Dorothea Lange and What Is Sharp

Dorothea Lange At The Barbican Art Gallery

This summer, Barbican Art Gallery stages the first UK survey of the American documentary photographer Dorothea Lange (1895–1965), one of the most influential photographers of the 20th century.

If you are in London and want to see Lange’s work, there are 250 of her photos along with books, letters, and notes in an exhibition at the Barbican Art Gallery.

The exhibition describes how Lange started her working life as a society portrait photographer in San Francisco and was doing very well for herself.

Then the Depression came and the Government Farm Securities Administration hired her and other photographers and writers to document the exodus of Oklahoma tenant farmers to California following a drought that had turned the mid-Western states into a giant dustbowl.

The experience opened Lange’s eyes, and from then on her mission was to document social issues to bring about change to make a more equitable society.

The exhibition is well worth seeing if you have the opportunity.

What Is Sharp

Lange’s photos are held in the Library Of Congress Library. This one (held as a 58.5MB tif file) is Dorothea Lange’s photograph of Florence Owens Thompson and two of her children. It is one of a series that Lange shot over 10 or 15 minutes when she was following and documenting the lives of dust bowl tenant farmers. The photo is one of the icons of the period and has become known as the Migrant Mother photo.

Lange’s notes at the Barbican exhibition details what took place when she took the photographs. Lange mentions that the session was unusually short and she describes how she and Florence Owens Thompson and the children related during that 10 or 15 minutes.

I am not sure what camera Dorothea Lange used to take this photo. A search on the Web says she used a Graflex Super D for a lot of her work. The Graflex Super D uses or used 3 1/4″ x 4 1/4″ film, which equates to 82.5x108mm.

In principle, the bigger the linear difference (not the area) of one size film to another, the greater the detail that the film can show.

35mm film, the kind used in most film cameras before the advent of digital sensors, is 24x36mm.

So in linear comparison, the film in Lange’s camera was more than three times as long on each side compared to 35mm film.

But now we have digital sensors, and the vast majority of photographers shoot with cameras that have AP-C sensors, or micro 4/3 sensors, or smaller.

Here is a 35mm frame, and within it is an AP-C sensor, and within that is a micro 4/3 sensor, and then a 1″ sensor. The sensors in the majority of compacts cameras are smaller still.

The film that Dorothea Lange used would be several times bigger than any of these formats.

In other words, the sensors in most digital cameras are tiny compared to the size of the film that Dorothea Lange shot.

Here is a close up of part of Florence Owns Thompson’s face. I’d say the close-up represents about 5% of the full frame.

Looking at the full frame of Migrant Mother, it looks very pleasing, but home in on the detail and we can see that it does not look sharp. Of course, maybe her shutter speed was too low or her focusing was off – but still, it makes you wonder.

Well wonder no more.

In 2016, Ctein – a master printer who has printed medium format slide film and micro 4/3 digital files – was asked when micro 4/3 sensors would surpas medium format film for sharpness.

His answer was that micro 4/3 digital sensors had already surpassed medium format film and had done so back in 2010.

Why Get Hung Up On Sharpness

I could direct this question to myself, because I am always looking for that extra bit of detail in photos. The reality is that at a normal viewing distance we are already well past the point at which the eye can discriminate any additional amount of sharpness.

There’s one more twist, of course, and that is in Photoshop one can sharpen Lange’s photo by increasing the micro contrast. I did that with the close-up with this result.

I could have sharpened it more, but the grain started to intrude with big black and white splotches so I backed off at that point.

There is a lovely tonal range in the original Lange photo. And that ability to capture fine gradations of tone and not just sharpness is a bit part of what makes a pleasing photograph.

I would use film, but developing and printing film is a labour of love that requires a permanent darkroom in which to settle in and be comfortable. And we just don’t have the space.