Back focus on a K-x body...

corvin · 04-07-2018, 09:46 AM

I have 4 K-x bodies that, until yesterday, have been my only cameras (different lens on each to minimize lens switching). One of them focuses too far back and I would like to fix that.

I found this thread that discussed it:
K-x focus adjustment

But it's such an old thread (and such an old model) that the links are outdated.

Does anyone have links to the download still?

And any other advice I would really appreciate. The cameras themselves are pretty bulletproof (some have more than100k clicks on them)...and I intend to keep using them.

Thanks in advance.

maw · 04-07-2018, 10:15 AM - **1 Like**

Originally posted by corvin

Back focus on a K-x body...

Hi corvin,

A short time ago, I posted the correct procedure to set up the front & back focus, I put the link so you can test all the lenses if you want. Front & Back Focus

Kozlok · 04-07-2018, 10:42 AM

Sell it and get a K30? I loved my Kx, but the K-30 is better in every way.

corvin · 04-08-2018, 05:18 AM - **1 Like**

Thanks for the help, Maw. I ended up printing out a sheet linked elsewhere - served better than the one I'd made myself. Biggest question was how to get it into debug mode, but that thread I linked had the info in it. I had read too hastily.

It's still a little squirley on being dialed in 100 percent. Even on a tripod, each shot (100mm pentax 2.8 macro lens @ 2.8) is just slightly different when I refocus. Only minimally, but there's 1/2 line or so variation. I suspect that has to be normal, though. It's performing way better than it did.

Thanks again.

maw · 04-08-2018, 09:41 AM

Originally posted by corvin

Thanks for the help, Maw. I ended up printing out a sheet linked elsewhere - served better than the one I'd made myself. Biggest question was how to get it into debug mode, but that thread I linked had the info in it. I had read too hastily.

Thank you Corvin,

Yesterday I forgot to mention this article on pentaxforums,
which is basically similar to the method I posted, if you have one of those diagrams to perform front/back focus tests you can do so with as many optics as you want.
The precision of the focus is linked to the angle, to the angle illumination, and also do not remember if I wrote it, you have to disable the Shake Reduction,
another thing that can help you is in the camera menu to increase sharpness. Then it will be a matter of patience, but in the end you will be rewarded, sure.

I wish you all the best in your work

corvin · 04-08-2018, 06:38 PM

Thanks for the link and further advice. I think I've *almost* got it dialed in. But I'm going to try with my 50mm 1.8 tonight and sharpen the settings as you recommend.

Miles and miles better now than before, though. Straight from the camera...dog walk just got off the mountain. Almost passable.

maw · 04-08-2018, 07:26 PM

Originally posted by corvin

Thanks for the link and further advice. I think I've *almost* got it dialed in. But I'm going to try with my 50mm 1.8 tonight and sharpen the settings as you recommend.
Miles and miles better now than before, though. Straight from the camera...dog walk just got off the mountain. Almost passable.

I think you're on the right track, from the photos you can see that the symptoms of F/B focus seem to have disappeared,
it's an operation that should be done even if sometimes it's long and boring, but the results will surely pay off for the time.
On your door now you can write work in progress

Good job

corvin · 04-09-2018, 02:35 PM

Thanks again, Maw.

I really have to wonder if everyone gets such inconsistent results. Still fiddling with it. But it's just not the same every time. Within just a few hairs, but not exactly spot on with each shot. And I think my variables are pretty consistent.

maw · 04-09-2018, 03:05 PM - **1 Like**

Hi corvin,

Exactly, sometimes are the small details that make the difference, the three important things (but there are many others), the correct exposure, the correct focus, and the correct framing,
are some of the neglected fundamentals of photography.

I found an article substantially similar but it is well explained, I think it will help you even more.

Why Calibrate?

By Mario

corvin · 04-10-2018, 10:10 AM

Still having fits. Just cannot get it dialed in properly.

In debug mode, my options are:

AF Area Test (0-3)
AF Area Number (0-10)

Then the FocusCorr bar

I've been messing with the FocusCorr bar (sliding scale - moving it to the right to compensate for back focus...stuck at 170um for best results, but not great) - and that at AF area 0.

I assume AF Area Number is for the 11 AF sensors.

But I have no idea what the 0-3 (4 possiblities) of AF Area Test are. And I've only been working with AF Area Test 0.

There's an article here on the K10D that might have info in it.

But I'm stuck on the K-x.

maw · 04-10-2018, 04:02 PM - **1 Like**

Originally posted by corvin

Still having fits. Just cannot get it dialed in properly.

In debug mode, my options are:

AF Area Test (0-3)
AF Area Number (0-10)

Then the FocusCorr bar

I've been messing with the FocusCorr bar (sliding scale - moving it to the right to compensate for back focus...stuck at 170um for best results, but not great) - and that at AF area 0.

I assume AF Area Number is for the 11 AF sensors.

But I have no idea what the 0-3 (4 possiblities) of AF Area Test are. And I've only been working with AF Area Test 0.

Hi Corvin,

I don't think the menu of the K-x is very different from that of the K20 and other cameras, but I don't know if that's what you mean. In K20,
The path is > Custom setting > AF Adjustement, you will find a scale from -10 to +10, remember that if the positive (+) values are sharper you are in Back Focus and vice versa,
so you have to find the one that comes closest to the sharpest 0 point, increasing or decreasing on the scale, you can reset everything,
start again from 0 and focus on the area that seemed sharper, in the previous session, take note.

* I assumes AF Area Number is for the 11 AF sensors.

I recommend using the center point and spot reading, with good lighting.

Cheers Mario

corvin · 04-10-2018, 04:15 PM

Mario,

My question was what do the four variables in the first menu control? (AF Area Test)

This is exceptionally difficult. I can move the focus from back to front, but cannot settle on a sweet spot between. The results are incredibly inconsistent even when I hold the variables steady (tripod, light, distance, aperture, etc.). Five shots on exactly the same settings (taking it out of focus manually between) produce five different results.

Makes me wonder if I'm adjusting the wrong thing - or if there's something wrong with the autofocus itself.

maw · 04-10-2018, 05:03 PM

Originally posted by corvin

My question was what do the four variables in the first menu control? (AF Area Test)

Not being present, I have to rely on what actually happens to you and you refer me.You could tell me what type of Chart you are currently using
and where you are focusing on, at the maximum aperture of course (of course it must be the square on the left at 0), when the 0 line is more focused than the others
(for safety, repeat the test a few times), and if you have a remote control it is better.

Do it calmly and sooner or later you will find a point that is definitely the most exact of the others, then you will let me know.

04-07-2018, 09:46 AM	#1
corvin Forum Member Join Date: Oct 2014 Photos: Gallery \| Albums Posts: 59	Back focus on a K-x body... I have 4 K-x bodies that, until yesterday, have been my only cameras (different lens on each to minimize lens switching). One of them focuses too far back and I would like to fix that. I found this thread that discussed it: K-x focus adjustment But it's such an old thread (and such an old model) that the links are outdated. Does anyone have links to the download still? And any other advice I would really appreciate. The cameras themselves are pretty bulletproof (some have more than100k clicks on them)...and I intend to keep using them. Thanks in advance.

04-07-2018, 10:15 AM - 1 Like	#2
maw Pentaxian Join Date: Feb 2014 Location: Sassari (Italy) Posts: 1,118	Originally posted by corvin Back focus on a K-x body... Hi corvin, A short time ago, I posted the correct procedure to set up the front & back focus, I put the link so you can test all the lenses if you want. Front & Back Focus Last edited by maw; 04-07-2018 at 10:19 AM. Reason: replaced link

04-09-2018, 03:05 PM - 1 Like	#9
maw Pentaxian Join Date: Feb 2014 Location: Sassari (Italy) Posts: 1,118	Hi corvin, Exactly, sometimes are the small details that make the difference, the three important things (but there are many others), the correct exposure, the correct focus, and the correct framing, are some of the neglected fundamentals of photography. I found an article substantially similar but it is well explained, I think it will help you even more. Why Calibrate? By Mario Last edited by maw; 04-09-2018 at 03:29 PM. Reason: added link

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04-07-2018, 10:42 AM	#3
Kozlok Pentaxian Join Date: Jun 2012 Location: Albuquerque Photos: Gallery Posts: 3,148	Sell it and get a K30? I loved my Kx, but the K-30 is better in every way.

04-08-2018, 05:18 AM - 1 Like	#4
corvin Forum Member Join Date: Oct 2014 Photos: Gallery \| Albums Posts: 59 Original Poster	Thanks for the help, Maw. I ended up printing out a sheet linked elsewhere - served better than the one I'd made myself. Biggest question was how to get it into debug mode, but that thread I linked had the info in it. I had read too hastily. It's still a little squirley on being dialed in 100 percent. Even on a tripod, each shot (100mm pentax 2.8 macro lens @ 2.8) is just slightly different when I refocus. Only minimally, but there's 1/2 line or so variation. I suspect that has to be normal, though. It's performing way better than it did. Thanks again.

04-08-2018, 09:41 AM	#5
maw Pentaxian Join Date: Feb 2014 Location: Sassari (Italy) Posts: 1,118	Originally posted by corvin Thanks for the help, Maw. I ended up printing out a sheet linked elsewhere - served better than the one I'd made myself. Biggest question was how to get it into debug mode, but that thread I linked had the info in it. I had read too hastily. Thank you Corvin, Yesterday I forgot to mention this article on pentaxforums, which is basically similar to the method I posted, if you have one of those diagrams to perform front/back focus tests you can do so with as many optics as you want. The precision of the focus is linked to the angle, to the angle illumination, and also do not remember if I wrote it, you have to disable the Shake Reduction, another thing that can help you is in the camera menu to increase sharpness. Then it will be a matter of patience, but in the end you will be rewarded, sure. I wish you all the best in your work

04-08-2018, 07:26 PM	#7
maw Pentaxian Join Date: Feb 2014 Location: Sassari (Italy) Posts: 1,118	Originally posted by corvin Thanks for the link and further advice. I think I've almost got it dialed in. But I'm going to try with my 50mm 1.8 tonight and sharpen the settings as you recommend. Miles and miles better now than before, though. Straight from the camera...dog walk just got off the mountain. Almost passable. I think you're on the right track, from the photos you can see that the symptoms of F/B focus seem to have disappeared, it's an operation that should be done even if sometimes it's long and boring, but the results will surely pay off for the time. On your door now you can write work in progress Good job

04-09-2018, 02:35 PM	#8
corvin Forum Member Join Date: Oct 2014 Photos: Gallery \| Albums Posts: 59 Original Poster	Thanks again, Maw. I really have to wonder if everyone gets such inconsistent results. Still fiddling with it. But it's just not the same every time. Within just a few hairs, but not exactly spot on with each shot. And I think my variables are pretty consistent.

04-10-2018, 10:10 AM	#10
corvin Forum Member Join Date: Oct 2014 Photos: Gallery \| Albums Posts: 59 Original Poster	Still having fits. Just cannot get it dialed in properly. In debug mode, my options are: AF Area Test (0-3) AF Area Number (0-10) Then the FocusCorr bar I've been messing with the FocusCorr bar (sliding scale - moving it to the right to compensate for back focus...stuck at 170um for best results, but not great) - and that at AF area 0. I assume AF Area Number is for the 11 AF sensors. But I have no idea what the 0-3 (4 possiblities) of AF Area Test are. And I've only been working with AF Area Test 0. There's an article here on the K10D that might have info in it. But I'm stuck on the K-x.

04-10-2018, 04:02 PM - 1 Like	#11
maw Pentaxian Join Date: Feb 2014 Location: Sassari (Italy) Posts: 1,118	Originally posted by corvin Still having fits. Just cannot get it dialed in properly. In debug mode, my options are: AF Area Test (0-3) AF Area Number (0-10) Then the FocusCorr bar I've been messing with the FocusCorr bar (sliding scale - moving it to the right to compensate for back focus...stuck at 170um for best results, but not great) - and that at AF area 0. I assume AF Area Number is for the 11 AF sensors. But I have no idea what the 0-3 (4 possiblities) of AF Area Test are. And I've only been working with AF Area Test 0. Hi Corvin, I don't think the menu of the K-x is very different from that of the K20 and other cameras, but I don't know if that's what you mean. In K20, The path is > Custom setting > AF Adjustement, you will find a scale from -10 to +10, remember that if the positive (+) values are sharper you are in Back Focus and vice versa, so you have to find the one that comes closest to the sharpest 0 point, increasing or decreasing on the scale, you can reset everything, start again from 0 and focus on the area that seemed sharper, in the previous session, take note. * I assumes AF Area Number is for the 11 AF sensors. I recommend using the center point and spot reading, with good lighting. Cheers Mario

04-10-2018, 04:15 PM	#12
corvin Forum Member Join Date: Oct 2014 Photos: Gallery \| Albums Posts: 59 Original Poster	Mario, My question was what do the four variables in the first menu control? (AF Area Test) This is exceptionally difficult. I can move the focus from back to front, but cannot settle on a sweet spot between. The results are incredibly inconsistent even when I hold the variables steady (tripod, light, distance, aperture, etc.). Five shots on exactly the same settings (taking it out of focus manually between) produce five different results. Makes me wonder if I'm adjusting the wrong thing - or if there's something wrong with the autofocus itself.

04-10-2018, 05:03 PM	#13
maw Pentaxian Join Date: Feb 2014 Location: Sassari (Italy) Posts: 1,118	Originally posted by corvin My question was what do the four variables in the first menu control? (AF Area Test) Not being present, I have to rely on what actually happens to you and you refer me.You could tell me what type of Chart you are currently using and where you are focusing on, at the maximum aperture of course (of course it must be the square on the left at 0), when the 0 line is more focused than the others (for safety, repeat the test a few times), and if you have a remote control it is better. Do it calmly and sooner or later you will find a point that is definitely the most exact of the others, then you will let me know.