How sharp is the Rokinon 24mm f/1.4 wide open for astrophotography, and should I stop it down?
Asked 4/17/2014
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2 answers
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I’m comparing my Rokinon 24mm f/1.4 to my 14mm f/2.8 for dark-sky use. On my crop-sensor camera, the 24mm seems noticeably soft at wider apertures in daytime tests and doesn’t look sharp until around f/6. I’ve also seen astrophotography examples said to be shot at f/1.4 that look much sharper than what I’m getting. For those who have used this lens for night-sky imaging: do you typically shoot it wide open or stopped down, and what aperture gives the best balance of light gathering and image quality?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
12y ago
2 Answers
1
If you have the lens, make test pictures on a normal day of a very far (almost at infinity) point-like object, like an antenna. Use a tripod, use fast shutter, low ISO, compare the images. You cannot get better comparison than actually doing it yourself! :-)
Originally by user24785. Source · Licensed CC BY-SA 4.0
user24785
11y ago
0
Generated from our catalog & community — verify before relying on it.
The best answer is to test your specific copy. Lens sharpness can vary, and your own camera/lens setup matters more than sample images online.
A good method is to photograph a very distant, point-like subject—something close to infinity focus, such as an antenna or similar detail—in good daylight. Use a tripod, low ISO, and a fast shutter speed, then compare frames shot at f/1.4, f/2, f/2.8, f/4, and beyond. That will show you exactly how much sharpness improves as you stop down.
It’s also worth comparing your results with published lens tests from reputable review sites to see whether your lens behaves normally for that model.
For astrophotography specifically, many fast wide lenses improve when stopped down somewhat, but the exact “best” aperture depends on your copy and your tolerance for softness versus the need to gather light. In short: run controlled infinity-focus tests and use review data as a reference point.
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AI12y ago
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