[AtitG]

Hi, I am very interested in the new sigma 30mm 1.4 art but I'm worried about its AF issues. I would like to ask those who bought it, how much it limited its use with adequate lighting, and in low light conditions, where AF might actually get more difficult. Thanks in advance.

[chrisfer]

I have bought this Sigma 30mm Art, I have no AF problem, even at short distance and/or low light, no FF/BF, quick and accurate ; with K-5 II.

[THoog]

I have one, and on a K-5II or K-30, and in 5-point or 11-point autoselect AF mode, it sometimes hunts excessively and/or gives up. It never does this when the AF mode is Spot (center-point only) or Select. I prefer center-point focusing anyhow, so for me, it's a non-issue.

PS: The K-01 has a completely different focusing system, so it does not have problems there, either.

[AtitG]

Thank you very much for the prompt replies.

[cyberjunkie]

I thought writing the words "bad" and "Sigma Art" in the same sentence was considered a major blasphemy, punished with public Internet pillory! :-)
Being serious, despite my preference for Pentax A* primes (not enough characters left in my signature for all my P-K and M42 lenses, but all my A* are there, and proudly so..), i think that Sigma "Art" lenses are the cream of the crop, at least for our Pentax digital cameras!
In the reviews i have seen they score amazing numbers. Even in reviews which show a certain bias toward "original" glasses...
I tried my best to win a 30mm f/1.4 one, but it got sold for nearly 100 euros more than my max bid :-(
I think there are people who are prepared to pay a 2nd hand item nearly as much as a new one, as it's increasingly difficult to find them new, in Pentax mount.
If you found one for a decent price, better you buy it. I guess the prices will get higher in the near future.

At least i could purchase a Sigma 50mm f/1.4 AF, which looked very good in picture, and sold for a very interesting price (215 euros + shipment & import taxes). It's not a real "Art" lens, but it should be more or less in the same league. I'm looking forward for the moment i'll be back home, and i'll be free to test it ad lib :-)
The 30mm should be more useful, cause the alternatives are limited. Very good 35mm wide angle primes are not as good with digital.
On the other hand, F and FA 50mm primes are available on the second hand market, and are still a good choice for a f/1.4 portrait lens, with APS-C sensors.

I guess that FF or BF issues with Sigma AF lenses are way overrated.
There was a lot of complaining on the Internet, time ago, but i think that:
1) it's becoming less and less of a problem, with recently built lenses
2) even before, the majority of customers didn't have any reason to complain, it was the few who had problems who got all the attention
3) if you buy a new lens, there are good chances that Sigma will be able to fix the problem under warranty, if you find focusing problems in your sample

For all those who think that Pentax is pure gold, and all the rest is cow dung:
if your Sigma Art 30mm neither back-focuses nor front-focuses, but you find it unworthy, i will help you get rid of it, and will even pay you 250 euros, to help you sedate the remorse for such a wrong purchase :-)

cheers

P

[THoog]

The issue with the Art 30 is not back focus or front focus. It's sloooooow focus and/or failure to focus. Take a look at the PF review:

Sigma 30mm F1.4 DC HSM "Art" - Autofocus - Pentax Camera Forums

Contrary to what it says in the PF review, I have seen online discussions of similar problems with Canon and Nikon versions of the Art 30. I couldn't replicate the problem with a K-r in 11-point AF; it seems to be some combination of the lens and the AF system in the body.

[cyberjunkie]

Yes!
You're right of course. I forgot about that problem.
It must electronic incompatibility.
Hopefully Sigma will release an updated firmware, so the customers who are experiencing problems will be able to use their lenses in AF! :-)

From what i understand 11-points AF systems, like in my K-5 II, should not be affected. Isn't it?

ciao

P

[THoog]

It must electronic incompatibility.
Hopefully Sigma will release an updated firmware, so the customers who are experiencing problems will be able to use their lenses in AF! :-)

I'm not sure if it is electronic or optical. The Sigma Art 35 does not have the problem. The camera acts as if it can't find an AF point that is good enough. One Canon shooter suggested it had something to do with size of AF points. On my K-5 II and K-30, AF works fine in Spot or Select modes.

From what i understand 11-points AF systems, like in my K-5 II, should not be affected. Isn't it?

The K-3, K-5IIs, K-5II, K-50, and K-30 are affected.

[cyberjunkie]

I know nothing about modern AF cameras, even the LX has a few subtleties which i can't really master... but the more i think about it, the more i can't find a logical reason to believe that such a problem could be due to an optical reason.
The only non-electronic fault that comes to my mind could be related to inter-reflections which fool the AF system. In this case it would be more a mechanical problem (a fault in the project of the barrel), than optical.
I may be wrong, of course.
What i know is that the communication between lenses and camera bodies is getting more and more complex.

I guess that the camera which is less likely to have this kind of problems is the K-01.
Am i wrong again?

cheers

P

[phs]

This is an old thread. Just wondering if autofocus issue had been fixed? Ready to click the buy button on a new Sigma 30. Thanks.

[THoog]

This is an old thread. Just wondering if autofocus issue had been fixed? Ready to click the buy button on a new Sigma 30. Thanks.

I have not heard of a fix (or that Sigma admitted there was a problem). A quick search for "Sigma Art 30 focus" yields a lot of threads on different sites. While most are front focus/back focus issues, I found quite a few Canikon users that have similar slow focus/no focus issues on the Art 30. Center point and LiveView focusing work correctly for them, same as what we have seen on Pentax bodies. Even those that have sent it in for service say the problem persists. If you need 5- or 11-point AF or shoot a lot of fast-moving objects, it's probably not a good bet.

[AtitG]

i have bought the lens since i started this thread. I think the af in real world is as accurate as my other lenses (compared to da 18-135, da 35, da 50). its a so much quieter compared to the screw driven lenses. As added bonus, if you crop the image to 4/3 format, this will cover FF (used it on my film camera).

[MadMathMind]

I thought writing the words "bad" and "Sigma Art" in the same sentence was considered a major blasphemy, punished with public Internet pillory! :-)

I thought it was normal. The focus issues are legendary.

[cyberjunkie]

I know nothing about the Art version, but i own the non-Art. Never had focusing problems with the K-5 II.
It's a very, very peculiar lens. I loved it for street photography at night.
Unfortunately the front lens had a quite serious blemish that made it flare badly when strong light sources were within the frame.
I had it repaired (replaced front glass and updated software), i will try it soon in crop mode with my new K-1.
As far as i understand, the AF performance of Sigma lenses is affected in a major way by the software release.
Unfortunately there are no public informations about software releases for each model, and no way to assess the release by the user (unless you own one of the few lenses that can be used with the Sigma base/programmer, i think).
Some people suggest that the free replacement of the bayonet for certain models is mainly related to the need to update the software to the latest release (compatible with the K-1), than the rather silly micro scratch...
What i know for sure - being told that by the head of the italian repair laboratory - is that ANY lens they get their hands on is updated to the latest software version.
I am not saying the problems of some 30mm Art can be solved with an update, just reporting what i know

cheers

Paolo