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01-14-2011, 07:41 AM   #76
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QuoteOriginally posted by jolepp Quote
I quite agree: it is quite a letdown to discover your top-of-the-line K-5 has a problem which the "basic" k-x didn't have, in particular when it interferes with the key strength of your new pride&joy. IMO forums like this are about sharing the experience as well as the relevant facts :-)
That is a refreshing statement, and honestly reflects the views here of a letdown in valid expectations. I also think there is honesty here in wanting a "Fix" and not just using this as a bashing ground for Pentax. The people here want to be happy, they are not looking to bash or berate Pentax.....at least the vast majority, so the comments, when in moderation and reason, seem quite reasonable and expected to me.

And....I get to post my Jeep again...and Mrs Rupert too! Two great things in my life....and when the K5 is all straightened out, it will get to ride in my Jeep, right up front!
No, it won't go off road into the water without a snorkel, but I didn't order a Submarine....did I?
Best Regards!


01-14-2011, 01:20 PM   #77
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Well, this is no "news"; but I have a theory after reading many of the comments about FF with especially screw driven lenses under low light.

My reasoning follows these lines:
- Pentax is no new player in this AF business.
- Pentax has other cameras (functioning properly) with this same hardware.
- Pentax has certainly tested the prototype under low light conditions; as this was meant to be a selling point.
- The range of AF adjustment by the user is insufficient to correct the problem.

Here is my conclusion:
The placement / alignment of the low light AF sensor is faulty.
And, this must be a workmanship and QC issue.
I believe this can conceivably be due to a component being slightly thicker or thinner than the specification (can be about 50-100 micrometers). This results in a misplaced sensor.

Proof?
Of course lacking
However, my recent attempt at buying a K5 has just failed because the seller told me that he could not find a new unit for shipment! Could this be a potential proof?

Bad news?
If my reasoning and *guess* is correct, no firmware fix can resolve the issue. (Yet, all K5s are still under warranty).

Good news?
The issue is resolvable and people with "proper" K5s are going to be very happy owners!
01-14-2011, 02:20 PM   #78
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very very interesting BC THE PATH !! If you are correct on this I will call you JC THE PATH !
01-14-2011, 06:25 PM   #79
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QuoteOriginally posted by Rupert Quote
And....I get to post my Jeep again...and Mrs Rupert too! Two great things in my life....and when the K5 is all straightened out, it will get to ride in my Jeep, right up front!
No, it won't go off road into the water without a snorkel, but I didn't order a Submarine....did I?
Best Regards!
Looks good, Rupert! And the Jeep ain't bad either!

01-15-2011, 12:29 PM   #80
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I cannot make my K5 fail to autofocus, in any light.

What should I try to replicate the issues reported here?

S/N 39xxxxx, firmware 1.01.
01-15-2011, 12:40 PM   #81
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QuoteOriginally posted by peterh337 Quote
I cannot make my K5 fail to autofocus, in any light.

What should I try to replicate the issues reported here?

S/N 39xxxxx, firmware 1.01.
Why try anything? If your camera works, enjoy it.
If you don't want your camera to work, then keep making the conditions it has to work under more and more extreme until it fails.
01-15-2011, 12:42 PM   #82
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QuoteOriginally posted by peterh337 Quote
I cannot make my K5 fail to autofocus, in any light.

What should I try to replicate the issues reported here?

S/N 39xxxxx, firmware 1.01.
Try tungsten light, a 1:2.8 or faster lens fully open, close to min. focusing distance, light around 3-4 EV (0.5-1s f=2.8 ISO 100), not dark enough for AF assist light to turn on, though.
01-15-2011, 12:58 PM   #83
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It doesn't seem fair to force a failure....does it? I mean if it works for what you normally do, it should be good enough without worrying about why it won't fail?

Anyhow, I am running out of Jeep shots......but this is by no means the fault of the Jeep.......or Mrs Rupert. She is as defect free as the Jeep...just ask her!


Regards!

01-15-2011, 02:40 PM   #84
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QuoteOriginally posted by Rupert Quote
Anyhow, I am running out of Jeep shots......but this is by no means the fault of the Jeep.......
Regards!
best go take some more...after all that what we do
01-15-2011, 04:26 PM   #85
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Just wanna confirm that my New K-5 , got it yesterday, is suffering very bad FF in low light

S/n 39xxxxx V1.02
01-15-2011, 04:47 PM   #86
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The problem seems to start around EV2 and below. I was using a Sigma 30mm/1.4 - I'll try some more lenses shortly
01-15-2011, 11:25 PM   #87
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Enpä ole itse keksinyt viellä mitään asetuksia minun K-5 , että voisin ruikuttaa ja syyttää kameran huonoutta.
01-16-2011, 10:51 AM   #88
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QuoteOriginally posted by Smeggypants Quote
Just wanna confirm that my New K-5 , got it yesterday, is suffering very bad FF in low light

S/n 39xxxxx V1.02
QuoteOriginally posted by Smeggypants Quote
The problem seems to start around EV2 and below. I was using a Sigma 30mm/1.4 - I'll try some more lenses shortly
Tried the same test with my K20D ( same lenses ) and it focussed fine.
01-16-2011, 02:33 PM   #89
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QuoteQuote:
Try tungsten light, a 1:2.8 or faster lens fully open, close to min. focusing distance, light around 3-4 EV (0.5-1s f=2.8 ISO 100), not dark enough for AF assist light to turn on, though.
I have no lenses bigger than F4.

From the above conditions it looks like the issue is really a "gap" between the lower end of the illumination at which AF still works, and the upper end of the illumination at which the AF beam comes on.

1s shutter at ISO 100 is awfully low light - totally tripod territory unless you are doing some funny flash-assisted effects. And if you have a tripod you can focus manually (usually).

Presumably going to say ISO 400 sidesteps the issue, and on the K5 there is not a lot of difference in IQ between ISO 100 and ISO 400... in most situations where the shutter is open for 1s, IMHO.

It could be cured in firmware, for near objects, by making the AF light come on at a higher illumination level.

But surely any camera will fail to AF once the illumination goes below a certain figure. The AF assist beam solves only near-object situations, obviously.
01-16-2011, 03:43 PM   #90
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QuoteOriginally posted by peterh337 Quote
I have no lenses bigger than F4.

From the above conditions it looks like the issue is really a "gap" between the lower end of the illumination at which AF still works, and the upper end of the illumination at which the AF beam comes on.

1s shutter at ISO 100 is awfully low light - totally tripod territory unless you are doing some funny flash-assisted effects. And if you have a tripod you can focus manually (usually).

Presumably going to say ISO 400 sidesteps the issue, and on the K5 there is not a lot of difference in IQ between ISO 100 and ISO 400... in most situations where the shutter is open for 1s, IMHO.

It could be cured in firmware, for near objects, by making the AF light come on at a higher illumination level.

But surely any camera will fail to AF once the illumination goes below a certain figure. The AF assist beam solves only near-object situations, obviously.


This brings up a question that may apply to many shooters like me that are not really sure just what we are reading regarding the FF issue. We all take shots in low light at times, and expect some accuracy, but is what is being reported a problem for a large group of shooters or just a small few?

Could you give me some examples where I might have a problem.....It would be extremely rare for me to shoot less than 1/4 ISO 400 F2.8, in fact I can't recall ever shooting like that.....so what could I expect at those settings? If I went to ISO 800....would it improve the focus issue?

I think I may, just may, be holding off on a K5 for reasons that have little or no relationship to my shooting habits. Any examples that you can provide to clear this up will be appreciated....as you can see I am not a technical person, and the simpler the better.
Best Regards!
Rupert
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