Make Stellarium More Realistic when planning for a night shot
**Article by Darryl Van Gaal
As both a landscape, and deep space astrophotographer I find myself using Stellarium (stellarium.org) on a weekly basis. It's a great (free) program and in my opinion is one of the best out there competing with programs that cost hundreds of dollars.
I like it for the ease of use along with the reality of the night sky. If you use the right settings, the sky you see in Stellarium is strikingly similar to the sky you'll see when you look out your door.
Like I said, I do believe that it is an easy program to learn the ins and outs of, BUT, like anything, there is still a learning curve.
I've posted about Stellarium in the past ( http://darkclearskies.blogspot.ca/2013/04/one-of-landscape-astrophotographers.html ) teaching you how to simulate your cameras field of view with a particular lens on it. Which is aid in planning photography outings.
This post is similar as it will teach you how you can use it to help you get a feeling as to what you'll see in the night sky where you live, or where you are planning an outing.
With the program open you will notice when you move the mouse cursor to the bottom, and to the left side of the window, side menus will open up. Here you will see a particular icon that looks like a compass. When you click on this icon (or press f6) it will bring up the window for your location settings.
Setting Your Location
There are two ways to change your location settings. One is to manually enter the Lattitude, Longitude, and Altitude of your location (or intended location). This information is available on many GPS units, and also is available in many locations on the internet. (Google is your friend, use it!!)
Another option is to search for your city in the list provided. If you find it there you're good to go. If you have to manually input the data, do yourself a favour and click on the "Add to list" button so that you don't have to enter it again and again. If the location is your "home" location, you may want to make sure the check box is clicked in the lower left corner of the pop up box. This box is labelled "use as default". When this is clicked Stellarium will always open using this location.
If you press f4, or click on the third icon down on the left menu "Sky and viewing options window", a window similar to the one you see here will pop up. Make sure that you click on the tab at the top of the window labelled "Sky". Here is where we will make the sky look like the sky we can expect to see.
Most importantly, the area labeld "Show atmosphere". Here, we'll make sure that the check box is selected, and we need to set the Light pollution number to one reflecting the area we live, or are planning a shoot in.
The numbers run from 1-9 and are know as something called the "Bortle Scale" (Named after John E. Bortle created the scale, again, Google is your friend). I didn't know this when I started out, and I don't expect you to either. That is what the Internet is for.... Learning!!!
There are many sites where this information can be found. One of my favourites is ( http://www.jshine.net/astronomy/dark_sky/ ) at this site you will see an image like the one below
This particular map is showing North America. There are many sites on the internet that show different areas. Most if not all use the same colour scheme.
Next, we have to convert the colour into a number that we can use in Stellarium.
To make this easier I've created a legend that you can use to convert the colours to a number.
Changing Star Settings
The easiest thing to do here to make it most "realistic" is to make sure your settings are the same as mine.
I believe that the settings are like this by default (I can't remember for sure).
- Absolute Scale will change the size of the stars. A larger number makes larger stars
- Relative Scale basically makes bright stars larger, very similar to how they appear to us or in photographs.
- Milky Way Brightness changing this value will make the Milky Way either brighter or dimmer. The larger the number, the brighter the Milky Way. I find that 1 simulates what my eye sees better.
- Twinkle Clicking on the check box will make the stars twinkle, just like they do when we look into the night sky. Adjusting the value will change how much they twinkle. A larger number, more twinkle.
- Dynamic Eye Adaptation when you check this check box stars will get dimmer (or disappear) when a bright object is near them. You will notice that a star may be hard to find during a full moon. This is basically the same effect.
You will notice here that I have opened a window that lists different lenses that I use.
I will provide a link about how to set this portion up as I have created a post in the past that deals with how to use and set this portion up. http://darkclearskies.blogspot.ca/2013/04/one-of-landscape-astrophotographers.html
Toggle the Atmosphere
We have to make sure that all of the changes we just applied are applied to the screen view.
In order to do that we need to move our mouse cursor to the lower left portion of the screen to make the icon menu appear. Make sure the icon shown above is White and not Grey. White means that it is applied. Click on it to shut off the atmosphere settings, you will be amazed how much shows up.
This basically will set you up for you evening (or early morning shoot). Use +Stellarium to know what to expect, what direction to shoot in, and what will be visible at what particular time.
If you have any questions, feel free to contact me here or on my G+ Profile
+Darryl Van Gaal
Be sure to check out my other tips and tricks