jrista said:100 said:jrista said:Hannes said:jrista said:Actually, it probably has really huge pixels. There are Kodak astro CCDs that have 9µm and 24µm square pixels. If we figure that the pixel sizes for this 8x10 sensor are somewhere around there, the guy has ~640mp @ 9µm, and ~90mp @ 24µm. I figure, just from a space and processing standpoint, the pixels would have to be garganguan. I think 24µm pixels sounds more reasonable, and I guess it's possible they were larger than that. So this guy is taking maybe 70-90 megapixel photos with a giant 8x10 sensor with pixels that probably have about 12 times the sensitivity as the 1D X sensor. That would make full well capacity per pixel around 1.1me- to 1.5me-...WOW. Dynamic range on that sucker must be like, 150dB!![]()
In the comments he says it takes photos of about 10 mpix. Yup, ten megapixels.
In that case, I think the guy got ripped off.That means the pixels are 20mm in size. That's just a waste of space and fabrication power.
He just needed something to replace his large format polaroid. He shot 7 or 8 large format polaroid’s before taking the "real" pictures, for him that’s about $ 50,000 a year in polaroid’s alone...
By the way, 8 by 10 inch is 203 by 254mm which is about 50,000mm^2
Divide that by 10mp (10,000,000 pixels) and you get 0.005mm^2 per pixel.
Anyway, Canon also made a large (202 x 205mm) CMOS sensor back in 2010 that can do 60fps
http://www.canon.com/news/2010/aug31e.html
The technology for large format digital sensors has been there for years, but there is no real market.
I think you've got your math wrong somewhere. If we convert the sensor size into millimeters, it is as you say 203.2x254mm. We can then figure out how many pixels per row, and how many rows, assuming a 5µm pixel:
203.2/0.005 = 40,640
254/0.005 = 50,800
That is over 40 THOUSAND pixels per row, and over 50 THOUSAND rows. That's a LOT of pixels! Multiply the rows by columns to get the actual megapixel count:
40,640 * 50,800 = 2,064,512,000
That would be TWO GIGAPIXELS. You said it was 10 MEGAPIXELS. There is no way in hell that guy has 5 micron pixels on his sensor. If he did, that would be kick ass. I actually made an error in my math for the last answer, and I wrote the wrong units anyway. I said the pixels were 20 millimeters, that was supposed to be 20 microns, however correcting my math, its 72 microns:
203.2/0.072 = ~2823
254/0.072 = ~3528
2823 * 3528 = 9,959,544
That's a little more reasonable. I still think he could have easily gotten away with pixels ~15x smaller (about 20 microns square) and had more than enough signal to noise ratio and dynamic range, and had about 130 megapixels instead of 10.That wouldn't have required any special fabrication techniques or anything either, 20 micron pixels are monsters, and have more than enough room for very large, easy to fabricate wiring. I think the most difficult aspect of building a sensor that large is that you cannot fabricate it on a single wafer. You would have to fabricate a number of pieces of the sensor on multiple wafers, then assemble them together. There would certainly be additional cost there...but it isn't a new technique, it's been done before (Canon did it for that very same 202x205mm sensor you mentioned), however if you cut corners on readout rate (i.e. you went for one frame every 30 seconds, rather than 60 frames every one second), the task would be easier (Canon used a hyperparallel on-die readout and ADC system for that ultra large sensor.)
I wrote 0.005mm^2
the ^2 means square
1mm^2 = 1 mm² = 1 000 000 μm²
http://www.aqua-calc.com/what-is/area/square-millimeter
Upvote
0