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03-04-2016, 12:19 PM   #1
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Focus (LiveView)-Problems with Sigma 70-300 mm F4,0-5,6 DG APO on Pentax K30

Hi guys,

I use a Pentax K30 for 3 years now, and I just found something out now.

When I use my Sigma lens and focus normally through the viewfinder, the focus is good without problems.

But if I do it in Live view, the focus is always false, it looks like it searches for the right focus, finds it but then goes "too short" , a so called front focus I think.. How is this possible and what do you think I can do ?

03-04-2016, 12:29 PM - 1 Like   #2
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QuoteOriginally posted by LucaBumble Quote
Hi guys,

I use a Pentax K30 for 3 years now, and I just found something out now.

When I use my Sigma lens and focus normally through the viewfinder, the focus is good without problems.

But if I do it in Live view, the focus is always false, it looks like it searches for the right focus, finds it but then goes "too short" , a so called front focus I think.. How is this possible and what do you think I can do ?
Front focus doesn't apply to live view. However, lenses with a long focusing throw such as the 70-300mm tend to have sub-optimal live view focusing performance just because of the throw.

There are a few strategies you can employ to increase CDAF reliability. First of all, always opt for multi-point mode rather than spot mode with long lenses. Also, ensure that there is plenty of contrast in the scene, or that you're pointing the lens at something with distinguishable features. If you can manually keep the lens close to correct focus setting, that would also save you some time.

You might get better live view AF performance with the K-3 or K-S2, as those cameras (and newer bodies) have a more powerful focusing motor (up to 50% faster) and updated live view algorithms.

Adam
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03-04-2016, 12:47 PM   #3
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Alright thank you a lot Adam for that quick and enlightening answer
03-04-2016, 02:08 PM   #4
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When I got my Sigma 50-150mm f/2.8 it required a firmware update to focus in live view.

03-04-2016, 06:14 PM   #5
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Edgar is right some of the non DC Sigma's need a firmware update for CDAF to work properly.
03-05-2016, 10:01 AM   #6
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Oh, okay and how do I know if this is the case ? and is this done for free if in warranty- time ?
03-07-2016, 06:32 AM   #7
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I have the same problem with my Sigma 50-500 (pre-HSM) lens.
Will these lenses ever work with Live View?
03-07-2016, 08:50 AM   #8
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QuoteOriginally posted by LucaBumble Quote
Oh, okay and how do I know if this is the case ? and is this done for free if in warranty- time ?
Contact Sigma and ask them. Their customer service has been very responsive and helpful anytime I've contacted them, and I've heard the same from many others. Please don't forget to report back here if you get any information that might help others!

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