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06-22-2016, 11:09 AM   #16
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As I understand it, the fine focus adjustment to the AF is in the software and nothing to do with the hardware. Therefore for the street scene picture the focus adjustment does not come into play since I saw that the lens was on infinity and the focal point was 100 yards away and it therefore within the hyper focal range.

I agree that some focal adjustment may help the 2nd photo. My Canon 5D didn't have this feature however I didn't see a need for it as it did a fine job for people pictures, especially since I have a habit of using f8 which gives some room for focusing error.

I will do more experimenting using manual focus before deciding if I will keep this lens. Maybe I'm expecting too much from this lens and am spoiled due to the results I'm getting from the 645Z even using the older legacy lens.

06-22-2016, 05:02 PM   #17
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As I said previously, you are not expecting too much to get sharp/in focus images from your 24-70 on the K-1. Your sample image suggests you may simply require a bit of calibration using "AF fine adjustment".This is quite typical and does not indicate that your lens (or camera) is defective or poor quality. Surely it is worth giving it a go.

At first I was annoyed that it should ever be necessary to do this, but it is worth the effort to check/calibrate every lens you have on your K-1. If you do return the 24-70 then you should still do this for whatever lens/lenses you get. Good luck.
06-22-2016, 08:47 PM   #18
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I've spent some time shooting in manual. First use spot autofocus set on the background, in this case the tree line in the background and take a picture. Then switch to manual a make a shot slightly to the left and slightly to the right of the auto focus shot and compare the results in photoshop. It looks like the focus could be improved slightly my adjusting to the left.

I'm having trouble finding the fine adjustment in the menu. The manual says to got to C4 and select "25 find adjustment". I do not find this option at C4. Where do I find the fine adjustment.

Thanks for the replys so far!
06-22-2016, 10:33 PM   #19
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AF fine tuning is explained here:

Fixing Front and Back Focus - The Remedy - In-Depth Articles

06-22-2016, 11:16 PM - 1 Like   #20
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Different lenses have different performances at different focus distances.
For example, a lens designed for portraiture may perform vastly superior wide open when shot closer to it's minimum focus distance as opposed to at infinity. This isn't something I've actually experimented much with on the K1 with the Pentax 24-70. Generally speaking I've been very very happy with mine. It's as sharp as any other pro grade 24-70 out there. Probably better than most in the sense that you benefit from IBIS.
Another thing to try.... as you are testing on a tripod, have you considered disabling the shake reduction system?
Also try with live view to confirm if it's simply a case that you have a soft copy.

I've had the pleasure of trying two different 24-70's on two different K1's. Tack sharp at the point of focus wide open. Relative to most other pro grade 24-70's out there it's up there with the Canon L 24-70.
I'd be surprised if the PDAF needed much adjustment as the glass doesn't really suffer much spherical aberrations which can play havoc with PDAF on DSLR's. Possibly +/-2.

However keep in mind that (with your portrait sample) F2.8 is still a very narrow DOF so the suggestions about focus adjust are good to get critical focus.

I've also tried the 28-105 and that is a beautiful lens. However from a sharpness perspective the 24-70 is producing sharper results wide open that match what I've seen from the 28-105 at F4. In my mind it's no doubt the superior optic.



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Last edited by tomO2013; 06-23-2016 at 07:56 AM.
06-23-2016, 03:13 AM   #21
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I use a DFA 24-70 on a K-1 and have been quite pleased with the results. I do a lot of landscape photography and so I don't shoot at f2.8 very much, but when I do, it has good center sharpness, a bit weak on the borders. I do agree with the others about checking auto focus. I use live view to check lenses and it has been pretty easy and quick to do. There is an explanation of it here: AF microadjustment for the 1Ds mark III, 1D Mk3, 5D Mk2, 7D, 1D X.

Probably best way to check for things like decentering or sharpness is just to shoot a brick wall though, as uninteresting as that is and use live view auto focus to do it. If it is reasonably sharp there, then fixing PDAF should take care of it for normal shooting.
06-23-2016, 04:41 AM   #22
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QuoteOriginally posted by PhilRich Quote
As I understand it, the fine focus adjustment to the AF is in the software and nothing to do with the hardware.
Front and back focusing is a hardware issue and applies to *your* camera and lens, not anybody else's, since it comes out of their manufacturing tolerances.

Take the shot again, centre AF point in Live View as a test.

This process is immune from PDAF front or back focus.
06-23-2016, 05:44 AM   #23
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This the DFA 24-70 at 70mm and f2.8.



This is 24mm and f2.8 (a pretty dark situation so some softening from noise at the pixel level)



06-23-2016, 09:29 AM   #24
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It looks like I need someone to give step by step instructions on how to get to the correct menu item. According to the instructions the manual says to got to C4 and select "25 find adjustment". I do not find this option at C4. Where do I find the fine adjustment? The previous posts provided good info on how to make the adjustment, however, I cannot not find the place in the menu. My menu does not itemize the options my number, there is no "25" anywhere in the lists.

I've decided to keep this lens.
06-23-2016, 05:29 PM   #25
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QuoteOriginally posted by PhilRich Quote
It looks like I need someone to give step by step instructions on how to get to the correct menu item. According to the instructions the manual says to got to C4 and select "25 find adjustment". I do not find this option at C4. Where do I find the fine adjustment? The previous posts provided good info on how to make the adjustment, however, I cannot not find the place in the menu. My menu does not itemize the options my number, there is no "25" anywhere in the lists.

I've decided to keep this lens.
From Yvon Bourque's book on the K-1 ...

You might want to purchase it at this site.
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06-23-2016, 07:07 PM   #26
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QuoteOriginally posted by PhilRich Quote
My menu does not itemize the options my number, there is no "25" anywhere in the lists.
.
Just checked Custom 4 on my K-1. Number 25 fine adjustment is there, just as described by others.
06-24-2016, 02:53 AM   #27
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QuoteOriginally posted by PhilRich Quote
It looks like I need someone to give step by step instructions on how to get to the correct menu item. According to the instructions the manual says to got to C4 and select "25 find adjustment". I do not find this option at C4. Where do I find the fine adjustment? The previous posts provided good info on how to make the adjustment, however, I cannot not find the place in the menu. My menu does not itemize the options my number, there is no "25" anywhere in the lists.

I've decided to keep this lens.
Hit your menu key and then use the controller on the back to toggle once to the left. That is the screen that should have the number 25 on it with AF fine adjust.
06-24-2016, 03:04 AM   #28
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Excellent lens in every possible means.
Only downside is i got dust particle inside the rear element after 2 months usage, it doesn't influence the pictures, but WR is a bit disappointing

It is better than the FA* 28-70 at 28 & 70mm. Sold the FA* which bothered me because of the rotating front element and bought 3 years ago a perfect sigma ex dg macro.

The sigma ex dg macro i got is as good in every way as the DFA WR Pentax . Optically outstanding, AF accurate & blazing fast, built like a tank.
3 years of usage, rain, snow, dust, salted water in the atlantic and some photoprojects involving flying milk and painting left the sigma intact. It's screwdriven and seems immortal.

Try to find a good copy of the sigma before buying the DFA
06-24-2016, 11:10 AM   #29
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QuoteOriginally posted by Rondec Quote
Hit your menu key and then use the controller on the back to toggle once to the left. That is the screen that should have the number 25 on it with AF fine adjust.
This is the information I was looking for - thanks. I had no idea that there was more depth to the menu.
06-27-2016, 03:49 PM   #30
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This lens suffers from focus shift when stopping down so you need to focus after you have selected aperture. Also using live view may be a problem due to the fact that live view focuses wide open.

I also was not impressed but after a fine tune and knowing about the shift I now get sharp images. Still not impressed with the edge sharpness.
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