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05-09-2015, 08:26 PM   #571
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QuoteOriginally posted by infoomatic Quote
hm, maybe I am wrong, but what I have read so far is that when it comes to image quality (dynamic range, noise and NOT resolution because 16MP is enough for me) the K3 is actually a (little and almost unnotable) step back compared to the K5.
Perhaps you have read sources that did not compensate for the higher magnification of the 24MP sensor over the 16MP sensor. Once you normalise for the different pixel pitch, the noise levels are practically the same. I'd like to see the photography where the minuscule difference is actually of significance.

Back in the days of Pentax using Samsung sensors (K-7), they actually had a noise disadvantage, but the top-notch Sony sensors they have been using since then are all excellent.


QuoteOriginally posted by jatrax Quote
I do not find I need any more points than the k-3 offers but I would like it if they extended out to the edges a bit more.
There are technical limitations to supporting AF areas near the frame perimeter.

05-09-2015, 08:31 PM   #572
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QuoteOriginally posted by jatrax Quote
When are all the AF points of any practical use?
One advantage of many AF areas being featured that is effective even if you only ever use the centre AF area, is that the individual AF areas become smaller. This can considerably increase aiming precision.

Often people's AF issues can be traced back to the selected AF area being large enough to include another part of the subject or even background. The camera cannot know which image element within the AF area it should focus on, so it can only use heuristics (such as preferring the closest detail) but the latter will fail in some circumstances, leading to "AF errors" (which, of course, are not errors, technically).
05-09-2015, 09:12 PM   #573
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I mainly use manual focus lenses and the focus spot cannot be changed from center when using them.
05-10-2015, 05:05 AM   #574
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QuoteOriginally posted by Class A Quote
One advantage of many AF areas being featured that is effective even if you only ever use the centre AF area, is that the individual AF areas become smaller. This can considerably increase aiming precision.

Often people's AF issues can be traced back to the selected AF area being large enough to include another part of the subject or even background. The camera cannot know which image element within the AF area it should focus on, so it can only use heuristics (such as preferring the closest detail) but the latter will fail in some circumstances, leading to "AF errors" (which, of course, are not errors, technically).
IIRC, another use of many focus points in some camera models is they can be used in the viewfinder to show the user which elements of the image are in focus and which are not.

05-10-2015, 05:18 AM   #575
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AF points, AF-C and AF in general, is something they really need to work with. And they are. Cause when it comes to AF, Pentax is behind the best. But here's of the things i "work" with. I rapport back what i think and feel about the AF in my challenging work situations and what other pros feel is missing compared to their brands.

Even though many think so, I'm not signed to test new gear. That i do in my freetime because i want too.
05-10-2015, 05:47 AM   #576
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I shot a concert the other day. Piano + singer.
I used K-5 and 50-135. 135 necessary because I was a bit far away and I have nothing in that range brigther than my DA*50-135. (for the reccord, Iso was 800-1250).
The singer was moving a bit but enough for screwing up my AF-S center + recompose so I chose an AF point and let the camera AF-C on that point (around the eyes).

Worked well enough (given the capabilities of a K-5 of course).
05-10-2015, 06:28 AM   #577
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QuoteOriginally posted by jatrax Quote
I suspect the k-3II is the APS-C flagship for some time. At least until 2016 anyway. That is just a guess but I see no reason for RIcoh to bring out a k-3II and then replace it in anything less.

Curious but what's the deal with AF points? I only ever use the center point. Tried the multi thing once and the camera focused on what it wanted, rather than what I wanted. When are all the AF points of any practical use? Not picking a fight, really curious as to why so many people seem to think more AF points is better.
This doesn't work that well on shallow deph of field shoots let's say 50mm f/1.4. As the deph of field is quite small (arround 1cm), the recompose mean the focus is no longer on what you want (the eye for example).

You can manual focus with focus peaking or your bare eyes if they are good enough or you may not like the rendering and prefer more stopped down settings but when you are in that situation the center AF point + recompose isn't going to cut it.
05-10-2015, 06:35 AM   #578
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QuoteOriginally posted by jatrax Quote
Good point. Thanks. But when doing that is there any practical need for 11, 27, or 200? I guess it depends on how tightly you are focusing and how much DOF.
For manually selecting the focus point something arround 11 or 27 should be more than enough. What was the issue with the 11 AF point was the decision to make the AF point so big and so not very precise in what they track. But as far as selecting focus is concerned, on can always reframe a bit the picture if needed and having more points mean more time spent selecting the rigth one... not really that usefull.

For tracking and auto selection AF the more points the camera has, the more it can have a precise deph map in combination with the exposure sensor and the more it can understand the scene and help with the AF. Please notice that for this use case constrast AF point are a joke.

Also other feature like f/8 points (for better AF support of 1.4 TC on slow teles like DA560) and more f/2.8 point could make sense.

05-10-2015, 07:03 AM   #579
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The center point on the K5 series was so large that it was difficult to focus on the precise point unless it was very large. A whole head can fit into the space let alone the eye. The K3 is better, but there are still situations where the details within the point are on a different focal plane and the desired shot will be missed.

A smaller point although desirable for precise focus requires precision in technique. It is very easy for unsteady hands to have the desired focal point wander outside of the center point. Especially with a longer lens, but even a shorter lens handheld in a busy scene or busy circumstance. So a smaller point in isolation is problematic, and having a tight pattern surrounding it of equivalent points allows focus algorithms to follow the desired point and keep focus. This applies to many photographic subjects; a narrow dof lens where you want to focus precisely on the eye could chatter between the eye and the bridge of the nose. Or the eye socket.

Here the K3 is ok. The spacing has holes into which the desired focal point can fall and it has to extrapolate, and sometimes gets it wrong. The more points the quicker the logic needs to be as well; I think I get some out of focus shots where the hardware software system just can't keep up. Throw in the latency caused by the lens focus mechanism as well.

My sigma 500mm f4.5 has a fast screw drive and the k3 gets behind in its processing. The 1.20 firmware is pretty good. I'm wondering if the new long zooms have some kind of enhanced focus processing that assists the body. Maybe a more precise positioning that requires less feedback processing, or something like that.
05-10-2015, 07:31 AM   #580
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QuoteOriginally posted by Nicolas06 Quote
This doesn't work that well on shallow deph of field shoots let's say 50mm f/1.4. As the deph of field is quite small (arround 1cm), the recompose mean the focus is no longer on what you want (the eye for example).

You can manual focus with focus peaking or your bare eyes if they are good enough or you may not like the rendering and prefer more stopped down settings but when you are in that situation the center AF point + recompose isn't going to cut it.
There's always a use-case that will contradict my general statement about focus / recompose (which I gave as one choice of two).

However, I so rarely use an f/stop below 5.6 that, in my case, this use case isn't operative. I rarely have a use for tracking autofocus, for that matter.

Those qualifications being the case, the average camera buyer who thinks 65 AF points are better than 27 as a quantifying feature in a camera-buying decision - who doesn't know what they or for, nor would ever intend to use the feature for its true benefit - skews the feature/cost analysis in camera design away from true utility.

Though it matters not for the bulk of camera buyers in practice, Pentax AF is deemed inferior so the entire brand strategy is deemed inferior.

IOW, to sell cameras, a manufacturer must Invest to improve or add one comparatively less-used feature at the expense of another, more useful feature (at a given price point).
05-10-2015, 07:37 AM   #581
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QuoteOriginally posted by Nicolas06 Quote
This doesn't work that well on shallow deph of field shoots let's say 50mm f/1.4. As the deph of field is quite small (arround 1cm), the recompose mean the focus is no longer on what you want (the eye for example).
Good point. I rarely shoot less than f/11, sometimes f/8 if I'm daring so not really an issue for me.
QuoteOriginally posted by Nicolas06 Quote
But as far as selecting focus is concerned, on can always reframe a bit the picture if needed and having more points mean more time spent selecting the rigth one... not really that usefull.
Yes, focus and re-compose is what I am used to. Fiddling with the AF points seems to me to be just that, fiddly. I have certainly used it, when I remember, but mostly it seems to be one more thing that gets in the way of me taking pictures.
QuoteOriginally posted by Nicolas06 Quote
For tracking and auto selection AF the more points the camera has, the more it can have a precise deph map in combination with the exposure sensor and the more it can understand the scene and help with the AF.
Yes, I can understand that.

It seems the reason that I don't understand the need for more points is that the only situations where that is an advantage are things I never, or rarely, do. Good enough, thanks for the information.

---------- Post added 05-10-15 at 08:05 AM ----------

Ok, after thinking about this some more one thing still puzzles me.

I shoot with single center point when not on the tripod and when on the tripod single select and move that point to where I want the focus to be. So 1 AF point = 1 area of focus. I have a 100% chance of getting what I want in focus.

But if I have a camera with 65 AF points in auto or whatever it is called and I take a picture the camera will select one of those 65 points to be the focus point. So I now have a 1 in 65 chance that what I want in focus is going to be the focus area.

Now, I am sure I am missing something because otherwise people would be clamoring for less points not more so what am I missing? Maybe I am old, but I just cannot figure out how having 65 AF points does not cause chaos.
05-10-2015, 08:10 AM   #582
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QuoteOriginally posted by jatrax Quote
Now, I am sure I am missing something because otherwise people would be clamoring for less points not more so what am I missing? Maybe I am old, but I just cannot figure out how having 65 AF points does not cause chaos.
I believe the higher number of AF points probably relates to the efficacy of tracking autofocus using AF.C and back button. I've had a K-3 since December 2013 and never used that setting.

Doesn't mean the (comparatively few) people who loudly demand it don't drive the feature design decision (how much do you want to bet the next APSc Flagship has an OBF?).
05-10-2015, 08:33 AM   #583
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QuoteOriginally posted by jatrax Quote

I shoot with single center point when not on the tripod and when on the tripod single select and move that point to where I want the focus to be. So 1 AF point = 1 area of focus. I have a 100% chance of getting what I want in focus.

But if I have a camera with 65 AF points in auto or whatever it is called and I take a picture the camera will select one of those 65 points to be the focus point. So I now have a 1 in 65 chance that what I want in focus is going to be the focus area.

Now, I am sure I am missing something because otherwise people would be clamoring for less points not more so what am I missing? Maybe I am old, but I just cannot figure out how having 65 AF points does not cause chaos.
I shoot with AFC, sel3 which enables the twenty odd points. Center point is selected, I focus on what I want. If I hold down the AF button theoretically that selected part of my subject will remain in focus as long as it is within range of the enabled points. I haven't tried this with people so I don't know if it works, but with wildlife that tends to move around it follows and maintains focus reasonably well, sometimes.

That is the promise of multiple points smart focus. Lots of things get in the way such as lens latency, the processing ability of the body, the resolution of the focus points and the metering array from which the data is extracted. Pentax is probably a generation behind with their bodies and in the fog of the distant past with their lenses.

These are features that either work well or are turned off. Interestingly I had them turned off pre 1.20 and on since.

OBF? What is that?

---------- Post added 05-10-15 at 08:44 AM ----------

The flucard has an interesting feature that I have used to advantage. With a tripod mount, aimed at the subject you can touch the screen and it will focus on that point. I used it when I set up the body in a location and went around the corner to hide. I could focus on the bird as it alighted. What made it work was the ease of the interface. To implement something like this when holding the viewfinder to your eye would be very difficult.

If you shoot a repetitive framing, you can set the initial point to fit. I doubt that would work in practice.
05-10-2015, 09:01 AM   #584
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QuoteOriginally posted by derekkite Quote
I shoot with AFC, sel3 which enables the twenty odd points. Center point is selected, I focus on what I want. If I hold down the AF button theoretically that selected part of my subject will remain in focus as long as it is within range of the enabled points.
Sure and that is tracking, but you selected the point of focus first. What I mean is if the AF is just on auto how does the camera figure out what to focus on? There has to be something or no one with a multi-point AF system would ever get anything in focus except by luck. I get the need for lots of AF points for tracking, maybe on more sophisticated AF systems these are only used when in "tracking" mode? I guess I'm just not familiar with other systems. On Pentax I tried the multi-point, it focused on what it wanted and we agreed to disagree so I turned it off. I've used single point ever since. Maybe on newer bodies it does actually work and I'm missing out on something.

QuoteOriginally posted by derekkite Quote
OBF? What is that?
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05-10-2015, 09:01 AM   #585
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QuoteOriginally posted by monochrome Quote
There's always a use-case that will contradict my general statement about focus / recompose (which I gave as one choice of two).

However, I so rarely use an f/stop below 5.6 that, in my case, this use case isn't operative. I rarely have a use for tracking autofocus, for that matter.

Those qualifications being the case, the average camera buyer who thinks 65 AF points are better than 27 as a quantifying feature in a camera-buying decision - who doesn't know what they or for, nor would ever intend to use the feature for its true benefit - skews the feature/cost analysis in camera design away from true utility.

Though it matters not for the bulk of camera buyers in practice, Pentax AF is deemed inferior so the entire brand strategy is deemed inferior.

IOW, to sell cameras, a manufacturer must Invest to improve or add one comparatively less-used feature at the expense of another, more useful feature (at a given price point).
Sure what is important is what you care and do not care and to buy accordingly. This work very well if you are quite experienced and say need a new camera.

It work far less if you have no clue and want a good camera to take photos. If you hand up using it only for landscape and are not too picky on quality or do not want to spend time on advanced features (long exposure...), any DSLR would do, really as would also mirorless cameras or high end compact. If already you want to really have shallow deph of field, you'll want at least a m4/3 or APSC sensor with some fast primes. If you don't want to focus manually this require good off center AF points. If you are into actions shoots or wildlife, you'd want some AF tracking capabilities and good lenses... The price go up quite fast !

But the thing is if you really want to do many action/sport shoots it would be a just more difficult to take great shoots with a very average AF-C camera like a K5. As new photographers don't have a clue what they want or not and may want to just try many things, this is not easy for them to choose.
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