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02-20-2015, 12:15 PM   #1
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Sensor resolution that makes sense on FF and cost

Working in the semiconductor industry, there are some cost models that indicate that cost of silicon is not a function of image sensor resolution but it is proportional the silicon area and the number of steps needed in the manufacturing process. Therefore , FF cameras should have the higher pixel count , at the same price point as the lower pixel count , as long as the size of pixels does not impact the defect rate of the sensors. Practically, defect rate is a function of silicon area a defect density given a specific fab, rather than pixel density. Therefore, the new Pentax FF should be equipped with a 50Mpixels sensor, and not a 24Mpixels sensor.
Having the new Pentax FF with 51Mpixel has a lots of advantages:
- give a reason to k-3 owner to buy a FF cam
- sensor with 51Mpix gets rid of AA filter, same advantage as the K-3 but on larger sensor.
- sensor is almost the same cost with 51Mpix versus 24Mpix
- bring Pentax again very competitive in the full frame segment , able to compete with new Nikon FF and Canon FF (if Canon has done the 5DS, Nikon will follow).

What is your opinion?


Last edited by biz-engineer; 02-20-2015 at 12:27 PM.
02-20-2015, 12:34 PM   #2
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QuoteOriginally posted by biz-engineer Quote
What is your opinion?
Noise...I currently shoot with the K-3 and am happy with 24Mpx resolution, but would love to have the noise characteristics of the 16Mpx APS-C sensors. 24Mpx would do it for me with 36Mpx being the more logical target for marketing purposes. It would be nice it both were offered.

Next question...


Steve

(FWIW, the technical expertise needed to coax optimum sharpness and performance out of a 50Mpx FF sensor is beyond the capabilities of most photographers under field conditions. The recurring cry of "I can't get sharp photos with my K-3" on these forums is good evidence of such.)
02-20-2015, 12:37 PM - 1 Like   #3
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QuoteOriginally posted by biz-engineer Quote
Working in the semiconductor industry, there are some cost models that indicate that cost of silicon is not a function of image sensor resolution but it is proportional the silicon area and the number of steps needed in the manufacturing process. Therefore , FF cameras should have the higher pixel count , at the same price point as the lower pixel count , as long as the size of pixels does not impact the defect rate of the sensors. Practically, defect rate is a function of silicon area a defect density given a specific fab, rather than pixel density. Therefore, the new Pentax FF should be equipped with a 50Mpixels sensor, and not a 24Mpixels sensor.
Having the new Pentax FF with 51Mpixel has a lots of advantages:
- give a reason to k-3 owner to buy a FF cam
- sensor with 51Mpix gets rid of AA filter, same advantage as the K-3 but on larger sensor.
- sensor is almost the same cost with 51Mpix versus 24Mpix
- bring Pentax again very competitive in the full frame segment , able to compete with new Nikon FF and Canon FF (if Canon has done the 5DS, Nikon will follow).

What is your opinion?
Why is the Sony A7s with its paltry 12MP sensor so highly lauded? Megapixels aren't everything, and they certainly have no bearing on my desire to upgrade to FF.
02-20-2015, 01:04 PM   #4
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QuoteOriginally posted by enoeske Quote
Why is the Sony A7s with its paltry 12MP sensor so highly lauded? Megapixels aren't everything, and they certainly have no bearing on my desire to upgrade to FF.
Good point, although once downsized to 12Mpix, the A7 provides the same perf as the A7s. For development cost reasons (cost of lithography marks set), I bet the 12Mpix FF sensor does not exist, it's just a hard wired array of 2:1 logic adders l (FPGA) used as interface between the cmos columns of the 24Mpix sensor and memory bus. Basically, once you look at the image quality measurement on dxo mark between the A7s and A7, you see no difference. The advantage of tha A7 or A7r is that you can down size the image if you want less noise (=spacial averaging) and have the full resolution when there is enough light.

02-20-2015, 01:10 PM   #5
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I'm not sure I would I buy a 50mp camera, unless it was a 645z. The file size on the k-3 is already a challenge. I agree with Steve, less noise more dynamic range. Pixels (above 16mp) are largely irrelevant to me. For a dedicated landscape camera, maybe I would feel differently, but for a general purpose 35mm dslr I think 24mp maybe 36mp is the max I would want.
02-20-2015, 01:20 PM - 1 Like   #6
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I want at least 24MP when in crop mode.
02-20-2015, 01:35 PM   #7
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I'd rather see a camera with roughly the same pixel density as the 645z sensor, hopefully resulting in similar DR and noise performance. The z has roughly 188 pixels/mm of sensor (I think), which would make a full frame sensor at the same density about 30 mp? Someone correct me if my quick math is wrong, or my assumption that the pixel density will play a significant role in DR and noise performance.
02-20-2015, 01:42 PM   #8
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I wouldn't buy a 51mp FF. Even 36 seems to much for an FF sensor, in my opinion. The same problem signalled by Stevebrot with K-3 users, was with Nikon D800. To much Mp for common users. If I'm in a hurry, or I don't pay attention, I can take bad pictures even with my 16Mp K-5IIs.

IMO, Canon 51Mp cameras recently announced are just a reaction to Pentax 645z. How efective those cameras will be to keep proffesionals away from 645z, we will see. But with only 12800 ISO, and a much worse DR, I have doubts.

02-20-2015, 01:48 PM   #9
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The reasoning behind the 50Mpixel sensor is to equal the analog film in terms of resolution. How many Mpixel does analog film has? Infinite? Nobody complained about infinite resolution during the film era. If I understand correctly, with films the image is not sampled in the way digital sensors do, therefore, on film, the resolution is limited by the lens optical bandwidth and film grain (if I'm not wrong... actually I'm too young to remember how film works exactly). With 24Mpixels, a AA filter is needed (not needed for film) and therefore is an additional layer that reduce resolution and perhaps light transmission also for low frequency image components. With 50 Mpixel , no AA filter is needed, it's like if a 35mm film is directly replaced by a 35mm digital sensor.
02-20-2015, 01:55 PM   #10
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A lot has to do with how many sensors are manufactured. If Nikon has a Sony 36MP sensor and Pentax uses the same sensor it lowers the cost per sensor. Unless wall sized prints are needed or severe cropping is required there really isn't any need for a lot of megapickles. Canon has proved this with their 18-22MP sensors. I pull 16x20s from an uncropped 8MP sensor. But technology moves on. Ten years ago 8MP was the norm, today it's 24 or 36, and folks complained about noise at anything over ISO 400. No matter how good sensors get there will always be pixel peepers who'll complain about noise.
02-20-2015, 01:55 PM   #11
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QuoteOriginally posted by UncleVanya Quote
I want at least 24MP when in crop mode.
I agree, otherwise, I would have to keep my k-3 and use it as primary camera.
02-20-2015, 02:01 PM   #12
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24Mp effective is a very good number, here is why: 24M = 8M x 3 (RGB pixels), hence 8 Mpix of pure spacial resolution. 8M effective resolution is suppose to be all we need for enlargement if we look at 1 diagonal distance from the print.
It could be 50Mpixel without AA filter downsized in camera to 24Mpix raw format.
02-20-2015, 02:06 PM - 1 Like   #13
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Really?? This kind of stuff is what is fueling the MP war, even though MP is not really that important. Are photos today, with the high resolution cameras, really that much better or more important than photos in the past, taken with 6MP cameras or film?
02-20-2015, 02:08 PM - 1 Like   #14
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I don't really care how many megapixels the FF has in crop as long as the high ISO performance is as least as good as my K-5 (which is good for a APS-C).

Personally for what I shoot I find 16 MP more than enough. Granted an advantage of higher MP is that it gives more opportunity to crop more.

I'm hoping the FF is not over 36MP but then as long as high ISO is good I'm not that fussed.
02-20-2015, 02:15 PM   #15
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QuoteOriginally posted by kiwi_jono Quote
I don't really care how many megapixels the FF has in crop as long as the high ISO performance is as least as good as my K-5 (which is good for a APS-C).

Personally for what I shoot I find 16 MP more than enough. Granted an advantage of higher MP is that it gives more opportunity to crop more.

I'm hoping the FF is not over 36MP but then as long as high ISO is good I'm not that fussed.
Especially k-5 iis ...
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