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12-04-2023, 09:41 AM   #166
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QuoteOriginally posted by UncleVanya Quote
This may be worth reporting formally to Ricoh. If enough people document this, then firmware may be developed to address it on the k3iii.
I'll report, but I first need to run a few more tests to check if those kind focus issues are also present on my K-3II and if I can reproduce that behavior with my others lenses. I did only used 16-50PLM for landscape on my K-3II, but I never noticed such issues with K-3II and 70mm Ltd for portraits.

12-04-2023, 11:55 AM   #167
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Honestly I'm not sure what to report to Pentax. I'll have to test in a more controlled setup, but so far my 16-50 PLM seems OK at various focus points. My new 35 Limited Macro however will sometimes hit sharp center focus, and then immediately with the next re-focus on the same target be horribly off.
12-04-2023, 12:25 PM   #168
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QuoteOriginally posted by sebberry Quote
Honestly I'm not sure what to report to Pentax. I'll have to test in a more controlled setup, but so far my 16-50 PLM seems OK at various focus points. My new 35 Limited Macro however will sometimes hit sharp center focus, and then immediately with the next re-focus on the same target be horribly off.
Thatís a bit different. I was seeing several people saying what seemed to be a high portion of people missing focus using the 16-50 plm outside the central point. if thatís not a consistent issue Iím not sure what to think.
12-04-2023, 12:37 PM   #169
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QuoteOriginally posted by superdave Quote
first need to run a few more tests to check if those kind focus issues are also present on my K-3II
@superdave, posts 77 and 81 in this thread might be of use. Not sure whether you have seen them (the thread is fairly long!)

- Craig

12-04-2023, 02:53 PM   #170
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QuoteOriginally posted by c.a.m Quote
@superdave, posts 77 and 81 in this thread might be of use. Not sure whether you have seen them (the thread is fairly long!)

- Craig
Yes I see those posts and I especially like the idea to have multiple targets aligned to AF points. Your K-3III and lens combinations seems to work well. I will try to see if all my lenses or only the 16-50 do not work well with outer AF points, and after that I will probably go the to store to test another K-3III with my 16-50 or another lens copy will my K-3III...
12-05-2023, 12:49 PM   #171
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I did this with three different Bodys an 2 Lenses.
One of the body's where additional one month away for calibration as I couldn't believe this.
All shows exactly same behavior as I showed her long ago in the beginning of this thread (Test results included on page 3).

I use now the K3 III as I use my K3II: only Spot.... as many here say: very frustrating.
And I' my out of those discussion about tracking...when a lens shows this behavior in static situation...
... how can the performance be good in AFC and movement?
All videos of K3III on YT and deep discussion why a photo of a bird is not sharp although the red dot in the rear screen showed it must be sharp... How can you discuss this, when even static situation are not working?

Apart from that : Camera and Lens are excellent
01-04-2024, 10:48 AM   #172
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Here a few news:

As my lens was still within the two-year guarantee period in the EU, I contacted Amazon to request a replacement, and they sent me a new lens.

However, upon receiving it, I noticed that the seal of the box was missing, leading me to suspect that it might not be a brand new lens. Today, when I tested the lens, unfortunately, the autofocus was not reliable. I had good hopes because when doing test on a target, an autofocus adjustment of +6 for 50mm and 16mm, and for the middle, left, and right focus points seems to work. But in practice, it did not work so well. During my initial outdoor test at a greater distance, setting it to +6 resulted in a totally out-of-focus image. The left and right focus points also exhibited issues in practice, requiring a different AFMA.

Moreover, this new copy is noticeably less sharp when wide open (when focusing using LiveView) in the center compared to my current copy. It is also softer overall at almost every aperture and focal length. Additionally, there are areas of super blurriness on the left and right thirds lines at 50mm. During these tests, I discovered that my current copy also had these blurred lines, but at 35mm. However, the blurred lines disappear from f/5.6 and above at 35mm with my copy, while we can still see the blur at f/8 on the new copy.

In conclusion, I've decided to keep my current copy and I will try to live with the focus issues when using the viewfinder. I'll try to find settings that minimize this problem.

So far, I've tested a total of 4 copies of this lens, and the first two had one side of the image consistently soft at f/8 (I do not tested focus with those lenses).
My current copy was initially decentered on the left side, but was fixed by the Pentax technical service. Left side is still softer but not so much.
At least I know I have the best copy over 4 copies. It is almost perfect at f/8 for landscape work, center and right side are super sharp at f/2.8, left side is softer at 35-50mm f/2.8-4. And center focus point is working well using viewfinder.

Why is it so difficult to find a good copy of a (zoom) lens?
I'm starting to wonder if I expected too much of a zoom lens. Is it possible to find a perfect copy of 16-50 that is both sharp and focuses well? Perhaps my extensive use of prime lenses before returning to zoom lenses has affected my expectations?

As a side note, before acquiring the 16-50mm, I tried several standard zoom lenses. One observation I can make is that the 16-50mm PLM seems to be at least as sharp overall (considering all focal lengths) at f/2.8 than all the other lenses I tested at f/8 (two copies of 16-85, two copies of 20-40, Sigma 17-70). The exception is the Sigma 18-35 which may be sharper, but it's less convenient, focus so badly using the viewfinder, and I haven't been able to find a good copy after three tries.

Ah, and I tested my lens a lot with K-3II and the focus issue is also present, so it is not specific to K-3III. Probably that the construction of the lens make it difficult to properly focus with all AF points. A wavy field curvature may explain the issues I guess.

01-06-2024, 01:19 PM   #173
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Repeated focus without changing anything else

I've been watching this thread but not diving in because I seem to have a different problem. But let's see. In all the testing everyone has done for this thread, has anyone found that if they select a focus point, then repeatedly focus there, the focus will oscillate?

I've posted on another thread about improvements in the K3 iii over time because the OP was asking about focus. Mine has the latest firmware and the problem persists.

This is only at wide angles. At long focal lengths it's perfect.

I realised if I held the AF button down, the lens would focus sharply, hold it for maybe a second, then defocus, then come sharp again, and keep oscillating like that for as long as held the AF button. The degree of defocus wasn't really enought to see in the VF, only in final shots.

I tried other wide-angle lenses including the FA28 and DA15 and it did the same there. With those screwdrive lenses you can see the front focussing element find focus, pause, then turn several degrees, stop, pause, then turn back, and repeat. But not long FL lenses which are accurate and consistent.

It also does it at wide-angle whether I use spot-centre or select or auto AF, even using a clear target, and whether I use shutter or back button AF, and whether I use AF-C or AF-S with repeated focusing. And whether SR is on or off, as I wondered if that made a difference.

It just can't decide proper focus with a wide-angle lens.

I cleaned the mirror box and AF sensor exhaustively. In the end I took the camera back under warranty and Pentax UK replaced it with a brand-new one.

The behaviour of the brand-new one was EXACTLY the same. And remains so. So I use LV for wide angles, which I don't like because it slows the process and I like the S:R experience. LV feels clumsy, like shooting with a phone.

Paul
01-06-2024, 01:30 PM   #174
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QuoteOriginally posted by Paul_R_H Quote
I've been watching this thread but not diving in because I seem to have a different problem. But let's see. In all the testing everyone has done for this thread, has anyone found that if they select a focus point, then repeatedly focus there, the focus will oscillate?

I've posted on another thread about improvements in the K3 iii over time because the OP was asking about focus. Mine has the latest firmware and the problem persists.

This is only at wide angles. At long focal lengths it's perfect.

I realised if I held the AF button down, the lens would focus sharply, hold it for maybe a second, then defocus, then come sharp again, and keep oscillating like that for as long as held the AF button. The degree of defocus wasn't really enought to see in the VF, only in final shots.
Paul
Are you on continuous focus rather than single? If not, for giggles have you also tried setting on XS focus point rather than spot?

I've just tried setting the outermost allowed with XS, both left and right, and with both the 16-50 PLM at 16 and the Sigma 8-16 at 8mm. Both were spot on when previewed at 100%, essentially perfect. But using spot focus on the PLM and far left and right the focus was inconsistent, more so on the left than the right. The Sigma was still reliable.

Of course this was not an extensive test, just a half dozen images at each setting, and of the same scene focusing on a bird feeder a couple feet in front of a bush.

Last edited by gatorguy; 01-06-2024 at 02:00 PM.
01-06-2024, 02:36 PM   #175
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QuoteOriginally posted by gatorguy Quote
Are you on continuous focus rather than single? If not, for giggles have you also tried setting on XS focus point rather than spot?

I've just tried setting the outermost allowed with XS, both left and right, and with both the 16-50 PLM at 16 and the Sigma 8-16 at 8mm. Both were spot on when previewed at 100%, essentially perfect. But using spot focus on the PLM and far left and right the focus was inconsistent, more so on the left than the right. The Sigma was still reliable.

Of course this was not an extensive test, just a half dozen images at each setting, and of the same scene focusing on a bird feeder a couple feet in front of a bush.
Thanks. Yes, I've tried spot and Sel XS, with AF-C and AF-S. Just verified the result with the DA 15, as it's easy to do with that lens because I can hear the spasmodic buzz of it re-focusing.

Paul
01-06-2024, 04:41 PM   #176
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QuoteOriginally posted by Paul_R_H Quote
Thanks. Yes, I've tried spot and Sel XS, with AF-C and AF-S. Just verified the result with the DA 15, as it's easy to do with that lens because I can hear the spasmodic buzz of it re-focusing.

Paul
Well, it was worth a try. I'm not seeing the same with my wide angles, and it doesn't get wider than 8mm
I don't have the 15 any longer to check, but I'm not seeing it with any wide-angle lens I do have.
01-07-2024, 01:03 PM - 1 Like   #177
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QuoteOriginally posted by gatorguy Quote
Well, it was worth a try. I'm not seeing the same with my wide angles, and it doesn't get wider than 8mm
I don't have the 15 any longer to check, but I'm not seeing it with any wide-angle lens I do have.
Well I was rather naughty and also posted this question on the thread about 'has anything changed over time' where they were discussing AF as well. It was suggested I don't hold down the AF button but just press once to aquire focus and then as the subject is static let go of the button. It seems to be better on a quick initial test.

Paul
01-10-2024, 10:44 AM   #178
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In AF-S I never had the oscillate behaviour.

In AF-C, it may be possible, especially if the AF micro adjustment is not right for the AF point you are using.

Strange that you have the same issue with two totally different lenses, and two bodies.

For 16-50, I still think that the lens complexity make extremely difficult to get a good copy.
01-11-2024, 12:49 AM - 2 Likes   #179
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QuoteOriginally posted by superdave Quote
In AF-S I never had the oscillate behaviour.

In AF-C, it may be possible, especially if the AF micro adjustment is not right for the AF point you are using.

Strange that you have the same issue with two totally different lenses, and two bodies.

For 16-50, I still think that the lens complexity make extremely difficult to get a good copy.
No, it doesn't happen in AF-S, but I use back-button focussing. It means you have both AF-C and what is in effect AF-S Ė all without changing any setting. For AF-C you hold the back button. For "AF-S", press the button to focus, then release and recompose and finally press the shutter when you are ready.

Anyway, as was suggested to me in the other thread, two things improved it. Changing 'AF-hold status' from 0 to 2, and changing 'AF 'Focus sensitivity in AF-C' from 5 to 3. Both are sun-menus within 'AF with viewfinder' menu item 1-1.

Also I now remind myself not to hold the AF-C button down when nothing is moving.

I went for a photo walk yesterday with the lens permanently at 16mm and f/4, shooting alternately near and far subjects, and got a very high success rate.

(Also, for action photography where I want low focus hold and high sensitivity, those setting are in my U1 and U2 setups.)

Paul
01-12-2024, 12:22 PM   #180
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QuoteOriginally posted by Paul_R_H Quote
No, it doesn't happen in AF-S, but I use back-button focussing. It means you have both AF-C and what is in effect AF-S Ė all without changing any setting. For AF-C you hold the back button. For "AF-S", press the button to focus, then release and recompose and finally press the shutter when you are ready.

Anyway, as was suggested to me in the other thread, two things improved it. Changing 'AF-hold status' from 0 to 2, and changing 'AF 'Focus sensitivity in AF-C' from 5 to 3. Both are sun-menus within 'AF with viewfinder' menu item 1-1.

Also I now remind myself not to hold the AF-C button down when nothing is moving.

I went for a photo walk yesterday with the lens permanently at 16mm and f/4, shooting alternately near and far subjects, and got a very high success rate.

(Also, for action photography where I want low focus hold and high sensitivity, those setting are in my U1 and U2 setups.)

Paul
Glad you got it sorted!
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