What would the FFF have to do in order to be competative?

dellaaa wrote:

Reading a recent post that included a 60M pixel Bayer sensor shot, the the discussion turned into a debate as to whether the FFF would ever arrive.

Looking at the Bayer photo what do you believe the FFF sensor would have to do better than the current generation of Bayer sensors? What are the design criteria the FFF design team have?

I don't know but given the physics of the design and the past Foveons, low light performance would most likely not be on par with the Bayer, agreed?

Foveon has three photodiodes per pixel, none with correlated double sampling. This means very high read noise which means high noise floor which mean poor performance in areas with little light. This means poor low light performance and relatively low dynamic range.

The issue with read noise can not really be solved - there will naturally be more photodiodes, but also CDS is quite impossible to achieve with this kind of design. Some fancy non-destructive multiple sampling might be possible but it would not only slow things down even more, but also not be as effective.

From QE point of view the advantage of Foveon is not having colour filter array blocking light, but on the other hand there is plenty of dead space between the photodiodes. I'd guess one might be able to achieve slightly larger QE with Foveon which would help somewhat in low light situations, but not with the noise floor itself.

Historically, Sigmas have required extensive image processing both while taking the shot and afterwords (SPP). Will the FFF shoot at the frame rates of the current Bayers? Again, given the history, this seems doubtful.

Foveon's problem is the very poor color separation. In principle this could be helped by placing narrow band color filters on top of the sensor, but then some wavelengths would be totally lost and could cause some interesting artifacts.

To get decent color out of Foveon the processing indeed will be rather strong - this increases noise for color photography.

So with low light and speed out of the equation, whats left, detail and color rendition.

The main advantage is reduction in false color artifacts (e.g. moiré). This advantage goes away once diffraction (and lens deficiencies) does anti-aliasing, but it's still a long way from today.

Detail situtation has many variables, but regardless of them lots and lots of pixels would be needed in this hypotetical FFF to compete.

Color accuracy is vastly better on conventional sensors. That's why the CFA is there for.

Foveon type multi layer system might work better in the future with different materials, maybe organic materials or perovskites. Plenty of perovskite developement is being done due to their potential for solar cells and at least one multilayer demonstration does exists (with hideous image quality). Maybe 15 years from now?

As for detail, how would the specs of the proposed FFF stack up against the 60M plus Bayer sensors? Would the advantage in detail make up for the shortcoming?

No. You need likely something like 70% of the pixel count to match conventional sensors, maybe more nowdays as AI-based demosaicing is on its way. This also diminishes the false color advantage.

Anyhow, as even 10MP is enough for very large prints...

The remaining design criteria, is color. Would Sigma's color rendition be enough for people to buy it?

Some like it's different colors and I'm sure many fans would buy because of them, but as the colors can be very problematic and lack in accuracy and because the conventional cameras are not exactly lacking in color accuracy, it's hard to see how the general public would get interested in this.

I don't know and would like rational, opinions as just what will the FFF bring to the table, and why any non L mount people in 2023 would buy it when 100M pixel Bayers are on the horizon that take great low light picture at high frame rates.

At this point, fanboys aside, the fact that we are still discussing this seems a bit absurd to me, so why did I start this thread lol?.

Foveon is very interesting concept and I'm happy it was brought to life. But it feels more like a hobby project, a niche project for those who desire something different. There aren't really any advantages over conventional sensors while the drawbacks may cause issues.

I hope a FF Foveon does see the light of day, but not only I'm not holding my breath, I'd expect the product to be a very low volume very high price item.