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Forum: Pentax DSLR Discussion
05-21-2017, 12:33 PM
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No, because when you'll press the shutter button again, even if the lens is already prefocused, you'll still need to have AF lock done in AFS because the camera release the shutter. When using back AF only mode, when you press the shutter the camera takes the shot.
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Forum: Pentax DSLR Discussion
05-21-2017, 11:24 AM
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Same for me, unless training to get used to it, back button AF requires additional attention, I just prefer to have AF done via the shutter button.
I think, the back button AF is not only for AF.c, also works with AF.s. Using the back button AF allow to disconnect AF from shutter release, which means, for example in low light, you can focus with the back button AF and even if it is too dark for AFs lock, you can still take the shot by pressing the shutter button and your shot will be in focus. You can use the back button AF to prefocus, than you don't need to keep your finger on the shutter button, and when you press the shutter button the lens is already prefocused where you want it to be (lag = 0). You can also use the AF back button to inhibit focusing of the shutter button. Using AF.s with the shutter button, the lag is very short (as you say), but if you program the back button AF for focusing, then the lag for shooting bursts is even shorter, it's immediate. Typically, I used that for photographing a kingfisher; this guy either does not stops or he lands on a perch above water, but he only stay for a very short time, he may take off immediately. So, I use the back button AF to prefocus on the perch, and when the kingfisher lands on the perch, I fire a burst to catch the moment.
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Forum: Pentax DSLR Discussion
05-21-2017, 03:50 AM
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I don't care, it's not my money. I just think we are soaked into marketing completely disconnected from reality.
Marketing talk is one thing. Real photos from the Sony 24-240 tell a different story. In fact, at 24mm full frame, the sony images are worse than any images taken with a Pentax apsc gear at the same settings.
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Forum: Pentax DSLR Discussion
05-18-2017, 10:46 AM
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The strategy of desire from camera marketing business is working very well on you. Don't argue, don't wait, tomorrow, check your credit card and run to Sony camera shop and buy a Sony A9, don't complain again and go try to find fast moving things to enjoy autofocus. Anyway, after having played around and be amazed by AF speed for a few weeks, you'll soon not enjoy more than anything else, but Sony will have your money in their pockets LoL.
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Forum: Pentax DSLR Discussion
05-14-2017, 01:29 PM
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I really like your way to swap things around, at least that works well to trigger people's reactions. Pfft that's the kind of question I won't answer as I'm not the one evaluation cameras by the latest fad is the best.
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Forum: Pentax DSLR Discussion
05-14-2017, 12:14 PM
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They are as neutral as anonymous PF members commenting about why EVF and fast AF are needed to take photos. Regarding DPR, Rishi went on a business trip to Sony HQ and on Day1 the A9 was announced , there were already hundred of video on youtube and a dozen of articles on DPR and Imaging-Resource and DXO. I want to believe that those guys are super fast and work the whole night to be the first to comment on the A9, while the more realistic version is that Sony marketing planned the go to market at least several month in advance, signed non disclosure agreements and paid content marketing contract with all the reviewers who prepared some content and presented it to Sony for agreement before publishing. DPR is a web marketing agency, they aren't photographers more than you, and most likely less qualified than you, but their jobs is to get paid for advertising new products.
Apparently, here https://www.lensculture.com/ we have to look very hard for find any photo that requires a fast AF. I don't think they care much about the camera used. Some of them still use film view cameras.
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Forum: Pentax DSLR Discussion
05-14-2017, 01:46 AM
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You show how the Nikon lens is faster to focus than Pentax, and you say that Nikon is twice as fast. Actually, if you did not buy the Nikon gear, that must be because you did not want to spend the money for it. So I guess you are expecting Pentax to deliver the same performance to you free of charge? unless you remain a spectator comparing camera performance but neither buying it nor using it.
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Forum: Pentax DSLR Discussion
05-13-2017, 11:28 PM
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Those are actual photographs. Please keep in mind that most of the people judging AF speed are doing is by comparing with other cameras. Some people are commenting on camera products and have not taken a single photographs in the last 6 months and some people are still commenting on Pentax forums while having no camera and not taking any photograph. They are commenting on camera performance like seating on a bench drinking beer at a horse race and betting on what horse will win the race.
I did not know that photography is about betting on which horse is the fastest. I mean, commenting on horse is free of charge and does not engage anyone, owning a horse requires a much higher commitment.
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Forum: Pentax DSLR Discussion
04-01-2017, 06:04 AM
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I have no evidence to prove how much is the contribution to noise of the area taken by on sensor dual pixel AF. The area covered depends on the need for low light AF capability, for -3ev sensitivity, the area is comparable to what's used for PDAF on DSLR. No miracle, law of physics apply. Can you provide evidence that on sensor dual pixel AF has no effect? Strangely we can't compare Fuji on sensor AF DR and SNR to Pentax with DXO, the Fuji are not tested.
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Forum: Pentax DSLR Discussion
04-01-2017, 03:58 AM
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Apparently, there is not free lunch, on sensor pixel used for AF receive 50% less light, explained by Fuji: https://www.dpreview.com/articles/2151234617/fujifilmpd
"'The AF sensels are only arranged in the center area of a CCD, so when phase detection AF is activated the AF point is fixed to the center of an image.' Of course this means some sensels are receiving 50% less light than their neighbours. Yamashita suggests it need not be a big problem: 'we use several tens of thousands of pixels in the center area of a CCD, which is a very small number of pixels compared to the 12 megapixels used for imaging.' And, he says, they don't simply go to waste when taking pictures: 'sometimes they are used to compose image data and sometimes not, depending on the situation."
I guess the pixels used for AF are interpolated from the neighborhood.
Anyway, Fuji process their raw data quite a lot. Thanks to precise color processing, Fuji images look good when zoomed out, but as soon as iso increases a bit (400 ISO onwards), images look blotchy.
Fuji are really smart in marketing, they position their stylish camera for people's photo, studio, wedding (+ flash as work around for high iso)... People's photo don't require high resolution nor dynamic range.
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Forum: Pentax DSLR Discussion
03-24-2017, 11:05 AM
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Typical tricky photographic case is the one of slow walking person of a wedding in dim light in a church.
Regardless of the camera brand you use, Pentax, Nikon, Canon, if you use AFS, the subject inevitably has moved between the time of the AF lock ( t0 ) and the time of shutter open ( t1 ).
Now, if you use AFC (AI servo for Canon), you have the problem of tracking slow moving subject because prediction is not good.
I discussed this topic with Canon, and it's the same problem. Technically, there is always an error.
So, what's the solution?
Well, the solution is to use a fast lens and stop it down.
Why?
Because when the lens is wide open, the DoF is small and the camera focuses fairly accurately. And when the shot is taken, the lens diaphragm closes , that make a new DoF wider, so that the error due to the subject position having changed is still within a zone of acceptable sharpness. Faster lenses have two advantages even if not sharp wide open: 1) brighter viewfinder and 2) enhance AF accuracy
Moreover, if that technique is not sufficient for Pentax Canon Nikon because it is dark, you have two more options:
1) Set the camera AFS to FPS prio and shooting right after the first AF motion step.
2) Use the back button AF (what Canon and Nikon (AF ON) also added to their camera for a good reason)
Et voila.
You've been to laos... have you seen what's the standard of living over there compared to yours? And you complain about a camera AF that's a tiny bit slower in darkness. I mean, for some people, this is very very far from being a concern in life, as their main problem is to have food, electricity and water, and in-spite of their situation that is much worse than yours, they smile.
Best regard.
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Forum: Pentax DSLR Discussion
03-24-2017, 10:23 AM
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The funny thing is, today I handed my K1 to a Fuji and Canon shooter and he found the K1 AF to be fast... go figure...
AF does not seat on a island on the camera body, it is a looped back system , half of the performance depends on the lens.
Take a DFA28-105, you'll be surprised how zippy it is.
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Forum: Pentax DSLR Discussion
03-23-2017, 02:18 PM
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Ah ok.
Anyway, AF on static subjects with Pentax or any other camera, frankly speaking , checking for differences is splitting hairs. Then you have the low light cases etc... you can always put ANY the camera are the border of capability, you'll also put the best one to fail. Someone tested 1Dx or D5 at -2ev and was disappointed. I've also been taking photos in ugly lighting , and whatever the autofocus performance was, the results were never so great. Doing test shots at home in the dark after work with artificial lighting , berk, just more photos to delete. When the lighting is good to produce nice shoots, everything works out, I tell you.
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Forum: Pentax DSLR Discussion
03-23-2017, 12:19 PM
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There is the effect of the SDM drive , for sure. And also the Pentax algorithm that never changes...Pentax focuses in two stages: 1) direct move up to a point (like Nikon and Canon) and 2) fine-tuning and lock (what Canikon aren't doing). Stage 2 is the problem every time, the focus is already well reached and the Pentax camera tries to tweak the last bit. They should give the choice to users (e.g C menu setting) to disable this tweak. When the conditions are good, the tweak may give a tiny bit more accuracy, but when in poor lighting (weddings etc), not doing the last tweak would be more beneficial than doing it: without the tweak you get a rapid focus of 99% in focus shot before the subject - photographer distance changes, and with the last tweak you get worse out of focus image because the subject-photographer distance may have changed by the time the camera is able to lock focus. The issue with Pentax is that they can't care less about what's I'm writing here.
That's it.
It is possible to emulate the Canikon way by setting AF to FPS prio, or use the back button AF, and make the decision of when to shoot for the camera.
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Forum: Pentax DSLR Discussion
03-22-2017, 06:56 PM
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DFA28-105. I sold all DA lenses. I now use only DFA lenses. I had the 17-70 SDM , finally with AF problems , I sent it for repair and sold it.
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Forum: Pentax DSLR Discussion
03-22-2017, 06:41 PM
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You must have setup some kind of difficult conditions to have the K3 not able to lock focus every time. I've tried your experiment.I had the K3 and now using the K1, I use the K1, defocus the lens and focus again, I can do it 100 times, and it nails focus every time without hesitation. Too bad that I don't have a cam to make a video of the K1 focusing... I'd do a 200 times AF with the K1, just to show everyone how it is. I believe there is not difference between cameras in AFS. I think your K3 has a problem.
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Forum: Pentax DSLR Discussion
03-19-2017, 03:36 AM
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For the same size of camera body, mirrorless has the advantage over any DSLR, except in low light.
The whole problem of AF performance is the sampling time on the AF sensor itself, a small module does not allow fast sampling because of the integration time required on the AF sensor itself. A higher sampling rate of the AF sensor phase signal, keeping acceptable precision, requires a larger sensor area. Getting down to -3ev require more integration time or a larger sensor. My guess, it is hardly possible to fit a Canon 7DII / 5DIII AF module into a K1 body. All high performance AF DSLR are large and the AF module occupy a significantly higher volume than the Pentax Safox module. Some people buy Pentax DSLR because of the smaller size compared to Canon/Nikon. I'm sure Pentax could do another AF module to the level of Canon and Nikon but it would not fit into a KP (KP = size of XT2). + lens optical stabilization that help AF performance. Shaky image in front of the Pentax AF sensor is a serious problem for the AF loop regulation because of adding error to AF sensor reading. Given the amount of noise that Pentax users have made for years about Pentax AF, Ricoh is certainly very aware of it, but they remained silent for a very good reason.
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Forum: Pentax DSLR Discussion
03-18-2017, 03:53 AM
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They've created a special website for the K1 (my guess, they outsourced the website), but it looks like it stopped there. What I thought about this website was a failed good idea because if you want a website to be effective, you must generate traffic. Unfortunately, if not linked to social media, that Pentax K1 site is only known by existing k mount users , I better there is nearly no traffic, no impact on customers outside the k mount user base.
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Forum: Pentax DSLR Discussion
03-18-2017, 02:31 AM
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At any point in time, if we consider only one parameter, there is always a camera better than others. Say, Ricoh is the market leader in Pixel shift , if we consider that pixel shift is a must have (questionable). Nikon has the leadership with autofocus. Canon leadership in portfolio of lenses. Single point AF is very much used, the Pentax one is as good as others. When Ricoh will align with Canon's 65 points AF, it will be way better than now, but it won't be at D500, Pentaxians will still complain. Pentax would need to deliver a new AF in the future; whether it should be D500, is not justified , all of photographers don't need a D500, even Canon and Nikon know that, they feature lower performance AF modules in other camera models. When Ricoh would release a camera with 65 AF points and better tracking, and Canon release 150 AF points, Pentaxians will complain again, this is consumer behavior, and this is boring to death. If you want a killer AF, get yourself a D500, it's the best but it's $2K and 21Mpixels APSC, if you do landscape it is not the best, and if you do portraits it is not the best either. Then you can buy 2 cameras, or 3 , take the best for each type of photography you do, if not specialized, you end up with 3 to 5 camera models, that's ok when having the money to pay for it.
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Forum: Pentax DSLR Discussion
03-18-2017, 01:18 AM
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On this one, it's a fail for Ricoh. If their engineers and marketers are not technical enough, are too busy, they could open a 3 month student internship as a technical writer who would write some application papers aimed at customers.
I mean, it takes a few days to write a paper and then have it reviewed by peers and correctly over a few weeks. If a company like lensrental can do it, the only thing that come to mind about Ricoh is negligence.
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Forum: Pentax DSLR Discussion
03-17-2017, 12:17 PM
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Sure, that was my expectation as well, and disappointment when using Pentax K3 AFC until I had a chance to show it to owner of the 7D.
He said "Yes, that's the same with 7D AI servo, it is not mean to adjust for each shot but it is meant to track the subject's trajectory and that's why not all shots are in focus".
Every using of Pentax K3 AFC wondering why not all shots are in focus in AFC mode, should first use a 7D and read the manual.
Expecting all frames in focus in AFC is plain wrong because that's not how predictive AF is supposed to be, but the idea on Pentax forum is sticky.
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Forum: Pentax DSLR Discussion
03-16-2017, 04:16 PM
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That's normal. Pentax can't have AF tracking as good as Canikon, they know it. Fast and accurate AF tracking requires optically stabilized lenses to begin with.
In body image stab. has the advantage for prime lenses, but for sport lenses, that solution is the least adequate for high performance AF tracking. Any camera company knows this. I've been able to have smooth predictive AF with the K3 and K1 when I could keep the subject in the AF area. It's always the same, can't have it all.
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