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07-20-2009, 05:50 AM   #16
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QuoteOriginally posted by lol101 Quote
Does the K-7 have such an option or is it in "focus priority" by design?
AF.C is "release priority" and cannot be changed on the K-7 and all previous Pentax DSLR as far as I know.

AF.S is "focus priority" and cannot be changed either.

07-20-2009, 06:24 AM   #17
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QuoteOriginally posted by falconeye Quote
Thanks for taking the time to this. Looking forward to part II (kids running araound) because that's what I think most people mean by "AF-C", but I suspect they'd be surprised how badly Canikon do at that range as well. If you do a part III, BIF would be good...
07-20-2009, 06:44 AM   #18
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QuoteOriginally posted by falconeye Quote
I've run an AF.C reference test
Falk Lumo: K-7 and its continuous autofocus -- PART I
The test setup was standardized by a German photo magazine and results for various brands and models are known.
As you can read, the K-7 delivers 14 images within 3.6s (13 which of were good, run #3). This not only is 3.9 fps in AF.C, it is an exact match of the D300 performance too (13 good images for the same test).
That's interesting because I can't get much more than 3fps in AF-C even in bright light with stationnary subjects. Maybe your pre-production camera was tweaked differently or there is a bug in the final version?

I also noticed that the metering could impact speed in low-light. It's very apparent when you switch between an automatic exposure mode (let's say Tv to not have a shutter speed too low) and manual mode, the fps speed change dramatically.
07-20-2009, 06:56 AM   #19
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QuoteOriginally posted by kenyee Quote
Thanks for taking the time to this. Looking forward to part II (kids running araound) because that's what I think most people mean by "AF-C", but I suspect they'd be surprised how badly Canikon do at that range as well. If you do a part III, BIF would be good...
I bookmarked this thread on dpreview:
Can the D3 AF track a child? [Page 1]: Nikon D3 - D1 / D700 Forum: Digital Photography Review

Even using a D3 and a fast SDM lens is apparently not enough for "kids running around".

07-20-2009, 07:27 AM   #20
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QuoteOriginally posted by ManuH Quote
I bookmarked this thread on dpreview:
Can the D3 AF track a child? [Page 1]: Nikon D3 - D1 / D700 Forum: Digital Photography Review

Even using a D3 and a fast SDM lens is apparently not enough for "kids running around".
If we use AF-C of K-7 with moving objects, no any chance to get even 3.5 fps.
Approx. 2-3 fps. Not bad. But...

D3, D700 and D300 has more ADVANCED AF system and it's real to be close to announced specs in AF-C mode with almost 100% results.
07-20-2009, 08:11 AM   #21
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QuoteOriginally posted by RBellavance Quote
AF.C is "release priority" and cannot be changed on the K-7 and all previous Pentax DSLR as far as I know.

AF.S is "focus priority" and cannot be changed either.
Then shouldn't the K-7 blast at full 5.2fps in AF-C, no matter if focus is achieved or not...?
07-20-2009, 08:49 AM   #22
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QuoteOriginally posted by kenyee Quote
Thanks for taking the time to this. Looking forward to part II (kids running araound) because that's what I think most people mean by "AF-C", but I suspect they'd be surprised how badly Canikon do at that range as well. If you do a part III, BIF would be good...
Part II was out long ago
-> Falk Lumo: K-7 and its continuous autofocus -- PART II
Maybe, lock at my conslusive review report (latest blog entry) where I listed all review parts I've done.

I asked a friend to move as erratically as possible (so, she came really close as well ). K20D was a complete fail, K-7 went down to 1.5fps and 25% in focus only. BUT ... as the next cited post points out, NO camera out there can do this. It is just not state of the art. According to a little math I did, focussing would have to be as fast as 50ms but no camera out there can focus faster than 200ms (K-7: 300ms).
QuoteOriginally posted by ManuH Quote
Even using a D3 and a fast SDM lens is apparently not enough for "kids running around".
QuoteOriginally posted by ManuH Quote
That's interesting because I can't get much more than 3fps in AF-C even in bright light with stationnary subjects. Maybe your pre-production camera was tweaked differently or there is a bug in the final version?
I don't think so. But you're right, my figure was with a beta firmware. I've seen figures as bad as 1.5 fps too (cf. above). It may be a question of subject speed, available AF contrast or which lens was used, or what aperture. Dunno. My test used a car's radiator grill as mandated by the standardized test setup.
QuoteOriginally posted by lol101 Quote
Then shouldn't the K-7 blast at full 5.2fps in AF-C, no matter if focus is achieved or not...?
No.
AF.C means that refocus is required in between the black out phases. A contrast autofocus system (if fast enough which nobody seems to be able to do right now) could maintain full speed in AF.C. Not a phase autofocus system, from no vendor.
If the K-7 drops from 5.2 to 3.9 fps in AF.C mode, then the time per image increases from 192 ms to 256 ms, so the additional focus is done in only 64 ms per image which already is a very good figure. Maybe, the black out phase on the K-7 is shorter than 192 ms (as would be the case if 5.2 fps is processing-speed limited -- which I don't think as 4 read-out channels can maintain 6 fps). But figures are still rather good.

Note that in my car test, the K-7 did not refocus between every image. It verified focus and in maybe 50% of images, kept it. This is one advantage of fast fps: there is less refocussing needed per image, and if it does refocus, it travels less.

So, whatever be your brand, switch to AF.S and maybe, lock exposure, to achieve full fps.

BTW, the K-7 even outperforms the marketing spec in that it can sustain 5.2 fps until card full with fine-tuned settings (like high JPG compression).
07-20-2009, 08:54 AM   #23
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QuoteOriginally posted by Bunny Gear Quote
I'm a bit confused with AF-C speed of K-7.
It really works good, better than K20D, but it's hard to exceed 3 fps (even without CA and distortion correction).
For example, D300 can make 6 fps till buffer filled, with 100% result in focus (not always, of course, but it could be REAL), K-7 can't make 4-5 fps.
The average speed (depends on lens) approx. 2.5-3 fps. It's true.
The specification of K-7 is marketing trick.
5.2 fps is only in AF-S.
I am sure if you were tracking football players it would be much much harder to get 5fps (this is where the D300 shines), but if you were to do race cards, track, baseball, basket ball (to some extent) the K-7 should deliver 3-5fps depending on the lens.

lol, I know I can't get more than 2fps when tracking with my k10D.... Why can't christmas come sooner??????

07-20-2009, 09:31 AM   #24
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somebody needs to shoot different lenses here since it is one of the factors that contribute to fps speed. otherwise we dont have fast lenses for nothing or the term fast lens, dont we?

I don't want to shoot anybody here but who has done multiple fps speed tests using different lenses on the K-7? I suspect that the people that are concerned about fps slow-downs never used beyond 2 lenses to test the fps speed at AF-C on the K-7.

please do include more parameters or atleast have a complete and extensive testing before arriving to what as considered as a general conclusion. results may vary from one to the other.
07-20-2009, 10:04 AM   #25
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QuoteOriginally posted by falconeye Quote
I don't think so. But you're right, my figure was with a beta firmware. I've seen figures as bad as 1.5 fps too (cf. above). It may be a question of subject speed, available AF contrast or which lens was used, or what aperture. Dunno. My test used a car's radiator grill as mandated by the standardized test setup.
I tried in very good light with stationary subjects and without calculating it precisely the fps drop is very noticeable vs AF-S.


QuoteOriginally posted by falconeye Quote
Note that in my car test, the K-7 did not refocus between every image. It verified focus and in maybe 50% of images, kept it. This is one advantage of fast fps: there is less refocussing needed per image, and if it does refocus, it travels less.
I may try this test, as weird it may sounds maybe it's faster when it's tracking (the focus is calculated rather than sought for with the sensors).

QuoteOriginally posted by Pentaxor:
I don't want to shoot anybody here but who has done multiple fps speed tests using different lenses on the K-7? I suspect that the people that are concerned about fps slow-downs never used beyond 2 lenses to test the fps speed at AF-C on the K-7.
I tried briefly on athletes training (to run) with a Sigma 70-200 HSM, very fast but still no more than 3 fps (3 pictures with the same time stamp, maybe if I calculated precisely I'd get 3.5... but still...). I tried with various lenses and different light. In low-light, the frame rate can drop dramatically to around 1-1.5fps (and here the metering mode can impact the performance, Manual is faster).

There is also the test cited by RiceHigh (you may not like him but he didn't invent this information). Even if the test is a bit flawed (testing a Tamron 17-50 on the Canikon vs the DA* 16-50 on the K-7 when they could have used the same lens) it shows a big performance disprepancy with the market leaders.
07-20-2009, 10:05 AM   #26
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QuoteOriginally posted by Bunny Gear Quote
If we use AF-C of K-7 with moving objects, no any chance to get even 3.5 fps.
Approx. 2-3 fps. Not bad. But...

D3, D700 and D300 has more ADVANCED AF system and it's real to be close to announced specs in AF-C mode with almost 100% results.
And you have personally done the test with D3, D700 and D300 in AF-C? Just like you have personally done the test on the K7, right?
07-20-2009, 10:17 AM   #27
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QuoteOriginally posted by Bunny Gear Quote
If we use AF-C of K-7 with moving objects, no any chance to get even 3.5 fps.
Approx. 2-3 fps. Not bad. But...

D3, D700 and D300 has more ADVANCED AF system and it's real to be close to announced specs in AF-C mode with almost 100% results.
I really need to see the results coming from your 3 Nikon gears (if you really own them). though you may gotten your information from 3rd party source, I would appreciate it if you were the primary source. we need results here, not word of mouth, inorder to determine clear and complete facts, not assumed or partial facts.

we would like to see sequence photo samples with time stamps by the milli-seconds or atleast seconds for evaluation. of course, all of these must be done under AF-C mode.
07-20-2009, 04:52 PM   #28
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This is really strange. I had no problems getting 3fps with my Nikon D80 in the past. I have no problems getting 5-6fps with our Canon 50D bodies.

I read the manual of the K7 that AF-C is shutter priority:

"The subject is kept in focus by continuous adjustment while
the shutter release button is pressed halfway. Even if the
subject is not in focus, the shutter can be released when the
shutter release button is pressed fully."

That means it should be shutter-priority
07-20-2009, 05:14 PM   #29
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QuoteOriginally posted by soccerjoe5 Quote
This is really strange. I had no problems getting 3fps with my Nikon D80 in the past. I have no problems getting 5-6fps with our Canon 50D bodies.

I read the manual of the K7 that AF-C is shutter priority:

"The subject is kept in focus by continuous adjustment while
the shutter release button is pressed halfway. Even if the
subject is not in focus, the shutter can be released when the
shutter release button is pressed fully."

That means it should be shutter-priority
What you have described is release priority, where the camera allows the photographer to release the shutter even if the camera's AF has not yet locked focus with the subject.
Shutter priority relates to the auto exposure mode where the photographer selects the shutter speed and the camera determines the corresponding aperture value according to the prevailing light level and metering profile.
They are two different things altogether, one relating to AF and the other, auto exposure mode.
07-20-2009, 05:28 PM   #30
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QuoteOriginally posted by soccerjoe5 Quote
"The subject is kept in focus by continuous adjustment while the shutter release button is pressed halfway. Even if the subject is not in focus, the shutter can be released when the shutter release button is pressed fully."
That means it should be shutter-priority
I think there is some misconception of the entire feature.

AF.C implies that the camera tries to focus on a (moving) subject. This is allowed to consume time. We don't discuss the K-7 here, not even Pentax or any brand.

The so-called shutter priority (over focus priority) is a priority rule only: that it shall take less time to focus which in turn is allowed to be less accurate. It does not say that focus is irrelevant, nor does it say that shutter release must be immediate.

Of course, if you keep the shutter half-pressed, the auto focus will have completed at the moment of the full press. So, AF.C may feel immediate if not combined with burst mode.

The mode to completely ignore focus information is called manual focus, not AF.C. Why do so many people think that pressing the shutter in AF.C must be immediate and must not trigger an auto focus operation? The "A" in AF.C stands for auto ...

I believe that K-7 will release the shutter in AF.C after about 0.7s of unsucessfull attempts to focus. In AF.S it would never release the shutter without a focus lock.
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