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04-02-2014, 10:58 AM   #61
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Chris,

Interesting post and discussion. My own experience mirrors yours, though I have spent much less time trying to document it thoroughly. I own a K-5 and K-5IIs and rented a K-3 for a week to check out the new and improved autofocus. I also shoot with a Canon 1Ds, 6D and 7D.

Without getting into great detail, Pentax autofocus is still way behind anything Canon has to offer. With my Pentax gear -- including the K-3 -- I often find myself fighting the equipment for focus. That can be true, depressingly, even for landscape photography in decent light.

I have continued to shoot with Pentax because I like its other virtues. Ultimately, any camera is a tool, and all tools require practice with their use and accommodation to their flaws. I don't, for example, take my Canon gear out hiking in a driving rainstorm.

I am a little surprised to see people argue that Pentax autofocus is just as good as Canon's -- that it's somehow more accurate, or that Canon cheats by beeping confirmation too soon. That certainly hasn't been my experience with any Pentax or Canon body I've owned or used.

Finally, I appreciate your going the extra mile to return your K-3 and give Pentax a chance to examine it. They said it works the way it's designed to. I have to respect their opinion on that and so assume that the sometimes-stuttering K-3 I used was also within spec.

Bob

04-02-2014, 04:05 PM   #62
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Hi Bob and thanks for your input!

You pretty much expressed many of my thoughts to. I loved (and still love) my father's Spotmatic dearly. I shot some great portraits and landscapes with it and I still enjoy many of the work methods and tools that to me seem quite normal - among them my Lunasix F.

For a long time I could not afford a new camera, so I had to use what I could borrow. That is where the old rebel came in to play. Last year I got a new job and I could afford a new camera. So I went out to research what was on the market. At the time, the dancing wasn't really part of the equation, because I had given that up years ago - including shooting photos of dancers. I narrowed the choice down to: Nikon D7100 and D800, Canon 70D and 7D and the K-3. The D800 was soon out of consideration because it's just too pricey. The 7D is a good camera but it has been around for quite a while and is missing several new features like WiFi. The D7100 and 70D don't have the magnesium alloy (IIRC the D7100 in part, the 70D not at all). Additionally, the K-3 has a 100% viewfinder, shake reduction in the body, weather sealing (although that was not a major consideration) and a bunch of other features.

I watched lots of reviews on youtube and read even more - not only of the K-3, but also of the Canons and Nikons. The K-3 looked good in all reviews. The AF was sometimes criticized, but more along the lines of it not being as good as the D4's AF. By what we are looking at here, you'd expect the reviews to call the K-3's AF seriously flawed and not just "not quite on par with Canon and Nikon". I expected the AF to be slower than Canon's or Nikon's but the difference only to be noticeable in direct comparison. I did not expect to run into problems during a dancing shoot.

After having used the K-3 for several weeks now, there are only four things I could complain about:
  • AF
  • The shutter button feels cheesey and wobbley-
  • I keep pushing the shutter button on the battery grip accidentally with my lower hand.
  • The battery grip is a little cheesey (no magnesium, only plastic) and only takes one battery. The other battery must be inserted into the camera's main slot which means the battery grip has to be removed to get at it,
Apart from those (of which only one is a real issue) I am really happy with the camera and I want to keep it!


Cheers
Chris
04-02-2014, 04:27 PM   #63
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QuoteOriginally posted by PixelGeek Quote
I do not doubt for a second that you guys are really trying to help me out here and I hope you believe that I really believe, I want to learn something. But for that to work we have to be talking about the same things. I have stated several times that neither the 50mm Sigma prime nor the 85mm Sigma prime is any faster (at focussing) than the kit lens (DA 18-135mm) - and yes I did try all of them. If you suggest the 85mm SIgma when I write about slow AF, then one of us is missing something. I will go into the focal length issue a little further down.
QuoteOriginally posted by PixelGeek Quote
Photography is a hobby of mine. This means, I watch my budget and although I probably could spend more money on my stuff, the money is a very important factor to me. I also tend to buy less lenses and try to get good ones. I actually bought the two Sigma lenses for portraits, not for action. I do not make any money with my photos, I take photos because I enjoy doing so and it relaxes me. Unless I suddenly turn rich, I will probably never buy a second body.
This is why I was trying to help you get one lens that works, rather than three that don't.

The problem here is that few people, if any, have experience with all the lenses that are reasonable possibilities. And since Pentax has been traditionally been weaker in action AF performance (and though significantly better now, still is), the 2nd best lens solution still might not be good enough, whereas the 3rd or 4th best might work fine with Canon.

So all of us have to make a few guesses, based on our experience combined with what others have told us. Perhaps I was being flippant, having not used the DA18-135. But my experience with similar lenses tells me it's a bad idea. And there's a reasonable likelihood the HSM on those particular Sigma lenses is slow too - after all, such primes are typically not designed for action, while the Sigma 70-200/2.8 is.



Since you want the shorter focal lengths, and you don't want primes, my best idea for you is the Tamron 28-75/2.8, which is also relatively affordable (especially used). That's what Cruel1 used at the same event, along with the latest Sigma 70-200/2.8 OS HSM: IMGP9052_zpsa4a4c94d.jpg Photo by res1g8hf | Photobucket The Tokina AT-X 28-70/2.8 also has an outside chance - the IQ is probably even better than the Tamron, but it's considered a bit heavy by some, and it's difficult to discern what the AF performance will be on the latest bodies, since it isn't so common.


But I really do think AF-C, properly used, is the way to go for you, because you have the focus already set up before you're ready to take the shot, and then when the time comes you can take it immediately. Some people still use Manual Focus techniques very successfully, but that isn't necessarily the better way to go anymore.

QuoteOriginally posted by PixelGeek Quote
As I have said, the focus motor is not the issue here. I have seen reviews of the 16-50mm where people say the motor is slow. This is not my problem. The speed of the contrast AF I could work with, no worries.
Also, very few people use Live View (contrast AF) for action shots, as far as I'm aware. Accuracy can be quite good, but speed of AF is traditionally not. I may have misunderstood you, but If this is the method you're using, then most of our advice may be irrelevant. I don't believe the 2003 Canon 300D even had this focus method, did it? In fact, the repair center will probably assume you're using Phase Detect AF, unless you say otherwise.

QuoteOriginally posted by bkpix Quote
I am a little surprised to see people argue that Pentax autofocus is just as good as Canon's -- that it's somehow more accurate, or that Canon cheats by beeping confirmation too soon. That certainly hasn't been my experience with any Pentax or Canon body I've owned or used.
I hope others aren't claiming Pentax AF is better (although it can now focus in lower light than many other cameras) - I certainly wouldn't. But many of us have found it to be workable, and that's what I'm trying to encourage here. Otherwise, I'd encourage a Canon 7D (or possibly 70D) like PixelGeek was originally considering, ideally with something like a 24-70/2.8 L lens.


But if subject isolation and narrower DOF is not a priority, perhaps a more modern design like a m4/3 or even a Nikon V3 would actually be more appropriate - I certainly keep an eye out for these newer cameras, and regularly try to re-evaluate my still and video needs in light of them. The K-3 is a great overall camera, but pairing it with a DA18-135 may not as good as some alternative setups for this type of shooting. These scenarios usually call for an f/2.8 zoom with reasonably fast AF, at a minimum. I've managed to get a few good running shots with my DA*50-135, but more often I just want to scream at it for its slow AF. That's why I don't even bother putting it on the camera when I've got much better alternatives for shooting action.

Last edited by DSims; 04-02-2014 at 05:12 PM.
04-02-2014, 08:21 PM   #64
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Hi Chris

Pentax SDM are slow (not faster than pentax screw drive lens), so they are slow to make the micro adjustment, and it will not improve the situation compared to 18-135 (in fact worse)....

Most of the canon USM lenses are very very fast (try using a 24-70L or 17-55) and the micro adjsutment is done extremely quickly. Recent sigma lenses are still better than Pentax, which is why i suggested you try Sigma's 17-50 F2.8 which is one of the best standard zoom lens for Pentax systems (both in terms of IQ and AF speed)

Pentax AF system was lousy in the past, it has improved recently (since K-5), but it will never improve enough unless the lens is upgraded. What i am trying to say is that the bottleneck is more the lens than the body (it used to be both before K-5), the body AF responsiveness of K-3 (or even K-5) is not worse than a rebel (about the same which is not good btw as rebel is an entry), and as lens lineup do not change in a matter of months, the problem is here to stay unless pentax invest the next few years introducing very fast AF lenses (or sigma improves further their AF speed)

The only quick solution is to try to borrow a sigma 17-50 to see if it improves the situation. Otherwise a modern canon model like 70D combined with any decent canon lens will simply blow away if the critical criteria is stopping the action at the moment you see it in the view finder....(to do that you need a lag of around 100 ms)

And yes you are absolutely right, the reviews never focus enough on the auto focus aspect. They are usually very brief, and in my opinion very carelessly analyzed, and as of today there is not a lot of thorough review avaliable on websites regarding AF speed. For example, very few people will know that the lag between Canon and Nikon mid-range system can be quite significant (due to mid-tier lenses on nikon being quite a bitslower than canon in terms of AF speed + AF confirmation speed of the body also being worse in Nikon)

Then there is also the aspect of tracking (AF-C), which is a whole new story which i dont' think is your focus so I won't go there... With a pentax system you have to do a bit of anticipating shooting to get the right moment (e.g. shoot 0.1-0.2 s before your anticipated moment)... sad isn't it ??

Rgds
CJ

04-02-2014, 08:53 PM   #65
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Yes, thanks CJ, I almost forgot. Does anybody know if the AF speed on the latest Sigma 17-70/2.8-4 is very good? The FL is about what's requested (though I doubt anything wider than the Tamron's 28mm is really needed for dance events) and many people seem to like this lens.
04-03-2014, 07:34 AM   #66
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From what i gathered (i did not use it directly), it is not as fast as 17-50 F2.8, I did hear good comments about its IQ, and has also the benefit of smaller size. With pentax, if speed matters even a little bit, you need to use the fastest possible AF lens, and even then you are basically at the level of a mediocre zoom in canon in terms of single shot AF.

However i would also say that canon is exemplary in terms of AF speed, try a entry level nikon (D5xxx, D3xxx) with its kit lens, it is NOT faster than a pentax and is quite a bit slower than canon... Nowadays fast mirrorless cameras and premium compacts are actually sometimes even better than mediocre DSLR PDAF systems (i have a EM5 and, RX100 and they aren't slower than my K-5...)

I attach a couple of photos i took with 18-135 and K-5 where my kid was running towards me at full speed (he was trying to throw the snowball at K-5, and succeeded..), in broad daylight and at not too demanding situation like this (18-135 doesn't have fast aperture, so there is more tolerence to missed focus), its still OKish...

All in all, I think there is some sort of satisfaction in the color rendering, the overall functionality (small but well built, well customizable), the small sized lens (where else can you get a 18-135 whose size is only 7cm in length), the slient shutter sound ... which makes it hard to decide whether we should go for other systems that are much better on some areas (such as AF speed, lens lineup), but does not have those goodies.... On my side, I plan to repurchase a canon body (such as 50D) for the part that demands AF speed

CJ



04-03-2014, 07:58 AM   #67
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I have none of the slow focus issues described here. I've shot hundreds of action shots with my K-3; BIF, hockey, motor vehicles, running dog, using the DA 18-135 and DA*300. No trouble with AF, it is fast and accurate, far more capable than the K-5 and older Pentax bodies. My action settings are TAv, AF-C, focus priority and expandable AF-point.

It's truly odd that the OP finds CDAF faster than PDAF. CDAF on the K-3 is horribly slow. I was expecting it to be as fast as the K-01 but it's not even close. Compared to PDAF on any Pentax, it's not in the ballpark.

PS There seem to be lots of comments in this thread about the K-3 and DA 18-135 from people who own neither.

Last edited by audiobomber; 04-03-2014 at 08:29 AM.
04-03-2014, 08:09 AM   #68
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It's interesting about Pentax AF. My problem with it hasn't been for action; I've shot outdoor tennis, for example, with the K-5 and 50-135 DA* and had perfectly good results. The place I run into trouble is shooting people at events (like parties and conferences), where the autofocus seems to hang and search interminably at times, especially indoors.

04-03-2014, 01:22 PM   #69
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QuoteOriginally posted by cjsong79 Quote
All in all, I think there is some sort of satisfaction in the color rendering, the overall functionality (small but well built, well customizable), the small sized lens (where else can you get a 18-135 whose size is only 7cm in length), the slient shutter sound ... which makes it hard to decide whether we should go for other systems that are much better on some areas (such as AF speed, lens lineup), but does not have those goodies.... On my side, I plan to repurchase a canon body (such as 50D) for the part that demands AF speed
I like your photos - the first thing I noticed was the sharpness and how nice the color came out. Good thing you had WR too, when you're having snowballs thrown at it!
04-03-2014, 01:43 PM   #70
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QuoteOriginally posted by cjsong79 Quote
I attach a couple of photos i took with 18-135 and K-5 where my kid was running towards me at full speed (he was trying to throw the snowball at K-5, and succeeded..), in broad daylight and at not too demanding situation like this (18-135 doesn't have fast aperture, so there is more tolerence to missed focus), its still OKish...
This is focus tracking, which is a weakness of the K-5 and older bodies. According to Pentax, tracking was improved for the K-50 and K-5 II/s. It is hugely improved over any of these with the K-3; 27 focus points, colour tracking has been implemented, and the AF Hold menu puts tracking a step beyond previous Pentax bodies.

Last edited by audiobomber; 04-03-2014 at 02:07 PM.
04-03-2014, 04:41 PM   #71
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Yes, on bodies that can do proper focus tracking, it will not be a matter of AF speed, but AF tacking precision/granularity (and K-5 has none). However, the photo was more to illustrate that during daylight moderately fast objects moving towards you at moderate apertures will stay in focus even with a K-5 + 18-135 (at least that was my experience). It will be a different story if it is more at the tele part of the reach, or lowlight condition..

Sorry for saying the same thing again, but if i had one wish, it would be pentax to start to develop fast standard zoom AF. It would be a logical choice, afterall in K-3 they invested in the AF system. Until then, on my side i decided to try and re-purchase canon bodies for situation that is more demanding on the shot timing (the other drawback of Pentax is that pre-focus lag is about twice as long as canon or nikon mid-level bodies... 100 ms vs 50 ms, for me this is the most annoying part as kids change their expression or turnaround very quickly...)
04-03-2014, 06:05 PM   #72
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I'm quite happy with the tracking on my DA*300. It's certainly faster than the Sigma 150-500mm HSM I used previously. I've had good success with the 18-135mm. Please note that you are making pronouncements of Pentax AF based on a two-generations old body. The AF system of the K-3 bears little resemblance to a K-5; 27 points. tracking sensitivity controls, improved accuracy under artificial light, three f/2.8-sensitive sensors. The K-5 I owned was hopeless in tungsten light.

Last edited by audiobomber; 04-03-2014 at 06:28 PM.
04-03-2014, 11:01 PM   #73
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Hi Dan

i did not make any comment on tracking ability as I think that was not the subject of interest for Chris (and indeedI was considering to switch to K-3 precisely for the fact that it can properly track).

In fact, If you have a look at my earlier comments, i am basically trying to explain to Chris that under single-shot AF (not C-AF), the larger determining factor is the lens, not the body... and the lenses tend to be faster on canon bodies than pentax (by a fairly large margin) as he was surprised on old entry rebel could be faster than the latest flagship pentax model.

I'm a little surprised that there is a tendency of criticism between the different replies, everyone has their perspective based on their personal experience, and on slightly different scope (C-AF and S-AF is a totally different subejct) which may or may not be relevent to others, and its just a sharing of opinions.

In my personal opinion, pentax is a very good system, and only got better with K-3 (and i have been using pentax as my main system for almost the last 10 years), but still, i would love to have a lens like canon's 17-55 or 24-70 in the pentax lineup (in terms of AF speed), and I would have loved (and probably would have decided to upgrade) if K-3 had the same degree of pre-focused shutter lag as the upper canon/nikon bodies (shutter lag of 50-60 ms vs 100 ms for the K-3)
04-04-2014, 05:10 AM   #74
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QuoteOriginally posted by cjsong79 Quote
I would have loved (and probably would have decided to upgrade) if K-3 had the same degree of pre-focused shutter lag as the upper canon/nikon bodies (shutter lag of 50-60 ms vs 100 ms for the K-3)
Where are you getting these figures? Milliseconds are not something one could measure at home.
04-04-2014, 07:40 AM   #75
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you can try this website, in my opinion, they are very reliable when it comes to pre-focus AF speed as its easy to measure (but a bit miss leading when it comes to real AF speed measurement)... otherwise you can try the two camera side by side and 50 ms difference is more than noticeable if you are paying attention.

Pentax K-3 Review: Now Shooting! - Performance
Canon 70D Review - Performance
Nikon D7100 Review - Performance

But again, it depends a lot on the shooting style, if your shots are rarely pre-focused, this doesn't matter (it does for me, as majority of my shot is focused in advance, and i am just watching for a particular expression before i fire)
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