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Large Format Lenses – The Standards

Part 4 of a Series on Large Format Photography

Tim Parkin

Tim Parkin

Amateur Photographer who plays with big cameras and film when in between digital photographs.

Flickr, Facebook, Twitter

Richard Childs

Richard Childs

Richard trained as an Orchestral Percussionist in the 1980's but his true love has always been the outdoors and particularly mountain environments. Throwing in his drumsticks to become a full-time photographer in 2004 he continues to work with a large format camera alongside digital equipment and exhibits his work in solo and group exhibitions as well as at his own gallery in the Ironbridge Gorge. Links to Website and Facebook

UPDATE:Richard Childs and Tim Parkin will be running a large format residential workshop in Glencoe from the 31st of October to the 3rd of November and due to a cancellation, there is a free place. More details are available here and please ask about a discount for late booking.

When people first try out large format photography and they come to the choice of lens for their first kit, they typically make a few common mistakes. Hopefully, this article will address some of these and also expand on what makes the large format lens such a unique object.

Lens Equivalents

The first problem most people encounter is choosing a focal length. Received wisdom has it that the conversion factor from 35mm to large format (5x4) is 3x. Sadly this received wisdom causes no end of people to buy lenses that are far too wide for day to day use and is a real barrier in certain conditions. The actual answer is a little more complicated because the aspect ratio of the two formats are different. To this end, I’m going to give two sets of tables and which table to use depends on how you plan on photographing with large format camera.

If You Take Panoramic Pictures...

If you typically use your 35mm camera to take horizontally oriented photographs or crop to create panoramic photographs then the difference between the two formats is the ratio of the film/sensor sizes longest edges. 35mm film/sensor is 36mm across the long edge and 5x4 film is 120mm across the long edge. Hence the conversion ratio is 120/36 = 3.333x

Here’s the conversion table for common LF focal lengths

5x4 Focal Length35mm Focal Length

If You Usually Crop Your 35mm Photos to 5x4 or Square...

If you commonly crop your 35mm images to 5x4 or even square then the difference between the two formats is dictated by the short edges of the film/sensor. 35mm film/sensor is 24mm and 5x4 film is 96mm. This gives a ratio of 96/24 = 4x

Here’s the conversion table

5x4 Focal Length35mm Focal Length

If we had used the 3x conversion and were typically using a 24-70 zoom lens, our LF equivalent lens range would be from 72mm to 210mm. A 72mm lens is actually a bit of a monster and quite hard to see in the corners in darker conditions and if you typically crop to 5x4 or square then this is actually equivalent to an 18mm lens, not 24mm. Quite a difference!

Given the ‘I crop to 5x4 ratio’ condition, a 24-70 lens is actually from 100mm to 300mm. If you talk to a lot of large format photographers you’ll find that there is a very common lens ‘set’ of 90,150,210 plus sometimes a 300mm and this matches quite closely with the 24-70 zoom lens.

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