Beginner Could be a daft question.
- Thread starter sureshot
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- Tim
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For Astro you would do better with a lens that opens up wider than f4. f4 will still work just need longer exposure time to collect enough light....and that may result in star trails rather than pin points. If that is ok depends on what image you want.
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- Jan
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If you're using a tracking mount it's not a problem - you'll just need a longer exposure than you would with a faster lens to collect the same amount of light. I use a Sigma 150-600 on a driven equatorial mount, and that's rather smaller than f4 when it's wide open. I use f2.8 for wide field stuff, but that's because I happen to have the Tamron 17-50 f2.8.
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- Jan
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That depends on what you want to do with it, now and in the future. Don't you already have a scope you want to replace with one you can use for photography? I have a Skywatcher 3-2, which is fine for the camera and Sigma lens, and which I can use from the garden. I don't and never will have a scope for imaging, so my mount is good for what I want it for. You need to think about the total weight you might want to put on it, how portable or otherwise you need it to be, and budget of course. The Skywatchers are good value for money.
