Hot answers tagged stars
51
I found this image while checking my stats on Flickr. (I'm the photographer that shot this photo)
I thought I'd respond with details of how I created this image since I see multiple theories here.
First - this is not a stacked exposure. The entire image is a single exposure (30 secs). I used a Nikon D700 DSLR at ISO 3200 to capture this image (at ...
17
Stars move. Like with any other movement, what we care about is how much they move on the sensor during exposure: A movement that occurs only within a single pixel is not a movement the sensor can capture, i.e. the movement appears frozen.
But when movement takes a point across several pixels during the exposure, it will be visible as movement blur, in this ...
11
Unfortunately, a lot of images like the one you show here are digitally altered and it is difficult to get comparable results. The image above shows the Milky Way, looking approximately at its center, which appears to us to be in the constellation of Sagittarius.
To get such a detailed view of the comparatively dark nebulous structures, however, you need ...
8
The light from such objects is nowhere near bright enough to cause damage to the sensor, however using really long exposures to capture dim distant stars could damage the sensor by overheating.
Most modern DSLRs have heat sensors and cutoffs to prevent this, but if you're using an older camera and keeping the shutter open for hours with an external power ...
8
Camera is better at seeing than our eyes. According to http://www.cambridgeincolour.com/tutorials/cameras-vs-human-eye.htm astrophotographers have estimated that human eyes have a ISO rating of 500-1000 after being properly acclimated to dark conditions. The example photograph has used something like ISO 3200.
Cameras can also take longer exposure (=gather ...
7
The rule of 600 states that to 'eliminate' star trails the exposure time in seconds should be 600 divided by the focal length of the taking lens. 20mm lens could go to 30 seconds, 300mm lens could go to 2 seconds.
Of course (like any motion blur) you will never eliminate star trails- you merely reduce the trail to an acceptable level for a given ...
7
Its probably due to a narrow aperture. On professional grade lenses, you can usually stop down a bit and still maintain a rounded aperture, however on cheaper lenses, or on all lenses at very narrow apertures, the opening becomes polygonal. That causes the diffraction of light as it passes through the aperture to produce a star pattern (the exact nature of ...
7
You can't see the colours in the milky way (or other stars for that matter) as the light coming from the milky way is too dim to be picked up by the cone cells in our eyes which distinguish colour. Instead the light only trips the more sensitive rod cells (which are usually used for detecting motion) hence we see the brightness but not the colour of the ...
6
If you have an android phone with geolocation and compass, Google nightsky is outstanding. Or if you're on your computer http://www.google.com/sky/ google sky. I'm sure you could find better software for the task, but if you're just trying to get the milky way or a constellation or two, it will do the trick.
6
The moon is not anywhere close as bright as the sun (it's basically a giant diffuse, grey reflector), and so there is little risk. According to Wikipedia, the full moon at its brightest is about 400,000 times dimmer than the sun. That's 18 1/2 stops!
However, the moon does tend to get overexposed in photographs, since it's hard to fill the frame without a ...
6
An equatorial mount and a computer controlled mount are two different things. A mount can also be both.
A equatorial mount has one axis aligned with the spin of the earth (pointed towards Polaris for those north of the equator.)
A computer controlled mount is a mount that knows where the objects in the sky are. You can say, "point at Jupiter" and it will ...
5
The "basic gear" is a digital camera and tripod. Point the camera at the sky for 30s with the aperture wide open at the maximum ISO setting. With the right atmospheric conditions and location you can get some surprisingly good results.
Moving on from there a DSLR with RAW support (the 60D is fine) fast lens (such as a 50mm f/1.8) is advisable, as well as an ...
4
Your problem consists of two parts.
Star trail stitching
First you want to combine the photos of each camera separately into star trail images. Your result will be a star trail image from the 7D and one image from the XTi.
This answer has more details on astrophotography. The relevant part is under the heading Capturing Star Trails.
For the stacking you ...
4
This is a repeat of
http://physics.stackexchange.com/questions/25825/can-you-damage-your-eyes-viewing-venus
No, there cannot be any damage, not to the camera and not to your eyes either.
In the case of the moon and/or planets, there is not enough brightness to cause any damage, and the lens cannot increase the surface brightness. In the case of the stars, ...
3
Star Trail Photograph is one of the most challenging activity, I've learned it from here:
http://www.jamesvernacotola.com/Resources/How-To-Photograph-Star-Trails/12233655_V7cX4D
http://www.nikonusa.com/en/Learn-And-Explore/Article/h0ndzhvw/photographing-the-night-sky-star-trails.html
3
I've not done star trails but I've done a few moon shots.
Specific things for the D90 are that you need a very solid tripod as the D90 has no mirror lockup for shooting to prevent movement/vibration. Turn off the Long Exposure NR, VR on the lens autofocus and auto-iso. If you have a remote release like the ML3 then use that otherwise use the self timer.
...
3
In order to photograph the milkyway you want to capture as much light as possible within a certain timeframe.
This means:
Highest ISO you think is acceptable with your body
Widest aperture
Shutter speed as long as possible, without setting it too long so you can see the movement
So looking at your settings, indeed the aperture could have been wider, ...
3
There is a wonderful and hugely popular, open source, cross platform based software called Stellarium which is available at http://www.stellarium.org/. It is free and has tons of features. You can track almost every celestial object with it.
3
This rule applies to the shutter speed you should use when taking photographs of the night sky. The rule is as follows:
When using a lens of focal length L to take a long exposure photograph of the night sky (with a stationary camera), the maximum shutter speed you should use to avoid blurring of the stars is 600/L seconds.
For example, if using a 300mm ...
2
The most important feature is to have manual settings. With just (semi)automatic, you can't do much. Since the best camera is the one you actually use and bring with you, don't get to cheap on it.
If you need (close-up) photos on jewels, you would most likely either need a great compact, or a DSLR combined with a macro lens. The latter one is very ...
2
First of all, you see that your ISO is high. Because of this, your image is full of electrical noise, which makes your picture grainy. You said you used auto settings, and probably camera was not set to use lot of mechanisms (Long exposure noise reduction, High ISO NR) to achieve better quality. What about tripod, did you used one, or you put your camera on ...
1
In the case of preserving folder structure i would probably copy your top hierarchical folder to another area... run a search of only that newly copied top folder (and subfolders) of: "*. jpg Rating:<3 stars" and delete all the results.... just make sure you know what you are deleting because if you accidentally do a global search you'll delete your ...
1
Consider using a higher ISO, but that will create more noise in the image, and is likely to catch much more of a sky glow if you happen to be near a city or town.
Best shoot in raw and try out a large number of ISOs for the shot, and then see how much detail and noise you could recover using Photoshop/Lightroom/Aperture/Other Software. You'll have to ...
1
You can make a physical mask with a circular hole much like people use to make the "shaped bokeh." This just becomes a larger pinhole camera.
Challenge becomes how to make a nicely round hole in a fairly sturdy material. Consider using aluminum foil pierced with a pin or other small device.
1
There is a bunch of real time apps for the iPhone and iPad. I played with an app a few months ago which used the camera with the location services and it was projecting constellations and stars directly onto the image captured by the video camera in real time. I think the app is SkyView. (there is a free version of that too) Pretty cool but it was ...
Only top voted, non community-wiki answers of a minimum length are eligible
