What is the best way to reduce overexposure in DSLR astrophotos?

  • Stargazing
  • Thread starter QuantumPion
  • Start date
  • Tags
    dslr
In summary, the problem with taking deep sky images is that the light from the city is too bright and causes the pictures to be washed out and overexposed. There are some simple things that can be done to fix this, such as adjusting the ISO setting or clipping the low end with the levels function in Photoshop. However, the main issue is skyglow, which can be easily fixed by using darken the backgrounds with the de-haze feature in Lightroom.
  • #1
QuantumPion
Science Advisor
Gold Member
902
42
Hi, I've been trying to take some deep sky images with my DSLR. However, my pictures tend to get washed out and overexposed after more than just a couple seconds. Is there something I can do to fix this, or is this just an issue with ambient city light? I'm already using a lens hood, and viewfinder cap, and it's a moonless night. I am using a 50mm f1.8 lens.

IMG_1101.jpg

IMG_1102.jpg

image hosting api
 
Astronomy news on Phys.org
  • #2
Have you tried adjusting the ISO setting? Having it set too high is a common cause of poor contrast.
 
  • #3
What is "a few seconds"? But yes, that looks like a symptom of skyglow. Using the "levels" function in photoshop, you can clip the low end. It is a standard technique.
 
  • Like
Likes davenn
  • #4
QuantumPion said:
However, my pictures tend to get washed out and overexposed after more than just a couple seconds. Is there something I can do to fix this, or is this just an issue with ambient city light?

russ_watters said:
What is "a few seconds"? But yes, that looks like a symptom of skyglow. Using the "levels" function in photoshop, you can clip the low end. It is a standard technique.
very easily fixed in PS or lightroom ... lightroom has a nice feature called de-haze that darkens the backgrounds very well
let me see if I can find an example from my own collection

Dave
 
Last edited:
  • #5
OK here's a real fast comparison and edit of a pic of mine in lightroom The object is the LMC ( Large Magellanic Cloud).

first pic is the jpg out of the camera
second pic is the RAW file edited and a jpg conversion done
you can see the huge difference in colour, and detail

2015_05_08_3682sm.jpg
2015_05_08_3682-2sm.jpg
Note I used the term "RAW File" ... I don't know what camera you are using, hopefully it has a RAW imaging mode
if you are not using it, USE IT ! I cannot stress this enough. Editing jpg files is very self defeating because of the huge
amount of image compression done to generate the file ... lots of data is lost.Dave
 
  • Like
Likes sophiecentaur and russ_watters
  • #6
I don't have photoshop but I guess that is the only way around it! I'm using a Canon T5i. ISO was 800 or 1600 I believe. Exposure was 2 seconds for first picture and 3 seconds for second IIRC.
 
  • #7
QuantumPion said:
I don't have photoshop but I guess that is the only way around it! I'm using a Canon T5i. ISO was 800 or 1600 I believe. Exposure was 2 seconds for first picture and 3 seconds for second IIRC.

OK what about lightroom ?
These days you can get a photoshop and lightroom package for around US$10 - 12 / month subscription really good value
I had to look up a T5i ( that model naming style is mainly only used in the USA) ... ahhh, the EOS 700D ... It's one of the 3 Canon cameras I have :smile:
Also have the 5D MKIII and the 6D.
The 700D I did surgery on and removed a couple of the filters to make it a better astro camera ... more sensitive at the red end of the spectrum

you didn't respond to my comments on the use of RAW files ??
I hope my pic's helped you to show you how to overcome city light skyglow ?

Dave
 
Last edited:
  • #8
Yes thanks for the help. Next time I will get RAW's instead of JPEG's so that if I eventually get photoshop or lightroom I can mess around with them. Are there any free/open source tools that can do the required editing? Also, would image stacking multiple ~2 second exposure shots be worthwhile to try?
 
  • #9
QuantumPion said:
Are there any free/open source tools that can do the required editing?

there is GIMP -- free, I don't know if it has all the features that LR and PS have, but, from what I understand, it has many of them
I don't know if it is easier or harder to use

QuantumPion said:
Also, would image stacking multiple ~2 second exposure shots be worthwhile to try?

yes, that is always good ... it won't stop the sky glow, but will give more detail on the starfield

I have to assume you were shooting those images from a suburban area ... being that the trees were also well lit
find a spot out of your town/city where the ambient light and the sky glow level is low

for image stacking a commonly used and free program is DSS ( Deep Sky Stacker) use DSS only for the stacking
the processing is still done in your other fav editing program. DSS can do processing, but isn't as good as say LR or PSDave
 

Related to What is the best way to reduce overexposure in DSLR astrophotos?

1. What equipment do I need for DSLR astrophotography?

To take high-quality astrophotos with a DSLR camera, you will need a sturdy tripod, a DSLR camera with manual settings, a wide-angle or telephoto lens with a large aperture, a remote shutter release, and a tracking mount for long-exposure shots. You may also want to invest in a light pollution filter and a camera intervalometer for more advanced shots.

2. How do I set up my DSLR camera for astrophotography?

To set up your DSLR camera for astrophotography, first, switch to manual mode and set your ISO to its lowest possible setting. Then, set your aperture to the widest setting and your shutter speed to the desired length for your shot. Use your remote shutter release or intervalometer to avoid camera shake. You may also need to adjust your white balance and focus manually for optimal results.

3. What is the best location for DSLR astrophotography?

The best location for DSLR astrophotography is a dark and clear sky with minimal light pollution. This can include remote areas, national parks, or your own backyard if you live in a dark sky area. Avoid shooting near cities or areas with high levels of light pollution, as it can greatly affect the quality of your photos.

4. How do I edit my DSLR astrophotos?

To edit your DSLR astrophotos, you will need to use specialized software such as Adobe Photoshop or Lightroom. Some important editing techniques for astrophotography include adjusting levels and curves, reducing noise, enhancing colors, and sharpening details. It is important to not overprocess your photos and to maintain the natural beauty of the night sky.

5. What are some common challenges with DSLR astrophotography?

Some common challenges with DSLR astrophotography include camera shake, light pollution, and focusing issues. To avoid camera shake, use a sturdy tripod and a remote shutter release. Light pollution can be minimized by shooting in a dark sky area or using a light pollution filter. Focusing can be tricky in low light, so using manual focus and a live view mode can help ensure sharp images.

Similar threads

B Infrared Detectors & The 2nd Law of Thermodynamics
    • Thermodynamics
5
Replies
152
Views
5K
What Challenges Did I Face in Capturing Images of the Andromeda Galaxy and Mars?
    • Astronomy and Astrophysics
Replies
1
Views
1K
What colors and attributes could alien flora & fauna have?
    • Sci-Fi Writing and World Building
Replies
15
Views
3K

Hot Threads

Recent Insights

Back
Top