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Thread: dynamic range - small vs large pixels

  1. #1

    dynamic range - small vs large pixels

    Hello everyone, I have another question for you guys!

    In all the articles I read, people say that the sensor size is important, as well the size of the pixels in a sensor. Bigger is better they say, because bigger means more dynamic range, less noise, better image, etc...
    I´ve found that the Canon 7D (or the 550d) and the old Canon 350D have almost the same sensor size (1.6x crop f, 22.3 x 14.9). Of course 7d and 550d will give you more resolution, but doing the math I´ve found that canon 350D has bigger pixels in the same size area of the sensor. What does this mean? That Canon 350d will provide more dynamic range or less noise?
    You can say: it all depends, because the canon 350d´s technology is already old. But larger pixels are better, right?
    With a 7d you´ll have more resolution, but less dynamic range?

    Thank you!

  2. #2

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    Re: dynamic range

    Hi again Christian,

    Yes - many folks do say many of these things, but more often than not I think they're just parroting what they've heard from others, and often the information isn't complete. It's a bit like the old "sunny 16" rule - if you ask people what it is, many will say "on a sunny day - if you shoot at F16, your shutterspeed will be the reciprocal of your ISO" (eg at F16 - at 200 ISO your shutterspeed needs to be 1/200th). But how many are aware of the other part of the rule that also says "for a front lit subject, at least 2 hours after sunrise, and at least 2 hours before sunset"? So - just as with sensor technology - it's important to have all the facts, and include all of the variables (such as the generation of technology).

    So with regards to sensor size - how important is it really? Often I hear things like "Camera B with 10.3MP is better than "Camera A with only 10.0MP" when in reality, all the user may want either model for is a few holiday "snaps". Using the same logic, a 418 km/hr+ Bugatti Veyron is "better" than a 366km/hr Ferrari Enzo - but both are "more than adequate" for a trip down to the local corner dairy.

    Personally, I think "more than adequate" is a term that sadly missing from many camera discussion. So to answer your question about dynamic range, most prints display a dynamic range of no more than 4 stops ... most monitors display around about 6 stops of dynamic range. In contrast, the 350D has a dynamic range of 10.8 EVs @ base ISO (more than adequate) and the 7D has a DR of 11.7 EVS @ base ISO (also more than adequate).

  3. #3

    Re: dynamic range

    Thank you for your answer!

    Yes, many people give you an incomplete information. In conclusion, all the camera specifications are just orientative or just theoretical.

    You said: ¨ most prints display a dynamic range of no more than 4 stops ... most monitors display around about 6 stops of dynamic range¨ I know this, that´s why I´m not very concerned about the dynamic range ¨they¨ say a camera can provide. I just want to understand the phenomena, why smaller pixels today can give you (according to the camera´s manufacturers) more quality. Is this true because of the new technology?

    Thanks again!

  4. #4

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    Re: dynamic range

    Quote Originally Posted by Christian Thomas View Post
    . I just want to understand the phenomena, why smaller pixels today can give you (according to the camera´s manufacturers) more quality. Is this true because of the new technology?
    Hi Christian,

    In a word, yes. Keep in mind too that one of the advances in technology is gapless microlenses so although we now have more pixels in the same space, the pixels aren't necessarily proportionally smaller as there were bigger gaps between them with older technology.

    In rough terms, dynamic range stays roughly constant as the gain of better technologies only slightly offsets the competing issue of higher densities. The other variable is higher high ISO performance, but a large part of that appears to be coming from better noise reduction in in-camera processing (folks shooting RAW don't appear to be getting any where near the same amount of noise reduction as those shooting JPEG).

    At the end of the day, all modern camera take images that are more than adequate if used properly, so for me, it's other features that differentiate the models (such as weather sealing, firmware options, build quality, ergonomics etc).

  5. #5

    Re: dynamic range

    Thanks for the reply Colin, I really appreciate you!

    Bye!

  6. #6

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    Re: dynamic range

    Quote Originally Posted by Christian Thomas View Post
    I´ve found that canon 350D has bigger pixels in the same size area of the sensor. What does this mean? That Canon 350d will provide more dynamic range or less noise?
    Hello Christian. Simplifying things a bit, for similar sensor technologies it is the area of the sensor, not the area of the individual sensor elements (sensels) that matters. With some limitations, if you average a number of pixels together you reduce the noise of the new, larger combined theoretical sensel that you have created. So if you start with a higher number of pixels and average them down to a lower number of pixels covering a similar area, you effectively have very similar noise performance in both. Taking this to an extreme, you could average down cameras to one huge sensor-sized pixel, with (simplifying angain) similar noise and dynamic range performance.

    On the other hand, noise performance is related to the technology employed to make the sensor, and this improves from generation to generation. Barring this, megapixels are highly overrated.

    Cheers,
    Jack
    Last edited by Jack Hogan; 16th November 2010 at 08:05 AM.

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