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07-18-2009, 09:52 AM   #1
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K-7 Owners: How is low light AF with DA21 & FA 43.

Can a K-7 owner tell me how the low light AF with the DA21 and FA43 and possibly F28 in the K-7 compared to the K10D. For speed and accuracy. The DA21 accuracy and speed sucks in low light with the K10D, oh for the FA43.

Thank you.

P.S: Shoooot,......wrong forum.


Last edited by pcarfan; 07-18-2009 at 10:31 AM.
07-18-2009, 11:18 AM   #2
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I had to wait for the battery to be charged, but the first lens I used on the K-7 today (after I got it) was the SMC Pentax-F 50mm f/1.4. Mainly to check the focus accuracy (it's absolutely DEAD on!) but also the low light speed. I'm pleased to find that the lens does focus faster than on my K20D, but not by much. I've had a few instances where the green AF assist lamp kicked in, and that was definitely faster and less obtrusive than the 'AF-assist' in the K20D (with the help of the built-in flash).

I also have the F 28/2.8, do you want me to test something with that lens?
07-18-2009, 11:42 AM   #3
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I did a quick test with a DA21 on a K10D, a K20D and a K7, all targeting a dark object on a plain carpet under dim tungsten light. The K10 and 20D hunted for five or six nudges when the dark object was under the central AF point, and locked on eventually (probably taking two or three seconds). When targeting the plain carpet alone they couldn't cope and just searched between the stops before giving up. With the flash raised for AF illumination they did better, homing in on the dark object more quickly, though still taking almost a second. Even with the flash raised they could not cope with the plain carpet and just sat there blinking the focus warning. The K7 went straight to the correct focus (with the same dark object and using the central AF point) with no more than a single nudge. Its green AF assist was evident immediately. It also had no problems with the plain carpet and locked in correct focus very quickly, again having immediate recourse to the AF assist lamp. My estimate is that the K7 took no more than half a second, probably less. It was not a scientific test, just a quick point and try. The results were consistent though. The K7 was better by a significant margin.
07-18-2009, 11:52 AM   #4
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QuoteOriginally posted by Asahiflex Quote
I had to wait for the battery to be charged, but the first lens I used on the K-7 today (after I got it) was the SMC Pentax-F 50mm f/1.4. Mainly to check the focus accuracy (it's absolutely DEAD on!) but also the low light speed. I'm pleased to find that the lens does focus faster than on my K20D, but not by much. I've had a few instances where the green AF assist lamp kicked in, and that was definitely faster and less obtrusive than the 'AF-assist' in the K20D (with the help of the built-in flash).

I also have the F 28/2.8, do you want me to test something with that lens?
Thanks.....I am using the 21/43 combo most of the time for indoors. I bought the 28/2.8 due to LBA I guess, as the DA 21 at times can be too wide, but it crops so well, I kept using the 21.

07-18-2009, 11:55 AM   #5
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QuoteOriginally posted by Delgado Quote
I did a quick test with a DA21 on a K10D, a K20D and a K7, all targeting a dark object on a plain carpet under dim tungsten light. The K10 and 20D hunted for five or six nudges when the dark object was under the central AF point, and locked on eventually (probably taking two or three seconds). When targeting the plain carpet alone they couldn't cope and just searched between the stops before giving up. With the flash raised for AF illumination they did better, homing in on the dark object more quickly, though still taking almost a second. Even with the flash raised they could not cope with the plain carpet and just sat there blinking the focus warning. The K7 went straight to the correct focus (with the same dark object and using the central AF point) with no more than a single nudge. Its green AF assist was evident immediately. It also had no problems with the plain carpet and locked in correct focus very quickly, again having immediate recourse to the AF assist lamp. My estimate is that the K7 took no more than half a second, probably less. It was not a scientific test, just a quick point and try. The results were consistent though. The K7 was better by a significant margin.
Thank you so much...this is very re-assuring.

Can you do this test under artificial light, but not too dim, just like an indoor event. I think in these instances the green assist lamp will not fire, and I am curious whether the K-7 will still focus faster with the DA21 in indoor conditions where the AF-assist lamp is not necessary.
07-18-2009, 04:47 PM   #6
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Pcarfan: Again, this was not a scientific test, but under good artificial light (not requiring the AF assist lamp), the K10 still nudged its fine focus after the initial coarse focus more than the K7 (sometimes twice as much). I started both cameras from the infinity setting and focussed on something about ten feet away. The performance difference was nowhere near as much as it was under dim light, but to my eye end ear, still just measurable and consistent. The K7 appears to edge its predecessors under good light, and trounce them when the light becomes more of a challenge. The margin may be greater with an SDM lens (I didn't think to try one for the test).

Although this is not strictly in the scope of your question, I am also finding the performance of the K7's auto white balance breathtaking. AWB in the K10 and K20 was unreliable and I never failed to make a white balance reference card shot for post-production. Although I will continue to do this with the K7, the odds are that most of the time I will not need it. I love the way it interprets tungsten (the K7 gives two levels of correction, one is aggressive, but the other allows a little bit of warmth into the colour temperature, and this works very well). I have found it coped with other sources of artifical light extremely well. Also be aware that if you apply the camera's lateral chromatic aberration correction and distortion correction, it will choke after four rapid exposures (in DNG format). Switching these features off allows it to run at the frame rates advertised.
07-18-2009, 07:01 PM   #7
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QuoteOriginally posted by Delgado Quote
Pcarfan: Again, this was not a scientific test, but under good artificial light (not requiring the AF assist lamp), the K10 still nudged its fine focus after the initial coarse focus more than the K7 (sometimes twice as much). I started both cameras from the infinity setting and focussed on something about ten feet away. The performance difference was nowhere near as much as it was under dim light, but to my eye end ear, still just measurable and consistent. The K7 appears to edge its predecessors under good light, and trounce them when the light becomes more of a challenge. The margin may be greater with an SDM lens (I didn't think to try one for the test).

Although this is not strictly in the scope of your question, I am also finding the performance of the K7's auto white balance breathtaking. AWB in the K10 and K20 was unreliable and I never failed to make a white balance reference card shot for post-production. Although I will continue to do this with the K7, the odds are that most of the time I will not need it. I love the way it interprets tungsten (the K7 gives two levels of correction, one is aggressive, but the other allows a little bit of warmth into the colour temperature, and this works very well). I have found it coped with other sources of artifical light extremely well. Also be aware that if you apply the camera's lateral chromatic aberration correction and distortion correction, it will choke after four rapid exposures (in DNG format). Switching these features off allows it to run at the frame rates advertised.
Thank you very much.
07-18-2009, 07:39 PM   #8
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QuoteOriginally posted by Delgado Quote
Although this is not strictly in the scope of your question, I am also finding the performance of the K7's auto white balance breathtaking. AWB in the K10 and K20 was unreliable and I never failed to make a white balance reference card shot for post-production. Although I will continue to do this with the K7, the odds are that most of the time I will not need it. I love the way it interprets tungsten (the K7 gives two levels of correction, one is aggressive, but the other allows a little bit of warmth into the colour temperature, and this works very well). I have found it coped with other sources of artifical light extremely well.
Yes, AWB is impressively good on the K-7. I think there is an error in the manual because it quotes the same range of light under as the K20D for which K-7 AWB is supposed to work. But the K-7 is clearly able to correct tungsten almost perfectly. Not many cameras are able to do that if you check dpreview.

About AF, I'd say that in general I feel much more confident with the K-7 than I was with the K20D. Both for speed and accuracy. It's still not perfect and can be confused in low-light by moving subjects but it's a huge improvement over previous Pentax DSLR.

07-18-2009, 09:03 PM   #9
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QuoteOriginally posted by pcarfan Quote
Can a K-7 owner tell me how the low light AF with the DA21 and FA43 and possibly F28 in the K-7 compared to the K10D. For speed and accuracy. The DA21 accuracy and speed sucks in low light with the K10D, oh for the FA43.

Thank you.

P.S: Shoooot,......wrong forum.
I can only give you my impressions regarding the 43mm on the k-7 and k10. In good light the k-7 focuses more accurately and my impression is it's a bit quicker than on the k10. In poor light, there's no comparison between the two cameras. The k-7 and 43mm focus quick and accurately with far less hunting than the k10 could achieve.
07-20-2009, 04:27 PM   #10
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I appreciate the responses. Thank you.
07-21-2009, 07:10 AM   #11
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Another lens but my FA50/1.4 is faster and its focussing noise is higher pitched than with my k10D. Very noticeable.
07-26-2009, 11:10 AM   #12
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K-7 focuses significantly faster than the K10 with all my lenses under good light, medium light and poor light. Under good light it's only marginally faster than the K10, but still very noticable even then.

AF-C is now usable also, whereas on the K10 it was not usable.

c[_]
07-29-2009, 10:38 AM   #13
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QuoteOriginally posted by ll_coffee_lP Quote
K-7 focuses significantly faster than the K10 with all my lenses under good light, medium light and poor light. Under good light it's only marginally faster than the K10, but still very noticable even then.

AF-C is now usable also, whereas on the K10 it was not usable.

c[_]

I got my K-7 yesterday and came here to report the exact same thing. Also, The multi-zone metering is useful as well...with my K10D it was absolutely random and I always had to use spot metering...this in turn meant that I couldn't get a katz-eye screem for MF, now with this great green metering, I can get a katzeye and start using these wonderful Pentax Manual Focus lenses as well.
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