32 votes

Multiple copies of the same exposure, but randomizing the noise?

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.
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  • 9,440
22 votes

Can I use a single RAW file with stacking to reduce noise?

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'...
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  • 31.2k
20 votes
Accepted

What is the advantage of carrying a tripod and ND-filters when you could use image stacking instead?

I'd like preface my answer with a note that a tripod is not only useful in conjunction with ND filters — it also improves the results from image stacking as well. By fixing the position of the camera, ...
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  • 31k
19 votes

Multiple copies of the same exposure, but randomizing the noise?

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 ...
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  • 140k
15 votes
Accepted

Stack of 4 seconds exposure photos of Milky Way, how is it done?

Everyone talks about shortest focal length and lower aperture when shooting Milky Way, and this guy does it with f5 How is that possible? It is possible to shoot at f/5 because he is also shooting ...
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  • 168k
13 votes

Can I use a single RAW file with stacking to reduce noise?

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 ...
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13 votes

What is the advantage of carrying a tripod and ND-filters when you could use image stacking instead?

Well, with regards to your (1)... You could carry a light tripod (or beanbag or any other way of stabilizing a camera) and use only a single ND filter instead of several stacked filters. With regard ...
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  • 4,997
9 votes

Multiple copies of the same exposure, but randomizing the noise?

What you're asking about is generally called star-eating. From an algorithm point of view, in an astrophotograph, how can software determine what is signal (that is, stars) vs. what is noise? A ...
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  • 31k
8 votes

Linux software for stacking and RAW processing

Here is the process I use: cd ~/directory_with_raw_files ufraw-batch --out-type=tif --out-depth=8 --wb=camera --exposure=0.33 --black-point=auto *.NEF Of course, you will process CR2 files instead ...
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  • 712
8 votes

Are there image stacking (astrophotography) options on MacOS that don't involve running a Windows VM?

There are possibly several options available. From a cursory search, native Mac applications include: Nebulosity Keith's Image Stacker PixInsight (cross-platform) Starry Landscape Stacker If none of ...
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  • 31k
7 votes

Can 30 1-second exposures be combined to a form the equivalent of a single 30s exposure?

I didn't have enough "reputation" to address some of these answers as comments. AJ Henderson is wrong, 30 1s exposures will (for the most part) be identical to 1 30s exposure. If it shows up in a ...
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7 votes

How do I sum images?

Imagemagick cannot be used to compose 30 images in one step. The documentation states: Image Composition is the process of merging two (and only two) images in a variety of ways. The following ...
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  • 4,453
6 votes

What causes and how can I avoid this moiré pattern in a composite night sky photograph?

Even I had experienced similar problems while shooting night sky photos and later stacking them together although not as apparent of a moire pattern as you have. after a bit of troubleshooting, I ...
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6 votes

Possible to do median image merge in Photoshop CS6 (NOT Extended)?

Yes, I have done it in CS5 and CS6 with the following: File > Scripts > Load Files into Stack Select all layers and use Edit > Auto Align to align them Layer > Smart Objects > Convert to Smart Object ...
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  • 32.9k
6 votes

What is the advantage of carrying a tripod and ND-filters when you could use image stacking instead?

For me the main advantage is... Joy. I enjoy a lot more taking photos, people places, products, rather than editing the images, especially on automated tasks, like stacking photos. Of course, there ...
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  • 20.8k
6 votes

Will stacking more images produce more detail in this galaxy photo?

Stacking more images reduces noise to signal ratio, but don't add resolution or details. In order to enhance resolution, my advice is to use a prime lense, instead of a zoom one. Even if it has less ...
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  • 1,211
5 votes
Accepted

Why does frame stacking alter colours?

Based on the color swapping in the result, I would guess the blue values are being summed into the red result and vice versa. I've made sillier mistakes...
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5 votes
Accepted

Should I turn off in-camera long exposure noise reduction when shooting for image stacking?

Long Exposure Noise Reduction takes a dark frame of the same duration to subtract the noise from the image. That's why there is a long delay; a 30-second exposure plus a 30-second dark frame plus ...
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  • 712
5 votes
Accepted

How to stack photos manually?

When you set the opacity of a layer 50%, what you get is 50% of that layer, and 50% of all the layers underneath it combined. For this reason you should set the bottom layer to 100%, then layer above ...
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  • 117k
5 votes
Accepted

Can 30 1-second exposures be combined to a form the equivalent of a single 30s exposure?

Fundamentally you're capturing the same amount of light in either case so the results should be the same. Practically, there are 2 differences between stacking 30 one second exposures and shooting ...
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  • 117k
5 votes

How to know the resulting iso of stacked images?

It doesn't really work that way. But even if it did, it would depend on the way you stack the images. Do you add them together? Do you average them? Use some other even more complex method? Stacking ...
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  • 168k
5 votes

Multiple copies of the same exposure, but randomizing the noise?

As others have pointed out, what you describe is not possible. If you could randomize the noise, it would mean that you can already detect what is noise and what is not. Then you could just as easily ...
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  • 151
5 votes

Will stacking more images produce more detail in this galaxy photo?

In my limited experience (back when Astrostack was the hot item, and using video captured at 640x480 with a webcam -- call it 1998 or so), stacking more frames will decrease the appearance of noise by ...
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  • 6,158
4 votes

Stack star photos without trails but WITH sharp foreground?

I agree with Randy's response but believe I have a better solution for case a. If noise reduction of the sky background is your intent, you can take a few short exposures and stack them in DSS with ...
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  • 41
4 votes

How do I stack two photos in Photoshop to reduce noise?

You can also use an median blending (create image stack and apply the "Median" stack mode) File > Scripts > Load Files into Stack Select all layers and use Edit > Auto Align to align them (if ...
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  • 32.9k
4 votes
Accepted

How to Record Videos at Full Resolution with Nikon D750 for Astrophotography?

D750 won't output video at higher resolution unless a hack or firmware update are released D750 does most probably use line skipping and it seems that even Panasonic GH4 (or other camera with full ...
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4 votes

Possible to do median image merge in Photoshop CS6 (NOT Extended)?

There's a tool called imagej (or its newer equivalent fiji) designed for use on scientific images. It does this out of the box (assuming the images are aligned). You'd probably need to save as .tiff. ...
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  • 3,602
4 votes
Accepted

Why is my frame stacked image showing a grid?

TL;DR: The edge-discontinuity errors between 8×8 blocks introduced by the DCT compression used in JPEGs is magnified by your image stack, which is why the "grid" is so prominent. If the frame ...
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  • 31k

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