45
votes
Why do stars appear as circles, not points?
Whenever light passes a boundary, it diffracts, or bends, due to the wavelike property of light interacting with that boundary. An aperture in an optical system, typically circular or circle-like, is ...
- 31.6k
44
votes
Accepted
What are the reasons for not taking super long exposures (hours) in astrophotography?
@Michael Clark and @Itai have provided good answers. A few more thoughts from the perspective of the enthusiastic amateur:
Tracking technology isn't perfect and sometimes its better to work within ...
- 536
35
votes
Accepted
What makes the difference on partially and fully visible moon?
What makes the difference on partially and fully visible moon?
In a word: shadows.
I cannot understand why the IQ is extremely diminished when doing the same with an almost fully visible moon.
...
- 31.6k
35
votes
Accepted
How to capture more stars?
1) To capture more stars, go somewhere where there is less light pollution. If you can't see the north star, you aren't going to get much. I can't see the north star from my front yard, so attempting ...
- 1,192
34
votes
Accepted
Which planet looks the biggest through a camera? Which planet is the easiest to take a picture?
Because the distance from Earth to each of the other planets varies due to orbital mechanics, the size of each planet as seen from Earth can vary significantly. Which planet is the largest and the ...
- 173k
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.
- 9,539
27
votes
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Why is the North America Nebula so hard to see on this astrophoto?
Your exposures are very different. Ignore the quantity of images that you captured for a moment... and just compare the the single exposure settings (for reasons I'll describe in a moment).
Top: 13 ...
- 3,752
24
votes
Why are the star trails in Richard Angle's photos of a SpaceX launch and landing so non-uniform?
They are not uniform but they all show the same bright-dim-bright pattern. One explanation is that this is a composite picture of several exposures and that the middle exposure(s) was/were dimmed a ...
- 18.3k
23
votes
Which planet looks the biggest through a camera? Which planet is the easiest to take a picture?
Normally Jupiter is easily the largest seen from Earth, but depending on orbits, it could sometimes be Venus (next time in September, and then next in 2020).
This site will answer about details ...
- 12.8k
20
votes
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Photo of sprites in a clear dark sky, is this possible?
Shots I've done of the Magellanic Clouds required an 8 second shutter speed at f/3.5, ISO 3200. It is conceivable that he could have captured these events since he was trying to photograph Lyrid ...
- 2,653
19
votes
What are the reasons for not taking super long exposures (hours) in astrophotography?
It is firstly because we can now.
Bulb photography can indeed shoot exposures of minutes to several hours, depending on the camera. Using a film camera, astrophotography is done with very long ...
- 102k
19
votes
What are the reasons for not taking super long exposures (hours) in astrophotography?
The main advantage of stacking is to average out the randomized Poisson distribution "shot noise" that can be a problem in low light images such as astrophotography. Another advantage for stacking ...
- 173k
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 ...
- 142k
19
votes
Accepted
What kind of filter do I need for safe sun photography?
You need more than an ND filter and a polarizer. You need a solar filter specifically designed for imaging the sun. The danger to your eyes and camera are very real if you are pointing the unprotected ...
- 173k
19
votes
Why do I need a telescope for astrophotography?
In principle, there's no difference between a camera lens and a refractor telescope.
While focal distance is related with the magnification of the image, in astronomy, resolution is related to ...
- 1,241
19
votes
What causes the fake colors of stars on these pictures?
I can tell 3 common reasons for weird/fake colors in astrophotography:
Chromatic aberration makes some starts appear white in the center, but their borders blue or red, depending what of those two ...
- 1,241
18
votes
How to capture more stars?
Shoot when there is no moon in the sky. e.g. Near the "New Moon" or "Last Quarter Moon" if shooting after sunset. Get away from urban light pollution.
I've generated a simulated field of view (...
- 3,752
18
votes
Accepted
New Pi camera - any good for Astrophotography?
I have tested RPi HQ Cam for astrophotography over last month and it works quite well.
First, sample images:
Canon FD 200/2.8 lens, 42 minutes exposure time (not a high quality glass, and not long ...
- 334
15
votes
Accepted
How can I achieve more clarity in my photos of the moon?
Some possible reasons, arranged in the likely order of influence, for the lack of clarity in the example photo:
1) The optical limits of your lens. The EF 100-300mm f/4.5-5.6 was released as a budget ...
- 173k
14
votes
Accepted
What is the best way to focus when doing night photography or astrophotography?
For focusing on stars, I suggest using a Bahtinov mask, which uses purposely-created diffraction spikes to determine correct focus.
Bahtinov mask by Justin Dolske, from Flickr. CC BY-SA-2.0
This ...
- 31.6k
14
votes
Accepted
Does the EXIF data "DateTimeOriginal" get recorded at the start or end of the exposure?
The EXIF standard describes the DateTimeOriginal tag simply as "the date and time when the original image data was generated." It gives no guidance about what event (e.g., shutter released, shutter ...
- 5,492
14
votes
Why do I need a telescope for astrophotography?
@vsis already said this, but I'm going to be more explicit:
It's all about the brightness. Most astronomical objects worth looking at are dim. The more light your optical system "gathers," ...
- 636
13
votes
Does the EXIF data "DateTimeOriginal" get recorded at the start or end of the exposure?
Experimentally (on my EOS 70D), this is the beginning of the exposure, and not the end.
But:
this seems truncated to the second
it depends how accurate is the time of the camera (before doing this ...
- 18.3k
12
votes
Accepted
What are the features needed in a DSLR for astrophotography?
I already have a Nikon D5200 and I I tried so much to get a clear view of the sky and it didn't work so much.
The camera you have is a fine one to start with. You should spend some time working on ...
- 31.6k
12
votes
Accepted
How to take photos in burst mode, without vibration?
In theory, live view mode should ensure the mirror doesn't flip, if you don't use quick mode autofocus.
In practice, though, your camera is a very cheap one, that has probably an integrated shutter/...
- 6,453
12
votes
Accepted
How does one actually *use* a dark frame?
Straight away I should mention that lunar photography is different that astrophotography of deep-sky objects. The types of frames you are describing (calibration frames) are extremely helpful for ...
- 3,752
11
votes
What caused some of the bright, diffuse areas of sky in some of the Apollo images from the moon?
It looks like lens flare. It is an internal reflection inside the lens. It is caused by off axis light allowed to fall on the front surface if the lens from outside the field of view.
For an example ...
- 173k
11
votes
Which planet looks the biggest through a camera? Which planet is the easiest to take a picture?
Though the angular size of Venus in the Earth sky is larger than any other planet, because Venus is an inferior planet that largest angular size happens only when Venus in the the direction of the Sun....
- 312
11
votes
Accepted
How to take photos of planets with smartphone?
The best option is to attach the phone to a telescope. E.g. Jupiter with a phone and a 10" Dobsonian.
A 10" Dobsonian isn't small, you're attaching the phone to the scope rather than the other way ...
- 3,713
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