11-02-2011, 12:40 PM
[quote name='jamesm007' timestamp='1319993943' post='12576']
"Yes, it has occured to me and that's why I sent it back for an AF check-up. Pentax is not present in Switzerland, but they use a 3rd party company (it's only a single guy!), to deal with repairs and revisions."
IMO of course -
This is your problem! dSLRs have demanding specs/adjustments. I auto focused fine tuned my lens all the time. My K20D had no problems with focus. I could even nail many BIF with ease and that with a DA55-300mm! One day a few months ago my rear edial started to skip now and then (over 50,000 clicks!) and I sent it to a very large service center in the USA that has high standards. My camera came back all was good but the tech did say AF was off and he adjusted it. I thought wow I did not have problems. Sure enough my kit DA18-55mm WR that needed +8 AF fine tuning now needed 0. My Sigma 17-70mm, 10-20mm stayed the same. My DA55-300mm that needed 0 now needed +5 (go figure!)... and so on.
No lens had its AF improved but the DA18-55mm WR that had poorish boarders at 18mm f/3.5 became a whole lot better. None of it makes sence!
But you have to understand a Pentax service center uses special equipment to calibrate auto-focus. There are many adjustments for AF. AF fine tuning is a band-aid and does not come close to what can really be done with focus at the factory or proper service center.
Speaking of learning how to properly AF fine tune zoom lens. This was not the issue. But in any case. Did you know that the cross AF points are two AF sensors one vertical and one horizontal. Did you know the service manual tells the tech to do AF fine tuning with the camera both ways landscape and portrait! Makes sense and is something one would never think of. But doing only landscape is OK because its an average of both sensors. At the factory if they do both and the vertical reading is off they can adjust the AF module with 3 screws in the camera that can set the plane of focus square with the sensor. However if that does not do it. The sensor and platters can be adjusted as well!
Because of the amount of focus adjustments to your K5 and lens and how little AF fine tuning can do if things are really off makes me believe you have a bad K-5. The fact the a couple lens work fine does not surprise me as I still can't understand how my DA55-300mm which was perfect at 0 now needs +5, and my DA18-55mm WR now needs 0 instead of +8 and its IQ is much better. My other lens are the same! If they adjusted focus all my lens should change, no? But only two did.
Now trust me my lens are dialed in like a snipers scope. I have a board I made about 51cm wide and 90cm long. It is covered with paper and has a scale on both sides. It has an adjustable center target and I just use my tripod to set the camera to a 45 degree angle to it; and close enough so it fill the frame. This I hope shows how much a fine tuning freak I am.
You should have no major problems IMO your tech is making a mess of things, camera and lens. But what can you do?
If Nikon and or Canon have better service centers there (I am sure they do) I would make the switch. Sorry to see a fellow Pentaxian go but what else can you do?
[/quote]
"Yes, it has occured to me and that's why I sent it back for an AF check-up. Pentax is not present in Switzerland, but they use a 3rd party company (it's only a single guy!), to deal with repairs and revisions."
IMO of course -
This is your problem! dSLRs have demanding specs/adjustments. I auto focused fine tuned my lens all the time. My K20D had no problems with focus. I could even nail many BIF with ease and that with a DA55-300mm! One day a few months ago my rear edial started to skip now and then (over 50,000 clicks!) and I sent it to a very large service center in the USA that has high standards. My camera came back all was good but the tech did say AF was off and he adjusted it. I thought wow I did not have problems. Sure enough my kit DA18-55mm WR that needed +8 AF fine tuning now needed 0. My Sigma 17-70mm, 10-20mm stayed the same. My DA55-300mm that needed 0 now needed +5 (go figure!)... and so on.
No lens had its AF improved but the DA18-55mm WR that had poorish boarders at 18mm f/3.5 became a whole lot better. None of it makes sence!
But you have to understand a Pentax service center uses special equipment to calibrate auto-focus. There are many adjustments for AF. AF fine tuning is a band-aid and does not come close to what can really be done with focus at the factory or proper service center.
Speaking of learning how to properly AF fine tune zoom lens. This was not the issue. But in any case. Did you know that the cross AF points are two AF sensors one vertical and one horizontal. Did you know the service manual tells the tech to do AF fine tuning with the camera both ways landscape and portrait! Makes sense and is something one would never think of. But doing only landscape is OK because its an average of both sensors. At the factory if they do both and the vertical reading is off they can adjust the AF module with 3 screws in the camera that can set the plane of focus square with the sensor. However if that does not do it. The sensor and platters can be adjusted as well!
Because of the amount of focus adjustments to your K5 and lens and how little AF fine tuning can do if things are really off makes me believe you have a bad K-5. The fact the a couple lens work fine does not surprise me as I still can't understand how my DA55-300mm which was perfect at 0 now needs +5, and my DA18-55mm WR now needs 0 instead of +8 and its IQ is much better. My other lens are the same! If they adjusted focus all my lens should change, no? But only two did.
Now trust me my lens are dialed in like a snipers scope. I have a board I made about 51cm wide and 90cm long. It is covered with paper and has a scale on both sides. It has an adjustable center target and I just use my tripod to set the camera to a 45 degree angle to it; and close enough so it fill the frame. This I hope shows how much a fine tuning freak I am.
You should have no major problems IMO your tech is making a mess of things, camera and lens. But what can you do?
If Nikon and or Canon have better service centers there (I am sure they do) I would make the switch. Sorry to see a fellow Pentaxian go but what else can you do?
[/quote]