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03-28-2011, 02:21 PM   #151
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QuoteOriginally posted by Ash Quote
Tommo (and others interested), I gave my K-5 with v1.03 a low-light run with my DA 12-24 and DA 18-55 at their widest focal lengths, and after about half an hour of 'testing' I finally managed to get my K-5 to front focus! Once.
Oh, no! Now somebody's going to start a whole new thread about what a piece of junk the K5 is because he read that your camera would only shoot for a half an hour before developing FF problems.
Thanks a lot, Ash!!!



03-28-2011, 03:03 PM   #152
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As devastating that is for the K-5, to be fair I could get the K20D and K10D to do the same under the right conditions. I usually can tell that there is some front focusing happening through the viewfinder, and so I just re-engage the AF before releasing the shutter and lo and behold it focuses properly again.

By extrapolation, with that mindset, I suppose we can deduce then that the K10D, K20D and K-5 are all failures. Took a few million sales worldwide to finally figure that one out
03-28-2011, 03:48 PM   #153
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QuoteOriginally posted by Ash Quote
Smeggy, I still have my K20D and have given it a run alongside the K-5 I have now, and I can say the difference is quite clear. The K-5 is more direct, more sure with locking on focus and is not any less accurate with focusing in low lighting as far as I could tell. So I do wonder whether your previous K-5s had issues.
I think it sure did have issues. That's why I got it replaced

But my previous K-5 was always more sure and direct with focus. it was much quicker than my K20D. It just front focussed where the K20D didn't. Even with 1.03



QuoteQuote:
Tommo (and others interested), I gave my K-5 with v1.03 a low-light run with my DA 12-24 and DA 18-55 at their widest focal lengths, and after about half an hour of 'testing' I finally managed to get my K-5 to front focus! Once.

At about EV1-2 I took about 20 shots with both lenses knowing the exact focus point, and despite trying different AF points, different focus distances, using AF assist lamp or not, out of all these shots I got one from the DA 12-24 front focused by perhaps a couple of centimetres. But I could not get it to replicate the front focusing again. So I gave up.

I accept focusing won't always be perfect under these conditions, but from what I've seen the focusing has been pretty much spot on each time I've challenged it. Any more difficult conditions and I'd be wondering what I want in a photograph of the dull scene before me.
Have you tried @ f/1.4 ?
03-28-2011, 06:22 PM   #154
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I currently don't have an f/1.4 lens Smeggy, my fastest is f/1.8, and even then I could not make my K-5 produce any appreciable FF on a few test shots.

03-28-2011, 09:50 PM   #155
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QuoteOriginally posted by Ash Quote
Smeggy, I still have my K20D and have given it a run alongside the K-5 I have now, and I can say the difference is quite clear. The K-5 is more direct, more sure with locking on focus and is not any less accurate with focusing in low lighting as far as I could tell. So I do wonder whether your previous K-5s had issues.

Tommo (and others interested), I gave my K-5 with v1.03 a low-light run with my DA 12-24 and DA 18-55 at their widest focal lengths, and after about half an hour of 'testing' I finally managed to get my K-5 to front focus! Once.

At about EV1-2 I took about 20 shots with both lenses knowing the exact focus point, and despite trying different AF points, different focus distances, using AF assist lamp or not, out of all these shots I got one from the DA 12-24 front focused by perhaps a couple of centimetres. But I could not get it to replicate the front focusing again. So I gave up.

I accept focusing won't always be perfect under these conditions, but from what I've seen the focusing has been pretty much spot on each time I've challenged it. Any more difficult conditions and I'd be wondering what I want in a photograph of the dull scene before me.
thanks Ash...some rep added for your trouble old son...

Ill keep at it with th e 17-50..if I have a conclusion with it..Ill post here..

I must admit Im not too happy with this 17-50, my other was replaced as it had a faulty lens hood holder on the lens..I got this one about a month ago,{ same time as i got my replacement K5}...at the wide end 17mm, the center is sharp..but the edges are blurry..so my FF with that lens at wide FOV might very well be the lens .mind you using contrast AF..alls good.....my headaches again..
03-28-2011, 11:22 PM   #156
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Thanks mate.
Hope you find the FF anomaly not too troublesome for you - if perhaps this does not happen with another wide angle lens then perhaps it may have something to do with the 17-50 itself.
All the best in that.
03-29-2011, 03:44 PM   #157
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Ok.... Tonight I have just made an MDF lensalign. painted up and I'll stick the graphjcis on tomorrow.

Thursday I'm taking delivery of a second K-5. Then I've got some mass shooting. I'll try and get some more focussing tests done within the week and with a more accurate set up this time.
03-29-2011, 11:59 PM   #158
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i did some testing last night with my 17-50 sigma.....

what I found was troubling. and Im hoping for some ideas...

I set the camera to F2.8 4secs. tripod sr off cable release .... FF was present at 17mm right through to 50mm in varying degrees, but sometimes it would get focus spot on.....this was using a subject that was 400mm from the focal plane......Im not too worried about the above results as it was easily overcome by stopping down to F4 { increase DOF}

but heres the kicker.
when I move the tripod away from the subject. about 2 metres..50 mm was still with in my expectations ...but at 17mm the FF was a country mile , the text on the test subject was unreadable and clearly not a usable image by any expectations

any thoughts guys?....why would 17 mm be ok when shooting form very close and so far out when shooting further back, I expected the opposite as DOF would have increased at 2 metres ..

if anyone wants to see the images..Ill post them up ..but at the moment Im looking for suggestions here as to why this would happen

03-30-2011, 12:07 AM   #159
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Sorry to hear that mate.
Hopefully it's just that lens that's playing up with the K-5.
Suffice to say that it'd be great if nothing was playing up on the K-5...
03-30-2011, 01:49 AM   #160
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QuoteOriginally posted by Tommot1965 Quote
why would 17 mm be ok when shooting form very close and so far out when shooting further back, I expected the opposite as DOF would have increased at 2 metres
Does it do the same in daylight?
03-30-2011, 03:45 AM   #161
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Simco

it did tonight ..but daylight was fading, so not a fair test, although the EV allowed F2.8 1/100 , in my mind it should have been enough light at that EV ?..... Ill try again tomorrow

I rang the Aussie distributer and told them my woes...he suggested another test, as follows

first focus on the target at 50mm until I obtain focus confirmation..then zoom back to 17 mm and take the image..and see if its in focus..it was not..

I went one better, I tripod mounted again, focused at 50mm and take the image, I then checked that it was indeed in focus, which it was, I then switched the body to Manual focus and zoomed back to 17mm, I took another image...which was a mile OOF......if I then engage the AF, and refocus at 17 mm, the lens moves, i get focus confirmation, but the image is still OOF, but not as much

its got me beat...I thinking its the lens...the aussie importer has said they will take both my camera and the lens for calibration to see if thats a fix . right now Im thinking another lens !!
03-30-2011, 04:52 AM   #162
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QuoteOriginally posted by Tommot1965 Quote

first focus on the target at 50mm until I obtain focus confirmation..then zoom back to 17 mm and take the image..and see if its in focus..it was not..

I went one better, I tripod mounted again, focused at 50mm and take the image, I then checked that it was indeed in focus, which it was, I then switched the body to Manual focus and zoomed back to 17mm, I took another image...which was a mile OOF......if I then engage the AF, and refocus at 17 mm, the lens moves, i get focus confirmation, but the image is still OOF, but not as much
That suggests a lens issue, to me. That isn't to say that there isn't also an issue with the camera, but your second test should have produced an in focus image at 17mm no matter what camera it was on.
03-30-2011, 05:14 AM   #163
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QuoteOriginally posted by Smeggypants Quote
A quick test shows it's front focussing @ EV2 like my original copy, but perhaps not as much.
If you had performed your previous tests with more rigour (chart alignment) you'd now be in a position to quantify the improvement.

QuoteOriginally posted by jsherman999 Quote
.
If you want the best low-light AF on the planet, get the D700 - otherwise, I wonder if the K-5 might actually match most other aps-c-level models out there now.
I personally don't need the best low-light AF on the planet but just want a K-5 that performs at least as well as previous Pentax cameras.

QuoteOriginally posted by jsherman999 Quote
.
That's my main concern with Falk's tests - There isn't really much to fault technically, but the big underlying problem with the whole thing is that he does not test the 60D, 7-D, D90, D300, D7000, etc, and it may be that this 'AF problem' isn't really a problem at all when compared to other bodies shooting under the same conditions.
True. I wonder whether he still has his K-7 to compare to. But even if so, I wouldn't dare to propose putting the K-7 through the test mill. The way Falk performs tests takes a lot of time and it wouldn't cross my mind to suggest to him to put even more of his precious time into this. After all, only Pentax can improve the K-5 and he has given them a lot of food for thought already.

QuoteOriginally posted by jsherman999 Quote
.
I know my D90 spanks my K20D in low-light AF speed and accuracy, I'd really like to know how D90 stands up against the K-5. (I guess I'll just have to buy a k5 to find out, huh? )
+1 for your last thought.
I guess, however, we already know that the K-5 doesn't spank the K20D in low-light AF accuracy (maybe in speed). Given the reports posted to the forum, I have reason to believe that the K-5's low-light AF isn't as good as that of the D90 (at least with V1.02 and in Tungsten light).

QuoteOriginally posted by Smeggypants Quote
Ok.... Tonight I have just made an MDF lensalign. painted up and I'll stick the graphjcis on tomorrow.
Nice, hopefully you'll post some pics of your DIY effort.

You'll be in a great position to check whether the MDF LensAlign will produce any results different from shooting a flat focus chart from an angle. I'd be genuinely interested on whether or not you'll observe a difference. Of course, the focus chart you used in the past has a relatively deep focus target (because it uses a bar with a width, rather than a single black to white transition) but it should at least produce comparable results.

QuoteOriginally posted by Smeggypants Quote
Thursday I'm taking delivery of a second K-5. Then I've got some mass shooting. I'll try and get some more focussing tests done within the week and with a more accurate set up this time.
Sounds promising. Looking forward to your observations. Would be great if you could compare to another camera.
03-30-2011, 05:37 AM - 1 Like   #164
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QuoteOriginally posted by Tommot1965 Quote
first focus on the target at 50mm until I obtain focus confirmation..then zoom back to 17 mm and take the image..and see if its in focus..it was not..
Unless that lens is parfocal, it will *not* hold focus when zooming. I would not consider that particular result an indication of a lens problem, unless you know for sure that it is not a varifocal design.
03-30-2011, 06:14 AM   #165
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QuoteOriginally posted by RBellavance Quote
Unless that lens is parfocal, it will *not* hold focus when zooming. I would not consider that particular result an indication of a lens problem, unless you know for sure that it is not a varifocal design.
Ive never heard of those terms before, thanks for bringing it to my attentions,

after a quick google with results at this very forum..it turns out that the lens is a varifocal design.... obviously the aussies aint got a clue about what they are selling!!, as the ets I was told to do.. wouldst work, and shouldn't work

great forum , many thanks for the very helpful advice
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