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07-02-2012, 05:27 PM   #31
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QuoteOriginally posted by Anvh Quote
state of the art simply means it's new and AF systems are accurate up to a micrometer, dont know if you can call that high precision or if we would even notice more precise autofocus?
Also it says high-precision, nothing about that it is improved.

The lowlight error with the K5 and Kr is something else though, that was a design fault i think so that should be out of the new models!!!
I love this site, everyone is like a mobile dictionary with meanings and terms, that is why I said "in my mind', still it really is suposed to be "improved" over the k5.

OK, sorry Zafar, back to your issue.

07-02-2012, 05:49 PM   #32
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QuoteOriginally posted by Zafar Iqbal Quote
Ah, "good" to hear from someone who seems to be experiencing same issue. "can't really adjust for it because the value is different based on conditions" - exactly what I've been noticing as well. My K-5 shifted the focus as the light level went lower as mentioned earlier, and as I *just* wrote, seems very clear K-r is affected by not only light level, but light type as well (maybe they are related but whatever.. its not working whatever it is!).
I was actually quite happy with the K-5 when the mornings were still overcast. The focus was pretty accurate in most of my shooting conditions. Low light wasn't great, but better than the k-r, but now with the harsher sunlight, even shooting with, rather than against, it really kills the AF(fine adjustment values change, or maybe it's just wildly inaccurate). I have tried center focus AF-S, without re-composition, and the issue is still there. With any kind of cover it usually improves dramatically, and, of course, when the sun is lower in the sky. I've become spoiled by focus peaking, it is so much more accurate. With the K-5 I usually stop down to F4 or 5.6 as default. I'd rather have a k30 for that feature alone. Granted, harsh light isn't the best of shooting conditions, but I'd rather have a shot with harsh shadows than none at all. I can't to go shooting at 530am or 830pm everyday.

I wonder if a 1 stop ND filter would help things better than stopping down.

Last edited by kenafein; 07-02-2012 at 05:59 PM.
07-03-2012, 08:07 AM   #33
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Was out and shot a bunch of pics: 137 in total

29 tack sharp (no doubt about it)
36 close enough (some might be tack sharp but soft looking. Some looks like shifted focus either because of how AF works, or because of the issue I'm writing about - but these were all close enough to count as OK photos, yet not as good as the "tack sharp" ones)
69 out of focus (no doubt about it)

Even with the first two added, I still only get a 50/50 balance but in a non random way. For instance, it was hard to get red street lights in focus:

4 tack sharp
5 close enough
25 out of focus

Green lights:
5 tack sharp
3 close enough
3 out of focus

Pics with Micro Adjustment set to 0:
8 tack sharp
13 close enough
29 out of focus

Pics with Micro Adjustment at -9 (-10 seemed to much - but the severeity of the focus shift changed often, so... meh):
21 tack sharp
23 close enough
40 out of focus

I used Pentax 70mm Limited and Sigma 70-200mm. The degree of focus shifted *seemed* to be equal on both lenses.

Camera settings:
Release priority: Focus
AF-S
Single/center focusing point
AE-L to focus (no half press focusing at all
Never recomposed

Lightroom settings:
Default processing
White balance set to 5500k
Exposure equalized using "Match Total Exposure"
Default sharpness was dialed down to 0

Some of the shots might be flukes - ie. AF system being confused. But not in all cases.

My success rate with K-x is closer towards 75% (during a day with something like this:Copenhagen Carnival 2012 - Zafar Iqbal's Photos | SmugMug ). This K-r, which as mentioned earlier, seems to perform better than my K-5, is still too far off and unpredictable and apparantly is very sensitive about what I'm aiming at.

I've uploaded all "tack sharp" and "out of focus" photos: 2012.07.03 - Zafar Iqbal's Photos | SmugMug

I did not upload the "close enough" shots. I will do so if anyone insists.

I had shot 43.000 exposure before the purchase of K-5. some chance of user error here and there, sure. but I really can't believe I'm may not be getting better results because I might be doing something wrong, or may be using a wrong setting. there aren't even that many new/different settings that would allow such a thing. biggest one might be Release Priority, but I have that set to Focus. On my K-5 as well.

Edit: did the moire test again - while the cam is still set to -9 @ micro adjustment. It does *not* nail the focus as it did last night. If I dial micro adjustment to 0 or turn it off completely, focus then is once again on the dot.

Last edited by Zafar Iqbal; 07-03-2012 at 08:58 AM.
07-03-2012, 09:13 AM   #34
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Well i can't explain the differnces, have you done a firmware update recently?
Anyway do a update regardless to see if that has an effect.

07-03-2012, 10:06 AM   #35
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Can't explain them either, other than it must be a defect.

The K-r I current have is for borrowing while my own camera is being repairs. donøt think I should mess with it. I updated my K-5 when I had it. It didn't help.
07-03-2012, 10:29 AM   #36
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well, I am not 100% happy with my k-5 auto focus too. but that usually happen when I use f2.8. it always miss focus. I can test it very easily. If I take pic of same thing over and over. there must be several pic come out misfocus. but if I use f4 f5.6 and below. it is usually fine.
seems my k-5 can not get very consistant accuate focus when the DOF is very shallow.
actually my k-x is even worse when I use f2.8..my 16-50 become much more usable when with my k-5..
I hope next model can make the auto-focus better, so can eliminate any trouble caused by auto-focus
but overall my k-5 is fine. not too much complain..only hoping next model is better.

Last edited by liukaitc; 07-03-2012 at 10:46 AM.
07-03-2012, 10:36 AM   #37
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QuoteOriginally posted by Zafar Iqbal Quote
There is always a chance of user error and I wont deny it - but I will deny the chance of user error in *all* of the photos.
You can deny it all you like, but you can't make it not be true. Same user, same error. Repeating the same flawed test over and over won't eliminate the error; it simply confirms the flaws in your testing methodology. Which in turn stems from a lack of understanding of how the AF system actually works. Sounds like your later tests are improving in that regard. Same basic path I took - my first few months of testing showed my own errors, then as I learned through experience to perform better tests, miraculously, the focus of my camera improved.

Kind of like that old saying often attributed to Mark Twain about how ignorant his father seemed when Twain was a boy and how much the father learned by the time Twain turned 21.

Last edited by Marc Sabatella; 07-03-2012 at 10:42 AM.
07-03-2012, 11:15 AM   #38
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Every autofocus camera has a good share of misses compared to what the photographer wanted. That's why I still prefer my Leica M9 manual-focus rangefinder camera. When you focus every shot yourself with a good focusing mechanism it becomes second nature, and gives better consistency than I can get with any autofocus system.
You have to work more with manual focus - especially with fast moving subjects, and may lose some of those shots, but for everyday shooting it can't be beat - if you have a camera that has a great MF viewfinder.
Overall my K-5 has adequate autofocus, if you are not pixel-peeping. But it senses "acceptable" focus, and there is a range of results when repeating the same shot while focusing on something else between shots, especially at wide apertures. I think that's part of the reason today's lenses average slower than lenses back in manual focus film days.

07-03-2012, 11:18 AM   #39
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QuoteOriginally posted by liukaitc Quote
well, I am not 100% happy with my k-5 auto focus too. but that usually happen when I use f2.8. it always miss focus. I can test it very easily. If I take pic of same thing over and over. there must be several pic come out misfocus. but if I use f4 f5.6 and below. it is usually fine.
You are talking about smaller degree of mis focus - not something that is way off like in many of my shots.

QuoteOriginally posted by liukaitc Quote
actually my k-x is even worse when I use f2.8..my 16-50 become much more usable when with my k-5..
My K-5 was super reliable when I used it at a wedding workshop (along with my K-x which was super reliable as well - as it usually is). Not so much in low light, but I never worried once when I used it during the day. It would no longer function the same way in daylight after the repairs - low light focusing had improved though "yey!".

QuoteOriginally posted by Marc Sabatella Quote
You can deny it all you like, but you can't make it not be true. Same user, same error. Repeating the same flawed test over and over won't eliminate the error; it simply confirms the flaws in your testing methodology. Which in turn stems from a lack of understanding of how the AF system actually works.
You are more than welcome to add how you think I can improve my method. Criticizing it doesn't really do anything.
07-03-2012, 01:21 PM   #40
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QuoteOriginally posted by Zafar Iqbal Quote

Hate to say this, but when I get my K-5 back and it shows still has unacceptable issues, I'll ask for my money back and look for some other brand :/
No offense, but your last line is pretty telling. You've already decided it's going to be bad before you've even gotten it back. I'm not sure where you sent it because I'm not sure where you are from, but in the US, if I was having a problem like yours. I would send the camera back with the lens and copies of the photos to show the problem rather than rely on mere words to describe the issue. Hopefully that is what you did.

BTW: The best auto focus system in the world could be defeated by someone who moves the camera when they press the shutter release. Have you tried using a tripod and remote to see if it made a difference?
07-03-2012, 05:15 PM   #41
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QuoteOriginally posted by Tom S. Quote
No offense, but your last line is pretty telling. You've already decided it's going to be bad before you've even gotten it back.
Short answer:
No, you are very wrong.

Long answer:
None taken. I've had my K-x for more than 1½ year and have been nothing but satisfied. Then bought the K-5 and the very same evening noticed low light issues. One of the major reason to buy the K-5 was to gain better low light performance. AF and ISO. I Upgraded firmware. Didn't help.

I used it at a wedding workshop - and the week up to it. Some 8 hours of shooting only interrupted by small breaks and walks at the workshop. It worked great. It felt like a proper upgrade from K-x.

Had it then turned in for repairs. I personally added to the repair sheet, that the repair guys should call me so I could explain what was going on.They never did. They also couldn't fix it them self's so they shipped it to Germany (I'm in Denmark btw). They never called either.

I ordered S Type focusing screen for the K-5 (not as a compromise but because I like manual focusing. Voightlander 58mm and Samyang 85mm are amongst my fav. lenses). A rather expensive purchase of such a tiny item. I didn't buy it because I was looking for excuses to jump ship.

Got the camera back - now it focused like hell in normal/bright light. Much worse than what the K-r is doing. It was probably fine in low light (never did extensive testing. Couldn't be bothered) - so they might have fixed that problem. But they created a "bigger" one.

Went back to the shop. We tried the demo K-5. Same problem. They unboxed a brand new K-5. Same problem. Tried with different lenses including 18-135mm, which is slower but problems were still noticeable. Again, we aren't talking minor mis focusing here. But way off focus (yes not all of my pics show this - perhaps I should have filtered them). So much so that it couldn't be fixed with Micro Adjustment. One of the shop keeper is an amateur photographer himself and he gave it a try too (his approach was more coordinated than mine). Several times. Didn't change anything. Release Priority? Always on Focus. AF mode? Single shot etc etc. Can't see what else could be wrong regarding settings. User error? No, no and no. I've shot with Nikons as well, if anything I should have more problems operating those considering they are of a completely different brand. K-x and K-5 are not Apples and Oranges in that sense.

I handed my K-5 over again - they were helpful enough to find me a spare cam, the K-r - but it too has problems and here I am.

The way *I* see it, is that my K-x is a better performer than any of the cameras I've tried. They all suck when they all should be better, or the K-5s should be at least.

Was out again taking pics. Shot a red street sign 4 times. Each time taking few steps closer. 1 in focus 3 off. The closest one pretty much filled the frame.. but it wasn't the one in focus. 3rd one was.. random! another sign - across the streets. 1 shot. in focus. Random! Red street lights. Whats with that? Roses? Go away, wont focus. No, thats a lie. I was able to get them sharp and crisp @ f8. Shot a statue half carved out of a rectangular stony. Aimed for the head - which was tiny. Nailed it in one try! Yet, the cam can have bigger problems focusing on larger and less complicated/cluttered targets. A fluke? Well, lets just say so, then!

Can't see what else to do - feels like lottery now. Will I get a working cam or not. I *know* the K-5 can perform better than the issues I've been writing about.

If all issues are gone - I'll be a happy puppy. If not then what am I really supposed to do? Send it back for more repairs? Another 4-6 weeks with no K-5. Swap? Yah, but we'd have to find a K-5 within the first and *maybe* 2 tries. They aren't too happy about keep opening up new boxes and I can perfectly relate to that. If they had a qualified Pentax QA guy at the place - then perhaps we could - perhaps that's the route to take, *if* it's possible at all.

I *could* also be willing to see what shows up, if anything during fall.

If the issues I'm describing and showing pics of aren't issues at all, but "just Pentax AF thing", then it's still unacceptable. May sound arrogant, but seriously - none of the cams so far outperform my k-x! (except for my K-5 during most of the time prior to any repairs)

QuoteOriginally posted by Tom S. Quote
BTW: The best auto focus system in the world could be defeated by someone who moves the camera when they press the shutter release. Have you tried using a tripod and remote to see if it made a difference?
I'm not that old! The shots from last (window and moire test) night were taken using a tripod. Had planned on carrying it with me today as well, but It was raining so I left it - ironically it only rained till I reached the bus.. 2 minutes.. :|

Just had a look at some of the pics I took before turning the cam in for first round of repairs - kinda makes me even more sad: American Cars 2012.05.12 - Zafar Iqbal's Photos | SmugMug

I had lots of bad focused shots - but I also did use my Voightlander 58mm and Samyang 85mm quiet severely Amongst the AF lenses: don't recall them being an issue beides the usual. but the usual for me is K-x and the even was great with AF. Even at that light maybe some flukes but nothing that made me wonder.
07-03-2012, 09:17 PM   #42
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QuoteOriginally posted by Zafar Iqbal Quote
You are talking about smaller degree of mis focus - not something that is way off like in many of my shots.
Biggest thing is understanding how large the AF sensors are. The traffic light you mention trying to focus on would not have filled that are, so of course the camera Might choose to focus on the background instead - it's a much simpler target.
07-03-2012, 10:23 PM   #43
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My 2c, reflecting my usual bugbear: are you using any filters (UV, 'protection', whatever) on any of your lenses, especially the ones reporting AF issues?

If yes, get that rubbish off your lens asap. And shoot with a hood, even in low light.
07-04-2012, 03:19 AM   #44
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QuoteOriginally posted by Marc Sabatella Quote
Biggest thing is understanding how large the AF sensors are. The traffic light you mention trying to focus on would not have filled that are, so of course the camera Might choose to focus on the background instead - it's a much simpler target.
Yet I think it pretty clear the 3rd pic hows the focus is in the air somewhere between the street light and bus stop. 2nd could look like it too but is a bit harder to see. Pic 5 is again clear enough. 6, 7 and 8 with 0, -10 and +10 micro adjustment doesn't show any sign of where the focus is. The K-5 was back focusing by so much, that I couldn't bring the focus in front of the building or even just right on it. 10 and 11 should have been simple enough but the focus is still behind. Pic 15 should have been easy too. Pixels are soft in the middle but sharp towards the left. The side that is furthest away. etc etc.

QuoteOriginally posted by rawr Quote
My 2c, reflecting my usual bugbear: are you using any filters (UV, 'protection', whatever) on any of your lenses, especially the ones reporting AF issues?

If yes, get that rubbish off your lens asap. And shoot with a hood, even in low light.
Nah, I don't use filter.
07-04-2012, 04:28 AM   #45
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I can NOT use test charts (I did the moire test, however valid it may have been. Focus was spot on). The results differ depending on the light and *that* is why I've been shooting like I did. The Germans used test charts. They sent me 2 different prints to show they fixed the problem. Those were taken under low artificial lighting but I've since then had problems in natural light, and the degree of the mis focus *seems* to be affected by not only light level but light type and as discovered recently, colors. Red (not just street lights) are apparently very bad.

I'd love to do more controlled tests, but I've so not figured out a way to do so.

The basic symptoms of the K-r are very similar to the one on my K-5 except, it front focuses instead of back focus. I have enough shots with nothing in front of the target to potentially confuse the AF but the focus was still off.

QuoteOriginally posted by Zafar Iqbal Quote
A thing I noticed just 30 mins ago: the light illuminating from my monitor enables the K-r to focus properly on items that are illuminated sufficiently enough by the monitor. If I however turn the other way around and aim at something that is primarily illuminated by my energy saving bulb (orange light), the focus can be off by as much as 15 cm with a shooting distance @ approx 1½-2 meters. When I did the moire test, the cam was about 1.25m from the monitor - enough to fill the VF with the square from top to bottom.

Last edited by Zafar Iqbal; 07-04-2012 at 04:34 AM.
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