Artifacts on low light, 10 sec exposure

[Junvega]

This is a crop from a night image that I was playing with it. Lens is the Sony FE 24mm f/1.4 GM. shot at ISO 2000  f1.4  10.0sec exposure.  I seen these artifacts (squares) on another couple of long exposure shots. can someone tell me what they are, should i be concerned. how too correct? maybe sensor getting hot?   buy the way those are fireflies.

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[Chrissie]

My wild guess: this could be the compounding effect of Sony's raw compression, using bulb mode (see this for more detail), image processing and possibly another lossy transcoding into jpeg output. Also read the article on Digital Generation Loss for further reference.

On an unrelated note: I would have expected those fireflies to have left longer streaks during a 10-second exposure.

[Junvega]

Thanks for your informative answer, I'll take that in consideration. Information is king. The fireflies have a 5-6 light pulse when trying to find a mate. these are the synchronous fireflies, they are in this concentration for 2 weeks out of the year and their flight slows down when there sync.   they pulse for 5 seconds and stop for 5 by my observation. Again thanks for your answer.

[Chrissie]

1 hour ago, Junvega said:

Again thanks for your answer.

You're very welcome. Thanks for returning my favour, with respect to fireflies. Those are definitely not my core competency, and it was a pleasure to learn something entirely new about them. Never heard of the specific kind of "synchronous" fireflies before. Amazing!