Might the Alpha 7S III be Utilizing the Similar Sensor because the Alpha 1?

Could the Alpha 7S III be Using the Same Sensor as the Alpha 1?

A teardown by astrophotography website LandingField discovered that the 12-megapixel Alpha 7S III is utilizing 4 photosites to create a single pixel, which means its precise decision is 48-megapixels. Some have taken this to imply that it makes use of the identical sensor because the Alpha 1.

After tearing down the sensor and inspecting it below a microscope, Landingfield found that the sensor makes use of what the publication describes as a “2×2 binning” design, which ends up in the conclusion that the sensor within the digicam — the IMX510 — truly has a 48-megapixel native decision.

The RGGB Bayer sample is unfold throughout a 4×4 grid. After sensor readout, the 4 pixels in every of the identical shade are then mixed digitally to provide one pixel earlier than sending out on the SLVS-EC interface. This might clarify the rise in learn noise. From my information, none of Sony DSLR CIS helps cost binning because of limitation in its pixel structure. By combining 4 pixels digitally, you’d improve the noise variance by 4 and therefore learn noise nearly doubles (sqrt to RMS).

This assertion brings up a serious query: would what is going on right here be binning or oversampling? “Pixel binning” is described as utilizing a set of adjoining pixels to create a single pixel whereas oversampling is described as utilizing a number of full-size pixels to create one bigger pixel. It feels like semantics, however Sony truly particularly writes that the Alpha 7S III doesn’t have pixel binning in its press supplies throughout the launch of the digicam, which means the accusation of binning is fairly vital.

IMX510 (prime) 2×2 binning pixel below a 50x goal microscope. | LandingField
FSI single pixel in IMX235 below a 50x goal microscope. | LandingField

Particularly, Sony definitively acknowledged that the Sony Alpha 7S Mark III has no pixel binning or line skipping. Sony’s authorized crew can be unlikely to green-light this assertion if the digicam did actually truly pixel bin. It would come all the way down to what Sony’s engineers outline as “binning” or “oversampling.”

PetaPixel reached out to Sony, however the firm didn’t instantly reply. As a rule, nevertheless, Sony doesn’t present info on its engineering designs, so it’s unlikely the reply to those questions would come from the corporate direclty.

Few specialists on sensor engineering exist exterior of those that work for the digicam firms, however Imaging Useful resource’s founder Dave Etchells is one among them. PetaPixel requested him to supply a few of his ideas on the subject.

“It’s binning however in a unique sense than what folks have conventionally referred to as binning,” he tells PetaPixel after having a look at LandingField’s report. “It’s binning digitally which is totally different than oversampling as effectively. Usually after we say binning that signifies that they’re taking the precise cost that’s collected by every pixel and mixing it to a bigger cost earlier than studying it out [which isn’t happening here].”

Etchells says that a method to consider that is to consider the person pixels as cups of water and the capacitor as a bigger cup — rudimentary, however illustrative. With binning, consider these cups of water as being dumped into the bigger cup after which measured. What Sony is doing right here is as an alternative of that, the cups are being individually measured and never dumped into a bigger cup in any respect.

“What Sony seems to be doing on this sensor is that they measure every of the little ‘cups’ after which provides these numbers collectively. So the cost is combining the numbers as it’s being learn out,” he says.

“Sony is studying the voltage on every particular person capacitor and including the numbers collectively. So it’s not technically binning. It has the identical decision penalties the way in which binning does, however you additionally truly get a worse signal-to-noise ratio than in case you did bin,” he explains.

Trying again on the cups analogy, Etchells says it’s type of like studying imagining that there are measurement strains on every of the person cups and that there’s some degree of inaccuracy related to these strains if somebody had been to eyeball pouring liquid into these cups to measure them. Whether or not these strains are on every small cup or on the bigger cup, there may be some degree of uncertainty in studying it. If somebody was to dump all of the liquid of the small cups into one large cup after which learn it, there can be only one quantity of error. However when you have 4 little cups which are being measured individually as an alternative, that’s 4 potential errors which are being mixed collectively.

“Sony isn’t binning within the conventional sense, however they’re taking the indicators out of a gaggle of 4 pixels and measuring them and mixing these collectively earlier than they get despatched on to the processor. It’s the identical as binning from the standpoint that you simply’re dropping decision, but it surely’s totally different from binning in that you simply’re in all probability additionally getting extra noise,” Etchells says. “They’re combining 4 particular person measurements of pixel voltage and that mainly means you have got twice as a lot readout noise.”

Some have taken the construction of the sensor to imply that Sony used the identical sensor — or some derivation of it — within the Alpha 7S III because it did within the Alpha 1, because the Alpha 1 presents full-width 4K video seize with pixel binning from 48 million photosites. If Landingfield’s info is right, that is what was discovered on the Alpha 7S III, however the binning is as an alternative hard-wired into the sensor.

Etchells says this does make some sense, as it might be a comparatively minor change to regulate how the corporate was studying a sensor versus designing completely new pixels and would clarify why the corporate went with a route that truly launched extra noise than conventional pixel binning would. That is additionally one idea that LandingField’s report involves as to why Sony would go together with this design.

The opposite idea as to why Sony would do that is that for HDR, there may be probably a extremely large benefit in that every pixel can have totally different sensitivities. By various the sensitivity on every pixel it might give them extra dynamic vary, in idea, Etchells says.

Each the Alpha 1 and the Alpha 7S III have 759 phase-detection autofocus factors, which can lend credence to the concept that each use variations of the identical sensor. However on the flipside, 4 pixels making up one pixel within the 12-megapixel Alpha 7S III would imply 48-megapixels, which is fewer than the Alpha 1’s 50-megapixels. That would imply the sensors are totally different, however one may argue that Sony would possibly simply be cropping the Alpha 7S III sensor a bit.

So are each cameras utilizing variations on the identical sensor? In all probability not, but it surely’s inconclusive with out extra info.

“Based mostly on the recorded pixel pitch (Alpha 7S III is 8.4 versus the Alpha 1’s 4.16), There may be a few 2% distinction and so I strongly suspect they’re not the identical chip because it’s not precisely divisible into one another. However that is determined by if we’re taking a look at precise pixel dimensions printed by Sony or if we’re simply dividing sensor dimension by the variety of pixels,” Etchells continues.

He additionally says that is assuming that the 2 cameras have precisely the identical framing.

“If it seems that the Alpha 7S III is cropped simply barely tighter, I might then argue strongly that it was the identical chip. It could be attention-grabbing to have each cameras locked down with the identical lens to see the place the sides of the body can be.”

The complete breakdown of the sensor will be seen on LandingField, which it ought to be famous by no means particularly asserts that the sensor shares something in widespread with the Alpha 1. Nonetheless, it’s price contemplating what the corporate defines as pixel binning or oversampling and eager about what this implies so far as sensor growth.



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