47

This is a featured called Long Exposure Noise Reduction. To cancel out noise the camera will close the shutter and take an equally long exposure again, this time capturing a black image with only the electrical noise on it. This information is then used to reduce the noise on the original exposure. In the camera settings you can disable the Noise Reduction ...


22

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 ...


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

Look up Long Exposure Noise Reduction in your camera's manual. Depending on the model, you may or may not be able to continue taking photos. Some models do the processing immediately after the exposure. Some allow you to continue to take exposures, and then do the processing. This feature uses dark frame subtraction. The idea being that if you expose a ...


18

This looks like the effect of noise reduction at high ISOs. Heavy NR is common in compact cameras with small sensors. Fujifilm cameras of that generation did it very well compared to others of the time, but there's only so much blood you can get from a stone. On most modern high-megapixel point and shoot cameras, you'll see this even at low-ISOs if you ...


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 ...


12

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 story. ...


12

The key difference between the two is that one works on a post-digitized image, where as the other works on the pre-digitized analog signal. Whenever you work with an analog signal, you have the ability to be more precise and accurate, and can eliminate noise before it is "burned into" a digitized image. Thats most certainly not to say that applying noise ...


12

You can only preview noise reduction in RT when you zoom image to 100%, even in latest version. Many other tools have same limitations for previewing, they are marked with small "1:1" label near their names.


11

When I have extremely noisy images, I do two things: Use a 3rd party noise reduction plugin - in my case I use Topaz DeNoise - it, and others, have free trials - so you could give them a try if you want to experiment. These denoise plugins have sliders that will reduce noise, which softens the image, but you also have control over detail (you can decrease ...


11

The technique used by Cortex Camera is called Median Blending. Astrophotographers have been using this concept for years to combine multiple photos of dim objects in the night sky to reduce the noise and increase contrast and color. It is often referred to as image stacking in which hundreds of images of the same piece of sky are overlaid and the values for ...


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, ...


10

No Canon dSLR has built in image stabilization. Canon offers it in select lenses, known as 'IS' lenses. So, no, neither offer image stabilization. All Canon cameras also offer noise reduction, and of course, it can be applied (or not in the case of RAW) on the computer after the fact as well. Does it matter? Noise reduction matters, because all cameras ...


9

There has been an improvement between the 40D and 650D, but not that great. Certainly less than a stop. You'll get a far far greater improvement in image quality by getting more light onto the sensor. There are a number of ways to achieve this: Depending on what lens you're currently using you may be able to get a three stop improvement by switching to a ...


8

It boils down to power, and lack of market demand. There are specialty cooled-sensor cameras out there. They're generally just used for astrophotography. The cooler that is used in almost all cooled cameras is what is called a thermoelectric cooler, commonly colloquially called a "Peltier" or "Seebeck cooler". Generally, you will need a fairly chunky ...


8

Noise is random, it causes gray values to fluctuate from one pixel to the next. This is then random information present at the smallest scale in the picture. If you remove it, then it gives the illusion of the image having become less sharp, as the gray values are not changing as fast on the smallest scale anymore. This doesn't mean that removing the noise ...


7

It is poorly written. Indicated Green Background refers to the list below where lenses models with stabilization are highlighted with a green background like the AF-S 16-35mm in the wide-angle section:


7

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 ...


7

Active D-Lighting Active D-Lighting isn't necessary at all. It works by doing two things: slightly underexposing (by 1/3 to 2/3 stop) and applying some adjustments to raise the shadows back up It isn't needed if you shoot RAW as you can underexpose and raise the shadows in post It is only relevant if you are shooting high dynamic range scenes with bright ...


6

There is no "technically correct" answer either, for a number of reasons: Noise in images varies based on the actual exposure, and unless every image you take is evenly lit across the frame, the right amount of NR will vary. Different sensors have different noise characteristics. This year's models are so much better than those from five years ago that any ...


6

First, I must say that for a start, this is a great photo. Noise is a problem but your photo still looks great. Now I suggest you have a look to the software DeepSkyStacker, its website and documentation. They have a great page that explains the theory behind the software. Basically, you combine multiple similar shots to reduce the noise. You can also ...


6

The effect can be explained by heavy noise reduction caused by using too high a shutter speed for the circumstances. The specific camera is worse than most in its class in this respect. The 1/2000s exposure time is unnecessarily fast and as a consequence the ISO "film speed" is high, making the image more noisy than it needs to be. At a guess that ...


6

Whenever you see a truly breathtaking image, you can be sure that it's the culmination of doing a whole lot of things really, really well. In the examples you indicated, we're looking at images scaled to a size much smaller than the files produced by your camera, which suggests that at least some of the impact you're perceiving in the photos you're trying ...


6

This is normal considering the high ISO you are using on that camera. If you look at samples for each ISO with the Canon 7D, yours show more noise than the ISO 1600, similar to the ISO 3200 crop. Notice that I only shot full-stop ISO which is important with Canon DSLRs because the gain to obtain the 1/3 stops in between is applied in software by the ...


6

This is not only possible, but is in fact the way that some noise cancellation modes already work. Long exposure noise reduction (or LENR) will automatically take a dark frame of the same exposure length after a long exposure image capture. It then uses this dark frame for noise cancellation. More detail on LENR is covered in this question.


5

Temperature In silicon there is an effect called thermal noise (Johnson noise). This is basically electrons been torn loose from the substrate and adding to the electrons being knocked loose by photons. These electrons are then considered part of the "signal" from the sensor, creating noise. This kind of noise is Gaussian distributed and have a mean value ...


5

I'm not sure about GIMP, I use Lightroom 4 and there is this wonderful plugin Noiseware 5. I used it myself and I got good results. Some report Noise Ninja to be a good tool too but I didn't try it myself. I'm sure that you can do this in GIMP without plugins, a quick googling results that maybe helpful: Reduce Noise in GIMP Noise Removal


5

Most likely because it would be bulky, and have a very high energy consumption. Most cooling for electronics is for bringing it down closer to room temperature, but that wouldn't do much for a camera sensor, as it is mostly used for fractions of a second, so it won't heat up much. You would need a cooling element to get the temperature down, so it would ...


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