RichardE Loc: California

Does anyone know why there are no cameras with circular sensors? Seems then I could decide the picture size myself in PP. Or is it because the sensor has always been rectangular and the lens circular? I have seen some P&S cameras with rectangular lens entry configuration. Sony's rx100-III and the w-810 come to mind. And some Canon Powershots.

Searcher Loc: Kent, England

If there were circular sensors, to get the best out them there would have to be circular monitors and circular printing paper. "Straighten that horizon" would no longer be an issue.

There are circular sensors in fact, giant multiplex sensors with huge numbers of megapixels are usually circular and I am sure that I have see somewhere a picture of the round sensors used in space telescopes.

oldtigger Loc: Roanoke Virginia-USA

circular would reduce the sensor yield from a blank and cost too much plus increase size, weight and cost of camera.

RichardE Loc: California

Thanks, Searcher. But could I just crop as I see fit instead of having the camera do it?

RichardE Loc: California

Thanks 'oldtigger', I had not thought of the mfg cost consequences!

oldtigger Loc: Roanoke Virginia-USA

sure, but are you willing to pay twice as much for your camera?

RichardE Loc: California

Not till I win the lottery!

Searcher Loc: Kent, England

No you couldn't; draw a circle, then draw the largest rectangle possible in that circle. Obviously it will be a square, and that would be the maximum you could get out of that sensor. On your drawing, look at all those pixels you are not able to use.

If you enlarged the square beyond the circle boundaries, you would get fall off and vignetting.

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oldtigger Loc: Roanoke Virginia-USA

he could get a circle including all the cells on the sensor, not just a square within it.
He would not get fall off and vignetting beyond the circle because there are no sensor cells there to be read.
He could crop a triangle or even a donut out of the circle.

my question is why would he want to?

SonnyE Loc: Communist California, USA

Why reinvent the wheel? :hunf:

Searcher Loc: Kent, England

The outer edges of a sensor don't work as well as the inner ones - the effective photo-diode area is slightly less, so you may sometimes see in a camera spec. two figures for the number of megapixels. The image would vignette to white or streaky maybe,

I don't know why he would want to, but if it happened, half the photographers everywhere would be asking if sensors could be made rectangular in pro to monitors and paper, the other half asking if the hole in the donut could be enlarged or reduced.

Searcher Loc: Kent, England

I should have seen that coming !!!

SonnyE Loc: Communist California, USA

;) :lol: ;) :idea:

Not to be rhetorical, but paper is square. :lol:

DirtFarmer Loc: Escaped from the NYC area, back to MA

The main reason that comes to mind is that the sensors are linear. That is, pixels are lined up in a line, then another line below that, etc. If you do that on a circular image you have a bunch of very short lines at the top, getting longer until the middle of the circle, then getting shorter again until the bottom of the circle. The rectangular sensor keeps everything neat and tidy and all the lines are the same length.

I suppose it would be possible to arrange the pixels in a spiral, but I would think this would present readout problems (not to mention problems getting power and control lines to the pixels in the center of the circle).

Then printing your photo would be a problem. Circular paper is not readily available and printers aren't set up to use it. Frames are generally rectangular also.

As far as the horizon is concerned you might think a circular sensor would eliminate the necessity to keep the camera level. However, if the pixels are arranged in lines as they are today the angled-line jagged edges would start to show up. Maybe with a spiral array you wouldn't have a problem.

And what would you do with the rule of thirds? How does that work in polar coordinates?

It is true that a circular sensor would maximize the capabilities of our lenses. Lenses have circular symmetry so the image produced by a lens is really circular. If you place a DX lens on an FX camera you can see this. Some lenses will be better than others, but the DX lenses that don't work on FX cameras will have a circular area where the image is in focus. Outside that area you will get distortion, vignetting, and/or poor focus.

So why are sensors rectangular and lenses circular? Because we've always done it that way.

RichardE Loc: California

Dirtfarmer, I like the spiral idea. But "we've always done it that way" is an "in the box" thinking. And, we've come from sleds to wheels to 'magnetic repulsion' propulsion and where to next? I like to think that there might be a better way and maybe I might live to see it. But, I was just venting my curiosity about something I thought of last night. I understand the current physics as now explained by fellow HHG'ers and I thank you for all the input.