A Panoramic Digital Camera?

This is purely wishful thinking. I don't expect anyone is actually working on or intending to market the camera I'll describe here, but it's something that seems technically possible and it's something I'd like to see.

It's based on the fact that normal 35mm lenses have a 43mm image circle, which covers way more area than that of an APS-C sensor. The relationships between the image circle, a full frame image and an APS-C image are shown in the figure below:

As you can see, to cover a 35mm frame a lens needs an image circle of at least 43mm. The APS-C sensor covers only the center of the circle. My proposal for a panoramic sensor would extend the APS-C sensor out to 40mm width, while keeping the vertical dimension at 15mm.

Keeping the height at 15mm enables a number of useful features:

• By making the sensor the same height as an APS-C sensor it means that the mirror in the camera could be short enough to clear the rear element of EF-S lenses. This means that EF-S lenses could still be used - though not in a panoramic mode. They could be used to make images of the current APS-C size (15mm x 22.5mm) by electronically selecting just the center of the sensor.
• The total sensor size stays reasonable. The area of a 40mm x 15mm sensor is actually smaller than that of a full frame 24mm x 36mm sensor, so it's probably technically feasible to make and should be cheaper than full frame. In terms of area it would be the same as a 1.2x sensor with a 3:2 aspect ratio. It might even be possible to stitch two existing APS-C size sensors together!
• By going to 40mm wide you'd actually get a "digital reducer" effect of 0.9x, so a 20mm lens on such a digital panoramic camera would have the same horizontal field of view as an 18mm lens would have on full frame! Obviously the vertical field of view would be less (by the usual 1.6x multiplier factor).

What a panoramic sensor camera would be capable of

Here are two shots which show what a panormaic APS height sensor could do when used with a regular EF series lens:

This is a shot with a normal APS-C sensor DSLR and an EF series lens

This is what you'd get with the same lens with an expanded panoramic APS-C sensor

Obviously you can get the same thing by shooting with a wider lens and then cropping the image from an existing APS-C sensor. The difference would be that a cropped 10MP APS-C image would end up with 5.6MP, while the panoramic sensor image would be 17.8MP if it had the same pixel density. That's a very significant difference!

As an additional benefit, when used in portrait mode the panoramic vertical image could be cropped to yield exactly the same effect as using a shift lens (e.g. minimizing the convertging of verticals for tall buildings).

While you can make panoramics by stitching together multiple images, those who have done it will realize that it's a lot of work (needs a tripod at least, and maybe a panoramic head to do things right, plus good stitching software) and it's only usable with static subjects. A one shot handholdable panoramic camera has lots of practical advantages. It would be something like a digital version of the X-pan film camera.

There are a few downsides of course:

• Additional cost. If you only shoot occasional panoramics you'd be paying for a large sensor but only using part of it.
• It would require a larger (and heavier and more expensive) pentaprism.
• A more serious downside is that if the whole panoramic frame is visible in the viewfinder, the masked image covering the APS-C area would be quite small. It wouldn't be impossible to deal with this, perhaps using a magnifying viewfinder, but it would need some engineering. APS-C film cameras had a viewfinder that covered 3 different formats, so it is certainly possible.
• The lens hood used for full frame shooting would vignette. I can live with that since you don't have to use a lens hood, and if you did the vignetting should be pretty obvious in the viewfinder. Not everything needs to be "idiot proof".

I'm not very hopeful that we will see such a camera soon, if ever, and I'm not very hopeful that the price would be low enough for me to afford, but it's fun to think about and there's certainly no technical problem in making such a camera. It should be cheaper than an EOS 5D based on sensor area, though limited sales might make push up the price a bit.

Of course there's no need to make the sensor 40mm wide, that's just the maximum sise that 35mm full format lenses would support. The APS-H format has a 16:9 ratio and would result from a 15mm x 26.7mm sensor and you could get a 2:1 aspect ratio with a 15mm x 30mm sensor. In each case, EF-S lenses would be usable in APS-C format, but full frame EF lenses would support APS-H and a 2:1 format, perhaps at a lower cost than a full 15mm x 40mm sensor.

I suspect for quite a while we'll pretty much be stuck with 3:2 ratio sensors on DSLRs, though Panasonic have shown they are capable of "thinking outside the box" with the Lumix DMC-LX1 digicam which does have a 16:9 ratio sensor (albeit a pretty small one).

So Canon - how about it? I volunteer to do the beta testing if you make one!