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Sigma Cine lens coverage on Alexa Mini OG


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#1 Sean Emer

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Posted 21 September 2017 - 08:25 PM

Has anyone tried the Sigma Cine zoom lenses (not the primes) on the Alexa Mini when shooting open gate? Would like to know if it vignettes, and if so how badly. Haven't been able to find anything definitive online, and I won't be able to test in a rental shop for a week or two.


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#2 Dom Jaeger

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Posted 22 September 2017 - 12:50 AM

I don't have access to those zooms to check, but according to the lens specs provided by Sigma the coverage is only 28.4mm, well under the 33.5mm circle needed to cover Alexa Open Gate.

However sometimes manufacturers are conservative in their specs. It's possible that the lenses create a larger image circle, but the image degrades a bit outside the specification.

This review:
https://www.cinema5d...ma-lens-review/
tested both zooms on a Red Epic Dragon and found no vignetting on the 50-100, while the 18-35 only began to vignette at 18mm in 6K, which would put its image circle at around 32 or 33mm.

So if you were cropping Open Gate to 1.85 or 1.78 you may be OK.
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#3 Sean Emer

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Posted 22 September 2017 - 09:42 AM

That's about as far as I've gotten as well haha. I gaff'd a feature earlier this year that was running these zooms on a helium @ 7k with no noticeable vignetting, and it looked fantastic. The posted numbers just make me very skiddish despite my anecdotal experience. Thank you for the reply and the link to the other test!
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