My Sony 24mm f/1.4 GM isn't linear (manual) focus and it's supposed to be...

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Ron Sonedecker Junior Member • Posts: 30
My Sony 24mm f/1.4 GM isn't linear (manual) focus and it's supposed to be...

Either I have a bad copy (though there's nothing else I'm experiencing), or Sony is incorrect in labeling the 24mm GM as having linear focus (LR MF) or the implementation is poor.

My copy definitely has focus wander depending on the speed in which you throw the focus ring. During a documentary shoot I was trying to pull focus and couldn't figure out why my A and B points were wandering and after checking the rig to no avail, I decided to test the lens out. Sure enough - two points marked on the lens (for two items about 3 feet apart representing a focus pull between two people having a conversation) and various speed throws (slow, med, fast) between those points resulted in the focus points being lost.

My 35mm G and 20mm G, not an issue. They maintain A-B points accurately regardless of the speed of pull, and they are listed as being linear. They also have linear motors...

Sony says the 24mm GM has the DDSSM motor, but it's the only lens to have that motor and claim to also have linear MF. All the other lenses in Sony's line-up that are linear focus have single (LM) or dual linear motors (including the handful of new lenses (the 50mm GM, 35mm GM, and the new 24, 40, and 50 compact G's). Also, the 70-200 GM and the 70-200 f4 both have linear motors and are linear focus (tested both). I'm not claiming to know that's related, simply noting that coincidence.

Has anyone else been using the 24GM for video and had the same focus pull issues?

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