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11-28-2014, 04:42 PM   #1
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Autofocus on the K3

I saw an extended review on Amazon saying that the new screw drive autofocus motor on the K3, while quicker, is less accurate than K5II/s due to the emphasis on speed. (The feedback he got from Pentax on the issue was interesting.) Has anyone else experienced that?

Thanks

11-28-2014, 05:00 PM   #2
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QuoteOriginally posted by Spodeworld Quote
I saw an extended review on Amazon saying that the new screw drive autofocus motor on the K3, while quicker, is less accurate than K5II/s due to the emphasis on speed. (The feedback he got from Pentax on the issue was interesting.) Has anyone else experienced that?

Thanks
Not at all. My DFA 100, DA 40, Fa 31 etc, all screw drive lenses work better then ever on the K3.
11-28-2014, 05:19 PM   #3
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Oh no... The K-3 AF works better than any of the k-5 series. You will re-discover your lenses wide open...
11-28-2014, 05:24 PM   #4
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Some of the reviews on Amazon - on everything - are just weird (or funny) sometimes. This seems to be one of them.

I can't comment relative to the K-5II series, but the K-3 is perceptibly more confident, responsive and reliable than the K-5, with all forms of AF.

11-28-2014, 05:48 PM   #5
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Thanks, that's what I thought, but the review was so long and detailed and made a big deal about this. I just had to ask because he said the following:

"My conclusion is the change to a faster motor and faster focusing system has lead to inconsistency. I have made this known to Pentax and a reply was made to me "that given the new mechanical nature of the screw drive system, it is a possibility that this may contribute to less accurate results"."

Also, he wrote:
"DP Review severely down graded the score for Auto Focus Accuracy for the K3 vs the K5 which is rated very high. In addition, Pentax Forums In Depth Review (and Administrator "Adam") has constantly remarked that the K3 really only shoots well with SDM/DC based lenses, and is more "picky" about the lenses used with it."

So, it left me wondering
11-28-2014, 06:21 PM   #6
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Hmm interesting... I have not noticed any problem with FA lenses.
11-28-2014, 06:25 PM   #7
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QuoteOriginally posted by Spodeworld Quote
I saw an extended review on Amazon saying that the new screw drive autofocus motor on the K3, while quicker, is less accurate than K5II/s due to the emphasis on speed.
I have both bodies and can say that the K3 is just as accurate as the k5II/s on focus. And yes , the K3 is somewhat faster to focus on screw drive lenes.

QuoteOriginally posted by Spodeworld Quote
"DP Review severely down graded the score for Auto Focus Accuracy for the K3 vs the K5 which is rated very high.
It is possible that DPR was not testing with the latest firmware installed. It is also important to dial in accurately the fine focus of the K3 as this can be construed as a overall camera fault rather than a simple adjustment.

QuoteOriginally posted by Spodeworld Quote
In addition, Pentax Forums In Depth Review (and Administrator "Adam") has constantly remarked that the K3 really only shoots well with SDM/DC based lenses, and is more "picky" about the lenses used with it."
You would have to ask Adam for the definitive explanation of that remark but I would suspect he is referring to the fact the K3 gives best image results with high quality glass.
11-28-2014, 06:28 PM   #8
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Yeah, that's seriously not accurate. The FA31 is my AF champ on the K-3. Nails focus every time, regardless of aperture setting. In fact, the only lens that I have that has any issue at all is my Sigma 24-70HSM. I have to dial in a -5 adjustment for it and it gets it right about 95% of the time. No other lenses require any adjustment now. When the camera was new I had to make quite a few adjustments, but the several subsequent FW updates have remedied that.

11-28-2014, 06:36 PM   #9
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Well, the problem with reading reviews is ......
I remember buying the *istDS and K-7 without reading a single review.
I was never disappointed with the cameras.
11-28-2014, 06:49 PM   #10
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Thanks, its really good to hear that the experience here is different.
12-01-2014, 09:54 AM   #11
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It does behave erratically (regardless of AF/DC motor lens) sometimes, I think due to lighting and me not possessing "fast" lenses. Nothing in particular with screw driven lenses. If something I have tracked children using my DA 50mm 1.8 in poor light (F2.5, 1/250th second,ISO 5000) and got many keepers. This was next to impossible for not only my K10D but my friends Nikon D7000 as well!
12-01-2014, 11:30 AM   #12
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On my Tamron 17-50 f2.8 the AF is great, very accurate. I am really impressed. I had a K7 before, but the K3 is head and shoulders above it...VERY ACCURATE!
12-01-2014, 11:31 AM   #13
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The mechanical AF drive on the K-3 simply rocks. I suspect that the reviewer was not expressing themselves very well.


Steve
12-01-2014, 11:35 AM   #14
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Can you link the review given that it has detail that may help us understand why the poster thought it was less accurate?

If I were to hazard a guess, the k-3's higher resolution allows the user to see where things start being OOF easier, and that may give an impression of a lens performing worse on the k-3 than the k-5IIs. With the lens performing going worse, the user may either assume the lens is the issue or the camera is the issue - and if he finds that it occurs with several of his lenses then he might just blame the camera.
12-01-2014, 12:04 PM   #15
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QuoteOriginally posted by Spodeworld Quote
In addition, Pentax Forums In Depth Review (and Administrator "Adam") has constantly remarked that the K3 really only shoots well with SDM/DC based lenses, and is more "picky" about the lenses used with it.
Read the review on this site and you will find that the Amazon reviewer has a reading problem. The PF review does not say those things.

Was it the June 12, 2014 by "Amazon Customer"? I just read that one in detail and while not pure bull, it is pretty stinky. There are a lot of words, but it is obviously the user is either easily confused or has very limited experience with the K-3. To be blunt, my experience with the K-3 fully contradicts the review's list of cons and faults. None of an substance are valid and many simply don't make sense.* My read on the review is that the user has discovered that the K-3 is not a K-5 and that the differences are more than they can handle.

If you want a balanced and accurate review, go to Imaging Resources.

Edit: If the reviewer is a member on this site, I offer my apologies, but stand by my opinion and analysis.


Steve

* I still don't understand the described difficulties with on-tripod work. There is a dedicated button for meter mode and the info is displayed on both the top and rear LCD. Go figure...

---------- Post added 12-01-14 at 11:15 AM ----------

QuoteOriginally posted by JinDesu Quote
If I were to hazard a guess, the k-3's higher resolution allows the user to see where things start being OOF easier
Exactly! That is a well-known side-effect of high resolution media going back a hundred years or more. You can't see what is not there.


Steve

---------- Post added 12-01-14 at 11:38 AM ----------

QuoteOriginally posted by Spodeworld Quote
Also, he wrote:
"DP Review severely down graded the score for Auto Focus Accuracy for the K3 vs the K5 which is rated very high.
This is not true. DPReview did not compare the K-3 to the K-5*, nor did they have issues with the K-3 AF accuracy. They did have strong criticism of the AF tracking (AF-C) for subjects moving directly toward the camera. This they blamed on the AF speed of the in-lens motors and not on the camera.


Steve

* The DPR review of the K-5 AF system from 2010 was favorable, but was listed as a con in the summary. The 2013 review of the K-5II/IIs indicated an improvement in the AF system over the K-5, specifically in low light where the K-3 cleans house. The approaching subject tracking test was not done on any K-5 variant.

Last edited by stevebrot; 12-01-2014 at 12:50 PM.
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