> STACKED IMAGE VS. LONG EXPOSURE

  • Posted on: 14 February 2019
  • By: tihomiry

Witch is better. Stack or long exposure? It depends…
Long exposure will reveal more details but stack will improve the contrast and faint details by decreasing the background noise. It also decrees the atmosphere turbulence winch as the noise has a random distribution (of course this is more obvious for short exposures)
Long exposure is also hard to shoot as you need guider setup. Also at my place there is a lot of wind, so this is a hard thing to do. Best is to estimate the limited exposure of the sky background and do a stack with that exposure. To estimate it look at the histogram the peak should be 1/3 away from the left.

Below is a comparison of Galaxy M33 between long shot – 80 seconds at ISO 51200 and stack of 20 frames by 30 sec. at ISO 12800.
The single frame is easier to process but stacked frame give us more signal to noise ratio. We can always add more and more signal by taking extra frames. You can use higher ISO and reduce the noise that way.

SKY is the limit :)

One shot:

Stack:

When we have a new newton telescope we shroud avoid touch the collimation of the secondary mirror as we may get into troubles.

You no more need large sensors and heavy equipment to do good general photos. The recent development of image sensors put silicon chip capabilities to it's limit by

Knowing what you are looking for is more then half way to achieving it. Breakthrough Listen is a SETI kind of project that listen for artificial signals from 1700 nearby stars up to 160 light years.

Some shots from Sofia. A very bright sky place. Zenith sky brightness info (2015): SQM 19.13 mag./arc sec2 Brightness 2.41 mcd/m2, Artif. bright. 2230 μcd/m2, Bortle class 6.

Pages