Timeline for Why are larger sensors better at low light?
Current License: CC BY-SA 3.0
21 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Jun 16, 2020 at 11:21 | history | edited | CommunityBot |
Commonmark migration
|
|
| Mar 21, 2017 at 18:38 | comment | added | Michael C | @craesh Not really. f/2.8 would be equivalent in terms of DoF, but f/2 would be needed for equivalence in terms of exposure. | |
| Oct 14, 2011 at 16:30 | vote | accept | William C | ||
| Sep 20, 2011 at 1:48 | history | edited | jrista | CC BY-SA 3.0 |
Added a more "laymans terms" explanation of
|
| Sep 15, 2011 at 16:11 | history | edited | jrista | CC BY-SA 3.0 |
added 101 characters in body
|
| Sep 15, 2011 at 16:09 | comment | added | jrista | Thanks for the correction, Even. It is indeed µm, not nm. Matt, very true. I'll add a note about that to my explanation of "idealized". smigol: Indeed, it is a function of amplification, however there are two kinds of ISO "amplification"...one analog (native), and one digital. Digital amplification is an entirely different story, and can be done in post, while analog amplification cannot. Regarding tech, the 7D is a newer (by 3 years) sensor than the 5DII's...and it still has quite a bit more noise. | |
| Sep 15, 2011 at 15:05 | comment | added | smigol | I'd also like to note that ISO settings on digital sensors are actually a function of amplifiers. CCD/CMOS have a fixed response to light that does not change. There's no additional light being manufactured when bumping up the ISO setting. Instead, the processing converters tell how much the total data should be amplified - including noise. It's just like turning up the volume on a noisy cassette tape - you'll hear the hiss that much louder. Note that amplifiers and software improves over time so the effect of increased noise appears reduced. | |
| Sep 15, 2011 at 15:02 | comment | added | craesh | If you take with both sensors a picture, with a 50mm/f2.0 lens for APS-C and a 80mm/f2.8 lens for FF (they will have approx. the same aperture), you will get the same result. You say you gain a stop with a FF sensor compared to a APS-C sensor, but actually you gain that stop with your lens! | |
| Sep 15, 2011 at 7:09 | comment | added | Matt Grum | It should be made clear that the extra light gathering ability of large sensors assumes the same f-stop. This is not always possible in practice as maintaining the same angle of view means using a lens with a longer focal length, which tend to have smaller max apertures, e.g. when using a 200 f/2.0 on an APS-C body, you'll get a similar amount of light as using a 300 f/2.8 on full frame - as there is no 300 f/2.0 [currently in production]. | |
| Sep 15, 2011 at 6:05 | comment | added | Evan Krall | And, in fact, visible light is 380nm-740nm, so a 10nm pixel would literally be smaller than a single wavelength of light. | |
| Sep 15, 2011 at 6:00 | comment | added | Evan Krall | I should point out that the units on these pixel sizes should be µm (micrometers or microns), not nm (nanometers). a 10nm pixel would be tiny -- transistors in computer processors these days are generally on the order of 45nm wide. I've edited jrista's answer to take that into account. | |
| Sep 15, 2011 at 5:56 | history | edited | Evan Krall | CC BY-SA 3.0 |
Fixed conversion from mm^2 to µm^2 - the ratios stay the same, but we were off by a factor of a million on the area per pixel.
|
| Sep 15, 2011 at 5:23 | comment | added | jrista | @William: Regarding the Canon Pro70, don't forget that there have been many other advancements in sensor design since 1998. Even though the pixel size is larger on those cameras, technologically they were extremely primitive compared to todays sensors. For one, the pixel size is probably smaller (4nm?)...pixels had large gaps and no microlenses back then. CCD readout was much noisier, prone to read streaking, charge overflow into neighboring cells, etc. Sensitivity of the Pro70 was a lot lower too, ISO 100-200 in "high res" mode and ISO 400 in "low res" mode. | |
| Sep 15, 2011 at 5:18 | comment | added | jrista | It gets really crazy when you think about a 1/8" sensor...1.6x1.2mm, or an area of 1.92mm^2. At a common modern megapixel count of 8mp for many cheap P&S cams, the pixel area is a mere 0.24µm^2 (a 0.015µm pixel)! | |
| Sep 15, 2011 at 5:16 | comment | added | William C | Hah! You've intrigued me to the Canon Pro70, made in 1998. The Pro70 is F/2.0, ISO100-400, 1.5MP on a 6.4x4.8mm sensor (4.5nm pixels). :) | |
| Sep 15, 2011 at 5:01 | comment | added | jrista | @William: According to (Wikipedia)[en.wikipedia.org/wiki/Image_sensor_format], a 1/2.5" sensor is 5.76x4.29mm. At 2mp, the math is the same as above, so pixel area would be 12.4µm^2 (a 3.5µm pixel). Thats pretty small, about a whole nanometer smaller than the 7D 18mp sensor pixels. | |
| Sep 15, 2011 at 4:54 | history | edited | jrista | CC BY-SA 3.0 |
fixed math
|
| Sep 15, 2011 at 4:49 | comment | added | William C | @jrista: Do the 2-megapixel cameras of 1999 (2.5" sensors?) have large pixels? | |
| Sep 15, 2011 at 4:40 | history | edited | jrista | CC BY-SA 3.0 |
added light gathering difference in terms of "stops" and ISO levels
|
| Sep 15, 2011 at 4:27 | history | edited | jrista | CC BY-SA 3.0 |
added 1867 characters in body
|
| Sep 15, 2011 at 4:13 | history | answered | jrista | CC BY-SA 3.0 |