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  Previous versions of myron lee's message #11700199 « DxOMark reviews Sigma 18-35mm f/1.8 DC HSM Lens »

  

myron lee
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Re: DxOMark reviews Sigma 18-35mm f/1.8 DC HSM Lens


cputeq wrote:
^ Your math and/or logic is off. f/2.8 is ~1.2-1.3 stops off from f/1.8, not 2.5 stops.


Maybe you meant it lets in about 2.5 times more light?



Technically i mean t-stop. Which is the effective f-stop after factoring light loss due to transmission thru the lens. The 24-70 loses 1.2 stops more light than the sigma. Which means the effective f-stop of the sigma is 2.5 stops of light more than canon 24-70.

If I am shooting the sigma at f1.8 , 1/30 , iso 1600 then to get the same exposure with the canon 24-70, I may shoot f.2.8 , 1/30 , iso 9000.
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Nit picking aside, looks like a badass lens. If I shot a crop DSLR, I'd definitely be rocking it. Alas, I'm FF and XE1, so no Siggy for me.




Jul 24, 2013 at 06:20 AM
myron lee
Online
Upload & Sell: Off
Re: DxOMark reviews Sigma 18-35mm f/1.8 DC HSM Lens


cputeq wrote:
^ Your math and/or logic is off. f/2.8 is ~1.2-1.3 stops off from f/1.8, not 2.5 stops.


Maybe you meant it lets in about 2.5 times more light?



Technically i mean t-stop. Which is the effective f-stop after factoring light loss due to transmission thru the lens. The 24-70 loses 1.2 stops more light than the sigma. Which means the effective f-stop of the sigma is 2.5 stops of light more than canon 24-70.


----------

Nit picking aside, looks like a badass lens. If I shot a crop DSLR, I'd definitely be rocking it. Alas, I'm FF and XE1, so no Siggy for me.




Jul 24, 2013 at 06:12 AM



  Previous versions of myron lee's message #11700199 « DxOMark reviews Sigma 18-35mm f/1.8 DC HSM Lens »