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70

In photography, ISO generally refers to a measure of "Film Speed", which I use including reference to digital sensor sensitivity. In short, the actual letters ISO are a name for the International Organization for Standardization (not, officially, an acronym -- more information here), and in photography it refers to the ISO 12232:2006 standard and other ...


53

Is lower ISO always better? No! For a fixed amount of light coming into the camera, lowering the ISO will not result in a reduction of noise. The only way to reduce noise is to combine lowing the ISO with letting in more light by opening the aperture of leaving the shutter open longer. If the amount of light you can let in is limited (you have hit the ...


41

It would be wrong to think that increasing ISO results in no "physical" change in the camera at all. The problem with ISO is that people often call it sensitivity. That is really a misnomer...sensitivity is a fixed attribute of any given sensor, and it cannot be changed. Sensitivity is really more synonymous with the quantum efficiency of the photodiodes, ...


24

Noise is often defined as any deviation from a "pure" signal. The signal is taken to be brightness pattern of the image so any variation in the pixel values that represent the image is noise. These variations arise principally due to: Shot noise. The random way photons are emitted from a lightsource causes random variations in image brightness. The fewer ...


24

Regarding the statement: Is lower ISO always better? There seem to be a variety of opinions on this topic, and while they may seem mutually exclusive, I am not certain that is the case. There is no cut and dry "Yes, X ISO setting is always better." I think which is better is very dependent on context...on what it is you are trying to shoot, and what ...


23

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 ...


19

Cost. Every price raise results in fewer sales. Size. Cooling has to fit somewhere, those handgrips are already full of batteries... Weight. There's a reason P&S are popular and not lugging around a brick is one of them =) Battery Life. Cooling costs energy, lost energy means fewer shots in each battery pack. Minor Improvement: only shots pushing ...


19

Noise is a fact of life when it comes to astrophotography, with the exception being stacked deep sky photos taken on a tracking mount (more in a moment). Your photo is actually very low noise, in the grand scheme of wide field, single-frame astrophotography shots that I have seen...but it also lacks saturation. I think it really comes down to a matter of ...


15

ISO is effectively a sensitivity of the sensor, whether it be film or digital. In theory, ISO for a digital camera should be the same as for a film camera. The ISO on film is determined by the grain size of the chemical. What this will mean is that the resolution will be better with a lower ISO film. Also, because a film grain is all or nothing, this will ...


12

Noise originates due to a number of factors, see: What types of noise can be present in digital photographs? Increasing the number of megapixels keeping everything else constant (sensor size, technology etc.) will increase noise per pixel, but also has the effect of making the noise finer grained which is less objectionable. ISO does not by itself ...


11

It totally depends - it's an artistic vision thing, and I don't think anyone but you can really answer it. That said, I've rarely encountered folks who were insufficiently concerned about noise; far, far more often people are more worried than they should be. It might be worth your while to have some third-party critiques of prints you're concerned about. ...


11

It seems unlikely that a sensor cleaning would increase digital noise. (Not impossible, just unlikely.) It's more likely that you're just noticing the same amount of noise more now than you were before. If some sort of fluid were used to clean the lens, it's possible that there could be a residue on the sensor. This would cause general or spotty ...


11

The long exposure Noise Reduction takes a "dark frame" after the real shot, and then uses the noise pattern from that image to reduce the noise generated by the sensor. That's why the exposure takes twice as long as this NR were disabled. Long time exposure can increase the sensor temperature, and increased temperature also means more noise. So you should ...


10

The last two are really the same thing and works due to the fact that in most cases noise is just as likely to push the value of a pixel up as it is to pull the value down. Let's say the 'true' value of a given pixel is 100 (out of 255). Take 10 images of the same scene in noisy conditions and you might record the following values: 104, 99, 98, 100, 101, ...


9

A hot pixel is actually one or more hot photo sensors. Most camera sensor chips are made up of red, green and blue photo sensors, usually placed in a pattern similar to this: RGRGRGRGRG GBGBGBGBGB RGRGRGRGRG GBGBGBGBGB Each of these photo sensors ends up as a pixel in the final image, but as each photo sensor only has information about one color ...


9

Firstly had you lowered the ISO whilst staying at 30s f/4 you wouldn't have ended up with any less noise. There's probably nothing you could have done to prevent the noise, I presume f/4.0 was the maximum aperture and if you went any longer than 30 seconds you would get star trails. You might even get less noise if you raise the ISO but that's another ...


9

Reduce it, yes. For example, the Canon 5D Mark III is 2/3 stops better than the Canon 5D in high ISO performance, although their sensors are the same size, because it is seven years newer. Of course, past performance is not necessarily indicative of future results, but I see no reason for incremental gains not to continue to be made. Eliminating it ...


8

I was a big fan of Noise Ninja for the longest time until I got my hands on Topaz Denoise which produced remarkable results. I used to avoid 1600 ISO or higher for the longest time on my Pentax K20, but not any more. Here's a sample of ISO 3200 after Topaz Denoise: Here's the before (the change in colour is not related to noise reduction):


8

In general I wouldn't recommend doing anything in camera that is irreversibly "baked" into the image, as such things can always be done better, with more control, and more importantly the option to undo, in post on your PC. There is another feature called Long Exposure Noise reduction which shoots a black frame (i.e. one in which the shutter is closed) in ...


8

When you change the ISO value to a higher, you really change the amplification in the chip. Let's look at one single pixel first. During exposure the pixel receives a number of photons, which generate (let's say) 100 mV, and the chip's noise gives 10 mV. You have a signal-to-noise ratio of 10:1. Now, you need to expose half the time, and therefore you ...


8

I believe it may be a flaw in your testing. Raising ISO should not be getting you a higher signal to noise ratio (or usable dynamic range). You are raising the noise floor, without any corresponding increase in dynamic range at the bright end. Thus you should be left with overall lower dynamic range. It would not be possible to go the other way. Is it ...


7

The bigger the pixels, the less noise there is. This is a matter of physics. More light gets accumulated in each pixel and so it take more noise to appear significant. The 600D and 7D have APS-C sensors which are small and have a high megapixels count. This makes their pixels comparatively smaller than the 5D Mark II which has a larger sensor and hence ...


7

Provided your ISO100 image was not underexposed I wouldn't expect a noticeable reduction in noise (except maybe in the deep shadows) with the 5 1 second ISO1600 images blended together. In the infamous other thread I demonstrated that a 1/30s ISO100 will contain more noise (lower signal to noise ratio) than a 1/30s ISO1600 image. Same amount if light but ...


7

It already happened! On film, or early digital, high ISO meant 400, on latest full frame cameras it means 6400. Problem is that each time it happens, 'High ISO' gets redefined to be even higher, or in another words, high ISO always means "so high that current tech makes it noisy". As noted by Tony, there are eventually, physical limitations as to how far it ...


6

The pro's are self-evident: Lower noise on high-iso The biggest con: Loss of detail The high-iso noise reduction might remove detail mistakenly. While newer camera algorithms have gotten better at it, it's still not fool proof. The settings between Off, Low, Normal and High dictate the amount of tolerance used for the setting, which affects the ...


6

As with many such things, which is best has some level of opinion and which looks best to an individual. I think Noise Ninja products consistently produce some of the best results. Prior to Lightroom I used it within Bibble, and found it to be simply mouth dropping good. However, I have found Lightroom 3 to have nearly as good results, bringing it, to me, ...


6

This question is probably best answered in two parts. Part1: You may need to increase the ISO to combat noise. This sounds counter intuitive due to common misconceptions regarding noise. Noise is principally caused by lack of light. Lightsources emit photons randomly, the more photons you collect, the more the randomness averages out, leaving a smooth ...


6

I think you might be confusing a few issues here. The terms "Base ISO" or "native ISO" are often used to refer to the unamplified sensitivity of the camera. In addition to this digital camera sensors have built in amplifiers to amplify a weak signal (such as you get in low light) before it is digitised in order to reduce read noise and increase signal to ...


6

Image noise in a properly operating DSLR will be affected by shutter speed, but not in the linear relationship the question implies. In decreasing order of impact, image noise is a factor of: - Amplification applied to the sensor cells (higher ISO increases noise) - Thermal noise (hotter sensor is noisier) - Duration of exposure (longer the capture, more ...


6

The thing that creates noise is not enough light. You can think of your image has having a constant amount of noise (this is a big inaccurate over simplification, but it helps understand the issue), when you are photographing something nice and bright the sensor captures a lot of data and it completely overpowers the noise. On the other hand if you are ...



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