Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
12-18-2009, 03:58 PM   #1
New Member




Join Date: Dec 2009
Posts: 6
AF issues with K20D

I feel that most of the portraits I take with my K20D is ever so slightly out of focus. I wonder if anyone else has experienced the same problem and if so, if there are any ways to be corrected. I'm using the 50-135 and a 100mm macro lense for portraits.

I'm not inclined to believe it's a problem with the photographer anymore, since I've experimented a lot.

12-18-2009, 04:01 PM   #2
Damn Brit
Guest




Welcome to the forum.

Examples please with exif data. We can't determine anything from a few words.

We're not inclined to believe it's not the photographer without visual evidence because any of us are fallible to missing something, a picture doesn't lie.

It is possible that you are getting front or back focus and you can make adjustments on your K20, you'll find details in the manual. If you look around on PentaxForums, you'll find plenty of discussions about the subject.

Last edited by Damn Brit; 12-18-2009 at 05:29 PM.
12-18-2009, 05:39 PM   #3
Veteran Member
Raybo's Avatar

Join Date: Dec 2007
Posts: 871
I get quite a few OOF images with my K20 and it's mostly due to me.
12-18-2009, 09:58 PM   #4
Ash
Community Manager
Loyal Site Supporter
Ash's Avatar

Join Date: Mar 2007
Location: Toowoomba, Queensland
Photos: Gallery | Albums
Posts: 22,679
Welcome to the forum.
Do post some examples and tell us if it's consistent back or front focusing happening with one, some or all your lenses.

12-18-2009, 10:10 PM   #5
Veteran Member
Raybo's Avatar

Join Date: Dec 2007
Posts: 871
I just wish Pentax had a smooth diopter setting instead of the clicky style.
My diopter just happens to be on one of in between settings and it's really hard to get it just right.
12-19-2009, 08:04 AM   #6
Forum Member




Join Date: Aug 2009
Location: cincinnati
Posts: 88
i did too, but i still don't know the reason so i am gonna post some pics up later
12-19-2009, 12:58 PM   #7
Pentaxian
Marc Sabatella's Avatar

Join Date: Sep 2006
Location: Denver, CO
Photos: Gallery
Posts: 10,686
As mentioned, you need examples in order to get usable advice. But I'll guess anyhow: you're shooting at f/2.8, the camera is focusing on the tip of the nose, and DOF is shallow enough to put most of the rest of the face out of focus. You need to somehow make sure focus is on the eyes. Best way is is to use MF, but if you're lucky, you might be able to get the AF system to choose the eye if you select the focus point yourself and are taking enough of a closeup that the nose isn't within range of the AF sensor.
12-20-2009, 08:14 AM   #8
New Member




Join Date: Dec 2009
Posts: 6
Original Poster
Thanks a lot for your replies. I appreciate that you take the tiime to try to help me.

I've uploaded some examples. The main problem, is that I feel there is a slight blur on all the pictures. I try to adjust it using the sharpening filter in Photoshop, but it's annoying that I have to do that every time and they easily get too pixelated. I am always trying to focus on the eyes.

I'd be happy for any comments on the examples below. I don't know if it can easily be detected. I feel I see the "blur" when I zoom in to 60-70 percent

Flickr Photo Download:

Flickr Photo Download:

Flickr Photo Download: (The error in this photo may have been the shutter speed - 1/90 s)

12-20-2009, 09:22 AM   #9
Veteran Member
Ben_Edict's Avatar

Join Date: Jul 2007
Location: SouthWest "Regio"
Photos: Albums
Posts: 3,303
QuoteOriginally posted by stianb Quote
Thanks a lot for your replies. I appreciate that you take the tiime to try to help me.

I've uploaded some examples. The main problem, is that I feel there is a slight blur on all the pictures. I try to adjust it using the sharpening filter in Photoshop, but it's annoying that I have to do that every time and they easily get too pixelated. I am always trying to focus on the eyes.

I'd be happy for any comments on the examples below. I don't know if it can easily be detected. I feel I see the "blur" when I zoom in to 60-70 percent

Flickr Photo Download:

Flickr Photo Download:

Flickr Photo Download: (The error in this photo may have been the shutter speed - 1/90 s)
I find all three images acceptably sharp. All of them would stand up to more sharpening in pp, which is a necessity with all digital images anyway.

If you notice the blur at a certain magnification step, it might well be more an issue of screen interpolation, than a real issue with the image.

Ben
12-20-2009, 09:51 AM   #10
Veteran Member




Join Date: Mar 2007
Location: Boston, PRofMA
Photos: Albums
Posts: 3,053
looks ok to me as well...you can see the lines on her face. How sharp did you want this? :-P
12-20-2009, 11:13 AM   #11
Pentaxian
Marc Sabatella's Avatar

Join Date: Sep 2006
Location: Denver, CO
Photos: Gallery
Posts: 10,686
In picture #2, it seems the camera probably choose to focus on the hat rather than the face (a perfectly legitimate choice!), and the DOF wasn't quite enough to compensate, but still, that's pretty sharp considering. I'm wondering if you're familiar with the idea of DOF, and are expecting the entire face to be in focus? That's not going to happen at large apertures - the nose and ears won't be in focus at the same time.
12-21-2009, 08:04 PM   #12
New Member




Join Date: Dec 2009
Posts: 6
Original Poster
Thanks a lot for your feedback. Really appreciated. I'll experiment a bit more and take the comments into consideration.
12-24-2009, 02:21 PM   #13
New Member
stl_stadtroller's Avatar

Join Date: Jun 2009
Location: St. Louis MO
Posts: 23
I'm going to have to go with simple DOF on this too. The beard hairs in pic #3 give a perfect point of refference. Closer ones are sharp fine lines, but hairs just beyond are slightly blurred, getting more so as you go around the face.

Great subjects BTW!
12-26-2009, 11:32 AM   #14
Loyal Site Supporter




Join Date: Jun 2009
Location: Tumbleweed, Arizona
Photos: Gallery | Albums
Posts: 5,001
Morning,

I downloaded the first picture and used PhotoME on it to extract the exif metadata. You are using a K20, f 3.5 with a lens using a focal length of 63mm. Went to a DoF calculator at

Online Depth of Field Calculator

and entered the information, guessing the distance to the subject at 5 feet. This resulted in a depth of field of 4". If the distance was 10 feet the DOF would be 1 foot. Not a lot. It really depends on your focus point. It looks close, but its difficult to tell exactly where it is. To open up the depth of field, you would need to stop down some more, to say f5.6 (at 5 feet dof is 5"), f8 (at 5 feet dof is 7"), at f13 (at 5 feet dof is 1 foot). Either that or to back up a bit and increase the distance, but if you zoom in a bit more to say 100mm, you have achieved nothing as the dof goes back down. The best solution is to stop down to around f13 and have a bit more depth of field to get the subject in focus. If you backup some, adding distance, keep the same focal length and then crop to get the image you desire.

All in all, you have a great background and a wonderful picture. The gentleman is really well defined and pulled out (isolated) from the background.
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!
af issues, camera, k20d, pentax help, photography, portraits
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
For Sale - Sold: [Worldwide] Cheap K20D (w/ autofocus issues) dgaies Sold Items 6 03-05-2010 06:20 PM
K20D issues. Camera locking up. IN_Varmntr Pentax DSLR Discussion 8 07-07-2009 08:44 AM
Focusing issues, Pentax 80-320 w/K20D hudson2212 Pentax SLR Lens Discussion 2 04-27-2009 04:08 PM
K20D issues tmalkiew Pentax DSLR Discussion 18 10-16-2008 05:01 PM
K20D Front Focusing Issues switch79 Pentax DSLR Discussion 18 05-17-2008 02:57 PM



All times are GMT -7. The time now is 10:38 PM. | 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