RAD Thoughts

Another one of Pogue’s Imponderables is:

I’m told that they could make a shirt-pocket digital camera that takes pictures like an S.L.R., but it would cost a lot. So why don’t they make one for people who can afford it?

This is a long running meme that I think started with Mike Johnston’s Decisive Moment Digicam and continued with Thom Hogan’s Compact Camera Challenge. Both Mike and Thom want a pocketable digital camera with:

1. a large SLR-like sensor (four-thirds or APS size)
2. a “quality” lens
3. SLR-like performance
4. SLR-like control

I think Mr. Pogue, Mr. Johnston, and Mr. Hogan are chasing a digital unicorn. Well, Mr. Pogue is claiming others “told” him, yet, I think “shirt-pocket” is his own embellishment. Pocketable for Johnston and Hogan means “jacket pocket”.

The UnicornCam seems to have two major themes: 1) small like a digicam, and 2) takes pictures like an SLR. The second feature is hard to pin down but everyone seems to agree that it has something to do with the large image sensor. So what does a large image sensor buy you? First, I think a large image sensor gives you low-noise at high-ISO. Second, it gives you shallow depth of field (potentially).

The name Mike Johnston gives the UnicornCam is the “Decisive Moment Digicam” which is an obvious homage to Henri Cartier-Bresson and his book “The Decisive Moment”. Cartier-Bresson’s iconic images were made on a 35mm film Leica range-finder camera. His black & white images inspired thousands of street-photographers and photo-journalists.

If Henri Cartier-Bresson epitomized Decisive Moment photography then the Leica M8 must epitomize the ultimate price-is-no-issue “Decisive Moment Digicam”.

This camera with a 35mm lens (equivalent to Henri Cartier-Bresson’s tried and true 50mm) weighs 1.85 lbs and costs about $8000 ($5500 for the body, $2400 for the lens). In classic Leica range-finder spirit, this camera does not have autofocus. It also does not have live view so composition and focus is done through the optical range-finder.

Assume that a digital camera exists that is close to the Leica M8 in form and functionality but costs $1000 (still “expensive” for a digicam) and weighs less than a pound (both Johnston and Hogan aim for 14 oz). Will a digital range-finder with manual focus and only an optical viewfinder cut it? I doubt it very much.

The Leica M8 is instructional for a couple of reasons. First, the classic 35mm range-finder demonstrates the minimum thickness required for a large sensor camera body that does not use a mirror box like an SLR. The Leica is currently a bit too narrow since digital imaging sensors currently have trouble with a wide angle of incidence of light at the edge of the sensor. Special microlens configuration and software-based image correction is required to overcome this issue.

Second, fast autofocus is important and non-trivial for non-SLR cameras. From a technical standpoint, autofocus is the one area where innovation is needed. The dedicated autofocus technology in modern SLRs is exceptional. The “live view” feature offered in some digital SLRs demonstrates the compromises that are made with autofocus when the reflex mirror is up.

Even with an innovative breakthrough in autofocus, the UnicornCam still needs to make a compromise along two dimensions. Going with a large SLR-like imaging sensor results in a large lens and a total system size/weight approaching the current batch of entry level SLRs. Going with a small sensor provides small size and low weight but results in poor high-ISO performance and the inability to capture creative shallow depth of field images.

I think I’ll take a Malcolm Gladwell Perfect Pepsis stand on this one. There is no perfect UnicornCam only perfect UnicornCamS.