Sigma 30mm F1.4 Art slow focus in liveview.

[casperl]

Hello All:

I have been enjoying my Sigma 30mm f1.4 Art on my 70D for about half a year now. It produces wonderful photos and focus really fast through my viewfinder. However it focus super slow in the liveview. Lot of time it seems to hesitate/stuck for like 2~3 seconds before it even start to focus. I just got the USB dock and updated the firmware but it behaves the same. I researched online a bit and found some people mentioning just use continuous autofocus then shoot without trying to AF, but that sounds like a walkaround then an actual fix...

Just want to see if anybody is experiencing the same issue? Is this a common problem or I got the bad copy.I just got in touch with Gentec (Sigma's service partner in Canada) and they mentioned there might be an issue with the HSM motor, but I am not sure if they misunderstood my issue as the AF didn't work through viewfinder neither.

Thanks for the response in advance.

 

[drjlo]

My last Sigma lens experience ended due to live view AF problems as well. It focused well via viewfinder, but live view AF was super slow, and even after green square came on in live view, it was not in actual focus. Sent it to Sigma service who could not even begin to fix it.

It seems it is even more difficult to achieve good live view function for third-party lens menufacturers.

 

[Mt Spokane Photography]

Third party lenses seem to struggle in live view as a general rule, its often mentioned in reviews.

The exception is in dual pixel cameras where live autofocus is not contrast detect.

Canon contrast detection as used in live view for standard sensors requires that the focus group move back and forth rapidly while the output is analyzed to determine the sharpest auto focus. I'm guessing that the back and forth focus is slower and that slows down live AF. Another requirement is that aberrations must not interfere with the analysis software while the focus group is moving, perhaps another factor.

If I were using third party lenses on a crop camera in live view, I'd get a 70D or a 7D.

There are no dual pixel sensors for FF as of yet, so you have to suffer.

 

[casperl]

I guess it is just not gonna work well in Liveview then. A bit of a shame since it is such a nice lens, but I guess I can always compose with LCD then switch to viewfinder to take the shot for those weird angles.

And I am already using a 70D.

 

[rado98]

I use the same lens on a 7d and 600d. I have never noticed it being slower than any of my other lenses on live view. It certainly doesn't wait before starting to af.
Maybe Canon booby trapped the dual pixel af, its a shame if that is always the case.

 

[casperl]

After talking with Gentech (Sigma's Canadian Partner) about the slow liveview AF. They said it might be something to do with the HSM and asked me to mail my lens in, so I sent my lens to them and got it back in less than two weeks. I didn't have to pay anything other than the postage for sending it out. In the service record they did something like "W3 autofocus point reprogram", but it did absolutely nothing to the lens' performance lol. Liveview autofocus is still slow as before. Oh well I guess it was worth a try.

 

[casperl]

Just received my M2 two days ago, and my Sigma 30mm is focusing perfectly fine on it. So I guess it is indeed DPAF affecting its performance on the 70D.