Hot answers tagged

51

It looks like you've got a problem with the shutter. Possibly one of the "blades" in the second curtain is missing and allowing light to strike the sensor between the time after the second curtain has completed its travel and the time the sensor is read out. Here's what a 70D shutter curtain looks like. Does the shape of the 2nd of four individual blade ...


50

From what I see this is element from the shutter. And my humble advise is to send your camera to repair shop, give it in to the hands of professional, do not try to repair it.


45

You've asked several different questions, so here goes: How effective is it? It is a lot more effective in cameras that have it than those that don't. Not trying to be a smarty-pants, but since most manufacturers adopted automatic self cleaning systems, the number of complaints regarding dusty sensors went down by several orders of magnitude. See labnut's ...


44

Quick summary Yes, bigger pixels do improve performance all else being equal, and Apple is doing a good thing by focusing on sensor size. However in this case the increase in size is so slight that the difference will be negligible, probably not living up to the level of improvement you may expect from their marketing. What does bigger pixels mean? This ...


41

There is an ISO which is not necessarily 200 that is the native sensitivity of the silicon from which the sensor is made. That sensitivity depends on the sensor itself, so will vary between cameras, but it is almost always between ISO 100 and 200. The camera amplifies the signal to get higher sensitivities. It scales down the signal to get lower ones. ...


38

Nothing Special There is nothing particularly special about ISO 1600, although in some cases ISO settings beyond 1600 have incurred less effective and efficient ways of amplifying the image signal. When you set ISO on a camera, that is simply instructing the camera to change the maximum saturation point of the sensor, from which the signal will be amplified....


36

First, understand a couple of things: Even though we call these things "digital cameras," the process of turning photons into numbers is entirely analog. Analog circuits pick up all manner of noise from their surroundings. Noise isn't one constant value, it's a range of them that top out at a level called the noise floor. The processing you did on the ...


34

The DxO Mark scores are misleading, but that doesn't mean the gap in performance isn't real! Several Nikon bodies (D800, D600 many of the D3xxx and D5xxx series) are using Sony Exmor sensors which feature a cutting edge ADC/read noise reduction system to achieve massive gains in dynamic range compared to Canon sensors, which are designed and fabricated in ...


34

Unlike a mirrored camera, there is little likelihood of the sensing system in a mirrorless camera suffering a catastrophic failure so it is really up to your "taste" to determine when a sensor is too old. The primary causes of degradation to a CMOS sensor array are heat, dye neutralization and cosmic rays. Thermal Degradation Normally thermal damage is so ...


33

Why don't cameras offer more than 3 colour channels? It costs more to produce (producing more than one kind of anything costs more) and gives next to no (marketable) advantages over Bayer CFA. (Or do they?) They did. Several cameras including retailed ones had RGBW (RGB+White) RGBE (RGB+Emerald), CYGM (Cyan Yellow Green Magenta) or CYYM (Cyan Yellow ...


28

This data was iffy then — not really enough data points, and the trendline is dubious: Source: a very timely xkcd That said, the company DxOMark does measurements of camera sensors all the time, designed to be resolution-neutral. Here's a chart of the "Sports" score, which is based on SNR, from all tested APS-C camera models from 2002 to 2018: Given the ...


26

It's very important to realize that it is not the high ISO setting itself that results in noisy image, it's that fact that using a high ISO setting means you capture very little light. Light is made up of photons which are randomly emitted by a lightsource. When the light levels are low or the exposure time very short then the number of photons you get will ...


25

Like many questions about what setting works best: It depends. The native ISO for almost all Canon DLSRs over the last few years has been ISO 100. 'Full stop' intervals, such as ISO 200, ISO 400, ISO 800, etc. increase the analog amplification of the signal readout of the sensor. The 1/3 stops in between those full stops use software adjustments during in-...


24

It is somehow true! For a moment, forget about the live view and consider the case of long exposure. While long exposing, the sensor heats up and this will cause the infamous background noise. So in reality sensor over heating can cause the noise and what happens is that in low light, warmed pixels detect light when there is none. (This last sentence is very ...


23

Maybe it represents the small variation of the temperature of the sensor. A hot sensor produces more noise than a cool one. The small temperature difference can be explained by the presence of electronic components, or the way the sensor is in contact with other parts, allowing more or less heat dissipation. Some related links : http://en.wikipedia.org/...


23

As was said, the mechanical shutter has speed limitations. As to the slit, try to imagine without it. Suppose the shutter opens by moving from top to bottom of frame. And then of course, it has to close from bottom to top. So it is open longer on the top side than on the bottom side, which is uneven exposure. Modern fast curtains might move about 7 ...


23

The information your friend gave you was essentially correct for most digital cameras, particularly compact digital cameras with very small sensors, made about 15-20 years ago. Digital imaging sensors were more primitive and noise reduction techniques were less sophisticated. By placing the native sensitivity of a sensor at one stop higher than what ...


22

First, a little background to clear up a slight misunderstanding on your part. **The vast majority of color digital cameras have a Bayer filter that masks each pixel with a color filter: Red, Green, or Blue.**¹ The RAW data does not include any color information, but only a luminance value for each pixel. However, RGB filters necessarily cut out two thirds ...


22

Most DSLR cameras have a sign on the top (Plimsoll mark) which looks sort of like The line indicates the position of the sensor plane. I googled for pictures of the 600D. It also has this indicator on the left side of the camera top.


22

So, why can't the sensor's image data downloaded to the processor, globally? Why is it downloaded row by row? It's a matter of physical limitations and simplicity. The physical limitation is that there's only space for a certain number of external connections -- you couldn't possibly connect every pixel to the processor and grab all that data at once ...


21

The size of the sensor does not matter, it is the size of the pixel. Having that said, bigger sensors like in full frame cameras tend to have bigger pixels. You can estimate the size of the pixel by taking the size of the sensor and divide it by the number of pixels. This calculation is not accurate because most sensors have gaps between the pixels and ...


21

Thought experiment time. Assume we'd like a minimum exposure of 1/2000 of a second (500 microseconds) on a 35mm full frame camera. We have a single 'shutter' to move out of the way, and back. We'll tolerate one side of the picture being 10% more exposed than the other, so that means we allow 50μs to move the shutter back and forth. So the shutter has to ...


21

The item obstructing the sensor is a shutter blade. Your shutter has failed and needs to be replaced. There's no hack or DYI solution for this problem. This is a hardware problem and not something that can be fixed with software or some kind of hack. You should expect repairs to be in the $200+ price range. Since you can buy a used XTi for under $150, ...


19

I was surprised a few months ago to find that my machine vision camera SDK used nearest neighbor "interpolation" in its built-in bayer function. It is the fastest, but worst type, giving hard edges, especially when you start doing math on the image channels for colour constancy or brightness invariance. I found this review of algorithms: http://www.arl.army....


19

DXOMark primary "scores" are utterly useless. IGNORE THEM. It is a futile effort to try and reduce a complex entity such as a DSLR to a single, scalar number that tells you everything about it. It's a fallacy. There are too many factors to consider, and which factors are most important for a given photographer differ. A single score entirely defeats the ...


18

At very wide angles the danger is much less and taking photos with the sun in the field of view doesn't normally harm the camera or lens. When the sun is very low on the horizon the energy is also reduced as there is much more of Earth's atmosphere to absorb much of that energy between an observer on the ground than when the sun is high in the sky. More ...


18

Several models of zoom lens are designed in such a way that they likely inhale dust and may vent it into the body of the camera. How big a problem this is remains debatable (see this discussion for example). Also, most lenses are not externally dust sealed so air and fine particles are likely to make their way in over time. For these reasons it probably ...


18

Raw files don't really store any colors per pixel. They only store a single brightness value per pixel. It is true that with a Bayer mask over each pixel the light is filtered with either a Red, Green, or Blue filter¹ over each pixel well. But there's no hard cutoff where only green light gets through to a green filtered pixel or only red light gets through ...


18

It depends on how you define camera. In a sense, digital large format does exist, just not exactly in the way we might expect. There are commercial products called 'Digital Scanning Backs' that fit medium and large format cameras. Instead of a full grid that can be exposed from one side to the other very quickly via a focal plane shutter, they have one ...


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