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#41
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Sony A100 to A700
In article , Alfred
Molon wrote: In article 1212478815.530753@ftpsrv1, frederick says... And I stand behind my comments above - it's dishonest / unscientific to put the colour-resolution chart test in place of the normal chart tests. Since the world is not black and white, it makes sense to use colour resolution test targets instead of black and white ones. the world is indeed colour, but it's not saturated stripes with constant luminance. bayer sensors are designed to work the way human eyes do, and that's maximize luminance resolution. foveon is nice in theory, but it has a lot of shortcomings, such as metamerism, noise, very critical white balance and significantly more data to move. put a colour luminance chart on the wall next to a b/w chart and see how well *you* can resolve it (assuming you don't get a headache first from the colour chart). you'll find that you won't see anywhere near as much detail on the colour chart as the b/w chart. why bother capturing what you can't see? |
#42
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Sony A100 to A700
In article , Alfred
Molon wrote: In article , nospam says... there is no truth in the 'foveon pixel count.' pixels are pixels, regardless what sigma/foveon claim (and they even use the term inconsistently, further proof that their method is bogus). the reason for the difference is that sigma omits the anti-alias filter and thereby the sensor can resolve closer to nyquist, along with a lot of aliasing and heavy sharpening, which some people mistake for real resolution. it also does better on colour resolution charts but that isn't anything that matters to human vision. it just makes bayer look worse in an edge case that never occurs in nature. This has been discussed to death and there is no point to reopen the discussion. yes, it has been hashed to death on numerous forums, however, the myths continue. Do a Google search on the archives to find out why with Bayer sensors the effective resolution is lower than the nominal pixel count. it's the lack of an anti-alias filter in the sigma cameras along with sharpening in the raw processing (which bayer cameras generally are set to much less), and not anything inherent to foveon. |
#43
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Sony A100 to A700
In article , Ilya Zakharevich
wrote: You can count angels at the point of a needle as long as you want. The fact remains the fact. what fact is that? a pixel is a spatial element of an image, and not a layer within. the sd14/dp1 sensor has 4.7 megapixels. period. DPreview (which is often suspected for prejudice in Canikon direction) compares shots from a 5MP x 3 sensor, and from Bayer sensors with (several) larger MP count. The conclusion was quite surprising (for me). nothing surprising about an edge case designed to exploit a weakness in bayer, and one which doesn't matter to humans. there are edge cases where foveon falls apart too, and even more so than bayer does. |
#44
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Sony A100 to A700
Hey, a lot of good info'
But still undecided Ta Ron "Ron and Gail Smith" wrote in message ... Hi All Thinking of upgrading from Sony A100 to Sony A700 and wondering if anyone has done that and what your thoughts are? I'd been interested to know Regards Ron |
#45
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Sony A100 to A700
Alfred Molon wrote:
In article , Ilya Zakharevich says... Even kit lenses *at their best settings* outperforms 10-12MP half-frame sensors. (What one needs is to have MTF about 50% on the most area of the sensor, at the frequency about 70% of Nyquist [the latter number assumes Bayer sensors]. Just look at dpreview graphs.) And well-below-$1000 wide-range QUALITY zooms start to appear, which are getting "close" to such performance even when wide-open... A 10MP 3:2 sensor has about 2600 lines. The Sony 18-70mm f/3.5-5.6 DT kit lens has been reviewed by photozone: http://tinyurl.com/3rqwtf The MTF50 value reaches at best 2200 lines (centre, F5.6, 18mm). Otherwise it's between 1400 and 2000 lines. In other words, this kit lens is not good enough for a 10MP sensor. By the way, these MTF50 values are for MTF at just 50%. I'm puzzled by this arithmetic. A 10MP 3:2 sensor doesn't have about 2600 lines, it has about 2500 pixels down. To reproduce a series of closely spaced lines you need twice as many pixels, so that one line can be black and the next white. So aren't these lenses about twice as good as you're suggesting? Or is my arithmetic confused? -- Chris Malcolm DoD #205 IPAB, Informatics, JCMB, King's Buildings, Edinburgh, EH9 3JZ, UK [http://www.dai.ed.ac.uk/homes/cam/] |
#46
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Sony A100 to A700
In article , Chris Malcolm says...
Alfred Molon wrote: In article , Ilya Zakharevich says... Even kit lenses *at their best settings* outperforms 10-12MP half-frame sensors. (What one needs is to have MTF about 50% on the most area of the sensor, at the frequency about 70% of Nyquist [the latter number assumes Bayer sensors]. Just look at dpreview graphs.) And well-below-$1000 wide-range QUALITY zooms start to appear, which are getting "close" to such performance even when wide-open... A 10MP 3:2 sensor has about 2600 lines. The Sony 18-70mm f/3.5-5.6 DT kit lens has been reviewed by photozone: http://tinyurl.com/3rqwtf The MTF50 value reaches at best 2200 lines (centre, F5.6, 18mm). Otherwise it's between 1400 and 2000 lines. In other words, this kit lens is not good enough for a 10MP sensor. By the way, these MTF50 values are for MTF at just 50%. I'm puzzled by this arithmetic. A 10MP 3:2 sensor doesn't have about 2600 lines, it has about 2500 pixels down. To reproduce a series of closely spaced lines you need twice as many pixels, so that one line can be black and the next white. So aren't these lenses about twice as good as you're suggesting? Or is my arithmetic confused? In the above figures lines = rows of pixels. Otherwise they would be called libe pairs. -- Alfred Molon ------------------------------ Olympus 50X0, 8080, E3X0, E4X0, E5X0 and E3 forum at http://tech.groups.yahoo.com/group/MyOlympus/ http://myolympus.org/ photo sharing site |
#47
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Sony A100 to A700
[A complimentary Cc of this posting was sent to
frederick ], who wrote in article 1212482281.344227@ftpsrv1: Now we know that it is not a myph. Visual comparison of Foveon images and Bayer images gives an advantage of about 2x in pixel count. (Myself, I was expecting something about 1.5x...) I don't know what you are arguing about. 4.69 x 2 = 10mp I don't know what you are arguing about. As dpreview images show, there are some situations where 4.69x3 sensor gives better "visual impression of resolution" (sorry, can't find a better term) than 10mp Bayer sensor. *This* is what surprised me. IIRC DPreview already said the ("3.4mp x 3") SD10 was similar to 6mp dslrs in resolution - so nothing new here. Can't agree here - I do not remember anything about sd10 which would suggest getting close a factor of to 2x. 6/3.4 = 1.76 which is similar to what one would expect from inspection of images shot with Bayer sensors (see threads about "dead pixels" in relation to MTF). "So what we'd really like to see is a sensor that combines the Foveon's per pixel resolution with the output size of a modern DSLR. Do not think so. What "we'd really like to see" is a separation-in-silicon sensor with pixel count about 40MP per square inch, and capacitance/area and read noise similar to current Canon sensors. *This* would start to utilize the potential of the best lenses... Hope this helps, Ilya |
#48
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Sony A100 to A700
In article , Ilya Zakharevich
wrote: Now we know that it is not a myph. Visual comparison of Foveon images and Bayer images gives an advantage of about 2x in pixel count. (Myself, I was expecting something about 1.5x...) I don't know what you are arguing about. 4.69 x 2 = 10mp I don't know what you are arguing about. As dpreview images show, there are some situations where 4.69x3 sensor gives better "visual impression of resolution" (sorry, can't find a better term) than 10mp Bayer sensor. *This* is what surprised me. the 'visual impression' is nothing more than alias artifacts and a lot of sharpening in raw processing. some people like the look and others don't. in any event, it's not true resolution. |
#49
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Sony A100 to A700
[A complimentary Cc of this posting was sent to
nospam ], who wrote in article : I don't know what you are arguing about. 4.69 x 2 = 10mp I don't know what you are arguing about. As dpreview images show, there are some situations where 4.69x3 sensor gives better "visual impression of resolution" (sorry, can't find a better term) than 10mp Bayer sensor. *This* is what surprised me. the 'visual impression' is nothing more than alias artifacts and a lot of sharpening in raw processing. ??? There is no sharpening involved. Moreover, as resolution chart shots show, there is no significant aliasing either. some people like the look and others don't. in any event, it's not true resolution. Can't agree less. "True" resolution is what I can or can't see. Any other "objective" metrics are just, in some sense, a window dressing: trying to capture this - elusive - "visual impression of resolution" via some "scientific metric". People who look at images of resolution chart with Bayer sensors understand quickly how these data correlate with "visual sharpness" of images. It turns out that the (B&W) resolution charts do not fully correlate with "visual impression of resolution" if one compares them between x3 and Bayer sensors. (AFAIU, the "color resolution charts" of dpreview is an attempt to introduce an objective metric which reflects better the way our visual system works.) Yours, Ilya |
#50
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Sony A100 to A700
[A complimentary Cc of this posting was sent to
Ron and Gail Smith ], who wrote in article : Hey, a lot of good info' But still undecided I forgot another point where people report that a100 is "just a toy", and a700 flies: flash exposure. There is something very fishy with the algorithm of a100 (*very* unreliable). a700 is reported to perform very reasonably. Hope this helps, Ilya |
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