-170mm (‘six seventeen’, 4-on) and 230-240mm (‘six twenty-four’, 3-on).

As you can see, all the nominal dimensions are, indeed, pretty nominal, though 56mm is is 2.2 inches, close to ‘two and a quarter’. Most of these formats deserve separate analyses, as each has its own merits and uses, but before that we should look at film location and flatness, and at lenses.



Roll film was originally designed for making contact prints from pictures taken with modestly-priced amateur cameras fitted with relatively slow lenses. This meant that depth of focus wasn’t very important. Depth of focus is the mirror image of depth of field. It is the range within which the image projected by the lens will still be acceptably sharp. Obviously, if the film is too far forward, or too far back, the effect is the same as the lens being too close for sharp focus, or too far away.

With a wodge of paper behind the film, achieving precise location can be quite demanding. Old films often varied quite widely in thickness, and so did their backing papers, so old cameras were often quite sloppy in this respect, to allow plenty of room for even the thickest sandwiches. Because the curled-up film was being unrolled and then re-rolled, the film in the gate might exhibit a significantly concave shape — though if, as was often the case, the lens had the right curvature of field, this might actually be to the good.

Six-20 Brownie D

Roger’s father bought this camera as a young sailor in the late 1940s; we still have a few family snapshots taken with it. Quality, with a meniscus f/14 lens, is predictably somewhat low, but adequate for contact prints.

On top of all this, the film (and still more the backing paper) can take a ‘set’ (kink) if it is left in the camera or holder for long, If this is then wound on to the next frame, the wavy area can be well within the image area. This explains the advice which is often given to wind on at least one frame, and (depending on the back and format) perhaps two frames before shooting close up or at wide apertures, especially with wide angles or very fast lenses, where depth of focus is smaller.


The smaller the format, the easier it is to hold it flat, and the easier it is to build a lens that is sharp or fast or both. Thus Leica offers an f/0.95 50mm Noctilux for 24x36mm, while f/1.9 is the fastest lens you normally find for 645 (Mamiya), f/2 for 6×6 (Hasselblad), f/2.4 for 6×7 (Pentax) and f/2.8 for 6x9cm (Zeiss for Linhof). And where the old standard for 35mm lenses was a 50/2 or 50/1.8, for roll-film it’s f/2.8 up to 6x6cm and f/3.5 or less for larger roll-film formats, though there was once a 150/2.8 Xenotar for 4×5 inch/9x12cm.

Of course you can build big, fast lenses, but quite apart from size, weight and cost, you soon run into problems with both depth of field and depth of focus: a 100/2.8 Planar on a Linhof is a brute.

If you need lens speed, therefore, 35mm is usually a better bet, though the smaller degrees of enlargement from roll film mean you can use faster films (with the same grain) and slower shutter speeds, which evens the score somewhat. Indeed, in the days of 4×5 inch press cameras and f/4.7 135mm lenses, shutter speeds as long as 1/5 second were commonplace, but at that point, subject movement can be a problem.

The Hunter

Roger used a 100/2.8 Planar on a Linhof Technika 70 with 6×7 Ektachrome (56x72mm) for this shot; he had no tripod with him, so he had to use a monopod and full aperture.




Equivalent focal lengths

As already noted, precise equivalents are impossible across formats of different shapes, because the horizontal and vertical coverages differ to varying degrees. The table on the left is based on diagonal coverage. There has been some rounding of focal lengths to reflect those that are actually available. Thus the 15 mm equivalent on 6×7 cm is actually 32 mm but the nearest lens commonly available with full coverage is 35mm, the same as for 6×9 cm. Likewise the 90 mm equivalent on 6×6 cm is 160 mm but 150 mm is normally all that is available.



With an area of about 2400 square millimetres, the smallest of the usual roll-film formats is about 2.8x bigger than 35mm, which can give a decisive improvement in quality. The cameras can be relatively small and light; the lenses, reasonably fast. On the other hand, 645 cameras are rarely as fast-handling as the fastest 35mm cameras, so there are those who reckon that if you are going to go the trouble of medium format, 645 is not worth bothering. Clearly this is a strong argument for larger formats in the studio, or if you are going to use a tripod, but it is a lot less compelling – indeed, it is a counter-argument – when it comes to hand-held photography, or if you are going to carry the cameras far.

Contax 645

Several 645 cameras have offered all the features of a high-end 35mm SLR, including auto-exposure and (latterly) autofocus. The Mamiya 645 was the first of these ‘super 35’ models, but arguably one of the most advanced was the (now discontinued) Contax 645 shown here. The autofocus was inclined to ‘hunt’, but when it did focus, the results were unparalleled for the format: you really could see the advantage over 35mm. All 645 SLRs have been of the ‘cuboid’ type (Hasselblad-style) rather than ‘giant 35’ type like a Pentax 67 or Pentacon 6.

Although you can just about fit 16 exposures onto 120, most manufacturers have gone for 15 in the interests of wider rebates between the negatives. With 15-on you have 5 sets of 3-exposure brackets, which is quite handy with slides; with 16-on, there’s a spare as well. Frame counting can be via the red window — each number for 8-on is wound into two windows in turn — but automatic counting is much more normal. Some old roll-film folders were 645, but as 16-on-120 is about the same size as 8-on-127 and 127 cameras were smaller and lighter, old folders offering 16-on-120 only were rare; most offered it as a ‘cut down’ option from 6×6 or 6×9, using a folding or slot-in mask. There has however been at least one modern 645 folder.


The 12-on square 6×6 format was popularized by the Rolleiflex twin-lens reflex, and was then eagerly adopted by the makers of single-lens reflexes, most notably the Hasselblad. Obviously, a reflex without a prism or a revolving back is much easier to build and to use with a square format. It also provides a useful film saving as compared with 8-on (50% more pictures per roll, in fact) which is why it also appeared in some roll-film folders, sometimes with folding or removable masks to allow either 8-on (in some cameras) or 16-on (in others).

Advocates of 6×6 point to the way you can compose ‘portrait’ or ‘landscape’, planning your crop in camera; to the way you can crop out the foreground, thereby giving the effect of a rising front (see movements); and to the fact that you can surprisingly often compose pleasing square pictures. Detractors point out that very few people do in fact compose square pictures; that usually, therefore, 6x6cm is cropped to effectively 645; and to the sad truth that if you let square transparencies out of your control, there is no telling what layout artists may do with them.


We inherited this 6×6 SLR from Frances’s father, and it gives extraordinarily good results; but if it ever breaks, it probably won’t be reparable, which is a great pity. Some cameras are a lot more reparable than others.

Battles with art directors explain why we switched from Hasselblad to RB67, but of course it does not apply if you do your own scanning or wet printing. Obviously you have 4 sets of 3-exposure brackets, which was more important in the days of professional trannies than it is now.

Again, backing paper is normally numbered for 12-on, and again. most modern cameras use automatic counting. One of the first automatic-spacing 6×6 cameras (from Zeiss) gave only 9-on, for some reason. It is worth knowing that with Rollei Automat models, you thread the film under a sensor roller which automatically starts the counter when it senses the extra thickness of the film/paper sandwich: hence the name. With most cameras, you line up an arrow on the backing paper with a mark in the camera, as described in How Do I… Load 120.


Linhof popularized the 10-on-120 ‘ideal format’ at 56x72mm, which when enlarged 3x is almost identical to the old ‘whole plate’ size of 61/2 x 81/2 inches, for decades the standard print size (alongside 8×10 inches) for reproduction. With an area of 4032 square millimetres this is 4.7x the size of 35mm and offers a very significant increase in quality. Indeed, a Linhof 6×7, ‘three up’ (3x) can be indistinguishable from a contact print.

In our view, this is indeed the ideal compromise for many purposes, though there is also much to be said for both 6×8 and 6×9. Because Linhof were great believers in 70mm, Linhof 70mm backs are not particularly uncommon. At 53 exposures per standard loading, they were much favoured by museums and other organizations who had to take lots of high-quality photos. Alpa also sold a 70mm back adapted for direct fitting to an Alpa.

There is also a masked down version of 6x7cm, the Alpa-unique 66x44mm format, which is designed to take account of the small circle of coverage of the Zeiss Biogon. There is a wide rebate between the image and the top and bottom of the film, and a wider-than-average rebate between each image.


Railway viaduct, Manchester


The 66×44 mm format is Alpa-unique, and now that the 38/4.5 Biogon is no longer offered in Alpa mount (only 100 were made) the modified 6x7cm back is now a special-order item.


Most modern books and magazines are A4, 210 x 294 mm, which is a bit longer and thinner than 6×7 (which needs to be cropped on the short dimension to fit) and a bit dumpier than 6×9 (which has to be cropped on the long dimension).  A format of 56 x 79 mm enlarges just about perfectly onto the A-series (3.75x to A4) and allows 9-on-20. Arguably this is even more of an ‘ideal format’ for today than 6x7cm, but it never really caught on before digital took over from roll-film. Also, of course, film-holders and the like were never common. It’s still an excellent format, though, and one that we use on our Alpas.


As already noted, this was the original ’20’ format and of course the aspect ratio (at the usual 56x84mm) is identical to 35mm, though the smallest 6×9 is under 8 cm on the long side and even the longest 6×9 rarely if ever achieves the full 9cm. Originally, 6x9cm was intended for tiny contact prints for the album – many family albums, including our own, still have plenty of these from the 1940s and before — but as films and lenses improved, ‘en-prints’ (postcard-sized enlargements) became more and more popular. It is worth remembering, though, that although we think of 6x9cm as a high-quality professional format today, many old 6×9 folders were intended to give prints no bigger than about whole-plate (a 3x enlargement) and that even this was unusual.

Chonor Lodge

With a modern, high-quality 6x9cm camera – and they don’t come any higher-quality than an Alpa – the richness you can capture on film is extraordinary, though a bit of fill from the left would have opened up the shadows a bit. Kodak Portra 400; 35/5.6 Rodenstock Grandagon.

For Frances, 6x9cm is her standard on roll-film, but Roger prefers 6×7 or 6×8 because they are not so long and thin. Another drawback to 6x9cm is that you only get two sets of 3 brackets on one roll, which is why, when we used to put roll-film backs on 4×5 inch cameras in the studio, he preferred 6x7cm.

6×12 TO 6×25: PANORAMAS

Disregarding those purists who maintain that the only true panoramic cameras are those with swinging lenses, we can lump together 6x12cm, 6x17cm and 6x24cm. The smallest can be printed in a 4×5 inch/9x12cm enlarger; the medium size in 5×7 inch/13x18cm; and the largest in 8×10 inch/18x24cm. Nowadays, of course, most people would scan them. If you have access to a big enough printer, it is worth noting that 6x17cm, scanned at 2400 dpi, can be enlarged 8x to give 450 x 880mm, or about 18 x 36 inches. Even 6x12cm, scanned at as little as 1200 ppi, enlarges 3x to 168 x 330 mm or about 6-1/12 x 13 inches at 300 dpi: more than the width of a double-page spread in an A4 magazine.

On the other hand, it is worth pointing out that although a great big transparency looks very impressive, especially to a client who has never seen one before, it is often completely unnecessary unless you really, really need the quality at a very big enlargement size. Taking the same 168 x 330mm print size as noted above for 6×12, you can crop the short dimension of a 6x9cm image to 43 mm and enlarge 3.9x, which should be well inside the limits of a good camera/lens combination and leads to much less trouble with film flatness.


Mono Lake, California


Roger took this on Kodak Ektachrome 200 using a home-made ‘Longfellow’ 6×17 cm camera constructed from two old roll-film folders.

Even so, we do own and (occasionally) use a 6x12cm back, and we know one professional who in the days of film  always used 6x12cm on his 4×5 inch cameras, because he got the same set of 2x 3-stop brackets as with 6x9cm and (as he pointed out) there were times when the extra width came in handy.


For most practical purposes, ‘medium format’ can be taken as synonymous with 120/220  roll film, though another way to define it is by what it is not: it is bigger than 35mm, and is therefore not ‘miniature’ (though in the 1930s some 120 formats were called ‘miniature’), but it is smaller than 9x12cm or 4×5 inch, and therefore not ‘large format’.

To confuse matters further, under the old British Purchase Tax regulations, quarter plate (3-1/4 x 4-1/4 inch) was still an ‘amateur’ format, and might therefore be considered ‘medium’, and there are other small cut film sizes: 6.5x9cm, 2-1/4 x 3-1/4 and 2-1/2 x 3-1/2 inch.

Polaroid 600SE

Polaroid pack film, and its successors from Fuji, was usually in the old ‘quarter plate’ size. The Polaroid 600SE can however be given a new lease of life via a (hard-to-find) adapter and a choice of roll-film backs from the Mamiya Press. The viewfinder is a ‘zoom’ Tewe from the 1950s.

Then there are other paper-backed roll-film sizes, of which the most commonly encountered are 127 (46mm wide, also known as 27, A8, VP for ‘vest pocket’ and British Standard code 1) and 116 (or 16, British Standard code 4) had the same 70mm (2-3/4 inch) width as the original Kodak film: 616, Z16, British Standard code 5 was like 116 but on a smaller spool.

Bilora Bella 44

At first glance, some 127 cameras can look like 35mm, but even before you look at the back of this one, with its red window film advance, or open it up and see the 4x4cm (nominal) film gate, the name of this camera gives the game away: ’44’ refers to the format, a rather pointless 12-on-127. Other 127 formats were 8-on (6x4cm nominal) and, quite rarely, 16-on (3x4cm nominal)

Even bigger sizes than 116 were once made: 118 (or 18) at about 85mm wide, 122 (or 22) at about 95mm and 130 (or 30) at about 75mm. Only 127 and 116 is likely to be available, the latter only seldom from specialist suppliers. Finally, as already mentioned under 6x7cm, there is 70mm perforated film in cassettes, a great idea which never really caught on. Some quite surprising cameras offered a 70mm option, including even Rollei TLRs, though from the pictures (we’ve never seen one in the metal) the Rollei 70mm back was a bulky brute.


Nowadays, most people who are choosing medium format will buy whatever comes up at the right price. On the other hand, we hope that this module and its associates (roll-film backs, roll-film folding cameras, 70mm and ‘Longfellow’) may make it easier to buy the camera that actually best suits your particular needs, without being blinded by mere availability.






Ilford XP2 Super 120 and Efke R100 127