The GetDPI Photography Forum

Great to see you here. Join our insightful photographic forum today and start tapping into a huge wealth of photographic knowledge. Completing our simple registration process will allow you to gain access to exclusive content, add your own topics and posts, share your work and connect with other members through your own private inbox! And don’t forget to say hi!

Testing out a Pentax K5

jonoslack

Active member
I got some unexpectedly oof shots today - it focused on the grass behind the dog (between it's legs).

I do think that the problem is the large AF points . . . but I'm not sure what the solution is.

Are we all using the 'select' option for AF?

I'm hoping that this is a 'learning to overcome the shortcoming' issue rather than a deal breaker - certainly dpreview thought that the AF was accurate.
 

raist3d

Well-known member
Again, I could care less (see my other reply) what dpreview says if it doesn't match my direct experience. I have found them make a few mistakes. Also it raises the question as for reviewers- if they are receiving "hot hardware" from manufacturers- meaning, that the sample given performs better than expected (this has happened before with other reviewers of other products). The only true honest review in this sense is the one you go ahead and buy at retail a product sample. Of course this can get expensive, but then that's how consumer reports does it precisely because of the objectivity issue.

I am using single center point. I think there is truth to the bigger than the square sensor, so want to see if I can catch a pattern; - and in good daylight - in general, I am getting good focus (but need to test a bit more there since I haven't tested in daylight that much). But tonight on low light I was both surprised and frustrated how well and then how bad the AF worked in terms of getting it right on.

As much as I am liking the K-5 nominally, this would be a deal breaker for me. I want a prospec cameraa for weddings/events that can get cash, I can't afford to play "did I get the focus right?" In fact this is the reason why I am looking beyond the 620.

Street life also requires this. If Panasonic had good micro four thirds lenses already (by good I mean, high quality, not so much distortion corrected and fast lenses) I would probably have picked the GH2 because the AF on the GH2 is spot on.

When I am finding my LX5 is focusing with more predictability than my K-5 something is not good.
 

jonoslack

Active member
My main frustration at the moment is the camera saying "yes, I did AF lock" when it didn't.
I think it IS locking - just not on what you thought it SHOULD be locking on to.I'm not making excuses, just suspecting that it needs a bit of learning . . . and it's possible that central spot isn't the best method (it IS what I'm using too).

As for wedding work - I think it would do really well, one is generally focusing on a face, and I've found it to be pretty infallible here. . . . . . . .but, truth to tell, if I had to do one tomorrow I'd still be using the A900 and the M9, but if someone snatched them out of my hands I'd certainly be happy to use the K5.
 

raist3d

Well-known member
Well, if the camera can lock by choosing a single spot that makes it unpredictable. It should. As for locking this shouldn't be that hard- it should lock in whatever I point the center point to. If it doesn't, then it's a back or front focus.

Locking onto something other than what I point with the center point, when I have the camera precisely set to use the center point is a problem.

Now, I just decided to adjust my DA70 mm with a -5 parameter ("focus futher away from me") and seems to be working better.

Ill check tomorrow in daylight.
 

jonoslack

Active member
Well, if the camera can lock by choosing a single spot that makes it unpredictable. It should. As for locking this shouldn't be that hard- it should lock in whatever I point the center point to. If it doesn't, then it's a back or front focus.

Locking onto something other than what I point with the center point, when I have the camera precisely set to use the center point is a problem.

Now, I just decided to adjust my DA70 mm with a -5 parameter ("focus futher away from me") and seems to be working better.

Ill check tomorrow in daylight.
Thanks for that - I need to do a bit of focus adjusting, but I hadn't worked out whether - was further away or nearer!

Maybe the option you have to take a camera back is causing you grief - I've got to like it or lump it, so rather than looking for things wrong I'm looking for ways around them.

I agree about the focus point - but it should surely be that the focus point in the viewfinder should be the same size as the actual focusing point. Which it appears that it isn't (not just with pentax though).
 

raist3d

Well-known member
Thanks for that - I need to do a bit of focus adjusting, but I hadn't worked out whether - was further away or nearer!

Maybe the option you have to take a camera back is causing you grief - I've got to like it or lump it, so rather than looking for things wrong I'm looking for ways around them.
Eh, come on. If I am paying $1,600 USD and considering a full system switch, isn't it reasonable to expect the camera works as it's supposed to work? I am also looking for things for it to work. Why else would I have bothered with the AF adjust? I definitively want to like this camera to keep at this point. But I am not going to be dishonest with myself if it doesn't perform to expectations because when I do a wedding there's zero excuses to make to the client.

I agree about the focus point - but it should surely be that the focus point in the viewfinder should be the same size as the actual focusing point. Which it appears that it isn't (not just with pentax though).
Yes, and who mentioned that here? Me right? :)

I don't see why it should come as a surprise I am "grilling the camera" on "an interview with me." $1,600 USD isn't pocket change and if it doesn't perform for what I need, can't have it. I am not saying it can't be, but I want to make that very clear.

I do this with all equipment, any brand. It almost sounds like you are suggesting say for example, my clearly back focusing E-3 "it's ok." It wasn't.
 

jonoslack

Active member
Eh, come on. If I am paying $1,600 USD and considering a full system switch, isn't it reasonable to expect the camera works as it's supposed to work? I am also looking for things for it to work. Why else would I have bothered with the AF adjust? I definitively want to like this camera to keep at this point. But I am not going to be dishonest with myself if it doesn't perform to expectations because when I do a wedding there's zero excuses to make to the client.



Yes, and who mentioned that here? Me right? :)

I don't see why it should come as a surprise I am "grilling the camera" on "an interview with me." $1,600 USD isn't pocket change and if it doesn't perform for what I need, can't have it. I am not saying it can't be, but I want to make that very clear.

I do this with all equipment, any brand. It almost sounds like you are suggesting say for example, my clearly back focusing E-3 "it's ok." It wasn't.
Hey Hey - I wasn't criticising, just stating that the ability to take a camera back has responsibilities as well as advantages (you simply can't do it in the UK unless it's faulty). If I decide it doesn't do what's required, then it's off to ebay I'm afraid.

The point being that in the UK one commits oneself when one signs that bit of paper, not 30 days later (or however long you can take it back for).

Personally, I've not really had much problem with the AF, or the colour (although I can see the issues). But I've had big problems with lens variability (and of course I can take back faulty lenses).

I don't know whether I'd be happy to do a wedding with it yet (and if I had one to do tomorrow I wouldn't use it except for the evening shots). But then I wouldn't have used any of the 4/3 cameras either, currently I've been using a Sony A900 and Leica M9, and I can't really see the Pentax replacing either of them.
 

raist3d

Well-known member
Hey Hey - I wasn't criticising, just stating that the ability to take a camera back has responsibilities as well as advantages (you simply can't do it in the UK unless it's faulty). If I decide it doesn't do what's required, then it's off to ebay I'm afraid.

The point being that in the UK one commits oneself when one signs that bit of paper, not 30 days later (or however long you can take it back for).
Well, ok. Not sure what responsibilities I am avoiding here by having the option of returning it, but if you mean it would be more pressure to have bought in the UK I can see that.

Personally, I've not really had much problem with the AF, or the colour (although I can see the issues). But I've had big problems with lens variability (and of course I can take back faulty lenses).
Cool.

I don't know whether I'd be happy to do a wedding with it yet (and if I had one to do tomorrow I wouldn't use it except for the evening shots). But then I wouldn't have used any of the 4/3 cameras either, currently I've been using a Sony A900 and Leica M9, and I can't really see the Pentax replacing either of them.
Well, ok but that's you. I am not suggesting even remotely that you benchmark your camera against my needs, wants and desires- your camera is up to you. I need to benchmark mine against my needs/wants/desires. I am trying to come up with a predictable model for the AF. If that can be done and it's reasonable, great. It's looking that, that's the case.

If I can't do that then I will have to look at other options.
 

jonoslack

Active member
Well, ok but that's you. I am not suggesting even remotely that you benchmark your camera against my needs, wants and desires- your camera is up to you.
and of course vice-versa
I need to benchmark mine against my needs/wants/desires. I am trying to come up with a predictable model for the AF. If that can be done and it's reasonable, great. It's looking that, that's the case.

If I can't do that then I will have to look at other options.
Quite right too - the only camera I have ever had that NEVER makes AF mistakes is the Leica M. . . . . . .
 

Paratom

Well-known member
I allready gave up on a 7d some months ago because of inaccurate AF, I have sent my M9 and several lenses to Leica for focus adjustment. I have to further see how the K5 delievers.
I will give it some time.

I am also starting to ask myself if I expect too much.

But then all Nikon bodies I had so far (d2h-d2x-d300-d3-d3x-today "just" d700) seem to work just fine even with very fast glass.

By the way - the 50-135/2.8 is one great lens IMO - very nice color, sharp even wide open and great bokeh. And all this quite light weight for such a lens.
 

raist3d

Well-known member
Here's a shot where the focus was missed (shot to the left, 100% crop on the right, DNG)



Now, this is *very* low light and bad light at that. What bugs me here is not that the focus was missed but that the camera said "yeah, locked it!".

- Raist
 

jonoslack

Active member
Wow - a wierd one - not seen anything like that.
It seems to have focused on the lady on the extreme left . . . if anything at all.
Completely blows the 'big focus point' argument out of the water.
No, I've definitely not seen that - faulty?
 

raist3d

Well-known member
The thing that bugs me is that the camera did use the green assist light, and with that it should have nailed it. I was shooting at F2.4 though which is definitively a stressor on the AF system. Again, I could understand the Pentax failing to focus (though not quite with the green light assist), but to report "yes, it's locked" and do this? hmm....

I had different degrees of non focus through other shots, not as bad. But it's so annoying when you have a "almost there but not quite" shot. You know that it's almost in focus but not quite.

To be fair, the conditions under which I put the Pentax last night were quite the test for something like this. It was very low light, colored too, certainly not easy. And some people also dancing/moving/whatever. I would like to think a working E-3 would have nailed but who knows. I know the E-3 hesitates too as lights go down and if you have moving people, it's enough of jarring situation for the AF system that it can't keep up as the camera is "getting there" the subject moved again.

Anyway, I am still not throwing the towel on my camera (other than the stains on the sensor), if there's a pattern or something that makes this reasonable and predictable I am cool with that. A normal wedding that I have shot has more light than this. I just don't want a "focus locked" and it didn't. That's... bad.
 

jonoslack

Active member
K-5 users are reporting AF inaccuracy low tungsten lighting - this problem did not exist with the K-7, though the K-7 would be much slower to achieve lock (or maybe not lock at all in those conditions). It's said that this will be resolved in a future firmware update:

http://forums.dpreview.com/forums/read.asp?forum=1036&message=37232186
HI Gerald
interesting . . thanks for the link, and it's good to know they're doing something. . but Ricardo's sample above doesn't look much like front focus (see the woman on the left).

all the best
 
P

photogerald

Guest
HI Gerald
interesting . . thanks for the link, and it's good to know they're doing something. . but Ricardo's sample above doesn't look much like front focus (see the woman on the left).
Hi Jono, you are absolutely right on that. Hopefully the reliability of the AF in general will be improved. I know that in past Pentax bodies the AF would not lock if the focus was not spot-on. And the AF would also do a little double check before locking. It sounds like in the K-5 they have totally revised the AF algorithms (in addition to updating the AF hardware) and it locks much faster now, but as shown here it can sometimes miss (I believe this was also mentioned in dpreview's review). It looks like they need to tweak it some more.

http://www.dpreview.com/reviews/pentaxk5/page11.asp

"The K-5's AF system is new, and Pentax's claims that it is faster and more accurate than the system used in the K-7 are bourne out in our shooting. It has the same SAFOX IX+ designation that is carried in the medium format Pentax 645D, - the 'x' denoting that the AF sensor is sensitive to light color, as well as intensity.

Whilst we do not have a specific testing regimen for AF, we have used the K-5 extensively, and we have found that its AF system is extremely capable, in both bright and very low ambient lighting conditions. In the dull interiors of bars and museums, the K-5 doesn't give 100% accuracy, but out of the hundreds of frames which we shot, only a handful are marred by focus errors. Autofocus acquisition is extremely fast and positive, with both conventional screw-driven AF lenses and SDM (ultrasonic-type) optics."
 

jonoslack

Active member
Hi Jono, you are absolutely right on that. Hopefully the reliability of the AF in general will be improved. I know that in past Pentax bodies the AF would not lock if the focus was not spot-on. And the AF would also do a little double check before locking. It sounds like in the K-5 they have totally revised the AF algorithms (in addition to updating the AF hardware) and it locks much faster now, but as shown here it can sometimes miss (I believe this was also mentioned in dpreview's review). It looks like they need to tweak it some more.

http://www.dpreview.com/reviews/pentaxk5/page11.asp

"The K-5's AF system is new, and Pentax's claims that it is faster and more accurate than the system used in the K-7 are bourne out in our shooting. It has the same SAFOX IX+ designation that is carried in the medium format Pentax 645D, - the 'x' denoting that the AF sensor is sensitive to light color, as well as intensity.

Whilst we do not have a specific testing regimen for AF, we have used the K-5 extensively, and we have found that its AF system is extremely capable, in both bright and very low ambient lighting conditions. In the dull interiors of bars and museums, the K-5 doesn't give 100% accuracy, but out of the hundreds of frames which we shot, only a handful are marred by focus errors. Autofocus acquisition is extremely fast and positive, with both conventional screw-driven AF lenses and SDM (ultrasonic-type) optics."
HI Gerald
Sorry to miss this one - been busy :eek:

I think this quote bears out my experiences exactly (i.e. very positive but not perfect) - but all the signs are that Pentax really are doing something with the firmware - it's a new system, and one should expect it to need some tweaking.

here's hoping, but just as it is, the K5 seems to me like an excellent camera.
all the best
 
P

photogerald

Guest
HI Gerald
Sorry to miss this one - been busy :eek:

I think this quote bears out my experiences exactly (i.e. very positive but not perfect) - but all the signs are that Pentax really are doing something with the firmware - it's a new system, and one should expect it to need some tweaking.

here's hoping, but just as it is, the K5 seems to me like an excellent camera.
all the best
Hi Jono, I've been busy too. Haven't been keeping up with things here. I trust that you're still satisfied with your K5?

Regarding the low-light AF issues, there have been some interesting developments. One fellow on the dpreview forum did some ingenious testing and found that the problem isn't caused by tungsten lighting per se, but rather low light levels in general (he used various ND filters in his testing). See:

http://forums.dpreview.com/forums/read.asp?forum=1036&message=37412306

Based on his results, the latest "theory" is that the AF colour temp compensation is doing more harm than good in low light levels, due to inaccurate readings from the colour temp sensor. The fix should be easy to accomplish in firmware, namely to back off on the colour compensation once a certain threshold is reach. Even better would be if the response of the colour temp sensor under these low lighting conditions is predictable/consistent, and to factor that into the compensation algorithm.
 
Top