Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
12-01-2012, 04:45 AM   #1
New Member
Enkhbayar's Avatar

Join Date: Jan 2012
Photos: Albums
Posts: 13
pentax k-r focus calibration

I've bought my K-r 1 year ago, this is my first DSLR so at first I did not notice focus problem on manual lenses.
on the DA 18 55 II kit lens it seems no focus problem.

I tried a rikoh 50/1.7 and another 135/2.8 on the camera both heavily lose focus.
both lenses can only focus on center point, on in focus the hex indicator lights, press the shutter the picture get always out of focus.

  • so I adjusted AF fine adjustment from the menu got nothing improved, but got the kit-lens out of focus. so cancelled this method.
  • after months, using Pentax's engineering mode software, focus calibration done on 135mm, the 50 lens and the 18 55 had failed. if calibrate on 50 the 135 would fail.
  • and later one day i opened k-r's bottom cover, found two screw, which hiding deeply in a hole but can twist with a screwDriver, this must be for focus adjusting. I carefully turn both screw with same amount same direction, result is the same with engineering mode focus calibration. so i'm almost disappointed and gave up.
  • today I thought what if turn focus screw independently? so i just tried, and got it fixed.

table in the attachment shows the operation and results. there are tools used to the procedure too.


Is there any service manual or something that telling how to calibrate? even though now my camera could focus on ricoh 50/1.7 and another maunal 135/2.8 lens roughly, without problem on kit lens. but the focus accuracy is not assured, and all have i done is just experiment, there is no theoretical instructions. seems that on my k-r left screw calibration effects longer focus range, and, right screw have no effect on this.

Attached Images
     
12-01-2012, 09:13 AM   #2
Veteran Member




Join Date: Nov 2010
Location: Edmonton, Alberta
Posts: 800
Whoa, I don't think I would be brave enough to start altering the mechanics of my camera. I would have just sent it away.
12-01-2012, 09:43 AM   #3
Inactive Account




Join Date: Jul 2010
Photos: Gallery
Posts: 328
Manual lense focus depends mostly on the Diopter eye adjustment and the focus screen, what you are doing is changing the
Placementof the autofocus sensor, not needed or recomended ! Autofocus fine adjustment is done in software.
First you must be sure that the autofocus is working as it is supposed to, use a tripod and a fixed target and focal length. Take a shot
Using the autofocus and the live view ( use the screen zoom to be sure ) and compare. The live view does not use the same sensors
And is accurate. When you are sure the autofocus is good focus on the target and don't touch the button. Look through the viewfinder
And carefully adjust the diopter until the image is as clear as possible. ( keep you eye glued to the viewfinder, there are so many people
That I know that are afraid to touch it and their eye is about 2" away from it, that never will work ! ) I you can't get a perfectly clear
View then the screen is not shimmed properly.
Try this and reply back with the results. ( Just hope you have not completly upset the mechanical adjustments )
12-01-2012, 10:08 PM   #4
New Member
Enkhbayar's Avatar

Join Date: Jan 2012
Photos: Albums
Posts: 13
Original Poster
thanks for advice.

I don't judge focus with my eye on manual lenses.
instead watch the focus indicator hexagon light. the focus indicator is working with the PD AF system.
I'm using a tripod and 1m long metal ruler for focus chart.

even though I write a log every little change, it is somehow messed... I turn both screw back to 0, I assume it's original position, but My 18 55 already out of focus.

so i guess the focus problem have several causes.
  1. the max aperture. camera do light metering and autofocus on max aperture. aperture is another word for light ray angle toward camera. So I open the 50/1.7 lens, and removed the diaphragm actuator so the aperture size would be determined only by the aperture ring, not controlled by the camera. so on the same lens I tested on F/1.7, F/2.8, F/5.6, result shows on all stops behaves identical.
  2. focal length. maybe the autofocus behaves differently on different focal lengths. because on same focal length different max aperture lenses have no focus problems according to previous testing. but as i mentioned in original post, if calibrated on 50/1.7(with camera debug mode), the camera out of focus on the 18 55, including its 50mm. but I've also tested on the kit lens's different focal lengths It does have different focal behaviors. btw kit lens aperture is too small that too hard to do the test.
  3. lenses are defective. such as the lens mount is tilted, or internal parts are become inaccurate.
now i don't have many other lenses, and have no friends using pentax, brought this camera from other country, and no pentax service nearby so I've done those by myself.

12-02-2012, 01:32 AM   #5
New Member
Enkhbayar's Avatar

Join Date: Jan 2012
Photos: Albums
Posts: 13
Original Poster
yesterday I calibrated on manual lenses and saw kit lens seems just fine, but when i test using focus chart find that already lose focus too much.

cost my whole day calibrating back on kit lens on 30/f4, 55/5.6 , so manual lenses are all front focus again. i'll never do again.

i've read on internet k20d can memorize idividual lens AF tuning, but k-r doesn't. its sad.
12-02-2012, 06:57 AM   #6
New Member
Enkhbayar's Avatar

Join Date: Jan 2012
Photos: Albums
Posts: 13
Original Poster
today i bought a focusing screen online. try after several days later, this is my last hope.
12-02-2012, 10:14 AM   #7
Inactive Account




Join Date: Jul 2010
Photos: Gallery
Posts: 328
Just remember AF is for AF lenses and has nothing to do with Manual focus lenses, use the Live View to focus on a FLAT area not a 45deg ruler.
Put apiece of paper with printing on it like a Soup label on the wall and get it perfectly sharp on the big screen, don't worry about the aperture setting it has
nothing to do with the focus. When you are sure the paper is perfectly focused manually switch off the camera and look through the viewfinder it should match the
big screen and be sharp, check using the diopter adjust. If it is not perfectly clear make a note of the position of the lens focus ring then turn it until the paper
is perfectly clear. Note which way you turned the focus ring to get the focus right on as this will tell you which way to add the shims if necessary.
Manual focus lenses need your eye to focus the Af indicator is just a helper it is not going to give you the perfect focus point on every lens.
for over 100 years there was no AF and the photos still came out in focus, your problem is at the back of the camera not the front.
12-02-2012, 10:21 AM   #8
Site Supporter




Join Date: Jul 2008
Location: Detroit MI, USA
Posts: 503
QuoteOriginally posted by Enkhbayar Quote
I've bought my K-r 1 year ago, this is my first DSLR so at first I did not notice focus problem on manual lenses.
on the DA 18 55 II kit lens it seems no focus problem.

I tried a rikoh 50/1.7 and another 135/2.8 on the camera both heavily lose focus.
both lenses can only focus on center point, on in focus the hex indicator lights, press the shutter the picture get always out of focus.

  • so I adjusted AF fine adjustment from the menu got nothing improved, but got the kit-lens out of focus. so cancelled this method.
  • after months, using Pentax's engineering mode software, focus calibration done on 135mm, the 50 lens and the 18 55 had failed. if calibrate on 50 the 135 would fail.
  • and later one day i opened k-r's bottom cover, found two screw, which hiding deeply in a hole but can twist with a screwDriver, this must be for focus adjusting. I carefully turn both screw with same amount same direction, result is the same with engineering mode focus calibration. so i'm almost disappointed and gave up.
  • today I thought what if turn focus screw independently? so i just tried, and got it fixed.
table in the attachment shows the operation and results. there are tools used to the procedure too.


Is there any service manual or something that telling how to calibrate? even though now my camera could focus on ricoh 50/1.7 and another maunal 135/2.8 lens roughly, without problem on kit lens. but the focus accuracy is not assured, and all have i done is just experiment, there is no theoretical instructions. seems that on my k-r left screw calibration effects longer focus range, and, right screw have no effect on this.
There are three screws! Two of them tilt the AF module side to side, the third moves it back and forth (up/down), just like a pan/tilt tripod head. I have the third screw marked in yellow for you in the pic below. Good news is all Pentax dSLRs have used this system to adjust the AF module. So I can give a link to a bunch of manuals (passcode 8639) for you to look at. But your suppose to use special equipment to do this adjustment. A computer really adjusts with humans turning screws. The small AF mirror can be adjusted, the Shake Reduction platter can be adjusted. There are many AF adjustments. All need special software and machines. I am not trying to discourage you. But want to inform you. The task of building a dSLR with high mega-pixel sensors, have the camera used in very hot and very cold weather (makes metal expand/contract), be bumped around and still keep tack sharp perfect focus with any lens (that may not be exact in its build) is daunting to say the least. And I would guess the more mega-pixels the more demands on the whole system including lens. Its truly mirrorless number one benefits. But I would not go mirrorless unless I could not get a dSLR.

Also the poster above, I agree with. You do not need to tune your dSLR when using manual lens. I see no need for it. When shooting at night under artificial light I know the AF will not be right anyways so I use my eyes to AF. You are harming your fully automatic focus lens by doing this. All lens do differ. Yes I do tune my lens (with a K20D) separate. But not by much I could just park it at +-0. If your focus is off that much...

As you now know those screws are held in place by glue. I strongly suggest just letting Pentax service tune it for you, the cost is not that much. Not cheap, but not expensive relative to the whole hobby. It will be as good as it can be without adjusting major components. Then you can focus on your lens (pun...?). Sometimes just getting new lens and selling the old ones till you get one that works great on your dSLR is a good thing. I have a set of lens (luck first time lens) that works perfect on my dSLR and I won't sell them. Now its not a bad thing to sell your bad lens because they may work great on someone else's dSLR. The chances are really pretty good.

Downloads

And the third screw



Last edited by jamesm007; 12-02-2012 at 01:54 PM. Reason: Spelling,...
12-02-2012, 05:18 PM   #9
New Member
Enkhbayar's Avatar

Join Date: Jan 2012
Photos: Albums
Posts: 13
Original Poster
QuoteOriginally posted by bobpur Quote
Just remember AF is for AF lenses and has nothing to do with Manual focus lenses,
the LV focusing is good but it need to zoom, use tripod, along with keep your composition. Sony got a good idea on this, focus peaking sounds very handy in LV mode.

now I bought a split-impage rangefinder that is on the shipment. have any suggestion or hints to this method?



thank you jamesm007, very informative post. i'm reading the manual mostly for interest, as you say every lens differs on pentax camera some lens is lucky for some camera body some are not, so I'm not going to tune and try to get fine on every lens.

the 18 55's aperture is too small that in indoor activities, scene pictures, it is not obvious even if out of focus.
after previous tuning I've shot some scene picture with 55mmF/8 the picture is very sharp no sign of focus issue.

but when i look back indoor pictures taken before the tunings, actually many seems out of focus slightly, not that perfect . on indoor home shooting the 18 55 too can isolate subject from background forground slightly.
the 18 55's DoF is too wide, harder to determine back/front focus with a focus chart. maybe need to print a gigantic version of the chart
12-02-2012, 06:01 PM   #10
Pentaxian
Na Horuk's Avatar

Join Date: Feb 2012
Location: Slovenia, probably
Photos: Gallery | Albums
Posts: 10,874
The thing is, some of us can't see that great and use the (auto)focus confirm to.. well.. confirm the focus. Of course, it doesn't work when the focus confirm lies. So something like this can be very useful, though it seems rather complicated. A good explanation on how to use these screws correctly would be great, though I guess most people will just stick to af fine adjust and maybe third party focus screens.
12-03-2012, 11:28 PM   #11
Veteran Member
sterretje's Avatar

Join Date: Dec 2008
Location: Roodepoort, South Africa
Photos: Gallery | Albums
Posts: 3,534
QuoteOriginally posted by Enkhbayar Quote
i've read on internet k20d can memorize idividual lens AF tuning, but k-r doesn't. its sad.
It's not as simple as you think it is.

The K20D can use one global adjustment that affects all lenses; that is what you need to use for MF lenses and works exactly as the K-r. It can also use individual adjustments for lenses that it recognizes (which excludes MF lenses). But using individual and global is mutual exclusive. So you either use global or individual; and you must remember to switch between the two when changing lenses.
12-04-2012, 05:50 AM   #12
Site Supporter




Join Date: Jul 2008
Location: Detroit MI, USA
Posts: 503
QuoteOriginally posted by sterretje Quote
It's not as simple as you think it is.

The K20D can use one global adjustment that affects all lenses; that is what you need to use for MF lenses and works exactly as the K-r. It can also use individual adjustments for lenses that it recognizes (which excludes MF lenses). But using individual and global is mutual exclusive. So you either use global or individual; and you must remember to switch between the two when changing lenses.
No, I just confirmed with my K20D, it will remember the global setting used for MF lens then each lens you set for its other 20 lens. If your saying when you set it to global with fully manual lens it will stay on global when you put on a fully atuo lens? I set my fully manual 50mm, the only option in the menu was the global setting. So I set it to +4. I then put back on the Pentax kit lens and it went to +3(confirmed in photome). Then put back on the manual lens and it went back to global +4 (again confirmed in photome). The setting I had it at. You can use the global setting for MF lens and not have to set anything going back to fully automatic lens. The only time you do is when the camera can't tell the difference between two non-Pentax lens. For example my Sigma 17-70mm and 10-20mm. The camera can't tell the difference between them I have to remember to set them. Lucky I don't really need to. But if I did I would then have to go to the menu.
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!
calibrate, calibration, camera, focus, k-r, kit, lens, lenses, pentax help, pentax k-r focus, screw
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Pentax K-R Broken Flash/Auto Focus omegawolf Troubleshooting and Beginner Help 6 11-27-2012 09:25 AM
Looking for Pentax K-r Camera Calibration Profile for Lightroom ashankar Digital Processing, Software, and Printing 12 02-14-2012 06:05 PM
K-r may need AF calibration service bwDraco Pentax K-r 36 01-25-2011 06:14 AM
Chat w/Pentax Regarding K-r Front Focus krebsy75 Pentax K-r 2 12-23-2010 06:46 AM



All times are GMT -7. The time now is 03:38 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