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09-02-2012, 05:12 AM   #31
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AF in live view compared to standard af?

A couple of folks recommended to shoot in live view to see what happens, then later on a few posts ago someone said if its accurate in LV then its the autofocus thats the culprit and not the lens. Could someone explain to me why this is? I understand they work differently yes, but why would the LV focus work and the autofocus not? I haven't tried it yet but will today b/c I figured if the focusing was screwed, it would be screwed up on both.

Although I've owned many cameras (a canon xsi, pentax k20d, kr, kx, and a d7000-which I didnt like) I've never had this problem or any problem for that matter so trying to solve this is way beyond me. After I sold my k20d I've regretted it ever since and every camera that came after that one didnt feel right to me like the k20d did, so I figured after the k5 dropped so much and I bought it I would feel like I did with the k20d.


Thanks to everyones input I really appreciate it, and no I'm not trolling... why someone would post bogus stuff is beyond me, I'm just looking for experienced help from advanced to pro Pentaxians that can point me in the right direction with all this and so far the help has been outstanding and I'm actually a bit suprised that so many people have offered their advice in attempting to help me solve this.

09-02-2012, 05:15 AM   #32
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Question for Nick

QuoteOriginally posted by Nick Siebers Quote
I had to send a K5 back to Prodigital2000, mine had been refurbished but came with the regular warranty. They replaced it with one that works, and were pretty good about it. But I did have to pay for shipping it back to them, which was expensive.
Just curious why you had to send it back? Also, how long did this take? At this point I dont mind paying for the shipping to make this thing right.
09-02-2012, 07:01 AM   #33
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Since the autofocus in live view uses contrast detect instead of phase detect, they are 2 independent ways of detecting focus for the camera. Contrast detect is usually very precise, it would tell if the lens can be in focus or not, and identify the problem as phase detect autofocus. You will still have to send it back so in the end it won't change anything for you, but we will be happy to know what it was because we are curious and have nothing better to do
09-02-2012, 07:51 AM   #34
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QuoteOriginally posted by harleynitelite Quote
A couple of folks recommended to shoot in live view to see what happens, then later on a few posts ago someone said if its accurate in LV then its the autofocus thats the culprit and not the lens. Could someone explain to me why this is? I understand they work differently yes, but why would the LV focus work and the autofocus not? I haven't tried it yet but will today b/c I figured if the focusing was screwed, it would be screwed up on both.
The normal AF uses a special AF sensor on the underside of the camera in the lightbox, liveview AF uses the actual image from the sensor and change the image to get the highest contrast.
So 2 completely different systems and ways are used.

You can calibrate the AF for 10 lenses or so with the K5.

09-02-2012, 10:23 AM   #35
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ok. this is my recent experiecne with newly acuqired canon 7d
I bought sigma 17-50 f2.8 and tokina 11-16 f2.8 with 7d at first
and both auto focus very well in live view mode and both focus very poor in VF
so I returned both lens and bought canon 10-20 and 17-55, and now they both focus very well in VF
so yes, even your lens can focus very well in live view does not mean it can focus very well in VF.
09-02-2012, 01:13 PM   #36
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QuoteOriginally posted by harleynitelite Quote
A couple of folks recommended to shoot in live view to see what happens, then later on a few posts ago someone said if its accurate in LV then its the autofocus thats the culprit and not the lens. Could someone explain to me why this is? I understand they work differently yes, but why would the LV focus work and the autofocus not? I haven't tried it yet but will today b/c I figured if the focusing was screwed, it would be screwed up on both.

Although I've owned many cameras (a canon xsi, pentax k20d, kr, kx, and a d7000-which I didnt like) I've never had this problem or any problem for that matter so trying to solve this is way beyond me. After I sold my k20d I've regretted it ever since and every camera that came after that one didnt feel right to me like the k20d did, so I figured after the k5 dropped so much and I bought it I would feel like I did with the k20d.


Thanks to everyones input I really appreciate it, and no I'm not trolling... why someone would post bogus stuff is beyond me, I'm just looking for experienced help from advanced to pro Pentaxians that can point me in the right direction with all this and so far the help has been outstanding and I'm actually a bit suprised that so many people have offered their advice in attempting to help me solve this.
Basically, when you auto focus with live view, it uses something called contrast detect auto focus, which occurs at the level of the sensor. Since the auto focus occurs there, it is much less likely to have errors, as long as the lens is OK and it 's pretty immune to front and back focusing problems. the problem is that it is pretty slow (particularly on the K5), but if you can get sharp focus with it, then it indicates that lens can be focused sharp, it just requires quite a bit of adjustment to fix the problem.

For auto focus adjustment, I use this technique, which seems to work fairly well: AF microadjustment for the 1Ds mark III, 1D Mk3, 5D Mk2, 7D, 1D X.
09-03-2012, 01:31 PM   #37
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Sending it back

Well, after messing around with this for the past week I've decided I'm sending it back. I've found even with precise manual focusing it just isn't cutting it and every other camera I've ever owned looked better than this and I think I got a dud lens. I'm hopeful Prodigital2000 wiil exchange it and the next one lives up to my expectations. Thanks for everyones input I do appreciate it.
09-03-2012, 02:58 PM   #38
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QuoteOriginally posted by Anvh Quote
The normal AF uses a special AF sensor on the underside of the camera in the lightbox, liveview AF uses the actual image from the sensor and change the image to get the highest contrast.
So 2 completely different systems and ways are used.

You can calibrate the AF for 10 lenses or so with the K5.
I never knew this. Can the sensor become dirty? Maybe that could mess things up?

09-06-2012, 12:54 PM   #39
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QuoteOriginally posted by harleynitelite Quote
Just curious why you had to send it back? Also, how long did this take? At this point I dont mind paying for the shipping to make this thing right.
Sorry, I missed this before. My first one was off with the AF, I could get most lenses sharp at +10 but a few needed even more. (more than the camera would do). The new one works just fine, and had fewer shutter clicks. Overall, it was a good experience.
09-07-2012, 10:01 AM   #40
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QuoteOriginally posted by GoldenRGuy Quote
I never knew this. Can the sensor become dirty? Maybe that could mess things up?
It can but never heard of the being the problem.
Here is the AF sensor inside the K30 http://www.benjaminkanarekblog.com/wp-content/uploads/2012/07/k30af.jpeg

This explanation how the AF sensor work, you can play with the first image.
Autofocus: phase detection

This contrast AF with the sensor.
Autofocus: contrast detection
09-07-2012, 12:04 PM   #41
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I just picked up the K5 and 18-135 combo a couple of months ago and was pleasantly surprised by the K5 output compared to the Kr. The 18-135 also exceeded my expectations and is comparable to manacho2005 above.
09-08-2012, 05:35 AM   #42
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QuoteOriginally posted by lenic Quote
I just picked up the K5 and 18-135 combo a couple of months ago and was pleasantly surprised by the K5 output compared to the Kr. The 18-135 also exceeded my expectations and is comparable to manacho2005 above.
iv got the k-r am still learning but I would like a upgrade I was thinking the k-30 or the k-5 what's the best out of the 2 thanks in advance
09-08-2012, 07:46 AM   #43
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I'm going back to the original photos (of the silver car) posted. I noticed that both were taken at iso800 and the Pentax photo is noisy from iso and cropping. Was noise reduction used on the nikon and not used on the Pentax? It's clearly not acceptable but I'm wondering if it isn't a combination of iso800 with no noise reduction, the cropping and missed focus. I'm not sure if I would be shocked if a photo turned out like that after cropping and no noise reduction at iso800.
09-08-2012, 08:32 AM   #44
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Noise reduction was on auto in camera. Prodigital 2000 requested samples emailed to them with the return and agreed something was not right. The nikon crop is at 100% as well. There were many shots where the focus just seemed to hang, like if I had put something in front of it say 10 feet away, focused on it, then removed the subject and took the picture resulting in everything being out of focus. The only time it really worked well was when I was zoomed in at least 80 mm. Pretty certain it was a bad lens, but being it was a kit I had to return everything. It made me feel better though they mentioned out of say 1,000 kits sold, only around 10 were returned with this problem as I described.
09-08-2012, 08:59 AM   #45
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that picture was certainly unacceptable but if I was trying to figure out what was wrong I would start with ideal conditions (low iso, MF, no SR, etc...) and then add in variables until you find the problem.

Another question - Did you use AFS or AFC?
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