Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
05-05-2013, 03:38 AM   #1
New Member




Join Date: Apr 2013
Posts: 6
Problems with K30 AF ?

Hi, I'm a relatively happy K30 owner since a month. I have two lenses, the 18-135 DA WR kit and the DA 50mm f1.8. I also tried a used FA 50mm f1.7.
None of these 3 lenses seem to focus reliably with spot AF. The f1.8, for instance, focusses short at distances 0-5m, which I can correct with a -3 adjustment on the individual lens micro-adjustment, but that still seems to leave it focussing way short at 30m. The 18-135 seems to have similar problems, but because of its narrower opening this is more difficult to pin down. The FA 50mm f1.7 was so soft and so all over the place when I tried to correct it that I returned it to the seller.

Has anyone else had this sort of problem with a K30 ? Is this something that can be corrected by the manufacturer ?

Thanks for any help / ideas. I may not be able to acknowledge replies immediately, as I'll be out for a couple of weeks from tomorrow, but I will get round to it.

Chris.

05-05-2013, 05:19 AM   #2
Pentaxian
Na Horuk's Avatar

Join Date: Feb 2012
Location: Slovenia, probably
Photos: Gallery | Albums
Posts: 10,331
We sometimes get people complaining about the AF and here are some answers they get - maybe you can apply some to your case:
- AF points are bigger than the little lights in the viewfinder. So sometimes the AF point will nail focus, but not on the object you want, and so AF will be blamed as being faulty
- Slow shutter speed can cause motion blur, which can be mistaken for misfocusing. Make sure the shutter is fast enough
- high ISO can cause noise which makes the image look less sharp. Its best to test AF with a tripod and low ISO
- Lenses and cameras are built to certain tolerances. It can cause a problem if each of them is slightly off in the wrong direction. AF adjustment can help here. You can also use debug mode and change the hidden global adjustment
- Some lenses are so fast that their DoF is very very shallow, which can be mistaken for misfocusing

Here are some other things you can try to improve AF:
- update firmware to the newest version
- make sure lens/mount contacts are clean
- use tripod and live view, try focus peaking, and PD AF to compare the results and pinpoint the problem
- try using a focus chart or focus calibration tools (software, charts, etc.). Some can be found online for free, others have trial versions, and some can be bought
- you can send the camera with the lenses to Pentax and let them "fix it" (calibrate the camera and lenses together). Maybe warranty will cover this
- if you are still under warranty, you can try claiming that the camera is faulty and get a replacement. This can fix the problem, but we have had cases on this forum where the problem was not the camera, so exchanging it didn't fix it

Best of luck
05-05-2013, 09:01 AM   #3
Veteran Member




Join Date: Mar 2007
Location: U.K.
Posts: 685
I would be surprised if it's a general problem with the K-30. AF accuracy in all types of lighting is one of its strengths IMHO. I have made a few minor AF micro-adjustments for my lenses but they weren't really needed, zero being quite acceptable throughout the FL range but there again my brightest AF lens is only F2.4. I wouldn't say a -3 adjustment is much though, it's just noticeable.
05-05-2013, 09:16 AM   #4
Senior Member
dragra's Avatar

Join Date: Dec 2010
Location: Ljubljana
Photos: Albums
Posts: 238
QuoteOriginally posted by Ati Quote
Hi, I'm a relatively happy K30 owner since a month. I have two lenses, the 18-135 DA WR kit and the DA 50mm f1.8. I also tried a used FA 50mm f1.7.
None of these 3 lenses seem to focus reliably with spot AF. The f1.8, for instance, focusses short at distances 0-5m, which I can correct with a -3 adjustment on the individual lens micro-adjustment, but that still seems to leave it focussing way short at 30m. The 18-135 seems to have similar problems, but because of its narrower opening this is more difficult to pin down. The FA 50mm f1.7 was so soft and so all over the place when I tried to correct it that I returned it to the seller.

Has anyone else had this sort of problem with a K30 ? Is this something that can be corrected by the manufacturer ?

Thanks for any help / ideas. I may not be able to acknowledge replies immediately, as I'll be out for a couple of weeks from tomorrow, but I will get round to it.

Chris.
This sort of post is a newbie classic. Next time you will be discovering unusual WB-issues or jerks in your video-footage..

It would be good to know if this is your first dSLR or whatever, this way we have a little more space for interpretation of your troubling issues. How were the tests done anyway? Did you shoot a chart under a tungsten lamp on your desk? Or was it real life photography? Besides, there are no known AF-issues with the K-30, since the camera is selling almost 1 year now.

05-05-2013, 11:52 PM   #5
Ati
New Member




Join Date: Apr 2013
Posts: 6
Original Poster
QuoteOriginally posted by dragra Quote
This sort of post is a newbie classic. Next time you will be discovering unusual WB-issues or jerks in your video-footage..

It would be good to know if this is your first dSLR or whatever, this way we have a little more space for interpretation of your troubling issues. How were the tests done anyway? Did you shoot a chart under a tungsten lamp on your desk? Or was it real life photography? Besides, there are no known AF-issues with the K-30, since the camera is selling almost 1 year now.
Hi, I don't find dragra's reply very friendly. I've been taking photos for over 50 years. My first SLR was 20 years ago. The tests I did were pretty exhaustive, using a gravel path for close focussing and a sunlit brick wall for medium distance. The type of tests I did were based on Roger Cicala's recommendations http://www.canonrumors.com/tech-articles/how-to-test-a-lens/ , as far as one can without investing in specialist charts.
Having read photozone's and slrgear's reviews of Pentax lenses.... nervousness about my recent purchase understandable ?

Steve B : "I wouldn't say a -3 adjustment is much though, it's just noticeable " It's enough to make the difference between the spot I focussed on being just outside the sharp zone and being in the centre of it, at portrait-taking distance with the 50mm @ f2.8. As you know you can forget about anything wider than f2.8 with the DA 50mm. And as I said, it leaves the focus point completely outside the sharp zone at 30m.

Na Horuk (? :-) ?) : thanks for your post. I don't have much time right now and I'll just say the speeds I used are between 1/350" and 1/2000", the equipment is new (so probably no contact problems or firmware problems), Highest ISO 800 (but mostly 100).

However, I'm glad you all like the K30. In general I find the tone of this forum pretty defensive :-).
05-06-2013, 12:50 AM   #6
Pentaxian
Zafar Iqbal's Avatar

Join Date: Oct 2010
Photos: Gallery
Posts: 1,157
The center spot on both my K-30's are fine, but I suspect (some of) the other AF points are far from it. I'm currently trying to get deeper into what's what.

https://www.pentaxforums.com/forums/general-technical-troubleshooting/219670-...cus-motor.html
05-06-2013, 01:35 AM   #7
Senior Member
dragra's Avatar

Join Date: Dec 2010
Location: Ljubljana
Photos: Albums
Posts: 238
QuoteOriginally posted by Ati Quote
Hi, I don't find dragra's reply very friendly...
Sorry, but your initial post didn't show your 50-years of expertise. If you have ever used an AF SLR in your life you would know that focus (especially with older lenses) can be critical, because each lens focuses a bit different. Film grain was much more tolerant to those focusing glitches, but a modern 16MP dSLR is not. This is why Pentax puts fine tuning AF-options into their cameras.
05-06-2013, 03:24 AM   #8
Veteran Member




Join Date: Mar 2007
Location: U.K.
Posts: 685
If you've done your testing using a tripod or stable substitute, especially for close-ups, then it has to be the lens causing it, not the camera. Your quoted Canon focus check article says that and I tend to agree. That article doesn't make it clear what the focus target is though, a lot are totally unsuitable for large AF sensors, I used an AF chart with a bold horizontal single black/white border, with no other line detail anywhere near the centre AF sensor area which is a thick cross approximately the size of the VF circle which can easily lock onto something unintended if you're not aware of its size.


Last edited by SteveB; 05-06-2013 at 10:16 AM.
05-06-2013, 07:59 AM   #9
Site Supporter
JimJohnson's Avatar

Join Date: Jan 2012
Location: Lake Superior - Michigan
Photos: Gallery
Posts: 2,165
QuoteOriginally posted by Ati Quote
In general I find the tone of this forum pretty defensive :-).
Actually Ati, I don't think so. We do have a few 'lesser knowledge and greater opinion types', but most people here are truly trying to be helpful. As it happens a number of new members don't have your background, but like yourself, they didn't flesh this experience out in their profile setups. We don't want to 'sing to the choir', nor 'talk over someone's head', but it is hard to know where someone fits until they start posting and/or put more into the parts of their profile that appear within their messages.

Will you help us out by editing your profile and including a brief bit about yourself in your signature tag line, and it also helps to know what region in the world you call home by completing the location field? .... this is helpful in several ways: we will try to steer you to resources available within your region, as opposed to half-way around the world, and at least some of us try to avoid local idiomatic phrasing when we know English is likely a second language. (although to be honest some of the non-native English speakers do a better job than I do in their written communications).

You are also going to find over time, that while everyone here is partial to their Pentax gear (this IS a Pentax forum after all), many members are also knowledgeable about other brands. I've been using advanced camera systems for approaching 40 years now, and simpler systems for much longer than that. I still learn a lot each time I visit this forum.
05-06-2013, 11:38 AM - 1 Like   #10
Pentaxian
Na Horuk's Avatar

Join Date: Feb 2012
Location: Slovenia, probably
Photos: Gallery | Albums
Posts: 10,331
QuoteOriginally posted by Ati Quote
Na Horuk (? :-) ?) : thanks for your post. I don't have much time right now and I'll just say the speeds I used are between 1/350" and 1/2000", the equipment is new (so probably no contact problems or firmware problems), Highest ISO 800 (but mostly 100).
Aha. So its probably not ISO or shutter speed problems. I still recommend a firmware upgrade because for some cameras in the past some AF improvements came with firmware updates.
Are we defensive? I would say that its possible, certainly. Thing is, we sometimes get people who are trying to blame the gear because their snapshots don't look like Ansel Adams photos, and often they turn it into "I should have gone with a better brand!" type argument. Sorry about that. But generally we try to give full, exhaustive answers to help the users
Oh and btw, there is a photo sample gallery on this forum, where you can look for photos taken with the same camera and lens that you have. Maybe that can help you out?
07-03-2015, 07:50 AM   #11
Senior Member




Join Date: Jul 2015
Posts: 110
Hi,
I'm new to the forum and Pentax. I've just got a K30 and am having similar problems. I'm just trying to update the firmware but the battery needs charging. I'll report back if this helps.
(Previous digital cameras are superzooms. Panasonic FZ150. Used to use Minolta SLR.)

I've tried boosting the ISO and that helps. The distance seems to be problem. Getting too close will obviously put the camera out of focus but the focus seems to lock in and appears OK through the camera. When you look on computer the resulting pictures aren't sharp though. I've messed around with basic settings and managed to get some good sharp images, but it seems a lot more effort than other cameras.

Can someone provide a link to details of how to do the fine tuning set up for lenses? I think it may be worth trying though I have had some good images. most are coming out a bit soft though.

Generally my photos seem to come out a bit dark too. Not sure why that is. I'm on the bright setting. I guess I could boost things with ev adjustment but that seems not the right approach to getting a basic good image output.

Any tips appreciated.
07-04-2015, 02:19 PM   #12
Senior Member




Join Date: Jul 2015
Posts: 110
Found some stuff online about adjusting lens focusing. Printed out a couple of charts.The more basic one here is taken at a 45 degree angle (approx).

My tripod is a basic one so I'm not 100% sure of its stability, but I'd have thought I should get better results with high shutter speeds.

(I am getting good shots from the kit lens now)
Attached Images
View Picture EXIF
PENTAX K-30  Photo 
View Picture EXIF
PENTAX K-30  Photo 
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
50mm, af, da, f1.7, f1.8, fa, k-30, k-50, k30, k30 af, lenses, pentax k30, pentax k50
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Anybody with mirror problems with K30? Focus problems. simbon4o Pentax K-30 & K-50 14 08-28-2013 10:39 PM
Pentax K30 with a AF-360FGZ flash question. VE2CJW Troubleshooting and Beginner Help 5 03-14-2013 06:31 PM
Any freezing problems with K30?(like those with K5) or any other problems? simbon4o Pentax K-30 & K-50 21 01-03-2013 01:54 PM
problems with AF and external flash dianeden Troubleshooting and Beginner Help 4 12-08-2012 09:31 AM
AF problems with the K-r Tokyohawk Pentax K-r 22 12-24-2011 12:31 PM



All times are GMT -7. The time now is 01:17 AM. | See also: NikonForums.com, part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top