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07-12-2018, 06:36 AM   #1
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Sigma 30mm f/1.4 ART - Autofocus Adjustment

Hello there,

I own a K-70 and one of my primary every day lens is my Sigma 30mm. I love the pictures I get with it and for the most part, it's a reliable performer. Though, my copy seems to have an issue with back focusing from time to time. It's not a deal breaker for me and I don't mind using manual focusing to help the lens out at times. However, I recently read about being able to make Autofocus Adjustments within your camera body. I'm new to this, so I'm wondering how much of an adjustment I should make. Does anyone have experience with this and this lens particularly? Any advice would be helpful. Thanks in advance!

07-12-2018, 07:36 AM - 1 Like   #2
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Fixing Front and Back Focus - The Remedy - In-Depth Articles

https://pentaxforums.com/search/?q=af+micro+adjustment&cx=partner-pub-889419...D%3A9&ie=UTF-8
07-12-2018, 07:37 AM - 2 Likes   #3
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The AF adjustments only work if the lens always focuses a bit off - so if the lens focuses right more often than not, then if you adjust the focus it will always default to the new setting and be off more often than not.
The Sigma 30 1.4 Art is known to have some issues with autofocus on all bodies (as do some other Sigma lenses), not just Pentax. With mine on the K-S1, I only use center point so 90+% of the time it focuses correctly and if I can see in the viewfinder that it is front or back focusing, I just hit the AF button once or twice again to make it find the right focus. I don't remember ever having to focus it manually, unless of course I use it on my old K10D, where AF fails 100% of the time and I only use it with manual focus.
I did have to set the AF on +1 on my Pentax, so you might play with the settings following the link that jlstrawman provided to see if you can improve it a bit.
07-12-2018, 07:42 AM   #4
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QuoteOriginally posted by ChristianRock Quote
The AF adjustments only work if the lens always focuses a bit off - so if the lens focuses right more often than not, then if you adjust the focus it will always default to the new setting and be off more often than not.
The Sigma 30 1.4 Art is known to have some issues with autofocus on all bodies (as do some other Sigma lenses), not just Pentax. With mine on the K-S1, I only use center point so 90+% of the time it focuses correctly and if I can see in the viewfinder that it is front or back focusing, I just hit the AF button once or twice again to make it find the right focus. I don't remember ever having to focus it manually, unless of course I use it on my old K10D, where AF fails 100% of the time and I only use it with manual focus.
I did have to set the AF on +1 on my Pentax, so you might play with the settings following the link that jlstrawman provided to see if you can improve it a bit.
That is some good food for thought, thank you. And yeah, most of the time this Sigma hits its mark but every now and then, it back focuses. This is more apparent in low light situations than day time.

I'll check out that link that was provided above and try some minor tweaks to see if anything improves. If not, no worries. I chose to buy this lens so I'll do my best to play around its shortcomings.

07-12-2018, 07:49 AM - 1 Like   #5
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QuoteOriginally posted by 24thNomad Quote
That is some good food for thought, thank you. And yeah, most of the time this Sigma hits its mark but every now and then, it back focuses. This is more apparent in low light situations than day time.

I'll check out that link that was provided above and try some minor tweaks to see if anything improves. If not, no worries. I chose to buy this lens so I'll do my best to play around its shortcomings.
It does sound like minimal or no adjustment is needed.
I agree that it is in low light and/or low contrast situations that the lens has a bit more trouble. The good thing is that the manual focus ring on the lens is a pleasure to use, and the even better thing is the results that the lens gets. It is a great lens even at f/1.4, but set it at f/1.8 and it's just phenomenal. This lens is one of the best things that happened to APS-C systems.
07-12-2018, 07:58 AM   #6
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QuoteOriginally posted by ChristianRock Quote
It does sound like minimal or no adjustment is needed.
I agree that it is in low light and/or low contrast situations that the lens has a bit more trouble. The good thing is that the manual focus ring on the lens is a pleasure to use, and the even better thing is the results that the lens gets. It is a great lens even at f/1.4, but set it at f/1.8 and it's just phenomenal. This lens is one of the best things that happened to APS-C systems.
I have to agree there. I was looking for an upgrade from some of the cheaper lens that I have, set myself a budget of $500 and found this. It's close enough to the nifty fifty focal length to where I like having it on my camera for a lot of situations. I've found that I really like the 35-45 range in terms of 35mm equiv. I had a K-3 II previously but this lens seems to perform noticeably better on the K-70 from my own experiences. There's still some hiccups here and there but they're minor to me and I've been shocked at how much of an upgrade in image quality this lens has offered me. Even wide open, I have many good shots. I do concert photography for a well known venue over here and having such a strong low light performer has been a real boon to my work. Also looks really nice on my black K-70 and everyone comments on how serious of a lens this looks like haha.

Last edited by 24thNomad; 07-12-2018 at 08:00 AM. Reason: Punctuation mistake.
07-12-2018, 08:14 AM - 1 Like   #7
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QuoteOriginally posted by 24thNomad Quote
I have to agree there. I was looking for an upgrade from some of the cheaper lens that I have, set myself a budget of $500 and found this. It's close enough to the nifty fifty focal length to where I like having it on my camera for a lot of situations. I've found that I really like the 35-45 range in terms of 35mm equiv. I had a K-3 II previously but this lens seems to perform noticeably better on the K-70 from my own experiences. There's still some hiccups here and there but they're minor to me and I've been shocked at how much of an upgrade in image quality this lens has offered me. Even wide open, I have many good shots. I do concert photography for a well known venue over here and having such a strong low light performer has been a real boon to my work. Also looks really nice on my black K-70 and everyone comments on how serious of a lens this looks like haha.
Aha yes, when I put on the hood, the lens looks like super-serious business! That hood makes it look twice its size..

I find the image quality similar to my DA 35 2.4 in the range they have in common, despite the quite different rendering, but of course the Sigma can go much brighter, and its bokeh is much better (at all apertures), so it is a very good upgrade in that sense. I do use the DA lens when I go somewhere that might be dusty or dirty (like at the beach) or if I just want to go light.
07-12-2018, 09:06 AM - 1 Like   #8
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QuoteOriginally posted by ChristianRock Quote
yes, when I put on the hood, the lens looks like super-serious business! That hood makes it look twice its size


07-12-2018, 10:41 AM   #9
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QuoteOriginally posted by Digitalis Quote
You probably think I'm exaggerating...

(not so serious)


(SRS BZNS)

Last edited by ChristianRock; 07-12-2018 at 11:52 AM.
07-12-2018, 11:14 AM   #10
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Invest in the Sigma dock (50eur ?)and customize the lens setting. I have got it in bundle with Sigma 24-35 and the software is good. Fortunately I had no AF issues with that lens
07-12-2018, 11:39 AM   #11
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QuoteOriginally posted by bm75 Quote
Invest in the Sigma dock (50eur ?)and customize the lens setting. I have got it in bundle with Sigma 24-35 and the software is good. Fortunately I had no AF issues with that lens
I need to remember to look into this. Half my lenses are Sigma and I was definitely interesting in getting more down the line. Thanks for the reminder about the dock. It's only $60 USD so I might as well pick it up at some point.
07-12-2018, 11:51 AM   #12
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QuoteOriginally posted by 24thNomad Quote
I need to remember to look into this. Half my lenses are Sigma and I was definitely interesting in getting more down the line. Thanks for the reminder about the dock. It's only $60 USD so I might as well pick it up at some point.
I was going to get the dock to get the 30 1.4 Art to work with my K10D, but when I saw how well it works with the K-S1 (and probably with the K-50 that I also have now...), I decided to leave it alone...
07-12-2018, 12:33 PM   #13
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QuoteOriginally posted by ChristianRock Quote
I was going to get the dock to get the 30 1.4 Art to work with my K10D, but when I saw how well it works with the K-S1 (and probably with the K-50 that I also have now...), I decided to leave it alone...
Same here.

Mostly, I use centre point AF with the 30/1.4 Art on my K-3 and K-3II, though I sometimes use other AF points, and it seems to work pretty reliably - certainly better than I'd expected, given some of the reviews. Occasionally, I need to press the rear AF button twice to get perfect focus, but my other Sigma lenses - the 17-50/2.8 HSM and 18-300 - require the same, so I don't see the need to mess with it
07-12-2018, 12:46 PM   #14
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Works ok on K30 or KS2 but it has problems under tunstgen on KP ? while other ..pentax lenses are fine under tunstgen on KP.. strange
07-12-2018, 12:55 PM   #15
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QuoteOriginally posted by AldaCZ Quote
Works ok on K30 or KS2 but it has problems under tunstgen on KP ? while other ..pentax lenses are fine under tunstgen on KP.. strange
I haven't used mine under tungsten lighting - only natural daylight and domestic LED, but neither of these has been a problem...
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