Lol, well I know you like the higher spatial resolution...but that only works if the lens is up to the task (at least for "spatial" resolution of the image itself...not for comparing final or effective resolution of the larger sensor to a smaller denser one at the same lens focal length, etc...obviously ultimate image quality is less of a factor in that case). Not many lenses are up to the task. Also I'm not saying the 600 ii is not able to pull it off, obviously of course it is. For astro imaging, would you not still need to do a similar multi shot NR process, even for a 6D, 5D3, or 1DX sensor? How about for the 24MP or 36MP Exmors? Wouldn't the A7r be an interesting option (since it can be adapted for EF lenses)? Or is the closer flange distance enough to discourage trying that, due to the higher ghosting? I assume in that process, you are not using (and would not want to try to use) ISO settings above 1000 or so (meaning the Exmors would have clear advantage).
If you are talking about astrophotography (honestly not really sure what your trying to get at here), then the answer would really be "none of the above". I use my 7D for AP only because it's what I have right now. As far as the best sensors for AP, one doesn't use a camera built for normal photography. Every normal photography camera "cooks" the images. Even Canon's, even though they cook them less than the competitors, are always modifying the raw signal in some ways, but more than enough that it can make it difficult to properly calibrate and integrate a stack of images to produce a low noise, easily stretched astro image.
Astro CCD imagers tend to be vastly superior to any CMOS image sensor from normal photography cameras. They are usually monochrome, therefor their spatial resolution, particularly for color filtered frames, is higher despite the fact that they often have slightly larger pixels. They use higher grade silicon and fabrication processes, and usually have higher Q.E. (55-65% is common for low end CCDs, 70-96% is what you get for higher end CCDs). They also usually have considerably higher dynamic range. About the best DR for a modern CMOS imaging sensor for a normal photography camera is around 40-43 dB. Even a lower end astro CCD gets about 55dB, and the midrange and higher end CCD can get anywhere from 70-105dB of dynamic range. About every 3dB is a one-stop improvement. Most of the nice high end astro CCDs that use the Kodak KAF-16803 full frame (36x24mm) sensor with 9µm pixels (or similar variants, some use a 36.7x36.7 4096x4096 pixel square Kodak KAF sensor, but it's specs are generally the same) get between 79 and 91 dB of dynamic range (depends on the actual grade). FWC is around 100,000e-, read noise is about 9-11e-, and dark current (when fully cooled) is around 0.02e-/s or less. Factoring in read noise, that's anywhere from 24-29 stops of dynamic range...which utterly TROUNCES the D800 and any other Sony Exmor based imager on the market.
When it comes to core technology, a lot of the technology that matters for normal photography really doesn't matter a wit for astrophotography. Spatial resolution is an important factor for normal photography. Not the single most important (you should know me well enough by now that I don't believe in the concept of a single most important feature for IQ
). When it comes to astrophotography, it's a very keen balancing act, between getting enough resolution, but not so much that your dramatically oversampling your subject. You have a number of factors that go into producing a "spot size", the size of a diffraction-limited star at the sensor. When you factor in seeing (atmospheric turbulence), most of the time it's difficult for amateur astrophotographers to find seeing good enough that stars are less than 2-3" (arcseconds) in diameter. For nebula, galaxies, clusters, basically anything non-planetary, you want your sensor resolution to be fairly close to your spot size, not oversampling them too much, but also not undersampling them. For the most part, a pixel size around 5-6µm is pretty ideal for this purpose, but most astro CCDs allow pixel binning, so you can make your effective pixels larger or smaller as necessary when adding barlows or focal reducers in order to match your pixel size to your seeing/spot size. Astrophotography is also dependent on having sensitivity to wavelengths of light that are either utterly unimportant for normal photography, or which may even have a negative impact on color accuracy (i.e. deep reds and near IR and near UV), while concurrently being averse to other wavelengths that are often very important to normal photography (i.e. the various bandwidths within which sodium and mercury vapor lighting emit...yellows, greens, and violets, which contributes to light pollution in cities, is often filtered out with light pollution reduction filters.)
What I need for astrophotography is very different than what I need for stills photography. There is nothing wrong with more spatial resolution for normal photography, more of it certainly doesn't hurt. Total sensor area is also important for normal photography for VERY different reasons that it is important for astrophotography. Total sensor area leads to higher real sensitivity with normal photography. Larger sensor will always trump smaller sensor when it comes to high ISO performance.
With astrophotography, most of what your imaging are point light sources. This makes full well capacity, quantum efficiency, and having a low gain setting far more important than high ISO performance, as the higher you crank gain (or ISO), the faster your stars saturate and "bloom" (clip, then begin to spill over into neighboring pixels, which also eventually clip). Physical aperture size vastly more important than relative aperture in astrophotography, as it doesn't matter so much how fast you image as how much light you get from each and every definable point of the sky that you are resolving. Physical aperture is also the primary factor in determining limiting magnitude, so a larger physical aperture, even if the telescope is effectively only f/8 or f/10, is important if your goal is to resolve very small details of very distant objects, or very small, dim stars.
It's generally illogical to compare normal photography needs with astrophotography needs. They are very different. What I argue for here on CR is very different than what I may argue for in the astrophotography threads here, or on astrophotography forums. Conflating what I've said about CMOS image sensors for normal photography with what I may have said about astrophotography is generally pointless, as there is no real correlation between those two types of photography.
Have you seen Sigma's internal balance sheets and accounting? You claim you know where their money goes. I admit obviously their foveon sensor is still very much in infancy, which is a shame. However, they did buy the rights to the design from the American company. And, they are the only ones producing a sensor like it (so far). They even have a new one (which you were quick to trash, without ever having tried it).
Your kind of missing the point of what I was saying. It doesn't matter how much money is involved. My point is that if they dumped their Foveon advertising budget into Foveon R&D, the money would be better spent. Regardless of how much they actually spend. A truly competitive Foveon (one that has BOTH the color fidelity advantage as well as competitive spatial resolution) would speak for itself, in images and by a much larger community and word of mouth.
I see nothing wrong with giving Sigma credit for trying, for being different...it seems like it works for the segment of the market they have laid claim to.
I've never faulted Foveon for trying. Ever. I've only faulted them for lying or being misleading and creating this mistaken notion that somehow, Foveon's layered pixels somehow give them the magical ability of creating more resolution out of nothing. Sigma has a misleading, fallacious advertising agenda for Foveon. They seem to think they NEED to falsely trump up Foveon's resolution capabilities in comparison to bayer sensors, when they really don't. That's my beef with them. If they were truthful and sold Foveon on it's REAL strengths, I'd have nothing to call Sigma out for, and we wouldn't be having this discussion.
Primarily they make lenses, after all. The cameras are a very small niche. Why would you expect them to be able to spend the funds necessary for the R&D to develop the sensor to your liking, when Canon and Sony have (as yet) not been able to do it? Canon is trying to do it, and they are the largest camera company in the world. Yet it's still not even for sale.
Based on the earliest patents from Canon for similar technology, they haven't been at it for even half as long as Sigma (or the prior owner of the technology). Hence my quip about Sigma better spending their money on R&D...it shouldn't take so long for such an intriguing sensor technology to go...almost nowhere. It was at 4-5mp for years, then it had a jump in the last couple of years to higher resolution, but it still lags behind bayer sensors. Foveon still suffers from noise problems, so it's never been as viable at high ISO (which immediately makes it a non-viable option for a LOT of photographers). Some of the technology in Canon's patents already surpasses Sigma's technology that is already in Foveon.
I sincerely hope that as more cash flows into Sigma from their lens division, they will be able to better prioritize more funds for Foveon R&D. I do like the core concept. I just don't believe that Sigma has done Foveon justice (so far). Things could change, and if/when they do, I'll applaud Sigma for the change...but to date, the snail is still losing the race.
(And let's face it, if Sigma spent $1 billion to develop it, it would still be a failure in your opinion, no matter how good it ultimately was...how is that fair or unbiased?)
Now your just assuming things. If you actually learned anything about me over my time on these forums, you would understand how ludicrous that assumption is.
I could care less, really, about how much money Sigma spends. What matters more to me is whether they money they spend results in progress that produces real value, and whether they HONESTLY sell the thing or whether they resort to misleading factoids and spurious claims. If Sigma could make the Foveon a truly competitive sensor TECHNOLOGICALLY (and it certainly has the potential, nothing wrong with the technology itself), it wouldn't matter if it cost $1,000,000 or $1,000,000,000...so long as in the end they turned enough of a profit to continue investing in the technology and keep
it competitive. If they end up failing in the end, well it still wouldn't matter if they spent a hundred grand or a hundred billion, it would all be a waste in the end.
It will be both interesting and amusing, to see your criticism of Canon's new camera (assuming it even uses this technique...for all we know the next full frame model may not even use it after all. It's just rumors...)
Again, your disgust with Sigma for simply existing, is juvenile, misplaced, and unnecessary. As is your harsh view of those who use, or have used their products. If we state our opinion of the images we got from using the camera, who are you to say we don't have a right to state it?
And were back to the personal insults. You and I do indeed have a mutual loathing of each other, and I have no interest in being friends with you...but I'm really trying to keep it off the public forum. No one else wants to see us fight, so I respectfully ask that if you want to insult me, please use PMs. Then you can get as nasty and hateful as you want.