Hi,
It would be interesting to hear from folks knowledgeable about the cost aspects of modern sensor designs.
My understanding is that increasing the sensor size over proportionally expensive.
But, I would assume that increasing the number of pixels would not be very expensive.
Clearly, increasing the complexity will increase the probability of component failure, but I also think that bad pixels can be mapped out. The complexity of the non pixel components should probably increase with the square root of pixel components. Doubling the number of pixels increases number of columns with sqrt(2).
It seems that APS-C is pretty much stuck at 24 MP and 24x36 is moving slowly upwards from 36 MP.
- There can be quite a few reasons for the slow development:
- Optimum balance between noise and resolution may have been reached.
- It may be that we get into diminishing returns with regard to resolution.
- It may also be that camera electronics can have difficulty to handle larger amount of data within limited power budget.
- Cost obviously is a factor that plays an important role.
On the other hand, we get into a situation when medium format uses smaller pixel size than 24x36 mm, something like 3.8 microns on the 100 MP 44x33 mm sensor.
Any comments from sensor experts?
Best regards
Erik
Image sensors are not leading edge semiconductor products at a fundamental level (which is not to say that design teams are not doing innovative work). Most of the constraints under which they operate are commercial and depend very much on the market. So, here is the first thing to take into account:
The market for large-sensor still cameras (which includes all ILC cameras) is a very small part of the overall sensor market. The sensor companies will tend to priorities their R&D expenditure where they see the biggest return. Right now, that's the automotive market. Recently cars have become plastered with image senosors, and the image sensor companies are falling over themselves to bag a part of that new market. New markets are few and far between. Whilst they do that, they aren't putting so much into large-sensor still cameras, which is a moribund market.
So, the question a sensor company is making is whether it can make money on each new sensor product, and this in turn depends on its customers. We could take as a case study the Nikon D850. This uses a Sony IMX309 sensor with 46MP. The D800 and D810 both used an IMX094 sensor with 36MP, and that sensor has been a successful product for Sony, going into two of Sony imaging's cameras, one of Pentax's and becoming popular in the scientific and industrial markets. If you want to build a camera around it, you can buy one for around $200. Sony imaging no longer uses that sensor, having commissioned a BSI alternative, the IMX193, but the sensor was still selling in other markets, so left to itself, Sony has no reason to replace it. However, Nikon clearly needed an upgrade for the D850, anything less would be seen as not enough in market terms. Now Sony has a customer for an upgrade, and the customer will set the broad parameters of the new sensor. Panasonic also expresses interest in a FF sensor in the 46MP range. Now Sony has two customers, and replacing the IMX094 becomes commercially viable, and Sony goes ahead and produces the part. There is nothing new in this sensor, it is an assembly of technology Sony already has. In fact, it's not close to the limits of what they can do.
So, in brief, the progress of the sensors that we see in our cameras has slowed because our cameras represent a shrinking market, and the there are no longer string drivers for investment in it.
As far as the relative expense of larger sensors versus more pixels, that is a complex question. The reason for the price drop of large sensors is reasonably simple, they can make use of fab plants which are no longer suitable for the small sensors. Thus they extract value from what would otherwise be an idle asset. Given that the major cost of semiconductors is plant, not raw materials, this means that the relative cost of the large sensors for our small market has declined rapidly. In fact, that is precisely why all the action is at FF and larger, for the still camera market, they represent opportunities for new sales where there is little elsewhere, and the opportunity to extract additional value from old lines is also attractive.
