who cares for bad AF under tungsten light ?

janneman · 12-27-2010, 12:45 PM

Originally posted by dgaies

Well, overall the AF of the K-5 is excellent, a solid improvement over the K-7, which itself was an improvement over the K20D.

I don't know specifically what kinds of tests they (DPR) ran on the AF system, but it seems like the (major) problems come into play when shooting low levels of tungsten light on low contrast targets. .

IIRC they were simply talking about taking the K-5 to a bar....

Urkeldaedalus · 12-27-2010, 04:08 PM

I've put about 7,500 shots on my K-5 since I got it in October with a lot of them coming in terrible light (ISO6400+) and I've only run into anything resembling this problem once in a meeting room lit only by horrendous orange (I assume tungsten) light. It was annoying, but I worked around it and got shots in focus. This may have been a lens contact problem, though, so I'm not sure if I actually even have had the trouble described in this thread.

In other words, I do hope that if this problem exists Pentax is working to fix it, and I'm thankful if this thread has helped bring it to their attention. On the other hand, in the thousands other shots I've taken, the K-5's AF has been not only functional, but very good. No reason to throw the baby out with the bathwater like I've seen some posters do.

janneman · 12-28-2010, 04:14 AM

maybe Pentax anticipated the demise of tungsten light, we cannot even get tungsten lightbulbs anymore....

falconeye · 12-28-2010, 04:58 AM

Originally posted by janneman

maybe Pentax anticipated the demise of tungsten light, we cannot even get tungsten lightbulbs anymore....

But candlelight is affected too.

Europe, in their great wisdom, banned tungsten but not candles. Because EU didn't care about carbon. They cared about making babies

dgaies · 12-28-2010, 05:18 AM

Originally posted by falconeye

But candlelight is affected too.

Europe, in their great wisdom, banned tungsten but not candles. Because EU didn't care about carbon. They cared about making babies

janneman · 12-28-2010, 05:56 AM

Originally posted by falconeye

But candlelight is affected too.

Europe, in their great wisdom, banned tungsten but not candles. Because EU didn't care about carbon. They cared about making babies

Who cares about brats??? They are hard to take pics of anyways, unless you use tape ofcourse.
Tungsten is banned because it uses much more carbon to produce the amount of energy needed to get light...

candles??? wouldn't that be because of low light instead of color temp?

glanglois · 12-28-2010, 08:44 AM

Up here in Wisconsin, we like our brats with brown mustard, onion (optional), frequently ketchup, and a heap of sauerkraut. I like to throw on dill pickle strips but then I'm a renegade .....

Indoors this time of year - I'm too old to tailgate when the beer is too cold to taste.

Winder · 12-28-2010, 10:31 AM

I keep hoping we will see Pentax address this issue with firmware. My K-7 is very inconsistent in low-light. I was blaming it on the Sigma 50mm f/1.4, but I had the opportunity to play with the DA70 over the Christmas weekend and I was getting the same results in low light. Consistent front focus at f/2.8 and under. When I added a couple of lights to the scene to fill the shadows and balance for the snow the camera focused correctly with both lenses. My 5D with the 85L had very few problems nailing focus when the light was so bad the K-7 (50mm Sigma) would just hunt. I was only using center AF for both bodies.

With the winter sun setting and a very gray sky I did not have a whole lot of time to experiment. When chasing the light I really need accurate AF. I was hoping the K-5 would be the answer to the AF problems. Nothing is more frustrating than inconsistent AF. Maybe Canon will introduce a K-5 sized body with a very quiet shutter.

PALADIN85020 · 12-28-2010, 11:28 AM

WELL. Hearing about this problem (which I hadn't experienced), I put my 50mm f1.4 lens on, opened it up to f/1.4, and tried to take a shot in my den, which was lit only by one tungsten-bulb lamp, at an object some distance away from the lamp. On AF, the lens just hunted and hunted. I was totally chagrined. So I put my 18-55 zoom on, and tried again. Same result. I was really freaked out, and had visions of having to return my until-now-perfect camera! I took the camera out in the back yard - and - get this - the camera was still hunting unmercifully on autofocus! OMG!

And then it hit me. When installing both lenses, I kept the lens release button pressed as I twisted the lens home, as some have advised me to do to cut the chances of minute metal particles dropping on the sensor.

A simple further twist until I heard a click put me back in business. IT WAS MY FAILURE TO ALIGN THE CONTACTS THAT WAS THE PROBLEM!

For what it's worth, I have no problems at all with autofocus in low tungsten light with a wide-open lens of any type, zoom or prime.

What a scare! For those having problems, twist that lens a bit to be sure you have it fully seated with the contacts aligned. Sure worked for me, and I'm happy to report everything is just fine with my K-5, thank you. If Pentax wants to work out a slight focus problem under these circumstances, great - I'll just wait for the firmware update.

John

bjan · 12-28-2010, 11:50 AM

I want to repeat a posting in this forum that I did earlier today in an other forum about the same issue.

Dear Pentaxians , I do feel that there might be still some confusing about the exact situations the issue occurs. The given DOF going with the settings and the lens should provide an outcome in the final pic that let us see what the issue is. For example if you make a pic under artificial light from a subject that is a few metres from the lens and with an aperture of 4.0 the issue will not be seen a all. But again that is not what many of us buy this "King of the Light " for . Shooting wide open with fast lenses is one of the temptation with the K5 isn't it ?
I could suggest the following standard test to make the issue foolproof visible :
1) Take a 40mm lens or longer ( e.g 50, 70, )
2) Use a 2.8 diafragma or larger ( e.g. 2.0 or 1.8 )
3) Take a pic from about 80 cms distance under daylight and the same pic with same diafragma and distance under artificial light. BOTH WITH AF on AF/S .
You will find the K5 not being able to focus I am afraid.
In practice the problem could come up for example when making a head shoulder portrait wide open in dim light in a room . If you focus on the eyes of that person you may be happy if the tip of the nose is in focus.

Urkeldaedalus · 12-28-2010, 11:57 AM

Originally posted by PALADIN85020

A simple further twist until I heard a click put me back in business. IT WAS MY FAILURE TO ALIGN THE CONTACTS THAT WAS THE PROBLEM!

For what it's worth, I have no problems at all with autofocus in low tungsten light with a wide-open lens of any type, zoom or prime.

I think this is what happened to me at the meeting, too. The funny thing is the first thought I had was that the SDM in my lens was failing, then I thought it was this tungsten problem. Oh, the power of suggestion.

However, I think the problem described in this thread likely does exist in some form. Why? Because it seems from several posters that Pentax knows about the problem and is working to fix it with firmware. It's funny to me that the ultimate confirmation is that they are working on a fix, and if they truly aren't working on a fix it's less likely there's really a problem. Either way, the problem gets solved, hopefully.

janneman · 12-28-2010, 12:27 PM

Originally posted by bjan

I want to repeat a posting in this forum that I did earlier today in an other forum about the same issue.

[...]

. But again that is not what many of us buy this "King of the Light " for . Shooting wide open with fast lenses is one of the temptation with the K5 isn't it ? .

Aha, a differnce between you and me, one of the reasons why I like the "King of light"is that I can shoot in fairly low light with fairly high speed and still have some DOF left... I can get nice results wide open with the K20D...

bjan · 12-28-2010, 01:07 PM

your are right Janneman. A different point of vieuw towards speed in a camera. Both are applicable of course.

deejjjaaaa · 12-28-2010, 01:18 PM

Originally posted by dgaies

But to be honest, in low light and low contrast targets, I've never expected the AF system to be perfect.

If I can hit the target which is a single black line on a white sheet of paper under the 100w rated tungsten bulb (~10-15" from bulb to the target) using my eye (20/20) + split prism + ome53 + fa50/1.4 then I kind of expect Safox-whatever to be able to do the same... surely I do not have K5, so my experience was limited to *istDL, K10D, K20D and Kx... none was able (that is w/o AF adjustments vs what was under the daylight).

Gimbal · 12-28-2010, 01:54 PM

Originally posted by bjan

I could suggest the following standard test to make the issue foolproof visible :
1) Take a 40mm lens or longer ( e.g 50, 70, )

My main lens is a Sigma17-70 and the FF is most obvious (by far) at the 17mm end, a meter or so in error on a 2,5 meters distance is the norm.

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12-27-2010, 12:45 PM	#256
janneman Veteran Member Join Date: Sep 2006 Location: Netherlands Photos: Gallery Posts: 908	Originally posted by dgaies Well, overall the AF of the K-5 is excellent, a solid improvement over the K-7, which itself was an improvement over the K20D. I don't know specifically what kinds of tests they (DPR) ran on the AF system, but it seems like the (major) problems come into play when shooting low levels of tungsten light on low contrast targets. . IIRC they were simply talking about taking the K-5 to a bar....

12-27-2010, 04:08 PM	#257
Urkeldaedalus Veteran Member Join Date: Dec 2008 Location: Iowa Photos: Gallery \| Albums Posts: 1,369	I've put about 7,500 shots on my K-5 since I got it in October with a lot of them coming in terrible light (ISO6400+) and I've only run into anything resembling this problem once in a meeting room lit only by horrendous orange (I assume tungsten) light. It was annoying, but I worked around it and got shots in focus. This may have been a lens contact problem, though, so I'm not sure if I actually even have had the trouble described in this thread. In other words, I do hope that if this problem exists Pentax is working to fix it, and I'm thankful if this thread has helped bring it to their attention. On the other hand, in the thousands other shots I've taken, the K-5's AF has been not only functional, but very good. No reason to throw the baby out with the bathwater like I've seen some posters do.

12-28-2010, 04:14 AM	#258
janneman Veteran Member Join Date: Sep 2006 Location: Netherlands Photos: Gallery Posts: 908	maybe Pentax anticipated the demise of tungsten light, we cannot even get tungsten lightbulbs anymore....

12-28-2010, 04:58 AM	#259
falconeye Veteran Member Join Date: Jan 2008 Location: Munich, Alps, Germany Photos: Gallery Posts: 6,871	Originally posted by janneman maybe Pentax anticipated the demise of tungsten light, we cannot even get tungsten lightbulbs anymore.... But candlelight is affected too. Europe, in their great wisdom, banned tungsten but not candles. Because EU didn't care about carbon. They cared about making babies

12-28-2010, 05:18 AM	#260
dgaies Veteran Member Join Date: Oct 2009 Location: Maryland / Washington DC Posts: 3,917	Originally posted by falconeye But candlelight is affected too. Europe, in their great wisdom, banned tungsten but not candles. Because EU didn't care about carbon. They cared about making babies

12-28-2010, 05:56 AM	#261
janneman Veteran Member Join Date: Sep 2006 Location: Netherlands Photos: Gallery Posts: 908	Originally posted by falconeye But candlelight is affected too. Europe, in their great wisdom, banned tungsten but not candles. Because EU didn't care about carbon. They cared about making babies Who cares about brats??? They are hard to take pics of anyways, unless you use tape ofcourse. Tungsten is banned because it uses much more carbon to produce the amount of energy needed to get light... candles??? wouldn't that be because of low light instead of color temp?

12-28-2010, 08:44 AM	#262
glanglois Veteran Member Join Date: Aug 2007 Location: Madison, Wis., USA Posts: 1,506	Up here in Wisconsin, we like our brats with brown mustard, onion (optional), frequently ketchup, and a heap of sauerkraut. I like to throw on dill pickle strips but then I'm a renegade ..... Indoors this time of year - I'm too old to tailgate when the beer is too cold to taste.

12-28-2010, 10:31 AM	#263
Winder Veteran Member Join Date: Apr 2010 Location: Tennessee Posts: 6,617	I keep hoping we will see Pentax address this issue with firmware. My K-7 is very inconsistent in low-light. I was blaming it on the Sigma 50mm f/1.4, but I had the opportunity to play with the DA70 over the Christmas weekend and I was getting the same results in low light. Consistent front focus at f/2.8 and under. When I added a couple of lights to the scene to fill the shadows and balance for the snow the camera focused correctly with both lenses. My 5D with the 85L had very few problems nailing focus when the light was so bad the K-7 (50mm Sigma) would just hunt. I was only using center AF for both bodies. With the winter sun setting and a very gray sky I did not have a whole lot of time to experiment. When chasing the light I really need accurate AF. I was hoping the K-5 would be the answer to the AF problems. Nothing is more frustrating than inconsistent AF. Maybe Canon will introduce a K-5 sized body with a very quiet shutter.

12-28-2010, 11:28 AM	#264
PALADIN85020 Veteran Member Join Date: Sep 2010 Location: Arizona Photos: Gallery \| Albums Posts: 442	WELL. Hearing about this problem (which I hadn't experienced), I put my 50mm f1.4 lens on, opened it up to f/1.4, and tried to take a shot in my den, which was lit only by one tungsten-bulb lamp, at an object some distance away from the lamp. On AF, the lens just hunted and hunted. I was totally chagrined. So I put my 18-55 zoom on, and tried again. Same result. I was really freaked out, and had visions of having to return my until-now-perfect camera! I took the camera out in the back yard - and - get this - the camera was still hunting unmercifully on autofocus! OMG! And then it hit me. When installing both lenses, I kept the lens release button pressed as I twisted the lens home, as some have advised me to do to cut the chances of minute metal particles dropping on the sensor. A simple further twist until I heard a click put me back in business. IT WAS MY FAILURE TO ALIGN THE CONTACTS THAT WAS THE PROBLEM! For what it's worth, I have no problems at all with autofocus in low tungsten light with a wide-open lens of any type, zoom or prime. What a scare! For those having problems, twist that lens a bit to be sure you have it fully seated with the contacts aligned. Sure worked for me, and I'm happy to report everything is just fine with my K-5, thank you. If Pentax wants to work out a slight focus problem under these circumstances, great - I'll just wait for the firmware update. John

12-28-2010, 11:50 AM	#265
bjan Senior Member Join Date: Feb 2010 Posts: 116 Original Poster	I want to repeat a posting in this forum that I did earlier today in an other forum about the same issue. Dear Pentaxians , I do feel that there might be still some confusing about the exact situations the issue occurs. The given DOF going with the settings and the lens should provide an outcome in the final pic that let us see what the issue is. For example if you make a pic under artificial light from a subject that is a few metres from the lens and with an aperture of 4.0 the issue will not be seen a all. But again that is not what many of us buy this "King of the Light " for . Shooting wide open with fast lenses is one of the temptation with the K5 isn't it ? I could suggest the following standard test to make the issue foolproof visible : 1) Take a 40mm lens or longer ( e.g 50, 70, ) 2) Use a 2.8 diafragma or larger ( e.g. 2.0 or 1.8 ) 3) Take a pic from about 80 cms distance under daylight and the same pic with same diafragma and distance under artificial light. BOTH WITH AF on AF/S . You will find the K5 not being able to focus I am afraid. In practice the problem could come up for example when making a head shoulder portrait wide open in dim light in a room . If you focus on the eyes of that person you may be happy if the tip of the nose is in focus.

12-28-2010, 11:57 AM	#266
Urkeldaedalus Veteran Member Join Date: Dec 2008 Location: Iowa Photos: Gallery \| Albums Posts: 1,369	Originally posted by PALADIN85020 A simple further twist until I heard a click put me back in business. IT WAS MY FAILURE TO ALIGN THE CONTACTS THAT WAS THE PROBLEM! For what it's worth, I have no problems at all with autofocus in low tungsten light with a wide-open lens of any type, zoom or prime. I think this is what happened to me at the meeting, too. The funny thing is the first thought I had was that the SDM in my lens was failing, then I thought it was this tungsten problem. Oh, the power of suggestion. However, I think the problem described in this thread likely does exist in some form. Why? Because it seems from several posters that Pentax knows about the problem and is working to fix it with firmware. It's funny to me that the ultimate confirmation is that they are working on a fix, and if they truly aren't working on a fix it's less likely there's really a problem. Either way, the problem gets solved, hopefully.

12-28-2010, 12:27 PM	#267
janneman Veteran Member Join Date: Sep 2006 Location: Netherlands Photos: Gallery Posts: 908	Originally posted by bjan I want to repeat a posting in this forum that I did earlier today in an other forum about the same issue. [...] . But again that is not what many of us buy this "King of the Light " for . Shooting wide open with fast lenses is one of the temptation with the K5 isn't it ? . Aha, a differnce between you and me, one of the reasons why I like the "King of light"is that I can shoot in fairly low light with fairly high speed and still have some DOF left... I can get nice results wide open with the K20D...

12-28-2010, 01:07 PM	#268
bjan Senior Member Join Date: Feb 2010 Posts: 116 Original Poster	your are right Janneman. A different point of vieuw towards speed in a camera. Both are applicable of course.

12-28-2010, 01:18 PM	#269
deejjjaaaa Veteran Member Join Date: May 2007 Location: steel city / rust belt Posts: 2,043	Originally posted by dgaies But to be honest, in low light and low contrast targets, I've never expected the AF system to be perfect. If I can hit the target which is a single black line on a white sheet of paper under the 100w rated tungsten bulb (~10-15" from bulb to the target) using my eye (20/20) + split prism + ome53 + fa50/1.4 then I kind of expect Safox-whatever to be able to do the same... surely I do not have K5, so my experience was limited to *istDL, K10D, K20D and Kx... none was able (that is w/o AF adjustments vs what was under the daylight).

12-28-2010, 01:54 PM	#270
Gimbal Pentaxian Join Date: Apr 2007 Location: Sweden Posts: 2,106	Originally posted by bjan I could suggest the following standard test to make the issue foolproof visible : 1) Take a 40mm lens or longer ( e.g 50, 70, ) My main lens is a Sigma17-70 and the FF is most obvious (by far) at the 17mm end, a meter or so in error on a 2,5 meters distance is the norm.