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Author Topic: sigma dock autofocus adjustment  (Read 1240 times)

candc

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sigma dock autofocus adjustment
« on: October 30, 2013, 10:10:50 PM »
i have the sigma dock and have had to use it on both the 120-300 and 18-35 which were grossly off. after doing focus adjustments on the lenses i have found that they work the same on the 2 70d's and the 40d which i have tried them on. that tells me the problem is with the lens itself and not the camera/lens pairing and also why afma with the camera doesn't work very well with the new sigma lenses, ae frontfocusing close and backfocusing at infinity and everything else in between. i am a big fan of what sigma is doing with the new products but i think this inexcusable and i will also write them and tell them so.
« Last Edit: October 30, 2013, 10:13:34 PM by candc »

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sigma dock autofocus adjustment
« on: October 30, 2013, 10:10:50 PM »

Mt Spokane Photography

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Re: sigma dock autofocus adjustment
« Reply #1 on: October 30, 2013, 11:43:01 PM »
Sigma lenses almost invariably have AF issues, its a near impossible situation for them, which is why the dock is a necessary thing.
 
Consider that a Canon camera does not recognize a Sigma lens, so Sigma must tell the camera that it is actually a Canon lens.  This is the source of a lot of the trouble, since the camera actually adjusts its operation based on which lens is installed.
 
Be thankful that you are able to adjust the lens to work well with a dock.  The lens will probably work differently with a FF body.
 
The 70D with its live view s3nsor based phase detect eliminates all the front / rear focus hassle, and is a good thing for wide aperture lenses, it gives sharp focus at any distance, and it is consistent, which is a issue for all cameras up to now.

arize84

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Re: sigma dock autofocus adjustment
« Reply #2 on: November 01, 2013, 07:12:07 PM »
i have the sigma dock and have had to use it on both the 120-300 and 18-35 which were grossly off. after doing focus adjustments on the lenses i have found that they work the same on the 2 70d's and the 40d which i have tried them on. that tells me the problem is with the lens itself and not the camera/lens pairing and also why afma with the camera doesn't work very well with the new sigma lenses, ae frontfocusing close and backfocusing at infinity and everything else in between. i am a big fan of what sigma is doing with the new products but i think this inexcusable and i will also write them and tell them so.

I assume you are saying that the dock fixed your AF issues?? I'm contemplating getting one....

candc

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Re: sigma dock autofocus adjustment
« Reply #3 on: November 01, 2013, 08:28:20 PM »
yes it did, the dock does exactly what it claims, you just have to be prepared to do a full on 4 focal range, 4 distance settings calibration to get the lens to work spot on. the infinity focus seems to be the hardest to get right. maybe you will get lucky and just have to make a minor adjustment at a particular range and setting or no adjustment at all, i was not so lucky.

AcutancePhotography

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Re: sigma dock autofocus adjustment
« Reply #4 on: November 04, 2013, 02:13:54 PM »
I am eagerly waiting for more Sigma lenses to come out that are dock-compatable.  I think it is a good idea and one that the other manufacturers will probably be copying soon.
I shoot with a Camera Obscura with an optical device attached that refracts and transmits light

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Re: sigma dock autofocus adjustment
« Reply #4 on: November 04, 2013, 02:13:54 PM »