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10-05-2013, 04:26 PM   #1
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Adjusting registration distance? K-7

Soooooooo.....long story short I fell a few weeks ago and destroyed my A35-105/3.5 and managed to strip a few screws on the bayonet ring of the K-7 that I *just* bought used a month or so ago. I managed to repair the screw holes thanks to another thread here on PF and looks like the mount is still miraculously parallel with the sensor and in good alignment. My real problem is this. Somehow the registration distance has moved. All of my lenses now focus past infinity. I tried to calibrate the AF so I could at least get focus lock at infinity on my MF lenses as they all now turn past infinity. The camera was at +5 globally when I bought it, so I know it didn't have perfect registration to begin with, but now taking it to +10 is still not enough, but gets it pretty close. It might need +15 or so. I know that I could go into debug mode and change AF adjustment to go past +10, but that isn't nearly as nice as every MF lens just stopping at infinity like most of mine do. It would be nice to get the distance scales accurate again as I tend to zone focus sometimes. So I'm down to live view or visual confirmation in the viewfinder to achieve critical focus and accurate AF is now no longer possible. I know what you all are going to say. "Send it in to CRIS." Its going to cost nearly what I paid for the camera, if not more, to have them fix the alignment. I may eventually do that if I can't come up with any way to fix this myself because my 2nd original K-7 body is pretty worn out at this point and needs a new shutter button assembly pretty badly, not to mention the sensor has some permadust on it now. Sooooo enough rambling. I obviously need to move my mount forward. does anyone have any idea what distance focus adjusting accounts for? also, can I get spacers anywhere that are thin enough and will fit around the screws? I'm thinking somewhere along .25mm in thickness and adding more as needed. It looks like it only needs a very small bump in distance. I know I can adjust this somehow. I'm ok with taking the time to unmount and remount the ring until I can get it to as close to 0 AF adjustment as possible. Anyone have any good ideas? I'm thinking some spacers would do the trick. I'm not looking for absolute perfection, but getting in the ballpark would be a lot better than what I have now. In the meantime I will just press on with the old workhorse until the shutter stops firing. At least that one has a perfectly registered mount.

10-05-2013, 04:42 PM   #2
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Well not to be sarcastic but, send it to CRIS.

Now that I've said that. As to washers, hmm maybe make your own from sheets of plastic? You can get sheets with particular thicknesses at craft stores or online at precision parts sellers. You will need a micrometer to really do this right and tell the difference between .25mm and .28mm or whatever.

Personally I doubt you can (or anyone) can get it right without a proper bench and alignment test gear. But I admire you for trying.
10-05-2013, 04:47 PM   #3
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QuoteOriginally posted by jatrax Quote

Personally I doubt you can (or anyone) can get it right without a proper bench and alignment test gear. But I admire you for trying.
Well, I made it this far with the repair. I won't be defeated so easily!
10-05-2013, 04:48 PM   #4
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QuoteOriginally posted by zosxavius Quote
Soooooooo.....long story short I fell a few weeks ago and destroyed my A35-105/3.5 and managed to strip a few screws on the bayonet ring of the K-7 that I *just* bought used a month or so ago. I managed to repair the screw holes thanks to another thread here on PF and looks like the mount is still miraculously parallel with the sensor and in good alignment. My real problem is this. Somehow the registration distance has moved. All of my lenses now focus past infinity. I tried to calibrate the AF so I could at least get focus lock at infinity on my MF lenses as they all now turn past infinity. The camera was at +5 globally when I bought it, so I know it didn't have perfect registration to begin with, but now taking it to +10 is still not enough, but gets it pretty close. It might need +15 or so. I know that I could go into debug mode and change AF adjustment to go past +10, but that isn't nearly as nice as every MF lens just stopping at infinity like most of mine do. It would be nice to get the distance scales accurate again as I tend to zone focus sometimes. So I'm down to live view or visual confirmation in the viewfinder to achieve critical focus and accurate AF is now no longer possible. I know what you all are going to say. "Send it in to CRIS." Its going to cost nearly what I paid for the camera, if not more, to have them fix the alignment. I may eventually do that if I can't come up with any way to fix this myself because my 2nd original K-7 body is pretty worn out at this point and needs a new shutter button assembly pretty badly, not to mention the sensor has some permadust on it now. Sooooo enough rambling. I obviously need to move my mount forward. does anyone have any idea what distance focus adjusting accounts for? also, can I get spacers anywhere that are thin enough and will fit around the screws? I'm thinking somewhere along .25mm in thickness and adding more as needed. It looks like it only needs a very small bump in distance. I know I can adjust this somehow. I'm ok with taking the time to unmount and remount the ring until I can get it to as close to 0 AF adjustment as possible. Anyone have any good ideas? I'm thinking some spacers would do the trick. I'm not looking for absolute perfection, but getting in the ballpark would be a lot better than what I have now. In the meantime I will just press on with the old workhorse until the shutter stops firing. At least that one has a perfectly registered mount.
So what you are saying is that the AUTO focus is off now.
That would indicate that the AF block got shifted when you dropped the camera. Adjusting the registration distance will just mess things up, specially if the LV and manual focus work O.K.
To DIY, the bottom needs to be taken apart to gain access to the AF block adjusting screws, AFAIK. I could be wrong how ever.

10-05-2013, 05:19 PM   #5
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QuoteOriginally posted by Ex Finn. Quote
So what you are saying is that the AUTO focus is off now.
That would indicate that the AF block got shifted when you dropped the camera. Adjusting the registration distance will just mess things up, specially if the LV and manual focus work O.K.
To DIY, the bottom needs to be taken apart to gain access to the AF block adjusting screws, AFAIK. I could be wrong how ever.
Yeah, but when you use and rely on AF for focus confirmation on MF lenses its a real serious PITA for it to be incorrect. The flange distance is too short. It needs to increase somehow. I'm going to try to shim this somehow. (good idea on making my own washers...) The distance my one lens moves is almost 1mm towards the mount before it gets into infinity, so I know a rough idea of how much it should move. On my first k-7 the mount is perfect and all of my MF lenses dead stop at infinity. On the second k-7 they focus past infinity, so clearly the mount registration is incorrect regardless of how accurate the AF is or where the AF block is sitting. I'm going to look for some premade spacers. The thinnest I can find so far is 2mm, so I might have to come up with something myself.
10-05-2013, 05:32 PM   #6
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QuoteOriginally posted by zosxavius Quote
Yeah, but when you use and rely on AF for focus confirmation on MF lenses its a real serious PITA for it to be incorrect. The flange distance is too short. It needs to increase somehow. I'm going to try to shim this somehow. (good idea on making my own washers...) The distance my one lens moves is almost 1mm towards the mount before it gets into infinity, so I know a rough idea of how much it should move. On my first k-7 the mount is perfect and all of my MF lenses dead stop at infinity. On the second k-7 they focus past infinity, so clearly the mount registration is incorrect regardless of how accurate the AF is or where the AF block is sitting. I'm going to look for some premade spacers. The thinnest I can find so far is 2mm, so I might have to come up with something myself.
OK. So to be clear, if you go to LV and manually focus and take an image, it is fine?.
10-05-2013, 05:38 PM   #7
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QuoteOriginally posted by zosxavius Quote
The thinnest I can find so far is 2mm, so I might have to come up with something myself.
I've used sheets of Post-it(r) notes to shim my focusing screen but as they are paper not sure how that would work on the mount.

But I am not sure you are looking at this right. I don't see how the mount can have moved and still be put back in place? I don't remember there being any adjustment there the one time I took one apart (on a film camera), just a solid screwed in mount. Are you sure it is not something else that is out of alignment? I'll admit I have no idea what, just trying to think of anything else it might be before you go to all the trouble.
10-05-2013, 05:44 PM   #8
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QuoteOriginally posted by jatrax Quote
I've used sheets of Post-it(r) notes to shim my focusing screen but as they are paper not sure how that would work on the mount.

But I am not sure you are looking at this right. I don't see how the mount can have moved and still be put back in place? I don't remember there being any adjustment there the one time I took one apart (on a film camera), just a solid screwed in mount. Are you sure it is not something else that is out of alignment? I'll admit I have no idea what, just trying to think of anything else it might be before you go to all the trouble.
Something else is out of whack. I am all for a DIY myself but this needs to be send in for repair IMO.

10-05-2013, 06:13 PM   #9
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QuoteOriginally posted by Ex Finn. Quote
Something else is out of whack. I am all for a DIY myself but this needs to be send in for repair IMO.
+1. I've done a lot of DIY but I would send this in for a quote to CRIS or contact Eric and see if he would look at it.
10-05-2013, 08:05 PM   #10
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QuoteOriginally posted by zosxavius Quote
Soooooooo.....long story short I fell a few weeks ago and destroyed my A35-105/3.5 and managed to strip a few screws on the bayonet ring of the K-7 that I *just* bought used a month or so ago. I managed to repair the screw holes thanks to another thread here on PF and looks like the mount is still miraculously parallel with the sensor and in good alignment. My real problem is this. Somehow the registration distance has moved. All of my lenses now focus past infinity. I tried to calibrate the AF so I could at least get focus lock at infinity on my MF lenses as they all now turn past infinity. The camera was at +5 globally when I bought it, so I know it didn't have perfect registration to begin with, but now taking it to +10 is still not enough, but gets it pretty close. It might need +15 or so. I know that I could go into debug mode and change AF adjustment to go past +10, but that isn't nearly as nice as every MF lens just stopping at infinity like most of mine do. It would be nice to get the distance scales accurate again as I tend to zone focus sometimes. So I'm down to live view or visual confirmation in the viewfinder to achieve critical focus and accurate AF is now no longer possible. I know what you all are going to say. "Send it in to CRIS." Its going to cost nearly what I paid for the camera, if not more, to have them fix the alignment. I may eventually do that if I can't come up with any way to fix this myself because my 2nd original K-7 body is pretty worn out at this point and needs a new shutter button assembly pretty badly, not to mention the sensor has some permadust on it now. Sooooo enough rambling. I obviously need to move my mount forward. does anyone have any idea what distance focus adjusting accounts for? also, can I get spacers anywhere that are thin enough and will fit around the screws? I'm thinking somewhere along .25mm in thickness and adding more as needed. It looks like it only needs a very small bump in distance. I know I can adjust this somehow. I'm ok with taking the time to unmount and remount the ring until I can get it to as close to 0 AF adjustment as possible. Anyone have any good ideas? I'm thinking some spacers would do the trick. I'm not looking for absolute perfection, but getting in the ballpark would be a lot better than what I have now. In the meantime I will just press on with the old workhorse until the shutter stops firing. At least that one has a perfectly registered mount.

Well the shake reduction assembly (that holds the sensor) sits on 3 adjusting screws with springs and lots of glue to hold its position after factory adjustment. It moves as the AF module, pan/tilt (distance from lens mount). I don't think most people are aware of how many adjustments there are just to get good auto focus in a dSLR. Its not a few screws, its a whole process, timely and expensive even on a large scale. Its why lens vary so much. Yep I said lens. Who knows Photozones K10D could have been close to the max/min of manufacturing tolerance and lens that are close... This was solved somewhat with AF fine tuning. Even AF fine tuning can't compensate for the pan/tilt motion of the AF module and sensor. They must be in exact alignment in all temperatures (expansion/contraction), knocks, bumps, drops, and hold it over time. I still say dSLR check ups are not a bad idea? And there is no such thing as exact, only good enough to our eyes.

Here is a link to some Pentax service manuals. Most Pentax bodies have the same basic design since Pentax first dSLR; same concept that is. If you study them enough you will get a good idea

Downloads

The password is in the folders but its 8639 to save you time.

Now this is not to stop you from the fun of trying to fix it. Its just showing you where the sensor is adjusted in relation to the lens mount. The whole Shake Reduction platter is adjusted. Its a non-serviceable assembly holding the sensor, magnets, coils, hall sensors, its a big piece of metal with three screws to adjust it.

The pic below is not showing the Shake Reduction-Sensor platter. Only first support and the shutter before it. The manuals will give you a clear insight.
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