[fstop18]

Normally there wouldn't be a problem with a lens out of the box, so how does the Sigma Dock help? I do own an 18-300 Contemporary lens and have found that there seems to be what I call 'dead spots', when the lens seems to freeze up and not focus, & not release the shutter at that point. Sometimes you have to turn the cam off & re-shoot. Other times I try to change zoom & then re-focus. With Pentax branded lens, there never seems to be a problem. I'm not knocking Sigma, but was wondering if their docking unit would help and how would it work. thanks.

[Adam]

It lets you (1) apply AF fine adjustments and (2) upgrade the lens firmware. This is not necessary for Pentax lenses since you can do the adjustments in-camera.

It doesn't sound like the dock would necessarily help with the issues you're having, though it could be as simple as bad connectivity between the camera and lens.

[kypfer]

I very occasionally have experienced "failed to focus" scenarios with my 150-500mm Sigma at maximum length on my K70 and I've been tempted to blame the small maximum aperture of f/6.3, as it's just outside the minimum recommended aperture for the autofocus system in the camera. My Tamron 18-200mm, also with an f/6.3 maximum aperture at 200mm can display similar symptoms, whereas my FA 100-300mm and my Tamron 90-300mm, both f/5.6, are more reliable in this respect. Note at this point the "problem" has only occurred in reasonably poor light on relatively low contrast subjects.


Yes I know that looks like overkill, with all those lenses at similar focal lengths, but the f/5.6 lenses were VERY cheap (single-figure prices) so I bought them "just to try" ... someone's got to do it

[Paul the Sunman]

No firmware update is available for that lens in K-mount. The dock is useless.

[zapp]

No firmware update is available for that lens in K-mount. The dock is useless.

Correct. And any lens should basically function and not require an Tyra piece to make it work. The dock has functionality for a very small number of K mount lenses from Pentax. You can fine tune the art 35 for instance. I got frustrated by it very fast. Pentax cameras deserve Pentax lenses.

[aslyfox]

here is the review

no recommendations

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Sigma USB Dock
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Sigma USB Dock
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Description:
The Sigma USB dock allows owners of Sigma Global Vision (Contemporary, Art, and Sports) lenses to install firmware updates and make fine AF adjustments at various focal lengths.

A different version of this dock is available for each supported mount (i.e. Canon, Nikon, Pentax, Sigma, and Sony).

The US retail price is just $59.00.

Read more at: Sigma USB Dock reviews - Pentax Camera Accessory Review Database

[Kozlok]

I recently acquired the 18-35, and the dock does a nice job of allowing that lens to be micro adjusted at various focal lengths. The focus system on that lens is still whacky, but when it hits focus now, it hits perfectly.

[UncleVanya]

I recently acquired the 18-35, and the dock does a nice job of allowing that lens to be micro adjusted at various focal lengths. The focus system on that lens is still whacky, but when it hits focus now, it hits perfectly.

Others tried that and find inconsistent results. Glad yours works well.

As for the dock, cross platform support via camera bodies for firmware update seems very hard to imagine. Panasonic and Olympus do have some cross body firmware update but they are in a consortium that has interoperability at the core. The dock is a reasonable way to offer updates when such collaboration isn't in place.

[Digitalis]

The focus system on that lens is still whacky

To this day even I cannot fathom exactly what went wrong with the AF on that* lens. I have numerous examples of perfectly focusing sigma lenses at my disposal, in multiple camera mounts with different AF motor technologies...this lens stands alone regarding its mystifying AF errors.


*Referring to the sigma 18-35mm f/1.8 ART

[Kozlok]

And it’s not just ours that are poor focusing. It seems to affect all versions of this lens.