medium format photography 101

I would like to think that I know enough of medium format photography to share some stuff with those interested to invest in one such system. Whether you are getting a 645 or 6×6 or 6×7, the following information will be useful to know.

Before i go further, familiarize yourself with these numbers:

135mm = 36mmx24mm = 3:2 ratio = D700, 5D Mark II those cameras

120mm = medium format camera = Mamiya, Hasselblad etc

Medium format cameras have three very common formats: 6×4.5, 6×6 (square) and 6×7.

6 X 4.5 cm (source: www.lumimous-landscape.com)
This is a rectangle that is very close in proportion to the 8X10″ print format and will enlarge to this format with very little cropping needed. The most popular cameras in this size are the Mamiya 645, the Pentax 645, Bronica 645 and the Contax 645. These cameras are the most like 35mm cameras in size and handling. Most now offer autofocus and extensive automation. They are the smallest SLRs that use roll film. 645 cameras get 15 or 16 frames to a roll of 120 film.

6 X 6 cm (source: www.lumimous-landscape.com)
6X6 is the most popular roll film format. Why is this? Part of the reason is that this square contains both a vertical and a horizontal composition on the same frame. A 6X6 image is composed of a vertical 6X4.5 and a horizontal 6X4.5. No need to rotate the camera. No need to rotate the film back. Just take one shot and get both compositions. Some people, myself included, also find a square image very appropriate for some subjects. One gets 12 frames to a roll of 120. 6X6 cameras give 12 exposures from 120 film. Cameras in this format include the famous Hasselblad 500cm/503CW (though all you need are different kind of film backs to shoot in other formats).

6 X 7 cm (source: www.lumimous-landscape.com)
6X7 is very popular for several reasons. Like 645 the format it enlarges to an 8X10″ print with little cropping. Though only slightly larger than 6X6. There are four popular cameras offering this format; the Mamiya 7II, the Pentax 67II and the Mamiya RB & RZ67. The Bronica GS1 is also a contender. One gets 10 frames to a roll of 120 with this format, and either 20 or 21 frames on 220 film, depending on the camera.

Taken with Mamiya 645 AFD, 80mm f/2.8 on a Leaf Valeo 11mp digital back

Focal Length

First of all, the focal length 50mm in your usual 135mm cameras (yes 5D Mark II, D700 those) DOES NOT EQUAL TO 50MM in medium format photography.

Now that i got that out of the way, let’s move on.

Medium format camera’s 80mm is the equivalent is 50mm in 135mm cameras. Therefore, if you want to calculate other focal lengths, you simply multiply/divide accordingly. Common focal lengths of medium format lens (to my best knowledge) are: 35mm, 45mm, 55mm, 65mm, 80mm, 120mm, 150mm and 200mm.

Here’s a chart I found on Clubsnap, which will make things easier to understand.

• 28mm (in 135mm) = 45mm (in 6×4.5) = 45mm (in 6×6) = 60mm (in 6×7)

• 50mm (in 135mm) = 80mm (in 6×4.5) = 80mm (in 6×6) = 110mm (in 6×7)

• 105mm (in 135mm) = 180mm (in 6×4.5) = 180mm (in 6×6) = 210mm (in 6×7)

• 200mm (in 135mm ) = 350mm (in 6×4.5) = 350mm (in 6×6) = 500mm (in 6×7)

Taken with Hasselblad H3DII-31 and 80mm f/2.8

Digital medium format photography

My level of understand here, is that digital back makers generally stick to the 6×4.5 (48mmx36mm) sensor size for medium format photography. Whether you are using a Mamiya 645, Hasselblad 503CW or a Mamiya RZ 67 camera, you will only obtain images that are in 4:3 ratio. In some case, these digital back makers like Phase One, Leaf, Hasselblad and Sinar make sensor sizes that are slightly smaller, giving them a crop factor of maybe 1.3x (think APS-C sensors in 135mm) I feel that this is so purely for marketing reasons.

Latest technology allows you to shoot in square format to mimic the 6×6 ratio as much as possible. I vaguely remember one of the Hasselblad digital backs being able to do that.

For older digital backs, you will see small sensor sizes like a 36mmx24mm like the Leaf Valeo 11. To be honest with you, this back gave me tons of headache because mounting the back on my Mamiya AFD (back then) means by crop factor is 2x. So shooting with a 80mm lens essentially produced a 160mm crop. The worst part: the crop is invisible through your view finder so very often i have to do some trial and error in terms of composition to get my shots right. That said, even these old digital backs are freaking amazing in terms of image quality.

That is why i love them so much that i find it hard to accept the image quality of 135mm cameras anymore.. not even your 1Ds Mark3 and 5D Mark II with L glass can top them.

You can see some shots i took with the Leaf Valeo (11 megapixels) digital back in my portraits portfolio section.

Update: This portraits series was also taken with the Leaf Valeo digital back.

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