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Josh are you using a cable release and mirror lockup?
If not then camera shake may contribute to your star trails.
Also my advice is to stick with "in cam n/r" with your short exposures until you're ready to start tracking, then think about Darks/Flats.
If you take a 25 sec shot then it will need another 25 sec for the in cam N/R.
There's a limit to how short an exposure you can go to avoid trails no matter how many lights you take, for example 5 sec @ ISO 1600.
The sensor just doesn't have enough time to record enough signal to overcome sensor noise.
So there's many factors that come into play, but without tracking you're limited and at the mercy of these factors.
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