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10-25-2017, 10:53 PM   #16
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QuoteOriginally posted by BruceBanner Quote
When you say 'AF to infinity' yer then obviously meaning the furthest mountain/skyline thingy away. Like also... with my DA 15mm lens, is infinity considered something like anything past as certain distance?

Wait... there's no way to bracket with different fine adjustments, so do you mean snap the shot, go into the camera, change the fine adjustment, shoot again, and so on so forth? Manually making the changes each shot? if I deem the file that is 15th out of 21 is the best then +4 is the adjustment used for the shot.
On a 15mm wide angle prime, I'd say anything 100 meters away is essentially infinity, but yes, mountains a few miles/kilometers away are just fine.

And YES the methodology you wrote is what I had in mind. Personally I would just start with zero, +2 and -2, and then analyze the results. If zero is the best, then you're done! If the +2 is slightly better then the other two, then I'd probably test +1 thru +10.

The only reason I think doing an infinity check would be useless is if you typically shoot with that lens with foreground subjects at 1 meter and backgrounds at infinity with a hyperfocal distance at 2 meters. IF that's the case, then I'd do the standard test with your chart at 2 meters.

10-25-2017, 11:04 PM   #17
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QuoteOriginally posted by Alex645 Quote
On a 15mm wide angle prime, I'd say anything 100 meters away is essentially infinity, but yes, mountains a few miles/kilometers away are just fine.

And YES the methodology you wrote is what I had in mind. Personally I would just start with zero, +2 and -2, and then analyze the results. If zero is the best, then you're done! If the +2 is slightly better then the other two, then I'd probably test +1 thru +10.

The only reason I think doing an infinity check would be useless is if you typically shoot with that lens with foreground subjects at 1 meter and backgrounds at infinity with a hyperfocal distance at 2 meters. IF that's the case, then I'd do the standard test with your chart at 2 meters.
Ah yes clever, efficiency! I will report back!
11-05-2017, 07:08 PM   #18
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I was hoping to get out today to do an infinity test, but the weather is pretty bad. I might do another Focus Sheet test with the DA15mm, and that got me thinking... I wonder if anyone finds a need for a different Fine Adjustment between Macro and Infinity use with the same lens? For example, I shot last week a nice macro with the DA15mm, in all honesty I haven't fine tuned the DA15 for that purpose at all, I either/or both spammed the shutter in AF.C or used MF and allowed my body movement and wind to find one shot in the 60 or so spammed that I felt hit the focus spot I was exactly looking for (pic is here by the way). It would be real swell to bring that spamming of 60 shots down to 10 lol.

But yeh, with the 5 user modes and the predominate use of this DA15mm on the KP, i would have the option of setting a 'Macro' mode as well as 'Infinity' if the Fine Adjustments for both differed. And it just got me wondering really if that was a genuine thing people found across various lenses and camera bodies, as it feels like that's what I experience time to time.
11-05-2017, 07:31 PM   #19
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QuoteOriginally posted by BruceBanner Quote
with the 5 user modes and the predominate use of this DA15mm on the KP, i would have the option of setting a 'Macro' mode as well as 'Infinity' if the Fine Adjustments for both differed.
Are you sure the KP will change the AF fine adjustment between different user modes with the same lens? That would be really smart, but I wasn't aware it had that capability with the same lens.

11-05-2017, 07:35 PM   #20
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QuoteOriginally posted by Alex645 Quote
Are you sure the KP will change the AF fine adjustment between different user modes with the same lens? That would be really smart, but I wasn't aware it had that capability with the same lens.
Oh... good point actually. I'll test that now, 2 secs..

EDIT: Correct, this actually can't be done at all. Seems a manual adjustment of Fine Adjustments would be needed if this was actually even a thing rather than a Bruce madness brain scheme malfunction...
11-05-2017, 08:09 PM   #21
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Ok, so I'm doing a 'macro' Focus test with the DA15mm, that is the lens is pretty close to the sheet. I noticed an oddity occurring that I don't think I picked up on when previously messing around calibrating lens equipment. Please have a look at the attached pic below.

Ok, so I have circled black in the middle of the sheet to highlight that I think you will all agree that the top '3' is in better focus than the lower '3', I drew arrows to the right as i think those numbers are even clearer to see the difference, top digits are better focused (this is back focusing i think?). But the red circles on the left, its harder to tell, but the lower '2 and 3' are actually better focused than the top sided '2 and 3'. It's as if the lens from middle to left has swapped focusing strength, going from back focus predominately towards more even or actually a tad fwd focusing ??

However looking at the same digits on the right and you can see it is more akin to the middle, ie back focusing.

What's going on? Bad set up? I got the tripod bubbles to be as centered as possible and then used the incamera sensors to get as centered X and Y as possible. When Focus Sheeting do we generally just ignore the side results more and concentrate on the mid?
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11-05-2017, 09:13 PM   #22
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Hi Bruce, insomniac Pete here again.

To answer the easiest questions first, yes generally just stick to the centre of the chart to fine tune the AF, and yes this appears to show a bit of back-focus.

Now the harder part, the edges. I am assuming your chart is perfectly flat and aligned because I know you have put a lot of effort into this. What you are seeing is probably a slight amount of decentreing of the lens or one of the elements is just a fraction out of alignment. This means that not all of the focal plane is uniformly in focus. Now nearly all lenses display a softness at the edge versus the centre, and you will find in practice that your difference here will not be noticeable in practice. It is magnified in the test as you are so close to the chart because it is a 15mm lens.

As a little test try this one again, but each time take the lens off the camera and give it a little shake or tap it gently, you may find different results each time !
11-05-2017, 10:01 PM   #23
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QuoteOriginally posted by pschlute Quote
Hi Bruce, insomniac Pete here again.

To answer the easiest questions first, yes generally just stick to the centre of the chart to fine tune the AF, and yes this appears to show a bit of back-focus.

Now the harder part, the edges. I am assuming your chart is perfectly flat and aligned because I know you have put a lot of effort into this. What you are seeing is probably a slight amount of decentreing of the lens or one of the elements is just a fraction out of alignment. This means that not all of the focal plane is uniformly in focus. Now nearly all lenses display a softness at the edge versus the centre, and you will find in practice that your difference here will not be noticeable in practice. It is magnified in the test as you are so close to the chart because it is a 15mm lens.

As a little test try this one again, but each time take the lens off the camera and give it a little shake or tap it gently, you may find different results each time !
Interesting that you should say that. After that testing with the KP and DA15mm I put the K-1 back on with the FA50 and 100mmDFA and retested. I found both needed changed, by a factor of 3-5 adjustments. I wonder if the act of taking off and putting back on affects focus... <sigh>

11-05-2017, 10:14 PM - 1 Like   #24
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QuoteOriginally posted by BruceBanner Quote
Interesting that you should say that
Welcome to the vagaries of camera autofocus !

AF is not the 100% accurate beast we may like to think it is. This is why it is so important that any AF adjustment be made only after at least 10 tests at each setting. If you get 7 out of 10 consistent results you are doing well.
11-05-2017, 10:39 PM - 1 Like   #25
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Bruce, the left vs. right issue is a decentered lens problem. Ideally the first thing you'd want to do are run these tests within the period that you could return a new lens or send it in under warranty to have the decentered problem fixed by Pentax. Back in the day, when there were many brick & mortar stores that actually carried a case load of inventory, I'd develop a rapport with the manager so that when I bought a new lens, I could try and test many. Some folks do this with B&H or Amazon, making note of the serial number and then returning every "dud" or less than perfectly centered lens they receive.

One potential issue you may be having in the inconsistent fine adjustment tests is that in your posted example, it says you used Pattern metered mode. That could throw things off; change to Spot so you know it is only trying to focus on that center spot target only.
11-06-2017, 12:21 AM   #26
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QuoteOriginally posted by Alex645 Quote
Bruce, the left vs. right issue is a decentered lens problem. Ideally the first thing you'd want to do are run these tests within the period that you could return a new lens or send it in under warranty to have the decentered problem fixed by Pentax. Back in the day, when there were many brick & mortar stores that actually carried a case load of inventory, I'd develop a rapport with the manager so that when I bought a new lens, I could try and test many. Some folks do this with B&H or Amazon, making note of the serial number and then returning every "dud" or less than perfectly centered lens they receive.

One potential issue you may be having in the inconsistent fine adjustment tests is that in your posted example, it says you used Pattern metered mode. That could throw things off; change to Spot so you know it is only trying to focus on that center spot target only.
Interesting, I didn't think the meter mode affected focus.
11-06-2017, 01:20 AM   #27
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QuoteOriginally posted by BruceBanner Quote
Interesting, I didn't think the meter mode affected focus.
Sorry, my bad; it isn't the exposure metering mode, so Pattern has nothing to do with it. I'm referring to the the AF mode on page 60 toward the bottom:

http://www.ricoh-imaging.co.jp/english/support/man-pdf/kP.pdf

The EXIF metadata doesn't reveal this, so perhaps you were already on spot focus in the AF mode?
11-06-2017, 10:11 PM   #28
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QuoteOriginally posted by Alex645 Quote
Sorry, my bad; it isn't the exposure metering mode, so Pattern has nothing to do with it. I'm referring to the the AF mode on page 60 toward the bottom:

http://www.ricoh-imaging.co.jp/english/support/man-pdf/kP.pdf

The EXIF metadata doesn't reveal this, so perhaps you were already on spot focus in the AF mode?
I was using the SEL AF Mode, whereby you choose the spot, I left it on the center. It wasn't the mode where it also has more faded boxes around it (SEL9?) or whatever, just the single spot. I thought this was the same as 'center spot' mode, but perhaps not?
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