| Joined: | Mon Apr 2nd, 2012 |
| Location: | South Lakeland, UK |
| Posts: | 4066 |
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What you are up agains is the rotation of our planet, any exposure of more than 10 seconds with a longer lens like a 300 will result in blur from the movement. the longer the lens, the worse the blur and the shorter the permissible exposure.
There are tables and calculators galore on the internet to allow you to calculate the allowable exposures. To improve things a little use VERY fast lenses like f1.4 but longer lenses don't come that fast and those which do are horrendously expensive.
For wider sky stuff I'm told the Samyang range may be affordable (for some!) but expect to return several lenses before you get a really sharp sample.
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Robert.