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12-05-2014, 06:14 PM   #16
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QuoteOriginally posted by Nicolas06 Quote
They already did it for K3 ... That just another step.
They improved upon the in-body system as they have always done it - DPReview stated that no matter which lens they used on the K3 (including 70 Limited, HD 55-300 WR, 50-135 SMD and DC 18-135 WR), in AF.C it struggled with any movements on the z-axis or z-/y-combination above pedestrian speed. They confirmed that the K3 was very good at detecting the target and holding on to it (so the K3 is not the problem!), but the lenses simply didn't execute the K3's commands fast enough. To catch up with CaNikon they need to make a much larger leap in their in-lens AF systems and that would require much more than just marginally improving on what they have. Then in-lens AF motor just needs to get more powerful, faster!

QuoteOriginally posted by Stavri Quote
All you have to do is get a Pentax-F/FA 135mm f2.8 or the 300mm f4.5, the AF screw-drive performance surpasses any SDM/HSM in existence. The -F 135mm f2.8 known as the "speed demon" gives the Canon 135mm f2 some serious competition.
So you mean the K3 with this lens would focus and track on a similar level as CaNikon?! I'd be interested to see that.

QuoteQuote:
(the screw-drive AF of the -F/FA on K-3 is as good as it gets for the Pentax system in my opinion) The jury on the DC motors is still out...
Is it much faster than the DA screw drives? I've got the 18-55 kit and DA 35 f/2.4 on the K3 and am not really impressed by the AF speed and AF.C.

12-05-2014, 06:45 PM   #17
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QuoteOriginally posted by Kevwaly Quote
I often read that Pentax is inferior to the Canikons when it comes to sports photography.
Actually only inferior to Nikon. Conventional wisdom around these parts is if you don't like Pentax AF, buy a Nikon and gloat in the glory of your empty wallet and nicely focused action shots. Truly!


Steve
12-05-2014, 06:48 PM   #18
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QuoteOriginally posted by stevebrot Quote
Actually only inferior to Nikon.
I doubt that any money can buy you a Pentax setup that equals the sports capabilities (especially AF.C) of a Canon 7D Mk II, or even 7D Mk I.
12-05-2014, 07:03 PM   #19
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QuoteOriginally posted by FantasticMrFox Quote
but the lenses simply didn't execute the K3's commands fast enough.
Yes, that is what they said.

QuoteOriginally posted by FantasticMrFox Quote
So you mean the K3 with this lens would focus and track on a similar level as CaNikon?! I'd be interested to see that.
That would be interesting to see, but hard to prove without an instrumented system such as that at Imaging Resources. Here are a couple of "points of truth":
  • Imaging Resources loves the K-3...they explicitly say so
  • The K-3 is really competent with the screw drive lenses
  • Even with light carriage screw drive lenses, the Pentax system lags behind certain of the competition in the Z-axis tests when driven by Imaging Resources test jig
  • There are no speed demon AF lenses with in-lens motors currently available in K-mount
Having stated the "points of truth", better known as conventional wisdom, I will insert my own anecdotal experience using the K-3 with the Sigma 17-70/2.8/-4.0 (C). I was shocked to find that the K-3 in AF-C mode (focus priority) accurately tracked dancers moving at greater than walking pace in the Z-axis at a cultural fair this last summer.

I suppose I could rent a D7100 for a day to get a taste of "the real thing", but why would I want to do that? I bought my K-3 for what it does better than the D7100.


Steve

---------- Post added 12-05-14 at 06:05 PM ----------

QuoteOriginally posted by FantasticMrFox Quote
even 7D Mk I.
I have never seen a 7D Mk II in the wild, but know that my K-3 does as well as my friends 7D Mk I with comparable lenses. Ditto for her 5D MK III. She and my other Canon friends are always complaining about their AF. I am acquainted with a group of rabid bird photogs that hang out daily at the local wildlife refuge. Within that group, it is the Nikon shooters that get the hard shots.


Steve


Last edited by stevebrot; 12-05-2014 at 07:08 PM.
12-05-2014, 07:13 PM   #20
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QuoteOriginally posted by stevebrot Quote
I have never seen a 7D Mk II in the wild ...
Me neither, but here's a demonstration (at 4:40):

12-05-2014, 08:58 PM   #21
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It's all in knowing what you're trying to accomplish. These were taken 3 days after I got my K-3. I previously used my K200D for Hydroplane racing and had lots of success over the years. I learned my technique years ago on my ME Super with manual focus lenses. It still serves me well today.

















12-05-2014, 09:12 PM   #22
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You might want to look at this thread, which I posted 2-1/2 years ago: https://www.pentaxforums.com/forums/6-pentax-dslr-discussion/181885-analysis-...provement.html

The suggestions are still valid even with the 27-point SAFOX 11 AF system. The way I see it, this is primarily a software/firmware issue. Pentax's AF algorithms need a lot of work.

—DragonLord

Last edited by bwDraco; 12-05-2014 at 09:20 PM.
12-05-2014, 09:32 PM   #23
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QuoteOriginally posted by MadMathMind Quote
.... But when the lighting is poor (indoor sports, night games), f/4 isn't going to get it done. That's where Pentax really lacks. I'm ok with it since I can't afford those massive lenses anyway, but the limitation is there.
F4. ISO was 3200, 6400 and 1600 respectively. Sigma 100-300/4 + 1.5 TC, DA 12-24 and DA 50-135. I have a few more here View and Purchase: Downloads & Prints | Brooke Meyer









12-05-2014, 10:01 PM   #24
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QuoteOriginally posted by Brooke Meyer Quote
F4. ISO was 3200, 6400 and 1600 respectively. Sigma 100-300/4 + 1.5 TC, DA 12-24 and DA 50-135.
That's fine, but dancers aren't moving like football players. 1/320 isn't going to be quite fast enough for high-speed athletics. To hit 1/1000 in the lighting of your shots here (very nice, all of them), you're looking at ISO10000, ISO25600, and ISO5000, respectively. Using ISO5000 is better than not taking the shot at all, but no one wants to shoot at that ISO if it can be avoided.
12-06-2014, 12:26 AM   #25
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This is not the first time in this forum people have critically discussed Pentax AF.
There is usually a pattern to these discussions - the discussion will range from: 'people shot action OK even before AF existed' through to ' buy another brand - problem solved'.

I fall towards the side of the discussion that says 'Pentax AF can do the job under most circumstances', even with dynamic subjects that make football players look as static as garden gnomes. Not automagically all the time, but it can be done if the light is good and some experience is applied.

Most recently, I've been able to directly compare the K-3 w Sigma 70-200 HSM II with a Nikon D610 w. Nikon 70-200 VR shooting very dynamic and unpredictable low-light rodeo action. Like, thousands of shots.

To be honest, they both work just as well as each other. The only major difference is the noise levels and IQ in high-ISO post-processing (advantage Nikon FF) , and the slight edge to the K-3 when the ambient light completely drops to almost black. The key to getting good focus results with either in AF-C has been (a) the AF motor performance of the lens, (b) choosing the right AF settings for the type of action and scene, (c) setting the right shutter speed, and (d) anticipating the action/ locating yourself in the right place.

Pix generally related, following the same subject (rodeo), ranging from K-x w. manual focus lenses to Nikon D610 with fast AF lenses.


Explosive entrance - Rodeo at Lismore Show 6/14
Pentax K-x, SMC Pentax M 75-150 f4, 1/2500, ISO 800


Bull riding - Rodeo at Lismore Show 12/14
Pentax K-x, SMC Pentax M 75-150 f4, 1/1250, ISO 800


Kyogle Bull-riding Spectacular - runaway
Pentax K-5, Sigma 70-200 f2.8 HSM II, ƒ/2.8, 83.0 mm, 1/500, ISO 25600


Yellow chaps 1 - Kyogle bull riding
Pentax K-3, Sigma 70-200 f2.8 HSM II, ƒ/3.5, 93.0 mm, 1/500, ISO 1600


Brown bull again
Pentax K-3, Sigma 70-200 f2.8 HSM II, ƒ/2.8, 70.0 mm, 1/400, ISO 6400


Red shirt struggling - Lismore Show Rodeo
Nikon D610, Nikon 70-200 f2.8 VRI, ƒ/2.8, 110.0 mm, 1/400, ISO 5000


Hereford sideways - Murwillumbah Show Rodeo
Nikon D610, Nikon 70-200 f2.8 VRI,ƒ/2.8, 160.0 mm, 1/400, ISO 20000

Last edited by rawr; 12-06-2014 at 12:33 AM.
12-06-2014, 01:51 AM   #26
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QuoteOriginally posted by MadMathMind Quote
That's fine, but dancers aren't moving like football players.
I agree, they'd get let go from the company if they were that clumsy. Besides being a lot more graceful and disciplined, they are generally more fit.


12-06-2014, 02:34 AM   #27
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Football players (no matter the code) play by the rules, and are herd animals
Makes them easy to shoot.
12-06-2014, 03:08 AM   #28
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QuoteOriginally posted by Stavri Quote
All you have to do is get a Pentax-F/FA 135mm f2.8 or the 300mm f4.5, the AF screw-drive performance surpasses any SDM/HSM in existence. The -F 135mm f2.8 known as the "speed demon" gives the Canon 135mm f2 some serious competition. The AF performance of SDM lenses is sub par and can range from "pedestrian to very good" but will never blow your mind (the screw-drive AF of the -F/FA on K-3 is as good as it gets for the Pentax system in my opinion) The jury on the DC motors is still out...
Totally agree with this statement. The F135 and 300 are super fast AF - add the FA*80-200 and F100/2.8 too on the K3. I was stunned with the speed and accuracy. I am yet to try sports photography with these combos but I can already say that I am excited by the prospect.
12-06-2014, 04:03 AM - 1 Like   #29
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QuoteOriginally posted by FantasticMrFox Quote
Then in-lens AF motor just needs to get more powerful, faster!
For the Z-axis, being precise is as important (or more) as being fast. Problem is Pentax K3 track but do not predict. When you predict you move the focus continuously direct to where the subject will be when you take the photo.

When you track you just recognize that the object is focus is the same as previous frame, you compute the shift to be in focus currently and order the lens to do it.

For sure, you need to be much faster because you are always late and because the subject continue to move. In particular there always a time between when you trigger the shoot and the shoot is taken. Something like 1/10s of second. Nikon advenced bodies (D7100 for example, but I would say not D610) know the exact time and estimate the object speed in all directions. So it know that in that 1/10s the object would have moved say 1m (that's already 36km/hour, as fast as world wide running champions) and they move the focus accordingly.

You don't need that much speed out of a lens to move it by the focus 1meter only (except if the subject is maybe 2m from you) because the change in focus is really small.

This is software computation, not hardware and K3 doesn't do it.

For sure, very fast lens will follow more accurately than slow lens but they'll never be as perfect as even a moderately fast lens but precise lens with predictive algorithms.

QuoteOriginally posted by FantasticMrFox Quote
Is it much faster than the DA screw drives? I've got the 18-55 kit and DA 35 f/2.4 on the K3 and am not really impressed by the AF speed and AF.C.
From my understanding, Pentax K3 screw drive is the most powerfull screw drive available all brands. Some lenses like all tamron 70-200 are slow on other brand but Ok on K5 already for example. On K3 it would be faster.

Now DA35 f/2.4 focus very fast in something like 0.2-0.3s. This lens would be fast enough for any action... But the focal lens might not fit.

I'd say 70-200 sigma + K3 will get you very satisfying tracking capabilities for a reasonable price (who want to spend 3000$ for the lens only from Canikon?). Still it will not be predictive algorithms.

The new AF sensor and metering sensor are new. The first body to use them is the K3. The metering is same level as highest high end Nikon body. AF sensor has no as many points but except if you try to track a very small object, this should not be the limiting factor. Agree that covering a wider area with maybe 50 AF sensor would help.

Still what miss is the algorithms. Before the software team had no chance to make them, the hardware was not here. Now they developped the basics to get tracking. Tracking in reality for me is following subjects and finally is just choosing the right AF point in the grid and let the AF sensor does it job as usual. Predicting is knowing in advence the right AF point but much more importantly predict the focus distance in advence. This is mostly for movement in Z axis. What you complain is not yet good.

For this, Pentax just need to improve their software. It is very likely that without any special effort (maybe 1-3 engineer working on it full time on software side for the next body) that they get that fixed.
12-06-2014, 04:10 AM   #30
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QuoteOriginally posted by MadMathMind Quote
That's fine, but dancers aren't moving like football players. 1/320 isn't going to be quite fast enough for high-speed athletics. To hit 1/1000 in the lighting of your shots here (very nice, all of them), you're looking at ISO10000, ISO25600, and ISO5000, respectively. Using ISO5000 is better than not taking the shot at all, but no one wants to shoot at that ISO if it can be avoided.
A human body will not move faster overall than 36km/h whatever the activity if not on bike, car, horse, whatever. Extremity can certainly move faster of course. But dancer do evolve as fast no issue.

The difference with your football player is maybe the focal lens. If there on the oposite of the field and you use a 600mm to get a close shoot, then you'll need 1/1000s at least or at least 1/200 or something with shake reduction. But while finding a 70-200 f/2.8 or equivalent is quite easy and even sometime affordable (like the old tamron), good luck with the 600mm f/2.8... Not sure there even many out there and you can play that without a high end tripod.
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