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60

From my understanding, higher ISO gives a more grainy photo I'm afraid your understanding is incorrect. High ISO doesn't necessarily give a more grainy photo as there are other factors involved. In some circumstances it can be the case that lowering ISO increases noise. I did an experiment a while back to prove this: http://www.mattgrum.com/ISOcomparison/...


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....


32

To achieve what you're thinking of you would have to know what the noise was. If you knew what the noise was then you could just remove that to get clean images.


32

I do expect work has been done on noise perception to build perceptual models to compress images and compare image quality. However, I am unaware of any studies that compare photographer vs non-photographer perception of noise in digital images. I also did not see any in the first several pages of results of a Google Scholar search. only photographers ...


30

So I first shoot with ISO 1600 and shutter speed set to 1/125 second and then I shoot with ISO 3200 and shutter speed set to 1/250 second. The amount of light should be identical and indeed both shots look properly exposed and exposed the same way. The amount of light is not identical. You let twice as much light into the camera at 1/125 second than at 1/...


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 ...


26

This is a perfect example of "expose to the right" — that is, even though you want the final result to be low key (largely dark), take the initial exposure as bright as you can (without blowing out the brighter part of the sky, reflections, or any more subtle brighter areas). When you expose so that dark areas are really dark — either because you are ...


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 ...


22

Looking at your samples, the answer seems clear to me: that's not grainy, that is, actually, out of focus. Here's a 1:1 crop of your wide-open image: It seems pretty apparent that the wooden sign is sharp but the dog isn't, and the appearance of the blur looks completely in line with what one would expect from out-of-focus blur, not noise or grain. ...


22

Can I get the same result by coping a raw ( same exposure ) file many times and stacking to reduce noise as I would if I used many separate exposures? No. If you stack copies of the same image, you'll amplify the noise right along with the signal. Stacking images to reduce noise is an averaging process. It's like a science experiment: you don't measure ...


21

While there may be truth to the principle that noise adds the illusion of detail, in this example I think you are misinterpreting what you are looking at. If I remove all the noise in its lower part, it will not look natural (from my point of view) This is mostly because no noise-reduction algorithm can perfectly remove all noise and retain all detail. ...


19

Image stacking works to reduce noise because the noise is random — or at least, ideally so — while the stars are (famously) constant. That means that (once you've corrected for rotation) the stars will be in every photo. But noise — at least, the kinds of noise that this can correct for — is already random fluctuations... maybe there in one image, and not ...


17

The sensor systems are different enough that direct comparison is hard. There are some similarities, but the sensor post processing is exceptionally well tailored to remove undesired artefacts and the maker has not provided a means to turn noise reduction off. Also, the image is developed by a custom algorithm and the system does not allow access to the ...


17

Based on my informal study of my customer preferences and anecdotal evidences, I found that some laypersons do notice noise. 'Noise' is not a familiar term to most non-photographers but I heard my customers say words like, 'dots', 'roughness', 'pixellation' etc. Those who noticed it disliked it and told me that they hoped that I will ensure that the the ...


16

Some of the following suggestions will depend on your camera (I have a Nikon so I'm not sure about Canons). Rather than press the shutter button directly, try using a remote shutter release or alternatively there may be a timer function which delays the shutter - this will allow (at least some) vibrations to settle down. Look in your camera manual to see ...


16

The difference between sharpness and clarity, is basically that clarity is a sharpness applied with a very large radius, a relatively low amount, and mostly to the midtones. This means that you have to use very much of clarity to get the same sharpening effect as sharpness, which also means that you add a lot of local contrast around details. When the ...


15

When it comes to night sky photography and stacking, there is no real substitute for actual SNR (Signal to Noise Ratio). You can virtually improve SNR by stacking hundreds of very short exposures (like stacking 720 10-second exposures), but the result will never quite be the same as if you stack say forty 3-minute exposures. Stacking a bunch of 30 second ...


15

DSLR camera sensors are only exposed to light when the picture is taken, so the sensor presumably produces less noise than if it was always exposed to the light. I find support for this in the way Canon warns about Live View extended usage. It's not the exposure to light that induces that Live View warning, it is the heat generated by the sensor being ...


14

Well, perhaps you should have gone out after all :) The noise is thermal noise, which will become noticeable as your sensor heats up during a long exposure. In astrophotography, it's quite a common problem. Some ways to reduce such noise: cool sensor down, e.g. by shooting in the cold weather. Note that cold also negatively affects battery life. set the ...


14

1600 is not a magical number, but with today's current technology many DSLR's commonly produce poor results above ISO 1600. On the other hand, you could argue that many still produce fine results at 3200 and 6400 - it depends on the audience and what technology they are familiar with. If you are reading this on a forum with many users of consumer level DSLR'...


14

In short, no. See What is noise in a digital photograph? for a fairly comprehensive overview of what does. The main aspect of a lens which might cause increased noise is if you are shooting at a reduced aperture and not compensating with a longer exposure — you'll have to increase the ISO, and that amplification will make more apparent noise. But if you're ...


14

I don't think you'll find that this topic has been studied to the degree that you're looking. You may have some luck in finding a study on perception based on some tangible knowledge or background - but what exactly that background/perception mix is...well, who knows? My wife is in school for her PsyD and has access to more reports than I could ever hope ...


13

You cannot. Removing noise via photo stacking works on the principle that the noise in your images is random, and appears in different places of the image between exposures. When you stack multiple exposures on top of each other, a common method to remove this random noise is called median blending. During this process, software will evaluate the same pixel ...


13

As to the trees being unsharp: It is very difficult to tell, but I think that the autofocus decided to get the house, not the trees in focus. It really is best to specify a certain AF point (p. 61 in the camera's manual). Or, if shooting from a tripod, use LiveView's freely movable contrast AF (p. 95, 102-106) - or focus manually (p. 98). My second guess, ...


12

Why are my low light photos noisy/blurry, but Alien is perfect? There's a world of difference between creating a dark image and creating an image in the dark! The scenes in a Ridley Scott sci-fi movie like Alien are often dark, but that doesn't mean that the set looked that way when the scene was shot. Directors and cinematographers think a lot about ...


11

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 ...


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