Sigma Cinema lenses vs GL optics Sigma Cinema Lenses

[Oron Cohen]

The SigmaCINE lens set uses a cam driven focus system that provides virtually the same amount of precise control at 180° as a linear focus system does at 300°. My analogy would be 10bit log vs 16 bit linear color. Yes, the 10bit log throws away some values - but testing shows that it retains 98%+ of the granularity of 16bit linear with a huge reduction in data load.

It's also worth noting that the cammed 180° throw makes pulling on the barrel much easier, especially compared to trying to twist your wrist for a big rack on a 300° throw. Bottom line - there's more to the story than 180 vs 300.

Cheers - #19

You are right that it's not only about the rotation but there is more to it then just cam driven to not, it's also the purpose the lens was build for.

Bare in mind, that they are many lenses that are cam driven and are 250-300 degrees rotation, Sigma indicated that one of the reasons for their lenses to be 180 degrees focus rotation is the fact they are aiming more for the owner-operator market, people that from the get go have no AC around to pull focus, or just shooting more run and gun.
Similar to say the Fujinon 19-90 which also have a short focus rotation.

 

[Peter Strietmann]

Using a smaller wheel on your follow focus gives more accuracy pulling focus.

 

[Blair S. Paulsen]

Using cams to improve focus action is not new, and can certainly be used to further refine longer throws. Just pointing out that the SigmaCINE design offers more precise control than one might expect from a 180° rotation, which makes the numerical comparison to the 300° GL throw misleading. Moreover, both the CINE versions of the Sigma ART primes and the GL Optics rehousings are aimed at motion work - so either one should be much better suited to what we do than a lens designed for shooting stills.

Cheers - #19