Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
10-29-2008, 07:11 PM   #1
Veteran Member




Join Date: Sep 2008
Location: Washington
Posts: 958
K20DStill Front Focusing: Dilemma

Last weekend I went through and calibrated all of my lenses. They were all front focusing. I applied the correction to the individual lenses (done in software somehow eh?) and figured I'd be good to go. The Plan? Use until after the holidays and send it in for the warranty fix me up.

Now that was looking like a sharp plan. I have pictures with sharp focus after the correction. Now, not so good. It is back to front focusing.

This weekend I am going to do the process again and this time apply the correction to the body and then tweak the individual lenses. I have my fingers crossed that it'll work out well enough to hold out until after the holidays.

Man, it is just the 1 month and all was going well time-frame without a camera I spent thousands of dollars on. (Can't use any of the lenses or flashes can I?) Just a little miffed.

Do wish there was a loaner program. Upon receiving my camera they send me a refurbished k20d and when they are ready I send theirs back they check it out and send me mine... Ah to dream.

Here is proof of the crime:



She's got mighty nice hands but clearly not what I was focusing on.

Well thanks for listening. BTW a quick read through other camera manufacture's user forums show there are all having such problems. I am good with Pentax for many enduring reasons. Mess ups happen, as they say. This one was on me.

A whole month! And if the camera won't stay in focus after this adjustment... I'll send it in by Monday...OMG ~I shake my head.

10-29-2008, 07:22 PM   #2
Veteran Member




Join Date: Mar 2007
Location: Toronto (for now)
Posts: 1,749
Are you selecting the AF point yourself or allowing the camera to do it?
10-30-2008, 12:13 AM   #3
Pentaxian
Marc Sabatella's Avatar

Join Date: Sep 2006
Location: Denver, CO
Photos: Gallery
Posts: 10,686
QuoteOriginally posted by metroeloise Quote
She's got mighty nice hands but clearly not what I was focusing on.
It might be clear you didn't *want* the camera to focus on the hands, but how did you communicate this fact to the camera? Note the various focus point areas are quite large; even if you select a point near the face, there is no guarantee the camera won't see the hands as being "close enough" to the focus sensor and decide to focus there instead. Assuming that this is what is gong on, this is *not* front focus and has nothing to do with the focus adjustments you made.
10-30-2008, 03:52 AM   #4
Veteran Member




Join Date: Sep 2008
Location: Washington
Posts: 958
Original Poster
here's some more information

QuoteOriginally posted by Alfisti Quote
Are you selecting the AF point yourself or allowing the camera to do it?
That is a good question. I have stopped trusting the auto select and never used the select options. I use the center one. As you can see here and throughout my flickr photostream, when I pick the center, the face, and it is quite some distance from the hands, and there is plenty of light, and I got tone (which I recently turned off) the indicator lit up, I was able to shoot, and it hit the hands.

For the past few months with my camera I have been making these excuses for the softness. Mostly figuring it was my error. Now as I get the skills in basic handling, and have gotten better results right after the calibration I did last weekend, I know better. It is the body.

In the photostream, I'll fish out some examples, I started adapting, picking points a bit further back and reframing. got it then. Still there are many that are soft.

Today is my Friday, I work Graveyard Shift, and will be at this when I wake up. First order of camera business is to reset the calibrations and redo them until they are spot exactly on. I will use the "to body" option then fine tune any lens. When they are right on I will save those captures for later reference (I dumped the others) and will set up test shoots in the wild.

All cool and I wait until after the holidays to send the body in. If in the mean time it stays in focus and the focus is true and sharp, maybe I'll hold off until more convenient. If not, and it is not usable through the holidays, I'll send right away.

I'll report back with the news soon! Thanks for all the comments and suggestions.

10-30-2008, 04:28 AM   #5
Senior Member




Join Date: Dec 2007
Location: Perth Australia
Photos: Gallery | Albums
Posts: 293
I have had a close look at your example image where you spot focussed on the face.
The pen is the sharpest part of the image and this is as it should be with Pentax auto-focus.
The system is optimised to work best on vertical or near vertical contrast edges. In your case the nearest vertical edge to the face is the pen. It so happens that the hands are better lit and fall within the plane of the pen and so draw the eye to them.
I have a good selection of fully manual M, non-autofocus A, auto focus F and DC lenses acquired during over 50 years of film and digital photography. None, I repeat NONE, exhibit any kind of back, front, whatever focussing on my K100D and K20D cameras. Nor did they ever on K1000, P30 and MZ series film cameras.
Any out of focus images I have taken I have been able to attribute to shooting at less than minimum focus, subject moving, me moving, miscalculating DOF and just me bad focussing usually in low light.
99% of the time, the camera is far better at focussing than I am.
10-30-2008, 04:45 AM   #6
Senior Member




Join Date: Dec 2007
Location: Perth Australia
Photos: Gallery | Albums
Posts: 293
Quite forgot the main point I wanted to make when starting the above rant.
SLR photography is purely about seeing in the viewfinder what goes onto the film or in this case the sensor. This is why you all purchased an SLR system. This includes focus.
10-30-2008, 04:53 AM   #7
Site Supporter




Join Date: Jan 2008
Location: Middle of Everywhere
Photos: Gallery
Posts: 1,169
QuoteOriginally posted by garth1948 Quote
Any out of focus images I have taken I have been able to attribute to shooting at less than minimum focus, subject moving, me moving, miscalculating DOF and just me bad focusing usually in low light. 99% of the time, the camera is far better at focusing than I am.
Agree... 100%!

It's really easy to let this FF-BF stuff make you crazy.

Examine then re-examine your technique. You may have developed a bad habit. The camera is neutral and consistent, obedient and unforgiving. It has no agenda. It does not want you to fail. With a little extra care, you might be surprised to discover that you are not its victim.

Discover and enjoy...
10-30-2008, 04:54 AM   #8
Senior Member




Join Date: Nov 2006
Location: NYC
Photos: Gallery
Posts: 107
QuoteOriginally posted by garth1948 Quote
Quite forgot the main point I wanted to make when starting the above rant.
SLR photography is purely about seeing in the viewfinder what goes onto the film or in this case the sensor. This is why you all purchased an SLR system. This includes focus.
Thanks for the reminder....

10-30-2008, 05:23 AM   #9
Veteran Member




Join Date: Sep 2008
Location: Washington
Posts: 958
Original Poster
Oh thank you for your guidance

QuoteOriginally posted by garth1948 Quote
Quite forgot the main point I wanted to make when starting the above rant.
SLR photography is purely about seeing in the viewfinder what goes onto the film or in this case the sensor. This is why you all purchased an SLR system. This includes focus.
I quite agree with all you said. As I pointed out there has been a learning curve on my part. Yet the focus charts quantifies what I see in my photos.

As for technique. the biggest break through for me was using AFC for moving targets! Duh. Another was learning how to adjust the diopter. Far sighted and that helps. I want to trust the AF. I understand about photography being about what you see... In the heat of fast movement I want to be able to trust the AF. I have to. I also don't use the preview while in a show since it is intrusive to others. Again, I need to trust the AF.

And since I can only fumble for the AF to manual switch, to fine tune a close AF is not realistic.

I have a manual lens; I have had no focus issues with it.

Here is one of my last captures: Hit the middle women in the chest.



I am heading into my weekend and will sort this out and report with evidence however it flows. Thanks.
10-30-2008, 06:34 AM   #10
Veteran Member
ghelary's Avatar

Join Date: Jul 2008
Location: Paris, France
Photos: Gallery
Posts: 617
Hi,

The photo above looks to me more of problem of long expose / shake on handheld camera. The rule of thumb before shake reduction appeared is that exposition should not be longer than the inverse of focal length.

Here we are at 1/15s at a focal of 63mm, much above the confort zone. Even the most calm and concentrated photographer would loose some sharpness because of hand/body shake.

Regards,
Guillaume
10-30-2008, 06:41 AM   #11
Moderator
Site Supporter
Blue's Avatar

Join Date: Jun 2008
Location: Florida Hill Country
Photos: Gallery | Albums
Posts: 17,212
QuoteOriginally posted by garth1948 Quote
Quite forgot the main point I wanted to make when starting the above rant.
SLR photography is purely about seeing in the viewfinder what goes onto the film or in this case the sensor. This is why you all purchased an SLR system. This includes focus.
It is amazing how this basic premise of an SLR gets overlooked!
10-30-2008, 07:57 AM   #12
Pentaxian
Lowell Goudge's Avatar

Join Date: Jan 2007
Location: Toronto
Photos: Gallery | Albums
Posts: 15,400
just a couple more dumb questions, is this AF-S or AF-C? and is the shot hand held or tripod. A little vertical shake could have you focused on the hands.
10-30-2008, 01:34 PM   #13
Pentaxian
Marc Sabatella's Avatar

Join Date: Sep 2006
Location: Denver, CO
Photos: Gallery
Posts: 10,686
QuoteOriginally posted by metroeloise Quote
I have stopped trusting the auto select and never used the select options. I use the center one.
As I said before, the center "point", like the other "points", is not a point at all, but a pretty large area. There is absolutely no doubt in my mind that on the first photo the hands were close enough to the center that they are what the camera focused on. Again, *not* front focus at all, but just a fact of life when trying to focus on objects smaller than the AF sensor.

And as another posted observed, the second picture is not showing a focus issue at all. It's motion blur pure and simple, caused by trying to shoot at 1/15" shutter speed. You've got both camera shake and subject motion going on there, and this is obvious by comparing the figures (who are clearly in motion) to the background.

Feel free to post other examples that demonstrate an actual AF problem, but these do not. If you're trying to test for FF/BF, you're much better off using a legit focus test chart to be sure it isn't simply a case of the camera focusing on an object other than the one you intended, such as was the case in the first post. And use a fast enough shutter speed to eliminate blur as the source of softness.
10-30-2008, 02:20 PM   #14
Senior Member




Join Date: Dec 2007
Location: Finland
Photos: Gallery
Posts: 185
Look hard

This is not really a front focus or back focus issue, since the same equipment seems to produce either one (not consistently one or the other). This is a bad focusing issue. Most likely the AF just hasn't had time to focus, or it has locked on to the wrong subject and stayed there though the camera has moved (AF-S) .
But it could be a quality issue that can be corrected by the service guys in a month or so. If you want to say something nice about Pentax in that situation, is it that the interim body you need to buy will be cheap.
10-30-2008, 04:00 PM   #15
Veteran Member




Join Date: Sep 2008
Location: Washington
Posts: 958
Original Poster
I wil look better.

QuoteOriginally posted by Marc Sabatella Quote
As I said before, the center "point", like the other "points", is not a point at all, but a pretty large area. There is absolutely no doubt in my mind that on the first photo the hands were close enough to the center that they are what the camera focused on. Again, *not* front focus at all, but just a fact of life when trying to focus on objects smaller than the AF sensor.

And as another posted observed, the second picture is not showing a focus issue at all. It's motion blur pure and simple, caused by trying to shoot at 1/15" shutter speed. You've got both camera shake and subject motion going on there, and this is obvious by comparing the figures (who are clearly in motion) to the background.

Feel free to post other examples that demonstrate an actual AF problem, but these do not. If you're trying to test for FF/BF, you're much better off using a legit focus test chart to be sure it isn't simply a case of the camera focusing on an object other than the one you intended, such as was the case in the first post. And use a fast enough shutter speed to eliminate blur as the source of softness.

thanks so much for your (and the other's) kind responses. I picked the second one to show since it was fresh out of camera and while I was preparing for work thought "Another one!" Focus test time! Just got up so will get on it...

Marc: What you are saying makes sense. I have been snapping fast and am just disciplining myself to slow down, work the shot.

A question: I had a bunch of shots at club shows, low light. The 50mm would focus hard on a passing microphone wire, stand, boom, mic! With the f/1.4 there's not much more room. The first few shows I worked the auto select and tried to get it on the correct spot. After a while I shifted to center focus. Hit them in the chest and reframe: better.

Still hit and miss. Figured I needed to use AF-C and now get better... Most every time I see the focus light on what I intended but the results are in front... again, a passing wire etc.

So the question is how to work that better in fast paced, low light situations? Some shows are like sporting event fast, (See my Love Me Nots set). The Focus light hits and it looks like it hit the target but... a passing wire. Like the women at the deli. That one I saw it hit her in the forehead, drop down a bit and snap: It really hit her pencil.

Thanks for the considered responses. I will shoot a set of Focus Charts for each lens (including the manual one) and report. Hope it is "merely" operator error! I know where that adjustment knob is! That'd be the best new.

Either way...I got some work to do. Thank you all.
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!
camera, correction, dslr, focus, front, holidays, lenses, month, photography, plan, weekend
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
K10 front focusing bannor75 Troubleshooting and Beginner Help 2 07-21-2010 11:00 AM
My new K-x is front focusing, now what? skid2964 Pentax DSLR Discussion 19 11-01-2009 11:16 AM
What Does Front and Back Focusing Mean? GregK8 Troubleshooting and Beginner Help 5 02-28-2009 11:47 AM
Front Focusing Done to Death NorrisTudor Pentax DSLR Discussion 42 12-08-2008 04:22 PM
Front Focusing Mark Castleman Pentax DSLR Discussion 23 01-27-2007 06:24 PM



All times are GMT -7. The time now is 09:29 AM. | See also: NikonForums.com, CanonForums.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