Is there time for an interchangeable sensor DSLR?

Started Oct 19, 2012 | Discussions thread
Joseph S Wisniewski Forum Pro • Posts: 34,141
More B&W and IR...
3

Tony Beach wrote:

Joseph S Wisniewski wrote:

Tony Beach wrote:

I don't think its biggest value is price, although there would be some cost saving to buying another sensor instead of an entire new camera.  I think its biggest value would be to be able to carry multiple sensors and use them on one camera -- I would like B&W as well as IR to go with the current 36 MP BFA sensor.  Since we don't get B&W or IR cameras from Nikon, it seems to me that interchangeable sensors would make that more likely.

IR is never going to happen,

Certainly true if we only have the major camera companies to rely on.  With interchangeable sensors though there might be an opening for a sensor manufacturer to offer sensors directly to customers.

Agreed. But it's a "side effect" of interchangeable sensors, not the overall goal. If the sensor were easily user removable, someone would definitely come up with a cottage industry of offering them with and  without IR filters, with and without anti-aliasing filters, maybe even "naked" (something we do in scientific imaging, remove the sensor cover glass so it can be used to 200nm "hard" ultraviolet) or refitted with a quartz window. I've done that a couple of times.

Heck, if you can get the sensor out easily, converting it to monochrome by dissolving the Bayer color filters isn't that hard. So, interchangeable sensors are an "enabler" for much easier IR mods. Easier to perform, easier to use (carry a second sensor, not a second camera).

Problem is that the camera companies are probably smart enough to realize this, or read it here, and the Sony lesson will kick in, and they'll quash their interchangeable sensor plans.

OK, a more serious, mainstream issue: B&W. It's obsolete. Not the art and craft of B&W, that's eternal and beautiful. The technology is obsolete. We did get a B&W camera from Nikon. It's called the D800. A 36mp D800 color shot, converted to B&W, outresolves an 18mp Leica M9M monochrome shot. Look at what Nokia did, a 40mp sensor in a phone camera. It doesn't deliver 40mp pictures, it delivers 8mp pictures, with the 40mp serving as "oversampling". That's the wave of the future. A 36mp color sensor, even with Bayer color filters and AA filter, extracts more information from the projected image than Leica's pure monochrome. But a 400mp sensor on an APS DSLR would extract everything that the lens had to offer. Oversample at 400mp, and knock it down to 100mp, either B&W or color, and you've got all the resolution you can expect from a real optical system (as opposed to a "synthetic" system like a stitched panorama).

The CFA reduces DR

Actually, it increases it by 1-2 stops. Unless an image has color transitions with such fine detail that there are color transitions between pixels, you can consider an image to be "locally monochromatic". That means, in the red of a flower petal, there are different intensities (L component in LAB) but the color (A and B components in LAB) remain constant. So, the red will record quite high in the red filtered Bayer cells (which means you can dig out shadow detail) while the green and blue record low (which protects against blown highlights). In a pure monochrome sensor, when you blow a highlight, it's gone. When you underexpose a shadow, it's gone.

I own possibly the world's only monochrome Nikon D90 and D100 (hint, guess who owns the domain monochromedslr.com?) and am friends with Iliah Borg (who did a monochrome D2X). I've worked on monochrome raw processing software, for both artistic and scientific applications.

The DR issue can be addressed, by making a sensor similar to the Fuju SR sensors, where they had a checkerboard pattern of low sensitivity "highlight" pixels. They did it with an actual metal aperture mask, but you could do it by the same screening process that makes Bayer sensors, just lay down 4 stop ND on every other pixel, instead of RGBG.

I was actually working with Fuji on that, before the Super CCD program got canned.

and makes the sensor less sensitive,

Now that is true. Even though my monochrome cameras have no microlenses (which lost them a stop of sensitivity) they still outperform the color cameras.

and BFA reduces resolution -- so why not just remove them if that's possible?

Resolution is a canard. We've just seen the first "oversampling" camera, from Nokia, of all people. Soon, everyone will be doing it. Sounds hard to believe, right? The digital music industry moved from high depth (16 to 22 bit) converters running at the desired sampling frequency (44.1k, 48k, 96k) to oversampling converters (4 bit or 1 bit) running in the megahertz ranges virtually overnight (about 3 years to exceed 50% penetration).

Imagine how well a 36 MP B&W FX sensor could do today, versus a 72 MP or even a 100 MP BFA FX sensor might do sometime in the future.

The 72mp CFA will win. I don't have to imagine, I've tested monochrome and color sensors.

In any case, we're moving in totally the opposite direction, towards sensors that can do more and more different missions, until we hit the point where one sensor really does it all, and there's no need to change one out.

Nonetheless, there is this patent that was mentioned, and there is a hole right now that is not filled by the yet-to-be-realized wonder-sensors.  Sure, for IR we could just slap an inefficient IR filter in front of the lens and crank up the ISO 4 stops to make up for it,

More like 10 stops, for modern IR blocking filters. That's why there's such a cottage industry grown around removing them. And yes, user interchangeable sensors will make that much easier.

and someday that will suffice, but I think even in the imagined future (and one many of us will not be around for) having the highest image quality by removing the unnecessary CFA and IR filters rather than counteracting their effects after the fact.

No. In the future, the quality of a monochrome sensor and a color sensor converted to monochrome will be identical. Infrared will always be a case of working better if someone pulls the filters out, but that is not something that requires an interchangeable sensor.

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Rahon Klavanian 1912-2008. Armenian genocide survivor, amazing cook, scrabble master, and loving grandmother. You will be missed. Ciao! Joseph www.swissarmyfork.com

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