Skip to main content

How to avoid star trails during night photography using 500 rule?

What is a star trail? Movement of star captured across several pixels of a given image leads to the formation of a star trail. This is a really common problem when doing long exposure night sky photography or astrophotography. Pretty sure most of us like to star gaze and observe those tiny little twinkling dots in the sky on a clear day. If our eyes can see it, so why not our DSLR? We want exact same tiny cute little stars to show up in our DSLR photos too. Once you have learned how to focus your DSLR lens to infinity, next thing to think about is how to avoid light pollution and star trails. 500 rule or 600 rule comes to the rescue when learning to avoid star trails. I have seen a lot of discussions about 500 rule vs 600 rule, I personally have always been happy with 500 rule only. Sometimes I even go for 400 rule but never 600 rule.
Who invented this rule? I did search but couldn't find anything relevant or meaningful. Only thing I know is all modern day astrophotography folks love this rule. I will try to explain the rule with two simple examples. If you are shooting RAw images, I would highly recommend turning off Long Exposure Noise Reduction in your camera settings menu. 

1) Canon T5i (cropped sensor) camera. 
Lens used: Tokina 11-16 F2.8 DX at 11 mm. 
ISO: 3200
F-stop: F2.8
Shutter speed:
Maximum shutter speed possible to avoid star trails: 500 divided by full frame equivalent focal length. So it is 500/(11*1.6) which gives us approx 28 seconds. 1.6 is the crop factor for Canon cropped sensor cameras, you can use 1.5 for Sony and Nikon cropped sensor cameras.

Star trails avoid during MIlky way photography
                                                                  20 seconds exposure 

2) Nikon D610 (full frame sensor) camera. 
Lens used: Tokina 16-28 F2.8 FX at 16 mm. 
ISO: 3200
F-stop: F2.8
Shutter speed calculation:
Maximum shutter speed possible to avoid star trails: 500 divided by full frame equivalent focal length. So it is 500/16 which gives us 31.25 seconds. In this case, I would use 30 seconds to be on the safe side. Take a few test shots and check your image by zooming in. If you see every star looking well rounded and crispy, you have taken an awesome shot. If not, try again with a bit lower shutter speed. You might get lucky to see a couple of shooting stars in your photos which adds more interest to the pictures. 

Hope this post would help you to take stunning and crispy star shots without any surprise star trails. If you like star trails, there will be a separate post talking about cool star trail formation ideas around the north star. 

If you found this post helpful, share the photography love by sharing this post. :)


  1. Thanks for the post. That was a big help. Will try it as soon as I get hold of an appropriate lense.

  2. Photograph clicked is amazing. I will surely try these lenses and your idea of photography.


Post a comment

Popular posts from this blog

Canon CR3 raw format guide

A raw image file is like a digital negative without any lossy compression and minimal processing applied to it. A digital camera shooting images in raw format provides output in the best possible quality, which means files are larger in size and take more space. The benefits offered by shooting raw format overpowers the slight storage hassle though. Few of the well known raw formats include CR2, NEF, RW2, RAF, PEF, ARW, etc.  In this post, we will talk about the new compressed raw format introduced by Canon starting with its mirrorless series of cameras.

History of Canon raw formats
Back in the early 2000s, Canon cameras produced raw photos in CRW format. Cameras shooting in CRW include Canon D60, Canon D30, Canon 10D, and Canon EOS 300D. Most of the cameras released after the year 2004 shoot raw photos in CR2 format. Examples of CR2 format Canon cameras include 350D, 6D, 7D, 5D, 5D Mark II and many more.
In 2018, Canon introduced its new mirrorless camera known as the EOS M50.  This …

Relation between ISO, shutter speed, aperture and light in photography

Photography is a word having Greek roots, which basically means "drawing with light". When I started doing digital photography a few years ago, this did not make sense to me at all. How can you make a picture just using light? Only light matters? My pictures were either black or completely washed out all the time, but I didn't feel like giving up. It took me a fair amount of time to understand controls such as shutter speed, aperture and ISO which was the outcome of non-stop reading and a lot of mistakes. Coming back to the concept of light, it started to make sense after attending a film photography workshop. The dark room with very dim or near to zero red lights was a whole new point of interest. My partner and I made a pinhole camera out of a pumpkin. 
The workshop made me understand how important light is when taking pictures, and the rules apply to both film and digital photography. Basically, the value of shutter speed and aperture directly affect the amount of li…

F2.8 vs F3.5 vs F4 lens aperture comparison with examples

I started the exciting journey of digital photography with 18-55 mm kit lens as my first glass. Being a variable aperture lens, it has a minimum aperture of F3.5 at 18 mm. The lens saw its fair share of adventures and ultimately was replaced with a fixed aperture lens.   Value of aperture is a part of the exposure triangle, which means it affects the amount of light hitting DSLR camera sensor. In addition to light, it also affects the amount of area in focus which is often referred to as Depth of Field. An image taken at F8 will have almost everything in focus when compared to an image taken at F2.8. Before someone jumps on me with their DOF vocabulary, this post is not about depth of field (DOF) in detail discussion. It is a simple comparison post for beginners to understand how lens aperture impacts background blur and low light performance. 
DSLR used: Canon 6D Lens used: Tamron 24-70 mm F2.8 DI VC USD
Bokeh (background blur) comparison:

Comparison animation in the above photo show…