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03-19-2012, 03:15 PM   #1
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K-01 , no AF fine adjustment , is this a problem ?

Hi,

I am considering K-01 instead of K-5 as my first DSLR and the only reason is price. I definitely wanna have 40mm prime lens, excellent AF accuracy and sharpness.

With K-01, this combo costs 900$, while with K-5 it is 1450$. 550$ differene is considerble, and image qualities look to be very close.

Since currently I have canon s95, I do not think I would have problem with no view finder.

The thing that concerns me, is lack of AF fine adjustment. I checked K-01 manual and it does not mention AF fine adjustment. Some say with mirrorless cameras AF adjustment
is not needed, but then I saw this review on K-01:

"Lenses. The copy of the Sigma I got is sharper, faster to focus, a bit brighter, and the Tamron copy has a slight back focus, so the Tamron goes back."
K-01 : ISO and Tamron vs. Sigma 17-50 f2.8 image series, learning: Pentax SLR Talk Forum: Digital Photography Review

Indeed Tamron 17-50 f/2.8 is the other one that i wanna have, after reading lots of posts and reviews on pentaxforums.

I think AF fine adjustment is a necesssary feature to get best focus and sharpness. Do you think I should avoid K-01 and go for K-5 for best focus accuracy ?

Thanks.

03-19-2012, 03:26 PM   #2
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QuoteOriginally posted by kamisu Quote
Hi,

I am considering K-01 instead of K-5 as my first DSLR and the only reason is price.
You're comparing oranges to apples. The K-5 is a high end DSLR, while the K-01 isn't even a Reflex camera. If you want good AF, but want to pay less, why not take a look at a less expensive DSLR, like the K-7 or a K-r?
03-19-2012, 03:33 PM   #3
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QuoteOriginally posted by kamisu Quote
The thing that concerns me, is lack of AF fine adjustment.
AF adjustments (even on the K-5) don't apply to AF using contrast detection (which is how the K-01 performs AF). So it has nothing to do with the K-01 being a high end model, it just has to do with the fact that you don't need AF adjustments since it is focusing directly on the image (and not in a separate AF module).
03-19-2012, 03:36 PM   #4
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Constrast AF is supposed to focus until the contrast is the sharpest possible - I don't know how a lens that back focuses or front focuses would even affect it. It would just go the extra bit to make sure the contrast is maximum, no?

03-19-2012, 03:46 PM   #5
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ticoun, as far as I know, no other pentax camera, or even most other brands, have dynamic range and image quality of K-5, which because of sensor (as some reviews confirm) ,
is the same as in K-01.

1. If AF adjustment is only neede for phase detect auto focus, does this mean with contrast detect AF all lenses would perform the same on a camera ?

2. Is back and front focus problem realted to lens or camera ?

3. If a camera, say K-5 has some back focus problem, is it only with PD AF, and the CD AF is flawless (as long as there is enough contrast).

Thanks.
03-19-2012, 03:51 PM   #6
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The "reviewer" didn't use a tripod for focus testing. 'nuff said.
03-19-2012, 04:39 PM   #7
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QuoteOriginally posted by kamisu Quote
ticoun, as far as I know, no other pentax camera, or even most other brands, have dynamic range and image quality of K-5, which because of sensor (as some reviews confirm) ,
is the same as in K-01.

1. If AF adjustment is only neede for phase detect auto focus, does this mean with contrast detect AF all lenses would perform the same on a camera ?

2. Is back and front focus problem realted to lens or camera ?

3. If a camera, say K-5 has some back focus problem, is it only with PD AF, and the CD AF is flawless (as long as there is enough contrast).

Thanks.
Again - contrast AF, unless someone informs me otherwise, is AF using algorithms to determine when the subject is showing the greatest contrast. A subject can only show the greatest contrast when it is in perfect focus. That is why lenses under CDAF will go past the focus, then come back - it needs to make sure it reaches maximum contrast.

Phase detect AF uses two sensors to make sure the green and red phase (or something like that) line up. If the sensors are not perfectly aligned, the camera will front or back focus. Similarly, if a lens is not build to perfect alignment, the red and green phases coming in will cause the front or back focusing.
03-19-2012, 04:59 PM   #8
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I have K5 and K01.. for AF use a K5.. for manual use the K-01 because it has Focus Peaking and Focus Zoom.

03-19-2012, 06:20 PM   #9
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So, to summarise, because the K-01 uses contrast detect AF, the issue of 'FF/BF' does not apply unless the lens is basically broken.

It is also worth noting OP that the issue of 'BF/FF' is often overblown by people. I have over 20 lenses - new lenses, 40 year old lenses, manual ones, AF ones etc - and 3 Pentax DSLR's and I've never seen the need to make any AF adjustments at all on any camera body of mine. Yet I seem to get pretty sharp photos most of the time, unless other things foul me up (motion blur mainly).
03-19-2012, 06:47 PM   #10
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QuoteOriginally posted by rawr Quote
So, to summarise, because the K-01 uses contrast detect AF, the issue of 'FF/BF' does not apply unless the lens is basically broken.

It is also worth noting OP that the issue of 'BF/FF' is often overblown by people. I have over 20 lenses - new lenses, 40 year old lenses, manual ones, AF ones etc - and 3 Pentax DSLR's and I've never seen the need to make any AF adjustments at all on any camera body of mine. Yet I seem to get pretty sharp photos most of the time, unless other things foul me up (motion blur mainly).
You say this, but it has burned me a few times. My Tamron 70-200 at 200mm F2.8 and 40 inches (which i believe is just past it's minimum focusing distance) gives me 3mm of DOF. Since the lens is 1/3 macro at 200mm and minimum focus, I use it to catch little flowers. My lens has a tendency to front focus a little bit (which I have accounted for), and it was giving me trouble because it would front focus by such a small margin. The resultant image was very soft and "bloomy" - I thought my lens was broken/mis-aligned from an impact. After testing it a few times, I realized that when it front focuses just barely, the bokeh effect causes the image to look soft and bloomy. It's very hard to distinguish from just "softness".

It's also troublesome because the lens FF at the long end, but is perfect below 175mm. So I have to just be aware of this quirk of the lens.
03-19-2012, 07:01 PM   #11
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Thanks every one. Now I know back or front focusing is not a problem on CD AF.

WWWench, I have seen focus peaking video and it looks really nice.

Please let me ask some more questions.

1. With this focus peaking, other than focus speed, is there any advantage in using AF, since it looks that focus peaking shows the region in focus better. If CD AF in K-01 is not as good as PD AF in K-5, at least it has the focus peaking, which can be used if AF does not work well.

2. Is holding the camera against the face and using viewfinder that much effective to get less shake and sharper result, compared to using LCD?

3. Since I am an absolute beginner and K-5 is kinda a professional camera, do you think K-01 is better for me, or still spending 500$ more and getting K-5 worth it.

Last edited by kamisu; 03-19-2012 at 07:16 PM.
03-22-2012, 09:16 PM   #12
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You will get better picture with K-01 if you don't want to go deep into DSLR.
High end DSLR like K5 can take better picture only if you are willing to learn how to get use of it.

While technique is more important, it all depends on which camera fits better for you.
03-22-2012, 09:29 PM   #13
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QuoteOriginally posted by JinDesu Quote

It's also troublesome because the lens FF at the long end, but is perfect below 175mm. So I have to just be aware of this quirk of the lens.
Again, that doesn't apply with CDAF, only with PDAF, Further, with Focus Peaking and up to 16x magnification you can both see what the actual image will be and have a bright-line indication of focus. I have actually watched the point of critical focus move back and forth on a flower as I moved the focusing ring.

For MF macro and very shallow DoF this is a wonderful system.
03-22-2012, 09:32 PM   #14
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QuoteOriginally posted by monochrome Quote
Again, that doesn't apply with CDAF, only with PDAF, Further, with Focus Peaking and up to 16x magnification you can both see what the actual image will be and have a bright-line indication of focus. I have actually watched the point of critical focus move back and forth on a flower as I moved the focusing ring.

For MF macro and very shallow DoF this is a wonderful system.
Yes - I wasn't referring to CDAF, just PDAF on my k-x.
03-22-2012, 09:38 PM   #15
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My K-01 AF is more accurate than my K-05 but slightly slower in AF speed (it also feels like the K-01 focuses faster than the K-05 in live view, but I have not tested officially so take with a grain of salt.) Outside or in good light, the difference is minimal. Depending on the lens and the lighting, it can be slower in darker conditions (though in fairness, my K-5 focuses fast and than hunts a little at the end in similar conditions, so maybe it is just perception.) Unlike the official review here on the forum, I have never experienced any real-world issue with the AF on my K-01 not being able to lock in the dark, but I've never gone into a windowless room with the lights off and tried it either. I do notice that the K-01 uses its focus assist light way more than the k-5 (which is good/fine with me.)

I think your decision should be based most on what kind of shooting you want to do most of the time. There are pluses and minuses to both and especially if Pentax is coming out with a new entry (K-r level) DSLR, you might wait and see.
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