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10-17-2011, 07:12 AM   #1
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K5 Auto Focus - LV vs Viewfinder

I continue to be dissappointed with the K5 AF when shooting using the viewfinder rather than the Live View method.

I realize that there is nothing that can be done to make the two methods of AF equal... (accurate) at this point. I don't think a firmware update will help.

Live View often results in more accurate AF than using the viewfinder and that is what bothers me the most. I bought the K5 because I am not a big fan of using the LCD for composition and focus but with the K5 it seems that the most accurate focus is achieved with Live View... in partiuclar when shooting wide open.. and I do that a lot.

I hope that the two methods of AF can eventually become equal in their performance. I love everything else about the K5 but the AF continues to bother me. I certainly have not reached the tipping point but I sure hate it when the AF is not spot on when not using Live View.

I had a frustrating weekend using the K5 and consider this nothing more than a Monday morning vent.

10-17-2011, 08:41 AM   #2
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I agree and I don't think there's much question that AF is the K5's weakest link. I'm pretty sure that there would be something that bugged me about every other system out there too, though. Top-notch AF is my sincerest wish for Ricoh to spend R&D money on.
10-17-2011, 09:31 AM   #3
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I completely agree with you Jim. Also, when the AF assist lamp kicks in the AF is likely to be spot on (in phase detect mode) but when it doesn't (which is the situation I find myself in quite frequently) the AF is significantly front focused. It's such a shame that the K-5 has such good high ISO but is totally let down by the focus problem. Wasn't this supposed to have been fixed in the last FW update?

When I send in my K-5 for the mirror flop issue soon, I will be sure to inform them of the persistent low light FF issue as well
10-17-2011, 09:57 AM   #4
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Jim, I was thinking i don't have that problem with the K-5's AF, and then realized i rarely shoot wide open. 2 different styles of shooting.

A coupla days ago, i was shooting a long row of fence posts in beach grass, and every blade of grass, seemingly, was sharp. uploaded it to my photoclub site, and got good reviews on the sharpness. Yesterday, i did get into use LV for shooting down low on a beach, because one can use the backscreen to review composition, sort of, without getting down on one's belly (in the damp sand. Think i'll be doing more of that - liked the shots that came out of it. The problems i had with LV is in low light, it seems to suffer earlier than with phase AF.

When i shoot live theatre rehearsals, i'm not having any particular problem with phase focusing, but then again, I rarely shoot wide open.

I've become more conscious of the relatively large diameter of the AF sensor - it seems to fill the entire center marks of the focus screen, so its not possible to focus on a small object if there is something else in that circular field that will attract the sensor instead. I remember someone suggesting the way to test it is to slowly pan into a change of distance until the AF triggered. I found that instructive.

There was that great thread reporting the results of a German test which concluded that Pentax passed their multiple focus tests in 1st place over the other brands. (the German lab did not test all possible AF scenarios - limited to a static situation) Falk (falconeye) had a thoughtful post that discussed phase AF had the potential to be superior to contrast detection, but was more prone to several vulnerabilities, e.g. tolerance stackups, calibration differences due to target distance from camera, etc. Often contrast detection was superior.

Are you having more problems after sending your camera in, or has the camera been consistent before and after the last repair?

10-17-2011, 10:41 AM   #5
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The focus on my K5 is the same as it was before it was sent in to repair the mirror-flop issue.

I do agree that the weakest thing about the K5 is the AF. I really dislike using LV and prefer to use the viewfinder but I find I am often forced to use Live View when I desire critical focus.

Yes, it's easy to stop down to get a sharp photo but that is not why I bought fast primes (31, 43 and 77)... I also notice the same issue with the DA * 50-135 (plus I have to dial in +10) on micro adjustment.

It's really a shame because everything else about the K5 is great.
10-17-2011, 11:51 AM   #6
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The K7 was the same way. It Auto Focused better in LV than with viewfinder AF. From what I understand, two different types of AF are used on these cameras. In LV, the camera actually focuses off of the sensor (Or something like that).

10-17-2011, 01:04 PM   #7
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Perhaps your K-5 has a problem... You should send it in...
10-17-2011, 01:27 PM   #8
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QuoteOriginally posted by JeffJS Quote
The K7 was the same way. It Auto Focused better in LV than with viewfinder AF. From what I understand, two different types of AF are used on these cameras. In LV, the camera actually focuses off of the sensor (Or something like that).

At least now with the K-5 the speed of LV focusing is good enough to be useful.
If I recall the K-7 LV focusing was too slow, and in my K-x it is like pouring molasses on a winter day

10-17-2011, 03:10 PM   #9
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Live view uses contrast AF with the camera's main sensor and the regular AF is phase system using a separate sensor. contrast AF is slower because the system doesn't know whether OOF is front or back focussed and uses trial and error. Phase method is faster because it does know in which direction to move the focus. I agree the phase AF culd be a lot better in the K-5
10-17-2011, 03:11 PM   #10
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QuoteOriginally posted by darrenleow Quote
I completely agree with you Jim. Also, when the AF assist lamp kicks in the AF is likely to be spot on (in phase detect mode) but when it doesn't (which is the situation I find myself in quite frequently) the AF is significantly front focused. It's such a shame that the K-5 has such good high ISO but is totally let down by the focus problem. Wasn't this supposed to have been fixed in the last FW update?

When I send in my K-5 for the mirror flop issue soon, I will be sure to inform them of the persistent low light FF issue as well

FW1.03 was supposed to fix or greatly improve the Low Light front focussing problem. It didn't fix it on my first K-5 so I got my dealer to replace the camera. The replacement was fixed by 1.03
10-17-2011, 03:17 PM   #11
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Well I do strugle with my K-5's but put time into adjusting AF to the situation where I'm working at the time. When things change fast then I do sometimes use LV, just to make it easy for myself. Otherwise I change the settings in the menu to my preference at the place I'm going to work.

from a test, so this is real 100% pixelpeeping:
K-5 with Sigma 70-200/f2.8 EX DG OS HSM at f3.2 1/640th and iso5000


This way gives me good results on average, but misfocussing is still a part of life.
10-17-2011, 05:24 PM   #12
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QuoteOriginally posted by crewl1 Quote
At least now with the K-5 the speed of LV focusing is good enough to be useful.
If I recall the K-7 LV focusing was too slow, and in my K-x it is like pouring molasses on a winter day
The K7 LV focusing wasn't very useful for something like action shots because it would cycle the lens to both extremes and then correct to find focus. It seemed not to matter which lens, it was just the way the algorithm was built. That's how I remember it anyway. The K5 behaves more like AF should in that, it always seems to be looking and will only make small corrections if needed.

Something interesting and a bit of a tangent, a Self Calibrated AF would be nice to have. That is, Pentax (or other) includes a focusing target in (or on) the box. Something that is pre programmed into the software as to exactly what it should look like. Put your lens on the camera, Aim it at the target (in their recommended light), push the AF button and let it work.

10-17-2011, 07:17 PM   #13
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QuoteOriginally posted by Smeggypants Quote
FW1.03 was supposed to fix or greatly improve the Low Light front focussing problem. It didn't fix it on my first K-5 so I got my dealer to replace the camera. The replacement was fixed by 1.03
Do I understand correctly that your replacement K-5 focuses accurately in low light? Do you consider the problem to have been fixed?

Jeff
10-17-2011, 08:42 PM   #14
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I have not noticed this on my K-5, but the discussion brings up an interesting question. Say I have a lens for which the focus is spot on using Live View but is slightly off using the viewfinder (seems like that's what is being postulated in this thread), but I don't realize it. I go through the steps to correct AF adjustment and I use the viewfinder to do it, and I find a correction value that works. Will it then be the case that the focus obtained using Live View will be off, i.e., the AF correction depends on which method I use to find the correction?
10-17-2011, 08:44 PM   #15
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QuoteOriginally posted by dshombert Quote
I have not noticed this on my K-5, but the discussion brings up an interesting question. Say I have a lens for which the focus is spot on using Live View but is slightly off using the viewfinder (seems like that's what is being postulated in this thread), but I don't realize it. I go through the steps to correct AF adjustment and I use the viewfinder to do it, and I find a correction value that works. Will it then be the case that the focus obtained using Live View will be off, i.e., the AF correction depends on which method I use to find the correction?
AF corrections do not apply to LV focusing, which uses a different AF system altogether.
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