[beholder3]

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Last edited by beholder3; 08-12-2013 at 01:39 AM.

[StigVidar]

Today, my friend let me borrow his 7D, and I had three people shooting the same RC helicopter with the 7D (70-200mm F4 L), K-5 II, and K-5 IIs (FA* 85mm F1.4).

I don't expect a slow focusing portrait lens to fare well on action performance :-)


The German magazine Colorphoto tested AF accuracy between K-5, EOS 7d and D7000 and found K-5 to be miles ahead of EOS 7D in accuracy.

http://www.colorfoto.de/testbericht/7/7/6/2/0/2/Test_Autofokus_ColorFoto_2011-09.pdf

[asp1880]

AF.S precision with the K-5 was already very good until light got really dim. Now it is just great. The AF works now where I can barely see. The one and only reason to upgrade was that I do a lot of available light shooting and there any improvement is appreciated.

Reasons to buy:
1. AF.S low light shooting
2. AF.S dimmed tiny tungsten bulb lighting issues are gone (for those who have encountered that before)
3. AF.S precision with fast lenses at very wide apertures (F1.4 to F2)

Drat. Those reasons would be precisely my reasons too. I may have to visit the camera store again (yes, my local store carries Pentax!)

Regards,
--Anders.

[Class A]

While you've got a valid point about the terminology, I think even the old K-5's AF was precise enough in that respect.

For f-ratios in the range of f/1.4-f/2.8, I'm sure the new f/2.8 sensor will bring improvements. As you can see from the ColorFoto Test (thanks StigVidar!), PDAF systems aren't that great in terms of accuracy compared to CDAF.

Most people are going to be more interested in the type of accuracy I'm referring to, I think.

I don't know, but perhaps it is worth bearing in mind that if someone shoots Pentax, they are unlikely to have fast AF high up on the priority list.

In any event, please make sure you use the term "AF accuracy" to refer to the level of precision an AF system achieves in static situations (just like ColorFoto did) and use a different term for what you are interested in.

I'd refer to the latter as "AF speed", which has two aspects

1. how quickly can a lens get through its focusing range and
2. how quickly can a camera lock and confirm focus on a target*.

* If the target is moving, we are talking about "continuous AF speed".

Surely point 2. above is slightly influenced by point 1. but not that much in real life when the lens is already focused near the point it needs to be.

Coming back to the question what most people are more interested in, I'm very happy that Pentax chooses to be slow but accurate. Canon partly achieves their AF speed by having a higher tolerance of what they consider "sharp". This allows the AF system to stop the focusing process earlier and it may even omit a double checking phase at the end (EDIT: The Canon AF does indeed omit a double-check in case the shutter release button is fully pressed and the lens only needs to adjust the AF a little. In other (half-pressed) cases, Canon AF also double-checks).

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Last edited by Class A; 10-28-2012 at 04:23 AM.

[Col]

I can't wait for the review. Based on the reviews, samples and AF videos I've seen, I'm sold. This camera gives me total confidence they are on the right track. I'll upgrade and patiently wait for a full frame down the road.

One thing I haven't heard much about is the flash performance. Will that be covered in the review?

Me too I want to know more about that clubhouse's flash unit
I'm trying not to go to the Pentax demo day next saturday at SRS, and frankly Adam your shots are not helping that mission

[westmill]

Accuracy is always going to be govened by the size of the sensors. Therefore it is always going be limited. Until Pentax get rid of the saffox system and its giant sensors.
Having said that, I think Pentax has taken a big leap forward. Its obviously still not the best out there but at least it should now be in the same ballpark.I would like to see how it works with flash too now.

[Class A]

Accuracy is always going to be govened by the size of the sensors.

What you really mean is not "AF accuracy" but "AF targeting precision".

SAFOX is better than many other AF systems in obtaining the best possible focus for a target that is stationary and unambiguously defined, i.e., in AF accuracy.

What you are taking issue with, is that the large size of the AF areas make it hard to single out a small detail in order to precisely focus on it. In other words, the AF will be very accurate but you cannot pin-point enough on what it will be accurate.

AF area size is a compromise between targeting precision and the ability to lock on anything at all. If you make the areas too small, you may have to move the camera around quite a bit in order to exactly align the AF area with a small detail.

There is also an issue with how precisely the positioning of the AF indicators in the viewfinder match the real AF areas. The smaller the latter become, the higher the matching precision needs to be. In practice, there is often a bit of a shift between the two (that doesn't matter too much due to the size of the AF areas).

Having said all that, I'd like smaller AF areas too, but I don't think that the current ones have "dinner plate size" or are unusable.

[westmill]

What I really meant is what I said ! but you described it accurately too, and while you dont think they are dinnerplate sized I do lol. Of course I think that is an obvious exageration since dinnerplates are bigger than the camera but Im guessing nobody would take it litraly. I also dont think they are unusable and I never said they were.
BUT... I do think the dinnerplate sized sensors are rubbish and a large drawback for the reasons you mentioned. The improvements go a long way to making it competative and far more usable in more situations. The dinnerplate sensors, while they exist is a major drawback. Thats just my opinion of course

[rawr]

In any event, please make sure you use the term "AF accuracy" to refer to the level of precision an AF system achieves in static situations (just like ColorFoto did) and use a different term for what you are interested in.

Good work. I wish all those who bemoan the 'lack of accuracy' of Pentax AF would pay attention to these distinctions.

[bxf]

Accuracy is always going to be govened by the size of the sensors. Therefore it is always going be limited. Until Pentax get rid of the saffox system and its giant sensors.
Having said that, I think Pentax has taken a big leap forward. Its obviously still not the best out there but at least it should now be in the same ballpark.I would like to see how it works with flash too now.

Having read quite a few posts relating to the above, I was quite surprised to come across this: Andre's Blog • Cross type AF points in EOS 7D

[Docrwm]

Pics made under VERY different light conditions,at different daytimes, s.EXIF. Sorry,I'm not impressed.Excuse mio inglese

Welcome Aboard. Interesting first post.

[rawr]

I was quite surprised to come across this

Wow - look at those large dinner-plate sized AF points, even on the 7D ...

[Qwntm]

I didn't criticise Adam for not doing an in depth review (and wonder what made you think I did).

I merely wondered how Adam was able to make a statement about AF accuracy. Obviously, I don't believe making statements about AF accuracy without proper testing to back one's claims up doesn't make any sense, but I didn't know what Adam had been able to do or not, hence I asked.

I don't doubt for a second that the 7D's AF beats the K-5 II's AF in almost any aspect, but I'm not sure accuracy is necessarily one of the aspects.

Sorry, I just read it that way, my mistake...

Questioning Canon's accuracy? I see you have used a 7D...

This is what makes it so hard to compare AF. The Pentax is slower, but the in focus rate is higher. So which is better? It kind of depends a bit on what your doing.

[westmill]

Wow - look at those large dinner-plate sized AF points, even on the 7D ...

Noooooo thems only golf balls lol They are only twice the size as the focus indicators. I would need to look through the viewfinder to see how big the focus squares are too, before I could judge them. Although I am surprised by that. It still does not make the K5s sensors any smaller even if there is camera out there with even bigger sensors. My guess is that the 7Ds focus points are still half the size of the K5s. Like I have already stated, I think the improvements Pentax has made puts the K5 at least in the same ballpark as the other systems now, despite the big sensors. In my opinion, the sensor size is now the one thing that will stop it from being great or better or the best, whichever way you want to see it. I am just stating what I see as a very simple obvious fact. I would expect everone would appreciate smaller sensors so I am at a loss why people get offended by my comments.

[beholder3]

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