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12-06-2014, 04:18 AM   #31
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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...
I fact for lenses, it is highly depend of the design be of the lens. How powerfull the motor is... And then what was the priority: being very precise or being fast.

For shooting portraiture or for macro, you want usually to be very precise. For shooting sport you don't give a shit of being precise, I mean it likely the best AF tracking/predictive and so own prediction will be seriouly wrong... By much more than 1-2cm precision you need for portraiture.

In case of screw drive motor what will count then is how the lens use it. They can mechanically make the movement having bigger effects up to a point... Meaning if the motor is powerfull enough they'll move focus far faster... But obviously far less accurately.

Or they can mechanically make the movement smaller... Meaning they'll go slower but get much more precise move.

For sure FA77 or DFA100 macro are slow and not made for sports. They are made for portraiture and macro.

Overall SDM motor is not good enough so all lenses using it are typically too slow (like 50-135).

DC motor is the screw drive motor from the body modified to be more silent and put into the lens directly. His performance should be quite similar as screw drive.

12-06-2014, 04:35 AM   #32
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QuoteOriginally posted by Nicolas06 Quote
Overall SDM motor is not good enough so all lenses using it are typically too slow (like 50-135).

DC motor is the screw drive motor from the body modified to be more silent and put into the lens directly. His performance should be quite similar as screw drive.
So if DC is almost as silent as SDM and faster, why doesn't Pentax just retire SDM in favour of DC?
12-06-2014, 05:37 AM   #33
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QuoteOriginally posted by FantasticMrFox Quote
So if DC is almost as silent as SDM and faster, why doesn't Pentax just retire SDM in favour of DC?
If you noticed:
- this is what they anounced officially on interviews.
- all new lenses are either DC or screw drive. No SDM. For example DA20-40, DA16-85, DA55-300 and DA560.

So the day the current SDM lenses are replaced, that very likely they go with a DC motor.

I suppose the real question you had was more why the transition is not yet done on all lenses (17-70, 16-50, 50-135, 60-250, 200, 300). Well first not sure we cannot say 17-70 isn't replaced in fact by 16-85... then for the others, they need to first clear inventory (lenses are made in batches) and then to invest for the new one, have the time for the new batches and likely redisgn the optical design too to adapt. That would be not that interresting to have an new DC version to replace the SDM and need an even newer version just after with improved optics.

Last but no least, many want Pentax to provide an FF... many also think they'll release one next year. If it is really the case (I would not put my hand on fire for that) the priority would be obviously to concentrate on new FF designs for lens (like the rumored 70-200) than to provide a new version of 60-250, 50-135 or 16-50 by definition limited to APSC format. If they really go FF, it likely futher redesign of APSC lens will wait 2-3 years.

If you want this to go faster... Buy more Pentax gear, including SDM lenses !

Last edited by Nicolas06; 12-06-2014 at 05:49 AM.
12-06-2014, 06:37 AM   #34
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QuoteOriginally posted by Nicolas06 Quote
If you noticed:
- this is what they anounced officially on interviews.
- all new lenses are either DC or screw drive. No SDM. For example DA20-40, DA16-85, DA55-300 and DA560.
Didn't know that.

QuoteQuote:
Last but no least, many want Pentax to provide an FF ... many also think they'll release one next year. If it is really the case (I would not put my hand on fire for that) the priority would be obviously to concentrate on new FF designs for lens (like the rumored 70-200) than to provide a new version of 60-250, 50-135 or 16-50 by definition limited to APSC format. If they really go FF, it likely futher redesign of APSC lens will wait 2-3 years.
I made a post about exactly that issue (no resources to focus on new AF breakthroughs) a couple of pages back

12-06-2014, 09:45 AM   #35
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I would argue that Pentax needs a breakthrough in autofocus more than it needs full frame (because no professional is going to be happy with a full frame camera that has the AF <sarcasm> abilities</sarcasm> of the current pentax lineup) but I'm afraid of being lynched by the fullframe gang so I won't.

Did I hear someone say "Get a rope?"
12-06-2014, 09:49 AM   #36
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QuoteOriginally posted by Homo_erectus Quote
Did I hear someone say "Get a rope?"
Who needs a rope when you have full-magnesium alloy bodies to club you to death with?

But I partly agree, the AF needs improvements. On the other hand I think the K3's AF coupled with DC lenses is fast enough for almost everything except for fast tracking of action and sports, which is something that not many pros have to do all the time and that would therefore put them off.
12-06-2014, 10:50 AM   #37
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QuoteOriginally posted by FantasticMrFox Quote
Who needs a rope when you have full-magnesium alloy bodies to club you to death with?

But I partly agree, the AF needs improvements. On the other hand I think the K3's AF coupled with DC lenses is fast enough for almost everything except for fast tracking of action and sports, which is something that not many pros have to do all the time and that would therefore put them off.
This is what I experiment and that not with DC lenses, more with screw drive lenses (DA15, DA21, DA35, FA77...). AF on K3 is quite fast, very accurate and precise. For general purpose it fit perfectly the bill and only few body manage to be as good in low light conditions.

I encourage you to take a look to the forum official review: Review: Pentax K-3 - Autofocus | PentaxForums.com Reviews

To put the K-3's high-speed focusing capabilities in perspective, we compared the it to the K-5 II (w/ Pentax 60-250mm F4) and the Nikon D610 (w/ Nikon 70-200mm 2.8) in the field, shooting a moving subject in focus priority mode to see how many sharp frames we could get. We made sure that the moving subject, a bicyclist, followed the same route when testing each of the three cameras. The subject's distance ranged from 10 to 100 feet. The K-3 was set to SEL-27 with focus priority, the K-5 was in 11-point mode with focus priority, and the D610 was in 3D Tracking mode (39 points total).

Camera

Photos in Focus

Total Photos

"Keeper Rate"

53% Pentax K-5 II s
67% Pentax K-3
97% Nikon D610

2 photos out of 3 are in "keeper" instead of 1 out of 2 for K5-IIs. I would not be surprised that with a lens more suited to the job (sigma 70-200 f/2.8) you would achieve something more in the 80% range.

This is not perfect but this isn't that bad... I mean that the most difficult shooting conditions we can find we speak of here, not everyday shooting.

Just wait for the next 70-200 of Pentax and next body and you might be well at 90%+ for equivalent test.
12-06-2014, 11:18 AM   #38
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QuoteOriginally posted by Nicolas06 Quote
We made sure that the moving subject, a bicyclist, followed the same route when testing each of the three cameras. The subject's distance ranged from 10 to 100 feet.

[...]

53% Pentax K-5 II s
67% Pentax K-3
97% Nikon D610
How fast did the subject move and how unpredictably? The score for the D610 might suggest a ceiling effect.

12-06-2014, 12:08 PM   #39
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QuoteOriginally posted by Nicolas06 Quote
DC motor is the screw drive motor from the body modified to be more silent and put into the lens directly. His performance should be quite similar as screw drive.
If this is true, then wouldn't it be sweet if they could modify in-body screw drive to be silent? I'm sure the problem is that the screw-drive motor has to work with every lens and every lens has slightly different drive requirements, so in-body motor basically runs at 100% all the time, while an in-lens motor can run at, say, 50% of what the in-body lens does and still achieve the same performance (for another lens, it may be 65% or 35%).

For lenses that use the MTF line, they might be able to have the motor adapt to the needs of the lens, reducing noise appropriately. Man, that would be a killer feature, wouldn't it? Canon could just eat it.

Too bad that it would be a major undertaking, since there's what? Like 50 lenses they'd need to do? If they just did the DA line, that would probably be enough, but even that is a significant task.
12-06-2014, 12:35 PM   #40
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QuoteOriginally posted by MadMathMind Quote
If this is true, then wouldn't it be sweet if they could modify in-body screw drive to be silent? I'm sure the problem is that the screw-drive motor has to work with every lens and every lens has slightly different drive requirements, so in-body motor basically runs at 100% all the time, while an in-lens motor can run at, say, 50% of what the in-body lens does and still achieve the same performance (for another lens, it may be 65% or 35%).

For lenses that use the MTF line, they might be able to have the motor adapt to the needs of the lens, reducing noise appropriately. Man, that would be a killer feature, wouldn't it? Canon could just eat it.

Too bad that it would be a major undertaking, since there's what? Like 50 lenses they'd need to do? If they just did the DA line, that would probably be enough, but even that is a significant task.
You know I don't even get noise from my screw drive prime in most situations. It is only when it miss the focus that there real noise involved.

But I wondered like you? Why the screw drive can't be silent?
12-06-2014, 01:01 PM   #41
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Well a subject that I would like to contribute.

I don't own the K-3 at this moment, but I did have one and went to a volleyball tournament with it:
https://www.pentaxforums.com/forums/172-pentax-k-3/246938-i-went-out-volleyball-tournament-33-images.html
Left some comments there and in general it is a better camera in technics then the K-5(IIs) is.

Is it a camera with the same options as the D4s and 1Dx are? Well not by far.

I once used the Sigma 300mm/f2.8 screwdriven lens on my K-5. And wow is that a fast lens in focussing. To my knowledge, since it's a few years ago, but no messurements the AF was about twice as fast as my DA*300mm. So the torck on the K-3 is even faster I guess it will be the winner. Much faster then SDM or Sigma's HSM. Short throw on the focusring and really superfast. So there is more to this story then just changing things in the camera.

Not all sportsimages require fast AF. I also have done sports with the K-01 and that is by no means a fast camera:


Sportsphotography has changed and moved over the past years. We want crisp sharp images that have nice background blur and isolation of the subject. This is done with mostly Full Frame camera's and long and fast lenses. So I have seen 200mm/f2.0; 300mm/f2.8; 400mm/f2.8; 500mm/f4 and 600mm/f4 lenses and the zooms like 70-200mm/f2.8 and 200-400mm/f4. This when it comes to CaNikon's own lenses. There are some Sigma's ofcourse.

The tracking function is great, but also a difficult thing to use. Getting most out of the camera will require some knowledge. This is where Pentax falls short at the moment. Also having the AF working fast enough to keep up the framerate with tracking and AF-C isn't in the same ballpark as some CaNikon's are. Improvement could be done there.

Only if Pentax wants to be in the professional sportsimages industrie, since otherwise there are some other stages where the camera can be more then adequate.

Does it need improvement? Yes
Does it need to be as good as CaNikon's professional gear? No
Do we need the big lenses (that go up to 10k $)? No
Do we need Full Frame? Well for this professional task yes, but you know that I think that APS-H is more then enough)
Should Pentax be in this professional sports image park competing? No, but improving om camera and lenses would make the brand better for more users.
12-06-2014, 02:21 PM   #42
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OK a theme within theme is emerging. Why isn't Pentax making screw drive quieter and why don't we have lenses like the 80-200/2.8 to get the best images in fast moving situations .....

Well, my response is get a K3 and whack a FA* 80-200/2.8 on it. Scorching performance! It is all there for the taking. Also, FA*80-200/2.8 lenses can be bought for a fraction of the high end Canikon equivalents and it is FF.

Our DA 60-250/4 might be highly regarded ..... but, it is f4 and it is that that creates the issue (IMHO). Critical focusing is best done wide open so getting f2.8 or better is paramount. F4 just doesn't do it!

Anyway, I kind of agree with RonHendrik's post above. We don't have to have a system good at everything.
12-06-2014, 02:30 PM   #43
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QuoteOriginally posted by Wild Mark Quote
Our DA 60-250/4 might be highly regarded ..... but, it is f4 and it is that that creates the issue (IMHO). Critical focusing is best done wide open so getting f2.8 or better is paramount. F4 just doesn't do it!
Good that you bring this up, since I forgot it.


The new centre AF points of the K-3 are f2.8 lightstrong. Great. The others are only f5.6.

We do need some extra and new F4 sensitive AF points on a new AF-module to give important lenses like the DA*60-250mm and DA*300mm the greatness in AF they can give us in images.
12-06-2014, 05:56 PM   #44
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QuoteOriginally posted by RonHendriks1966 Quote

I once used the Sigma 300mm/f2.8 screwdriven lens on my K-5. And wow is that a fast lens in focussing. To my knowledge, since it's a few years ago, but no messurements the AF was about twice as fast as my DA*300mm. So the torck on the K-3 is even faster I guess it will be the winner. Much faster then SDM or Sigma's HSM. Short throw on the focusring and really superfast. So there is more to this story then just changing things in the camera.

I have both the Sigma EX Dg 300mm f2.8 and the Pentax-F 300mm f4.5. Both AF are fast but the Pentax-F 300mm is noticeably faster at attaining focus, it's incredibly fast and hand holdable. (Sigma has a longer focus throw, compared to Pentax, it really needs a focus limiter). It seems that the DA* 300mm SDM is slower by comparison. Getting a F/FA 300mm f4.5 prime companion for the K3 should accomodate most shooting needs.
01-25-2015, 10:26 PM   #45
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One thing that rarely seems to be mentioned in these discussions is the demands on autofocus of event photography -- weddings, parties, conventions and the like.

I have shot a fair number of events (though no weddings) with Pentax gear (K-5 IIs + 16-50 DA*, 21/3.2 Limited and 70/2.4 Limited) and with Canon (6D plus 24-70/4 L IS and 28/2.8 IS). The Canon rig is enough faster -- and the 6D is actually dissed in the Canon world for its mediocre autofocus! -- that I've pretty much given up using Pentax for events.

Doesn't sound like this kind of photography should be as challenging as birds in flight or running halfbacks. But perfect expressions are exceedingly fleeting, and the light is often challenging. The Pentax rig is too often still trying to grab focus as the picture disappears in front of my eyes. Canon basically always gets it.

And, yes, I rented the K-3 for a week to try it out. It's better, but not enough to sway me. A big bottleneck for Pentax, I think, is the lethargic SDM on the 16-50 and 50-135 lenses -- which should really be the pro workhorse pair. Hope they manage to fix that.
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