Merco_61

The problem with 3:2 is that it seldom, if ever, occurs in nature. There is a reason why paintings are seldom 3:2. It is either too oblong or not oblong enough.

Large format negs are usually either 5:4 or some kind of panoramic format and professional medium format 6x4.5, 6x6 or 6x7. 

3:2 before 35 mm was mostly snapshot cameras like the box brownie and the folders. The reason for the 6x9 format was probably that you got 8 frames from the same roll film as the 12 frame square format Kodak A without anything extra going to waste.

I think that the familiarity with the format from using the box brownies made it easier to accept the small cameras, even if they were expensive.

It matches the classic 35mm format is all I can think of, (what most people had come to expect their photos to look like).

If you think further back in history, why did they decide on 24x36mm? The technical reason is easy to understand, but there were other factors.

I have found the reasons behind this format interesting for many years and have read quite a bit about it. I even used slide masks to get a 5:4 aspect ratio on slide film as I found it difficult to compose for 3:2 back in the analog days.

Oscar Barnack was the engineer at Leitz who was the mind behind the 35 mm camera.

The Edison patent format was, as you say 24:18. This is 4:3. Oscar Barnack found it easiest to double the length of the format and advance the film 8 sprockets instead of the cine 4 sprocket frame. That is the technical reason behind the 24x36 mm format.

There was a marketing reason as well. Here, Kodak were responsible, long before these miniature cameras were thought of.

Let's see if somebody has a theory...

That is a nice history of the Hollywood aspect ratios, but why did Barnack end up using the 3:2 ratio we still use today?

Time to bump this again.