Read on Twitter
1/n
How ISO can affect your astro photos: a thread and discussion using images and real data...GO!
Starting with these two #MilkyWay photos, ISO 12800 and 800, identically processed (minimally), with an exposure increase of 4 stops for ISO 800, to match.
#Astrophtography
How ISO can affect your astro photos: a thread and discussion using images and real data...GO!
Starting with these two #MilkyWay photos, ISO 12800 and 800, identically processed (minimally), with an exposure increase of 4 stops for ISO 800, to match.
#Astrophtography
1.1/n
I made an animated GIF to show both photos in succession. The ISO 800 (exposure +4 stops) and the ISO 12800 photo.
They both still look pretty good, right? Hmmm...
Download the full-res animation here:
https://drive.google.com/open?id=1aJzrzttH4G9G1aCDxFW_qC7UeNBeKg0T
I made an animated GIF to show both photos in succession. The ISO 800 (exposure +4 stops) and the ISO 12800 photo.
They both still look pretty good, right? Hmmm...
Download the full-res animation here:
https://drive.google.com/open?id=1aJzrzttH4G9G1aCDxFW_qC7UeNBeKg0T
2/n
Both photos were shot within a few minutes of each other. The sky conditions and camera settings for each photo are identical, except for the difference in ISO.
(I did this to test my camera, to see how ISO invariant the sensor might be...another discussion!)
moving on...
Both photos were shot within a few minutes of each other. The sky conditions and camera settings for each photo are identical, except for the difference in ISO.
(I did this to test my camera, to see how ISO invariant the sensor might be...another discussion!)
moving on...
3/n
In a previous thread, I was asked what the ISO 800 image looked like in-camera. (dark!)
So, I have attached it here, as well as the exposure boost of +4 stops (which made it match the ISO 12800 photo).
These are the same photo!
In a previous thread, I was asked what the ISO 800 image looked like in-camera. (dark!)
So, I have attached it here, as well as the exposure boost of +4 stops (which made it match the ISO 12800 photo).
These are the same photo!
3.1/n
I even made a GIF of this! Yay for GIFs.
The only thing different between the two is that +4 stop boost in exposure.
The. Data. Is. There.
Grab the full-res GIF here:
https://drive.google.com/open?id=1aHpUORFQRry-iWtwCo8sLdaTHX5zv33L
I even made a GIF of this! Yay for GIFs.
The only thing different between the two is that +4 stop boost in exposure.
The. Data. Is. There.
Grab the full-res GIF here:
https://drive.google.com/open?id=1aHpUORFQRry-iWtwCo8sLdaTHX5zv33L
4/n
Going back to the photos in the first tweet, the ISO 12800 and the ISO 800 photo (with exposure +4 stops).
They both look ok. Good enough. Or are they.
Yeah, the color cast is definitely different, but who cares, it looks good in both, right?
There's a problem...
Going back to the photos in the first tweet, the ISO 12800 and the ISO 800 photo (with exposure +4 stops).
They both look ok. Good enough. Or are they.
Yeah, the color cast is definitely different, but who cares, it looks good in both, right?
There's a problem...
5/n
The color cast in the ISO12800 image is...not REAL. The color noise is electrically introduced by the camera sensor, due to various reasons (heat/electrical/etc.).
If you don't care if your images are real or not, ok, just make sure you know.
Now, for the real difference...
The color cast in the ISO12800 image is...not REAL. The color noise is electrically introduced by the camera sensor, due to various reasons (heat/electrical/etc.).
If you don't care if your images are real or not, ok, just make sure you know.
Now, for the real difference...
6/n
When you zoom in (a lot), you can *really* see how gross the ISO12800 image is. Ew.
Both of these photos have the same amount of noise reduction applied.
Just look at the ISO 12800 photo...BLEGH.
When you zoom in (a lot), you can *really* see how gross the ISO12800 image is. Ew.
Both of these photos have the same amount of noise reduction applied.
Just look at the ISO 12800 photo...BLEGH.
7/n
Even in this animated GIF, you can see the nasty color cast, noise, loss of detail, etc. It's just gross.
And...it's not real. That crap in the ISO 12800 photo is noise, fake data, introduced by the camera-sensor.
Download the full res GIF here:
https://drive.google.com/open?id=1aMEMEgzY4jOPDquwL1ycXJOssrnGzAuT
Even in this animated GIF, you can see the nasty color cast, noise, loss of detail, etc. It's just gross.
And...it's not real. That crap in the ISO 12800 photo is noise, fake data, introduced by the camera-sensor.
Download the full res GIF here:
https://drive.google.com/open?id=1aMEMEgzY4jOPDquwL1ycXJOssrnGzAuT
8/n
Now, if you're only shooting for social media, people aren't going to see that high-ISO noise anyway...or will they? Probably not...but, in your heart you know it's there.
But, notice how the overall color cast changes between the photos. It's noticeable at any resolution.
Now, if you're only shooting for social media, people aren't going to see that high-ISO noise anyway...or will they? Probably not...but, in your heart you know it's there.
But, notice how the overall color cast changes between the photos. It's noticeable at any resolution.
9/n
For even more fun, I did identical photo tests from ISO800 all the way up to ISO12800.
Here are the first three, ISO800, 1600, and 3200. With post-exposure boosts to match ISO12800. Honestly, I am pretty happy with ISO1600 on my camera. Even 3200, probably.
For even more fun, I did identical photo tests from ISO800 all the way up to ISO12800.
Here are the first three, ISO800, 1600, and 3200. With post-exposure boosts to match ISO12800. Honestly, I am pretty happy with ISO1600 on my camera. Even 3200, probably.
10/n
...And here are the photos at ISO 3200, 6400, and 12800. This is when stuff starts getting nasty.
...And here are the photos at ISO 3200, 6400, and 12800. This is when stuff starts getting nasty.
11/n
A lot of things can affect this noise, like your camera and sensor make/model, ambient temperature, camera sensor temperature, exposure length, etc.
The colder the sensor, the better, in general, it can keep the noise away. That's why dedicated astro cameras are cooled.
A lot of things can affect this noise, like your camera and sensor make/model, ambient temperature, camera sensor temperature, exposure length, etc.
The colder the sensor, the better, in general, it can keep the noise away. That's why dedicated astro cameras are cooled.
12/n
Yes, stacking/averaging multiple photos to *REDUCE* the data down to only the real photons that were collected works nicely.
However, at very high ISO, small detail and dynamic range is lost, and some of that CANNOT be recovered no matter how many images you stack. Beware!
Yes, stacking/averaging multiple photos to *REDUCE* the data down to only the real photons that were collected works nicely.
However, at very high ISO, small detail and dynamic range is lost, and some of that CANNOT be recovered no matter how many images you stack. Beware!
13/n
Twelve+ tweets in...I hope that helps to explain ISO, #astrophotography, and your camera.
RECAP:
Low ISO is generally better
Cold temps are generally better
Every camera is different
Stacking helps
Whether this matters to you is up to you...but, reality matters.
K, bye!
Twelve+ tweets in...I hope that helps to explain ISO, #astrophotography, and your camera.
RECAP:
Low ISO is generally better
Cold temps are generally better
Every camera is different
Stacking helps
Whether this matters to you is up to you...but, reality matters.
K, bye!
