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10-06-2015, 08:04 AM   #1
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Why is focus failing on my K-30?

Recently I was attempting to take photos of stationary and slow moving people indoors in the evening with bright interior light with my DA*55mm at f/1.4-4.0 on my K-30. Normally this combination focuses quickly and accurately in a similar situation. However this time the camera/lens combo was having a heck of time focusing and doing so accurately. In one instance I was attempting photograph a person sitting still on a chair. The camera was set to center point focus, the lens would move through the zoom range and give up. This happened a few times until it would focus lock on the person. However the results are still out of focus. Is there anything I can check on the camera that might be the culprit for these poor results?



10-06-2015, 08:22 AM - 1 Like   #2
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Are you able to manual focus? How about live view? There is an issue with some K-30s and K-50s where the controller for the main mirror begins to fail resulting in difficulties for both PDAF and manual focus.


Steve
10-06-2015, 08:44 AM   #3
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QuoteOriginally posted by stevebrot Quote
Are you able to manual focus? How about live view? There is an issue with some K-30s and K-50s where the controller for the main mirror begins to fail resulting in difficulties for both PDAF and manual focus.


Steve


Thank you Steve. I did not try manual focus or live view. I assume you're suggesting live view so that I check contrast detection instead of phase detection. I didn't try manual focus because the f value was so low I thought getting correct manual focus would be too difficult.


Does this controller mean the mirror doesn't close all the way? If so that makes sense why focusing in manual would not work.
10-06-2015, 09:48 AM   #4
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QuoteOriginally posted by Newtophotos Quote
Does this controller mean the mirror doesn't close all the way? If so that makes sense why focusing in manual would not work.
The mirror does not return properly to the correct angle. The most obvious effect is that manual focus is difficult and/or impossible. Less obvious is that PDAF may fail. The light for the PDAF sensor is directed through the (half-silvered) main mirror and angle is important. Comparing with AF in live view (CDAF system) allows you to rule out the lens or the AF drive as the cause of the problem.


Steve

10-06-2015, 09:51 AM   #5
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Same problems/symptoms with my Tamron 17-50 on my K-30. IDK why
10-06-2015, 03:19 PM   #6
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I have had poor autofocus (on K3 or K5) when there was a lot of dust on the front element of the lens. Once cleaned, all was well again.
10-08-2015, 06:22 PM   #7
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QuoteOriginally posted by stevebrot Quote
The mirror does not return properly to the correct angle. The most obvious effect is that manual focus is difficult and/or impossible. Less obvious is that PDAF may fail. The light for the PDAF sensor is directed through the (half-silvered) main mirror and angle is important. Comparing with AF in live view (CDAF system) allows you to rule out the lens or the AF drive as the cause of the problem.


Steve
Thank you again Steve. Focus will go past and then back to the correct focus in live view (this is normal for CDAF right?). However in regular mode (using PDAF) the focus won't focus and I can't fully press down the shutter to take a picture. Consequently I think you are correct Steve on your diagnosis. What can I do to fix this problem? Is there anyway to know if it is the PDAF module or a mechanical issue inside the camera? I have a wedding in a week I'd like to get some good pictures at.

Cleaning the front element seems to have no effect. Is gently wiping the front element with cotton bad for the SMC coating?

Last edited by Newtophotos; 10-08-2015 at 06:31 PM.
10-09-2015, 07:02 AM   #8
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Is this something I can fix myself or do I have to send it in for service?

Interestingly I tried focusing with my DA*16-50mm and it has none of the problems the DA*55mm has. Could this be an issue with the 55mm?


Last edited by Newtophotos; 10-09-2015 at 07:38 PM.
10-10-2015, 11:27 AM   #9
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Since it seems to be lens dependent, with more of a problem with the faster lens, It's also possible that your AF sensor might have some specks of dust on it. I'd try a rocket blower on the sensor at the bottom of the mirror box with the mirror locked up. Afterwards, I'd also direct some air at the image sensor since you might blow some dust on it, then check the image sensor for dust.

Scott
10-10-2015, 06:11 PM   #10
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QuoteOriginally posted by snostorm Quote
Since it seems to be lens dependent, with more of a problem with the faster lens, It's also possible that your AF sensor might have some specks of dust on it. I'd try a rocket blower on the sensor at the bottom of the mirror box with the mirror locked up. Afterwards, I'd also direct some air at the image sensor since you might blow some dust on it, then check the image sensor for dust.

Scott
Thanks Scott. I don't have a rocket blower, will a can of compressed air work? I know there are so ingredients in compressed air to ward off drug users.

Also, some places charge $75 for professional cleaning services of a DSLR. Do these "professional" services include more than just using air to clean the inside of a camera?
10-11-2015, 12:58 PM   #11
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Hi NTP,

canned compressed air is not a good idea. Unless there has been some technical advancement in this, there are contaminants and possibly moisture released with canned compressed air. A Rocket blower or some other bulb blower has been the standard of the industry since before digital, but for sensor cleaning, there probably is no better tool. I'd invest in one, they're not expensive. One tip when using one. Compress the bulb a number of times out in the open before using it inside your camera. There might be some residual dust inside the bulb, and this can clear it out instead of depositing it in your camera.

Scott
10-13-2015, 07:24 PM   #12
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QuoteOriginally posted by snostorm Quote
Hi NTP,

canned compressed air is not a good idea. Unless there has been some technical advancement in this, there are contaminants and possibly moisture released with canned compressed air. A Rocket blower or some other bulb blower has been the standard of the industry since before digital, but for sensor cleaning, there probably is no better tool. I'd invest in one, they're not expensive. One tip when using one. Compress the bulb a number of times out in the open before using it inside your camera. There might be some residual dust inside the bulb, and this can clear it out instead of depositing it in your camera.

Scott
Thanks Scott. I took your advice and purchased the rocket blower. I compressed it a few times to blow any dust and then used it extensively on my white K30. Unfortunately it did not help.

Interestingly I tried the DA*55mm on my black K30 for the first time (which my father has had of the last few months) and the same inability to focus keeps occurring. The issue occurs at anywhere from f/8 up to f/1.4. Could it be a problem internal to the lens?
10-14-2015, 07:20 PM   #13
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Hi NTP,

Looks like you've isolated the problem, and you've gained a valuable internal cleaning device with the RB. I'd send the lens in to be checked. If the problem seems to be the same with both bodies, then it's most likely outside of spec, and should be able to be adjusted without sending in a body with it. If it's out of warranty, I'd consider sending it to a third party for repair, or at least make some inquiries via email before you decide. KEH, the used camera dealer, Lens Rentals, and Eric Hendrickson should all be good alternatives to Ricoh.Pentax for out of warranty lens repairs.

Scott
11-13-2015, 01:52 PM   #14
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QuoteOriginally posted by snostorm Quote
Hi NTP,

Looks like you've isolated the problem, and you've gained a valuable internal cleaning device with the RB. I'd send the lens in to be checked. If the problem seems to be the same with both bodies, then it's most likely outside of spec, and should be able to be adjusted without sending in a body with it. If it's out of warranty, I'd consider sending it to a third party for repair, or at least make some inquiries via email before you decide. KEH, the used camera dealer, Lens Rentals, and Eric Hendrickson should all be good alternatives to Ricoh.Pentax for out of warranty lens repairs.

Scott

Thanks again Scott,


Could it possibly be an SDM failure that is causing the problem? Are there any common symptoms of a SDM that is about to or has already failed?
11-15-2015, 06:25 PM   #15
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QuoteOriginally posted by snostorm Quote
Since it seems to be lens dependent, with more of a problem with the faster lens, It's also possible that your AF sensor might have some specks of dust on it. I'd try a rocket blower on the sensor at the bottom of the mirror box with the mirror locked up. Afterwards, I'd also direct some air at the image sensor since you might blow some dust on it, then check the image sensor for dust.

Scott
I was having the same problem trying to adjust the focus on my FA31 with my K-50. It would go from needing +10 to -10
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