Why do Pentax lag with autofocus?


dcweather

Link Posted 01/02/2013 - 18:26
Why is it some people on forums always want a fight! I give up.
I'll just wait to see how Ricoh get on in the future as they seem very sensible and probably know that AF is the major concern of otherwise very happy Pentax owners.
Dave
awaldram wrote:
dcweather wrote:
Quote:


Nope I think all manufacturers dumb down entry level cameras to hit a price point the k30 is no exception slow cpu with insufficient memory but passes the overriding criteria .....cheap.

.

--------------------------------------------
I'm not sure where you get the idea that the K-30 is some third rate entry level camera from. You would notice very little difference from your K-5. The "experts" and others on here spent a good deal of consideration as to what would be the better buy between the two when the K-30 came out and while the older K5 retained some advantages autofocus ability and image quality were not generally considered to be the main ones.
Dave

Ere ?? Strawman alert I said it was entry level not third rate.

You tell me which Pentax Dslr is marketed below the k30 and we'll raise the assessment, its entry level.

Where is the mic input hdmi , extended bracketing , fast shutter etc etc

If you really want to see the longevity of the k30 as a system camera then have a look ate accessories in your manual..!!

Though your right its IQ from the sensor is probably better than my K5 I don't see it as a pxssing contest , The K30 is a great camera but entry level and practically throw away it also is.

It built to a price and that price is low. Considerably lower than it's RRP today.

Why is it some people on forums always want a fight! I give up.
Back to AF.
I'll just wait to see how Ricoh get on in the future as they seem very sensible and probably know that AF is the major concern of otherwise very happy Pentax owners.

awaldram

Link Posted 01/02/2013 - 19:01
Not sure where you see 'wanting a fight' in simple facts but as you say to each his own.

Ps you seem to be repeating yourself you may want to remove the 2nd copy, saying the same thing twice is a little confusing.

I think raw performance of Pentax cameras is unlikely to alter at the price points there at the k5/ii already performs at teh same level of it competitors.

But what is likely to happen they will join the kidology of multiple sensor rapidly hitting 50+ just to con the naive.

With funding Pentax will introduce higher level cameras these cameras will have superior AF and decent predictive tracking due to fast ASIC and more cpu horsepower.

But don;t expect any changes in the K5 or k30 price point any time soon.
Last Edited by awaldram on 01/02/2013 - 19:21

Daniel Bridge

Link Posted 01/02/2013 - 22:14
Back to dcweather's original posts, I'm surprised that no-one's picked up on him saying he doesn't use AF-C. If not, and he's using AF-S, once the camera does lock on, it won't then try to follow focus, and will happily fire away with the subject getting further out of focus all the time.

My preferred technique (although it's not a subject I do an awful lot), is to use AF-C, auto focus points (if it's a relatively clean background, or more importantly really, clean foreground), and hope.

As far as I know, one of the major factors here is that Canon and Nikon both use predictive focus, and have done for years. The camera measures the speed that the subject's distance is changing, and then predicts where it will be once the mirror has flipped up (which also cuts off any input to the AF sensor), and the shutter has opened. This might only be a tiny fraction of a second, but it can be significant if the distance is changing rapidly.

Pentax just try to keep up with the subject, but have no predictive ability that I'm aware of. Once that mirror flips up, who knows quite what happens?

Having said that, I've got some decent shots of birds in flight, although they tend to be the bigger ones (Kites, Cormorants, Gulls etc), and have done since I used the K10D. The K-5 is definitely quicker, and better at focusing, than that ever was.

Dan
K-3, a macro lens and a DA*300mm...

dcweather

Link Posted 01/02/2013 - 22:56
[/quote]

Ere ?? Strawman alert I said it was entry level not third rate.

[/quote]

I don't really know what that means but it didn't sound overly friendly.
Thanks for the constructive comments from most. As far as I am concerned this thread has run its course.

Smeggypants

Link Posted 01/02/2013 - 23:22
A strawman in a debate is when one person effectively puts words in their opponents mouth do they can attack that fabricated argument.
[i]Bodies: 1x K-5IIs, 2x K-5, Sony TX-5, Nokia 808
Lenses: Pentax DA 10-17mm ED(IF) Fish Eye, Pentax DA 14mm f/2.8, Sigma 17-70mm f/2.8, Pentax-A 28mm f/2.8, Sigma 30mm F1.4 EX DC, Pentax-A 50mm f/1.2, Pentax-A 50mm f/1.4, Pentax-FA 50mm f/1.4, Pentax-A 50mm f/1.7, Pentax DA* 50-135mm f/2.8, Sigma 135-400mm APO DG, and more ..
Flash: AF-540FGZ, Vivitar 283

sbrads

Link Posted 02/02/2013 - 10:21
Daniel Bridge wrote:

As far as I know, one of the major factors here is that Canon and Nikon both use predictive focus, and have done for years. The camera measures the speed that the subject's distance is changing, and then predicts where it will be once the mirror has flipped up (which also cuts off any input to the AF sensor), and the shutter has opened.
Dan

My K100D manual from 2006 claims the K100D does tracking even in AF.S if the target is determined to be moving. I think it's not so much a question of whether Pentax cameras were using AF tracking, more a case of how well they were doing it.

Daniel Bridge

Link Posted 02/02/2013 - 17:47
The K100D just had the option of AF or MF on the switch by the lens mount. The K30 has the options AF-S, AF-C and MF, so it's down to the user to decide on the best mode.

Dan
K-3, a macro lens and a DA*300mm...

sbrads

Link Posted 02/02/2013 - 18:44
Daniel Bridge wrote:
The K100D just had the option of AF or MF on the switch by the lens mount. The K30 has the options AF-S, AF-C and MF, so it's down to the user to decide on the best mode.

Dan

So? You could still choose AF-S or AF-C in the K100D menus.

Daniel Bridge

Link Posted 02/02/2013 - 19:06
Well, it has always been my experience that if you set AF-S, that's single shot autofocus, and once it locks, it won't then track at all, because that's what AF-C does.

I've not used a K100D, so I can't comment on that specifically. Maybe I'll download the manual later.

On my *istD, K10D and K-5, the camera will not track a subject when using AF-S, that's why I mentioned it.

Dan
K-3, a macro lens and a DA*300mm...
Last Edited by Daniel Bridge on 02/02/2013 - 20:05

Daniel Bridge

Link Posted 02/02/2013 - 21:15
Just had a look at the manual, and amongst all the things that say AF-S locks the focus, AF-C tracks it, it does say that if it determines the subject is moving, it will track it, even if the focus is set to AF-S.

That's certainly not what I'd expect, but it would be a useful option, like AI-Focus on Canons. I've never had any of my cameras do this though, and would be surprised if the K30 did it, but maybe it does...

Dan
K-3, a macro lens and a DA*300mm...

walt

Link Posted 02/02/2013 - 22:24
Daniel Bridge wrote:
.....
That's certainly not what I'd expect, but it would be a useful option, like AI-Focus on Canons. I've never had any of my cameras do this though, and would be surprised if the K30 did it, but maybe it does...

K-30 has an af.a mode just like my old pentax Z20 fom the film days, it is just like the AI-focus on Canons and picks af.s or af.c dependent on subject motion.

Daniel Bridge

Link Posted 02/02/2013 - 23:45
walt wrote:
K-30 has an af.a mode just like my old pentax Z20 fom the film days, it is just like the AI-focus on Canons and picks af.s or af.c dependent on subject motion.

Well I never! Just had to check my K-5 to make sure it's not on there and I just hadn't noticed it - can't see anything, anybody like to point out I'm wrong again?

Now, if they could do 3D-Tracking like Nikon, that would be lovely!

Dan
K-3, a macro lens and a DA*300mm...

DanielH

Link Posted 03/02/2013 - 20:39
Id bet my bottom dollar that the K-5 has an Af.a mode just like the K-30 and I think the K-r!

JohnMcD

Link Posted 03/02/2013 - 20:48
The elderly Nikon D300 has possibly the best sports autofocus of any semi pro camera ever made so if your K5 isn't quite as good I wouldn't beat yourself up. It's also big and heavy and only 12MP with no video or weather sealing etc. Horses for courses.

Anyway sometimes it's easier to manual focus. I sometimes use an old Tamron 500mm mirror lens and it's very fast to focus and I do occasionally get the odd buzzard or seagull in focus without much effort. I gave the lens away though as it was a bit rubbish optically.

Daniel Bridge

Link Posted 04/02/2013 - 15:46
dannyh wrote:
Id bet my bottom dollar that the K-5 has an Af.a mode just like the K-30 and I think the K-r!

Might take you up one that... Just had a look for it in the K-5II manual and no sign of it there either.

Dan
K-3, a macro lens and a DA*300mm...
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