who cares for bad AF under tungsten light ?

Tommot1965 · 12-24-2010, 07:30 PM

Originally posted by jolepp

I understand EV is calculated as:

log2(f^2/t) + log2(100/iso)

So for the above:

log2(2.8^2 / 1/60) + log2(100/3200) = 8.877... + -5 ~ 3.9 EV

thanks for that mate , very decent of you to work that out for me

rep added to you sir

..so that should be bright enough for AF to work..I think wheatfield said it would work down to 1 EV..

dgaies · 12-24-2010, 08:23 PM

Originally posted by pcarfan

The K-5 AF specs are as follows " AF working range: -1 to 18 EV ". So, I would think the it's reasonable to expect it to work well under 3EV.

Also, if the K-7 can do it, there is no reason why the K-5 couldn't given the AF was improved.

I wasn't suggesting that the AF of the K-5 shouldn't be able to work properly in artificial light at 3EV, I was merely pointing out that reading through the posts it seems that is the level at which people are having issues. I was also pointing out that in absolute terms, 3EV isn't considered "bright light". The fact that the working range is spec'd -at 1 to 18 EV certainly suggests that there is some level of deficiency with the AF system at the moment. Since the K-7 didn't seem to have the same issue, it's fair to say that this is a bug/defect which will hopefully be addressed in the near future by Pentax.

Tommot1965 · 12-24-2010, 08:45 PM

Originally posted by dgaies

I wasn't suggesting that the AF of the K-5 shouldn't be able to work properly in artificial light at 3EV, I was merely pointing out that reading through the posts it seems that is the level at which people are having issues. I was also pointing out that in absolute terms, 3EV isn't considered "bright light". The fact that the working range is spec'd -at 1 to 18 EV certainly suggests that there is some level of deficiency with the AF system at the moment. Since the K-7 didn't seem to have the same issue, it's fair to say that this is a bug/defect which will hopefully be addressed in the near future by Pentax.

sorry ..I thought you were suggesting that it shouldn't work at that light level..no worries mate..sorry i misunderstood your post

dgaies · 12-24-2010, 09:07 PM - **1 Like**

Originally posted by Tommot1965

sorry ..I thought you were suggesting that it shouldn't work at that light level..no worries mate..sorry i misunderstood your post

No worries here either

Fer · 12-25-2010, 03:20 AM

Ok, so this is basically how this thread has evolved:

1. There's no issue with AF, works perfectly fine. You guys post some samples showing the supposed problem
2. Those samples show a problem indeed, but I have found no such thing with any of my lenses
3. Care to quantify the problem in EV terms? I'm just saying, but you guys are probably trying to use your K5 in pitch dark in a medieval cave (which btw shouldn't matter that much, since the AF is confirming focus anyway; if light is below what the AF can handle, why would the camera confirm focus without even hunting for a second?)
(4. Wait, I might have these problems too. Not too serious, though)
5. Yep, those EV values are a little on the verge of what the AF can handle, based on K5 specs
6. Wait, they aren't
7. Alright, so I have the problem too, and it's probably serious, but I trust Pentax to fix it, even though they have not shown the basic decency to tell their customers that they know about the issue and are working on it (which even as we speak, we cannot be 100% sure of)

I find it a little disappointing that some people get so defensive and need over 200 posts in the thread to grudglingy admit that there is a problem. No one here is out to put Pentax or the K5 down for spurious reasons.

Other than this, the K5 is a great camera, and I really want to keep it, but I won't unless this serious problem is fixed. It's not a mere bug, and it's not minor.

Above all, I'd like Pentax to treat me as their partner (as Wheatfield suggested), and change their stupid policy of not communicating at all with their customers whenever there is a problem. I've already shown my willingness to be their partner by shelling out the cash to buy their product above others from competitors, so let's see some reciprocity here.
I don't know which business/marketing school these guys got their MBAs or whatever qualifications in, it's disrespectful for your customers and awful business practice, no matter how you view it. And please, enough with the "it's the way they do things in Japan, we must accept it". I don't care if a company is headqueartered in Japan, Albania or Minnesota, they need to understand that we are now living in a globalized world, so they have to manage their clients' expectations everywhere.

And it is fair to say that, generally speaking, most of us don't care that much that there is a problem (after all, it's a fact of life), as long as we're kept informed in due time of the steps the company/service provider is taking to sort it out. I don't understand the kind of complacency that goes: "that's just the way they are, I don't care that they have not made an announcement, because traditionally they fix the issues anyway". Well, of course they do, otherwise they would be out of business. It doesn't change the fact that they should grow up as company and start communicating with their clients in a mature way.

End of rant, sorry if I got too carried away.
Merry Christmas everybody!

pcarfan · 12-25-2010, 06:08 AM

For those who may not be following this at DPR, a fellow who owns both the 645D and the K-5 (These share the same, identical AF module) had confirmed his K-5 to have the problem and not the 645D. So, now it's fairly conclusive it's not a hardware issue and will be fixed in the next firmware update.

Merry Christmas!

bjan · 12-25-2010, 07:05 AM - **1 Like**

Originally posted by Fer

Ok, so this is basically how this thread has evolved:

Merry Christmas Fer.

I would say ... This is basically how YOUR CONTRIBUTION in this thread has evolved. The thread itself evolves like a wake up call for many K5 users re the issue concerned. And that was the purpose of opening it .

Merry Christmas to everybode in this forum by the way !

kamayok3 · 12-25-2010, 07:51 AM

My new K5 having this focusing problem under tungsten light as well. Can even see that in my viewfinder that the subject is not in focus. I tried to focus the same spot few times. But still blur. Any way to explain this?

Regards,

Tom

Wheatfield · 12-25-2010, 10:17 AM

Originally posted by kamayok3

My new K5 having this focusing problem under tungsten light as well. Can even see that in my viewfinder that the subject is not in focus. I tried to focus the same spot few times. But still blur. Any way to explain this?

Regards,

Tom

Probably something in the previous 217 posts there should be a hint.

vcheng9 · 12-25-2010, 10:48 AM

I have similar problem with my k-5 and my Sigma 30mm 1.4, Pentax 43mm 1.9, 35mm 2.0 and 77mm 1.8. LV AF is accurate but I can't use it for certain situations (e.g running kids)
most of my Christmas dinner photos were just wasted.. and I don't have this problem with my K20D..

Should I ask for an exchange, or refund (and take the 15% RMA penalty from vendor) or wait for a firmware bug fix ?

Regards,

Vincent

dgaies · 12-25-2010, 11:26 AM - **1 Like**

For what it's worth, I just ran a quick series of tests to try and quantify the threshold of tungsten color light at which the front focus manifests itself. I used a room with three overhead 60 watt regular tungsten light bulbs. The lights are controlled on a dimmer and I reduced the light level gradually until the focus problem presented itself. I started with the blinds open using natural light around 5 EV and the focus was fine. I closed the blinds and turned the dimmer up to 6EV and the focus was fine. I tried a light level of 5 EV and it was fine. 4 EV was fine was well. 3 EV, however, was front focused. So I tried 4EV again and the focus was fine again. Down to 3EV, the focus was off. I repeated this a few times and have concluded (that at least for this particular combination of K-5 and FA43), at around 3EV there is front focus.

So I would conclude that at low levels of artificial, tungsten colored light (3-4 EV and below) is where the FF issue begins. I haven't had any major issues in actual use, but I suspect that is because my shots were either above 3-4 EV or were in light that was low enough that the AF-assist light kicked on and mitigated the problem.

Fer · 12-25-2010, 11:38 AM

Originally posted by bjan

Merry Christmas Fer.

I would say ... This is basically how YOUR CONTRIBUTION in this thread has evolved. The thread itself evolves like a wake up call for many K5 users re the issue concerned. And that was the purpose of opening it .

Merry Christmas to everybode in this forum by the way !

Not for the first time in this thread, I don't have a clue what you're talking about. If I'm not wrong, I was the first contributor in this thread to have posted actual samples of the problem:

https://www.pentaxforums.com/forums/pentax-k-5-forum/126234-who-cares-bad-aut...ml#post1308877

My contribution hasn't evolved because it was very clear to me from the start that there was a problem indeed.

Merry Christmas to you too!

bjan · 12-25-2010, 12:53 PM

No problem Fer. You are the best. Maybe you need a DSRD (digital self reflexion device) instead of a DSLR .

Fer · 12-25-2010, 03:32 PM

Originally posted by bjan

No problem Fer. You are the best. Maybe you need a DSRD (digital self reflexion device) instead of a DSLR .

Whatever floats your boat, pal. May I suggest you stop referring to what I think, say, or need? Thank you

Fer · 12-25-2010, 03:36 PM

Originally posted by pcarfan

For those who may not be following this at DPR, a fellow who owns both the 645D and the K-5 (These share the same, identical AF module) had confirmed his K-5 to have the problem and not the 645D. So, now it's fairly conclusive it's not a hardware issue and will be fixed in the next firmware update.

Merry Christmas!

Good news, I had missed that post, thanks for pointing it out.

12-25-2010, 11:26 AM - 1 Like	#221
dgaies Veteran Member Join Date: Oct 2009 Location: Maryland / Washington DC Posts: 3,917	For what it's worth, I just ran a quick series of tests to try and quantify the threshold of tungsten color light at which the front focus manifests itself. I used a room with three overhead 60 watt regular tungsten light bulbs. The lights are controlled on a dimmer and I reduced the light level gradually until the focus problem presented itself. I started with the blinds open using natural light around 5 EV and the focus was fine. I closed the blinds and turned the dimmer up to 6EV and the focus was fine. I tried a light level of 5 EV and it was fine. 4 EV was fine was well. 3 EV, however, was front focused. So I tried 4EV again and the focus was fine again. Down to 3EV, the focus was off. I repeated this a few times and have concluded (that at least for this particular combination of K-5 and FA43), at around 3EV there is front focus. So I would conclude that at low levels of artificial, tungsten colored light (3-4 EV and below) is where the FF issue begins. I haven't had any major issues in actual use, but I suspect that is because my shots were either above 3-4 EV or were in light that was low enough that the AF-assist light kicked on and mitigated the problem. Last edited by dgaies; 12-25-2010 at 11:32 AM.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Front Focus and tungsten light question	Big G	Pentax DSLR Discussion	8	01-18-2010 12:25 PM
released Kx firmware 1.01 anyone cares?	Mystic	Pentax News and Rumors	4	12-05-2009 09:19 PM
Can K20 be adjusted for indoor Tungsten light?	philbaum	Pentax DSLR Discussion	12	07-22-2009 05:40 AM
A ship in bad light	mingdie	Post Your Photos!	11	08-07-2008 03:52 AM
Tungsten light option k100d super problem?	demoleman	Pentax DSLR Discussion	17	02-18-2008 04:58 PM

12-24-2010, 07:30 PM	#211
Tommot1965 Veteran Member Join Date: Sep 2010 Location: Perth Western Australia Photos: Gallery \| Albums Posts: 1,026	Originally posted by jolepp I understand EV is calculated as: log2(f^2/t) + log2(100/iso) So for the above: log2(2.8^2 / 1/60) + log2(100/3200) = 8.877... + -5 ~ 3.9 EV thanks for that mate , very decent of you to work that out for me rep added to you sir ..so that should be bright enough for AF to work..I think wheatfield said it would work down to 1 EV..

12-24-2010, 08:23 PM	#212
dgaies Veteran Member Join Date: Oct 2009 Location: Maryland / Washington DC Posts: 3,917	Originally posted by pcarfan The K-5 AF specs are as follows " AF working range: -1 to 18 EV ". So, I would think the it's reasonable to expect it to work well under 3EV. Also, if the K-7 can do it, there is no reason why the K-5 couldn't given the AF was improved. I wasn't suggesting that the AF of the K-5 shouldn't be able to work properly in artificial light at 3EV, I was merely pointing out that reading through the posts it seems that is the level at which people are having issues. I was also pointing out that in absolute terms, 3EV isn't considered "bright light". The fact that the working range is spec'd -at 1 to 18 EV certainly suggests that there is some level of deficiency with the AF system at the moment. Since the K-7 didn't seem to have the same issue, it's fair to say that this is a bug/defect which will hopefully be addressed in the near future by Pentax.

12-24-2010, 08:45 PM	#213
Tommot1965 Veteran Member Join Date: Sep 2010 Location: Perth Western Australia Photos: Gallery \| Albums Posts: 1,026	Originally posted by dgaies I wasn't suggesting that the AF of the K-5 shouldn't be able to work properly in artificial light at 3EV, I was merely pointing out that reading through the posts it seems that is the level at which people are having issues. I was also pointing out that in absolute terms, 3EV isn't considered "bright light". The fact that the working range is spec'd -at 1 to 18 EV certainly suggests that there is some level of deficiency with the AF system at the moment. Since the K-7 didn't seem to have the same issue, it's fair to say that this is a bug/defect which will hopefully be addressed in the near future by Pentax. sorry ..I thought you were suggesting that it shouldn't work at that light level..no worries mate..sorry i misunderstood your post

12-24-2010, 09:07 PM - 1 Like	#214
dgaies Veteran Member Join Date: Oct 2009 Location: Maryland / Washington DC Posts: 3,917	Originally posted by Tommot1965 sorry ..I thought you were suggesting that it shouldn't work at that light level..no worries mate..sorry i misunderstood your post No worries here either

12-25-2010, 03:20 AM	#215
Fer Forum Member Join Date: Jul 2010 Location: Madrid Posts: 66	Ok, so this is basically how this thread has evolved: 1. There's no issue with AF, works perfectly fine. You guys post some samples showing the supposed problem 2. Those samples show a problem indeed, but I have found no such thing with any of my lenses 3. Care to quantify the problem in EV terms? I'm just saying, but you guys are probably trying to use your K5 in pitch dark in a medieval cave (which btw shouldn't matter that much, since the AF is confirming focus anyway; if light is below what the AF can handle, why would the camera confirm focus without even hunting for a second?) (4. Wait, I might have these problems too. Not too serious, though) 5. Yep, those EV values are a little on the verge of what the AF can handle, based on K5 specs 6. Wait, they aren't 7. Alright, so I have the problem too, and it's probably serious, but I trust Pentax to fix it, even though they have not shown the basic decency to tell their customers that they know about the issue and are working on it (which even as we speak, we cannot be 100% sure of) I find it a little disappointing that some people get so defensive and need over 200 posts in the thread to grudglingy admit that there is a problem. No one here is out to put Pentax or the K5 down for spurious reasons. Other than this, the K5 is a great camera, and I really want to keep it, but I won't unless this serious problem is fixed. It's not a mere bug, and it's not minor. Above all, I'd like Pentax to treat me as their partner (as Wheatfield suggested), and change their stupid policy of not communicating at all with their customers whenever there is a problem. I've already shown my willingness to be their partner by shelling out the cash to buy their product above others from competitors, so let's see some reciprocity here. I don't know which business/marketing school these guys got their MBAs or whatever qualifications in, it's disrespectful for your customers and awful business practice, no matter how you view it. And please, enough with the "it's the way they do things in Japan, we must accept it". I don't care if a company is headqueartered in Japan, Albania or Minnesota, they need to understand that we are now living in a globalized world, so they have to manage their clients' expectations everywhere. And it is fair to say that, generally speaking, most of us don't care that much that there is a problem (after all, it's a fact of life), as long as we're kept informed in due time of the steps the company/service provider is taking to sort it out. I don't understand the kind of complacency that goes: "that's just the way they are, I don't care that they have not made an announcement, because traditionally they fix the issues anyway". Well, of course they do, otherwise they would be out of business. It doesn't change the fact that they should grow up as company and start communicating with their clients in a mature way. End of rant, sorry if I got too carried away. Merry Christmas everybody!

12-25-2010, 06:08 AM	#216
pcarfan Veteran Member Join Date: Sep 2007 Location: Dayton, Ohio Photos: Gallery \| Albums Posts: 2,978	For those who may not be following this at DPR, a fellow who owns both the 645D and the K-5 (These share the same, identical AF module) had confirmed his K-5 to have the problem and not the 645D. So, now it's fairly conclusive it's not a hardware issue and will be fixed in the next firmware update. Merry Christmas!

12-25-2010, 07:05 AM - 1 Like	#217
bjan Senior Member Join Date: Feb 2010 Posts: 116 Original Poster	Originally posted by Fer Ok, so this is basically how this thread has evolved: Merry Christmas Fer. I would say ... This is basically how YOUR CONTRIBUTION in this thread has evolved. The thread itself evolves like a wake up call for many K5 users re the issue concerned. And that was the purpose of opening it . Merry Christmas to everybode in this forum by the way !

12-25-2010, 07:51 AM	#218
kamayok3 Forum Member Join Date: Apr 2010 Posts: 90	My new K5 having this focusing problem under tungsten light as well. Can even see that in my viewfinder that the subject is not in focus. I tried to focus the same spot few times. But still blur. Any way to explain this? Regards, Tom

12-25-2010, 10:17 AM	#219
Wheatfield Moderator Join Date: Apr 2008 Location: The wheatfields of Canada Posts: 15,981	Originally posted by kamayok3 My new K5 having this focusing problem under tungsten light as well. Can even see that in my viewfinder that the subject is not in focus. I tried to focus the same spot few times. But still blur. Any way to explain this? Regards, Tom Probably something in the previous 217 posts there should be a hint.

12-25-2010, 10:48 AM	#220
vcheng9 Forum Member Join Date: Jul 2009 Location: Seattle, WA Photos: Gallery Posts: 55	I have similar problem with my k-5 and my Sigma 30mm 1.4, Pentax 43mm 1.9, 35mm 2.0 and 77mm 1.8. LV AF is accurate but I can't use it for certain situations (e.g running kids) most of my Christmas dinner photos were just wasted.. and I don't have this problem with my K20D.. Should I ask for an exchange, or refund (and take the 15% RMA penalty from vendor) or wait for a firmware bug fix ? Regards, Vincent

Thread Tools	Search this Thread
	Search this Thread: Advanced Search

12-25-2010, 11:38 AM	#222
Fer Forum Member Join Date: Jul 2010 Location: Madrid Posts: 66	Originally posted by bjan Merry Christmas Fer. I would say ... This is basically how YOUR CONTRIBUTION in this thread has evolved. The thread itself evolves like a wake up call for many K5 users re the issue concerned. And that was the purpose of opening it . Merry Christmas to everybode in this forum by the way ! Not for the first time in this thread, I don't have a clue what you're talking about. If I'm not wrong, I was the first contributor in this thread to have posted actual samples of the problem: https://www.pentaxforums.com/forums/pentax-k-5-forum/126234-who-cares-bad-aut...ml#post1308877 My contribution hasn't evolved because it was very clear to me from the start that there was a problem indeed. Merry Christmas to you too!

12-25-2010, 12:53 PM	#223
bjan Senior Member Join Date: Feb 2010 Posts: 116 Original Poster	No problem Fer. You are the best. Maybe you need a DSRD (digital self reflexion device) instead of a DSLR .

12-25-2010, 03:32 PM	#224
Fer Forum Member Join Date: Jul 2010 Location: Madrid Posts: 66	Originally posted by bjan No problem Fer. You are the best. Maybe you need a DSRD (digital self reflexion device) instead of a DSLR . Whatever floats your boat, pal. May I suggest you stop referring to what I think, say, or need? Thank you

12-25-2010, 03:36 PM	#225
Fer Forum Member Join Date: Jul 2010 Location: Madrid Posts: 66	Originally posted by pcarfan For those who may not be following this at DPR, a fellow who owns both the 645D and the K-5 (These share the same, identical AF module) had confirmed his K-5 to have the problem and not the 645D. So, now it's fairly conclusive it's not a hardware issue and will be fixed in the next firmware update. Merry Christmas! Good news, I had missed that post, thanks for pointing it out.