Re: An odd K-5 problem

[Larry Colen]

I have been thinking of posting a related question.  When you determine 
the per lens focus adjustment for a lens on one camera, does that number 
tend to work on another camera, perhaps with a slight offset.


For example if on camera 1 you have
lens A  +5
lens B  +2
lens C  -1

would you use the same numbers? Or if lens A works out to be +4, could 
you assume that the corrections would be

lens A  +4
lens B  +1
lens C  -2

Or do they end up just being totally random?


Rick Womer wrote:

I am trying to sort out soft focus on my K-5 (especially with my 16-45/4 lens), 
and would appreciate some help.

I put my camera on a tripod, used the picket fence in our back yard as a target 
(with a card with an X sticking out), and shot repeated frames with 3 lenses 
(40/2.8 Ltd, DA 16-45, and DA 50-200) using live view (LV) or viewfinder (VF) 
autofocus. The focal length of the 16-45 was set at 34mm, and the 50-200 at 
50mm.

The results:

40/2.8: FF in LV, very slight FF with VF
16-45: FF in LV, BF with VF
50-200: on target with LV and VF

Two questions:
1. I thought that the fine AF adjustment (via menu C4) did not affect Live View 
AF. Is that incorrect?
2. What the heck is going on with the 16-45?

Rick









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Re: An odd K-5 problem

[David Parsons]

The adjustments would only be similar if the two cameras were
absolutely the same.  Tolerances will be different from body to body
and lens to lens, so you'd want to calibrate each lens to each body.

On Thu, Mar 17, 2016 at 7:03 PM, Larry Colen  wrote:
> I have been thinking of posting a related question.  When you determine the
> per lens focus adjustment for a lens on one camera, does that number tend to
> work on another camera, perhaps with a slight offset.
>
> For example if on camera 1 you have
> lens A  +5
> lens B  +2
> lens C  -1
>
> would you use the same numbers? Or if lens A works out to be +4, could you
> assume that the corrections would be
> lens A  +4
> lens B  +1
> lens C  -2
>
> Or do they end up just being totally random?
>
>
> Rick Womer wrote:
>>
>> I am trying to sort out soft focus on my K-5 (especially with my 16-45/4
>> lens), and would appreciate some help.
>>
>> I put my camera on a tripod, used the picket fence in our back yard as a
>> target (with a card with an X sticking out), and shot repeated frames with 3
>> lenses (40/2.8 Ltd, DA 16-45, and DA 50-200) using live view (LV) or
>> viewfinder (VF) autofocus. The focal length of the 16-45 was set at 34mm,
>> and the 50-200 at 50mm.
>>
>> The results:
>>
>> 40/2.8: FF in LV, very slight FF with VF
>> 16-45: FF in LV, BF with VF
>> 50-200: on target with LV and VF
>>
>> Two questions:
>> 1. I thought that the fine AF adjustment (via menu C4) did not affect Live
>> View AF. Is that incorrect?
>> 2. What the heck is going on with the 16-45?
>>
>> Rick
>>
>>
>>
>>
>>
>>
>>
>
> --
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>
>
>
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Re: An odd K-5 problem

[David J Brooks]

Rick, my 16-45 seems soft on my K-5 and k10d but it was very good on
my istd. Still confused over this.

Dave

On Thu, Mar 17, 2016 at 5:37 PM, Rick Womer  wrote:
> I am trying to sort out soft focus on my K-5 (especially with my 16-45/4 
> lens), and would appreciate some help.
>
> I put my camera on a tripod, used the picket fence in our back yard as a 
> target (with a card with an X sticking out), and shot repeated frames with 3 
> lenses (40/2.8 Ltd, DA 16-45, and DA 50-200) using live view (LV) or 
> viewfinder (VF) autofocus. The focal length of the 16-45 was set at 34mm, and 
> the 50-200 at 50mm.
>
> The results:
>
> 40/2.8: FF in LV, very slight FF with VF
> 16-45: FF in LV, BF with VF
> 50-200: on target with LV and VF
>
> Two questions:
> 1. I thought that the fine AF adjustment (via menu C4) did not affect Live 
> View AF. Is that incorrect?
> 2. What the heck is going on with the 16-45?
>
> Rick
>
>
>
>
>
>
>
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Re: An odd K-5 problem

[Bill]

On 3/18/2016 9:01 AM, Mark Roberts wrote:

David J Brooks wrote:


On Thu, Mar 17, 2016 at 11:36 PM, Bill  wrote:

Gentlemen, remember that with the K5, the AF accuracy can be thrown off
tremendously by the colour of the subject.


Sort of the Donald Trump of cameras then


Mark!
;-)




Can we please leave that person out of it?

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Re: An odd K-5 problem

[Bill]

I had one of the K5s that was so out of spec that nothing could fix the 
AF. I did the software upgrades, hoping that they would fix the AF, but 
it turns out the hardware was too flaky.
Mine was so bad that even in broad daylight, the AF would vary depending 
on the subject matter.
The only way I could secure reasonably accurate AF was to use live view 
and stop down to f/11.

I despised that camera.

bill


On 3/19/2016 8:43 PM, Rick Womer wrote:

Well, I have done a good deal of web research and experimentation.

First, and most importantly, since I use the viewfinder for 99+
percent of my shooting, I adjusted the AF for the viewfinder for my
three most-used lenses (16-45, 40 Ltd, 50-200). It is much better,
thank you.

Second, the K-5 did, indeed, suffer from very inconsistent viewfinder
autofocus (phase detection) with different intensities and color
temperatures of light. It needed light toward the blue end of the
spectrum to focus accurately, and low-level tungsten light just made
it wet its pants. From what I read, this was partially corrected in
firmware 1.03, and corrected further in 1.15. There were hardware
changes in the K-5 II and K-3 that reportedly eliminated the problem
entirely.

Third, even though contrast-detection AF (which is what Live View
uses) is working with the image on the sensor, it also can be crazily
inaccurate for reasons that nobody seems able to explain. So, I've
decided not to worry about it.

Cheers,

Rick
http://photo.net/photos/RickW


On Sat, Mar 19, 2016 at 9:18 PM, Igor PDML-StR  wrote:



Rick,

I am not sure. I can speculate that the difference could come from:
1) method of AF (isn't it different from LV and through viewfinder, - I
forgot how it is for K5/K3).
2) number of sensor points used in the two cases.

Also, Bill (or somebody else?) mentioned in this thread that some colors can
throw off the AF. I was not aware of that.

Igor





Rick Womer wrote on Fri Mar 18 08:36:46 EDT 2016:

The strangest things about these AF experiments are:

1. Front-focusing on LiveView, which (I thought) sought to maximize the
contrast of the image on the sensor, and thus should be IN FOCUS regardless
of the lens in use; and

2. The 16-45 front-focusing with LiveView, and back-focusing with viewfinder
AF.

Thoughts?

Rick


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Re: An odd K-5 problem

[David J Brooks]

I have a hell of a time getting a decent shot from live view so no
thoughts on your problem here.

Dave

On Fri, Mar 18, 2016 at 8:36 AM, Rick Womer  wrote:
> The strangest things about these AF experiments are:
>
> 1. Front-focusing on LiveView, which (I thought) sought to maximize the 
> contrast of the image on the sensor, and thus should be IN FOCUS regardless 
> of the lens in use; and
>
> 2. The 16-45 front-focusing with LiveView, and back-focusing with viewfinder 
> AF.
>
> Thoughts?
>
> Rick
>
> On Mar 17, 2016, at 10:57 PM, Igor PDML-StR wrote:
>
>>
>> Larry,
>>
>> I do not know what is _typical_ for different Pentax cameras and lenses, but 
>> from the general point of view, I fully agree with what  David wrote.
>>
>> Think about it this way: you have a set of deviation parameters
>> for the camera C1= {c1, c2, c3,c4, c5... }, and then a set of "coupled"
>> (sort of "reciprocal") deviations for the lens L1= {l1, l2, l3, l4, l5, ...}.
>> The number you get for each lens is an average number that sort of minimizes 
>> the combined deviations {(c1,l1),(c2,l2), (c3,l3),...}.
>> Since each of those individual parameters are essentially random,
>> for a different set C2, the way you will need to minimize the combined 
>> deviations C2*L1 could be very different from that for C1*L1.
>>
>> So, in general, yes, for the best result, you want to calibrate each lens on 
>> each camera.
>> However, I suspect that there will be some correlation. So,
>> your first scenario of calibration will give (with some good probability)
>> the result that on average [over all your lenses] is better than
>> in case you haven't adjusted the calibration at all.
>>
>> Igor
>>
>>
>> David Parsons wrote on Thu Mar 17 22:19:46 EDT 2016:
>>
>> The adjustments would only be similar if the two cameras were
>> absolutely the same.  Tolerances will be different from body to body
>> and lens to lens, so you'd want to calibrate each lens to each body.
>>
>> On Thu, Mar 17, 2016 at 7:03 PM, Larry Colen wrote:
>>
>>> I have been thinking of posting a related question.  When you determine the
>>> per lens focus adjustment for a lens on one camera, does that number tend to
>>> work on another camera, perhaps with a slight offset.
>>>
>>> For example if on camera 1 you have
>>> lens A  +5
>>> lens B  +2
>>> lens C  -1
>>>
>>> would you use the same numbers? Or if lens A works out to be +4, could you
>>> assume that the corrections would be
>>> lens A  +4
>>> lens B  +1
>>> lens C  -2
>>>
>>> Or do they end up just being totally random?
>>
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>
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>
>
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Re: An odd K-5 problem

[Rick Womer]

Well, I have done a good deal of web research and experimentation.

First, and most importantly, since I use the viewfinder for 99+
percent of my shooting, I adjusted the AF for the viewfinder for my
three most-used lenses (16-45, 40 Ltd, 50-200). It is much better,
thank you.

Second, the K-5 did, indeed, suffer from very inconsistent viewfinder
autofocus (phase detection) with different intensities and color
temperatures of light. It needed light toward the blue end of the
spectrum to focus accurately, and low-level tungsten light just made
it wet its pants. From what I read, this was partially corrected in
firmware 1.03, and corrected further in 1.15. There were hardware
changes in the K-5 II and K-3 that reportedly eliminated the problem
entirely.

Third, even though contrast-detection AF (which is what Live View
uses) is working with the image on the sensor, it also can be crazily
inaccurate for reasons that nobody seems able to explain. So, I've
decided not to worry about it.

Cheers,

Rick
http://photo.net/photos/RickW


On Sat, Mar 19, 2016 at 9:18 PM, Igor PDML-StR  wrote:
>
>
> Rick,
>
> I am not sure. I can speculate that the difference could come from:
> 1) method of AF (isn't it different from LV and through viewfinder, - I
> forgot how it is for K5/K3).
> 2) number of sensor points used in the two cases.
>
> Also, Bill (or somebody else?) mentioned in this thread that some colors can
> throw off the AF. I was not aware of that.
>
> Igor
>
>
>
>
>
> Rick Womer wrote on Fri Mar 18 08:36:46 EDT 2016:
>
> The strangest things about these AF experiments are:
>
> 1. Front-focusing on LiveView, which (I thought) sought to maximize the
> contrast of the image on the sensor, and thus should be IN FOCUS regardless
> of the lens in use; and
>
> 2. The 16-45 front-focusing with LiveView, and back-focusing with viewfinder
> AF.
>
> Thoughts?
>
> Rick
>
>
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Re: An odd K-5 problem

[Igor PDML-StR]

Rick,

I am not sure. I can speculate that the difference could come from:
1) method of AF (isn't it different from LV and through viewfinder, - I 
forgot how it is for K5/K3).

2) number of sensor points used in the two cases.

Also, Bill (or somebody else?) mentioned in this thread that some colors 
can throw off the AF. I was not aware of that.


Igor





Rick Womer wrote on Fri Mar 18 08:36:46 EDT 2016:

The strangest things about these AF experiments are:

1. Front-focusing on LiveView, which (I thought) sought to maximize the 
contrast of the image on the sensor, and thus should be IN FOCUS 
regardless of the lens in use; and


2. The 16-45 front-focusing with LiveView, and back-focusing with 
viewfinder AF.


Thoughts?

Rick


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Re: An odd K-5 problem

[Bill]

On 3/18/2016 1:51 AM, Larry Colen wrote:



Bill wrote:

Gentlemen, remember that with the K5, the AF accuracy can be thrown off
tremendously by the colour of the subject.
The AF on the K5 is like a whore turning her first trick.


It hasn't yet become jaded and bored by the whole process?






Sucks on several levels, none in in a good way.

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Re: An odd K-5 problem

[P.J. Alling]

That's what's nice about the K-5II it's Pentax Auto Focus that mostly 
works.  Mostly.


On 3/18/2016 8:22 AM, Bill wrote:

On 3/18/2016 1:51 AM, Larry Colen wrote:



Bill wrote:

Gentlemen, remember that with the K5, the AF accuracy can be thrown off
tremendously by the colour of the subject.
The AF on the K5 is like a whore turning her first trick.


It hasn't yet become jaded and bored by the whole process?






Sucks on several levels, none in in a good way.




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immortality through not dying.
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Re: An odd K-5 problem

[Larry Colen]

Bill wrote:

Gentlemen, remember that with the K5, the AF accuracy can be thrown off
tremendously by the colour of the subject.
The AF on the K5 is like a whore turning her first trick.


It hasn't yet become jaded and bored by the whole process?





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Re: An odd K-5 problem

[David Parsons]

I noticed similar with my 16-45 and K-5.  It was my favorite lens on
my K100D Super, and on the K-5, it lost it's luster.

Most likely due to the extra 10 megapixels to see the flaws, and it
makes a tripod even more critical for clean shots.

On Thu, Mar 17, 2016 at 5:47 PM, David J Brooks  wrote:
> Rick, my 16-45 seems soft on my K-5 and k10d but it was very good on
> my istd. Still confused over this.
>
> Dave
>
> On Thu, Mar 17, 2016 at 5:37 PM, Rick Womer  wrote:
>> I am trying to sort out soft focus on my K-5 (especially with my 16-45/4 
>> lens), and would appreciate some help.
>>
>> I put my camera on a tripod, used the picket fence in our back yard as a 
>> target (with a card with an X sticking out), and shot repeated frames with 3 
>> lenses (40/2.8 Ltd, DA 16-45, and DA 50-200) using live view (LV) or 
>> viewfinder (VF) autofocus. The focal length of the 16-45 was set at 34mm, 
>> and the 50-200 at 50mm.
>>
>> The results:
>>
>> 40/2.8: FF in LV, very slight FF with VF
>> 16-45: FF in LV, BF with VF
>> 50-200: on target with LV and VF
>>
>> Two questions:
>> 1. I thought that the fine AF adjustment (via menu C4) did not affect Live 
>> View AF. Is that incorrect?
>> 2. What the heck is going on with the 16-45?
>>
>> Rick
>>
>>
>>
>>
>>
>>
>>
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Re: An odd K-5 problem

[Igor PDML-StR]

MARK!

Bill wrote on Thu Mar 17 23:36:51 EDT 2016:

The AF on the K5 is like a whore turning her first trick.



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Re: An odd K-5 problem

[Bill]

Gentlemen, remember that with the K5, the AF accuracy can be thrown off 
tremendously by the colour of the subject.

The AF on the K5 is like a whore turning her first trick.

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Re: An odd K-5 problem

[Igor PDML-StR]

Larry,

I do not know what is _typical_ for different Pentax cameras and lenses, 
but from the general point of view, I fully agree with what  David wrote.


Think about it this way: you have a set of deviation parameters
for the camera C1= {c1, c2, c3,c4, c5... }, and then a set of "coupled"
(sort of "reciprocal") deviations for the lens L1= {l1, l2, l3, l4, l5, ...}.
The number you get for each lens is an average number that sort 
of minimizes the combined deviations {(c1,l1),(c2,l2), (c3,l3),...}.

Since each of those individual parameters are essentially random,
for a different set C2, the way you will need to minimize the combined 
deviations C2*L1 could be very different from that for C1*L1.


So, in general, yes, for the best result, you want to calibrate each lens 
on each camera.

However, I suspect that there will be some correlation. So,
your first scenario of calibration will give (with some good probability)
the result that on average [over all your lenses] is better than
in case you haven't adjusted the calibration at all.

Igor


David Parsons wrote on Thu Mar 17 22:19:46 EDT 2016:

The adjustments would only be similar if the two cameras were
absolutely the same.  Tolerances will be different from body to body
and lens to lens, so you'd want to calibrate each lens to each body.

On Thu, Mar 17, 2016 at 7:03 PM, Larry Colen wrote:


I have been thinking of posting a related question.  When you determine the
per lens focus adjustment for a lens on one camera, does that number tend to
work on another camera, perhaps with a slight offset.

For example if on camera 1 you have
lens A  +5
lens B  +2
lens C  -1

would you use the same numbers? Or if lens A works out to be +4, could you
assume that the corrections would be
lens A  +4
lens B  +1
lens C  -2

Or do they end up just being totally random?


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Re: An odd K-5 problem

[David J Brooks]

On Thu, Mar 17, 2016 at 11:36 PM, Bill  wrote:
> Gentlemen, remember that with the K5, the AF accuracy can be thrown off
> tremendously by the colour of the subject.

Sort of the Donald Trump of cameras then

Dave
> The AF on the K5 is like a whore turning her first trick.
>
>
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Re: An odd K-5 problem

[Rick Womer]

The strangest things about these AF experiments are:

1. Front-focusing on LiveView, which (I thought) sought to maximize the 
contrast of the image on the sensor, and thus should be IN FOCUS regardless of 
the lens in use; and

2. The 16-45 front-focusing with LiveView, and back-focusing with viewfinder AF.

Thoughts?

Rick

On Mar 17, 2016, at 10:57 PM, Igor PDML-StR wrote:

> 
> Larry,
> 
> I do not know what is _typical_ for different Pentax cameras and lenses, but 
> from the general point of view, I fully agree with what  David wrote.
> 
> Think about it this way: you have a set of deviation parameters
> for the camera C1= {c1, c2, c3,c4, c5... }, and then a set of "coupled"
> (sort of "reciprocal") deviations for the lens L1= {l1, l2, l3, l4, l5, ...}.
> The number you get for each lens is an average number that sort of minimizes 
> the combined deviations {(c1,l1),(c2,l2), (c3,l3),...}.
> Since each of those individual parameters are essentially random,
> for a different set C2, the way you will need to minimize the combined 
> deviations C2*L1 could be very different from that for C1*L1.
> 
> So, in general, yes, for the best result, you want to calibrate each lens on 
> each camera.
> However, I suspect that there will be some correlation. So,
> your first scenario of calibration will give (with some good probability)
> the result that on average [over all your lenses] is better than
> in case you haven't adjusted the calibration at all.
> 
> Igor
> 
> 
> David Parsons wrote on Thu Mar 17 22:19:46 EDT 2016:
> 
> The adjustments would only be similar if the two cameras were
> absolutely the same.  Tolerances will be different from body to body
> and lens to lens, so you'd want to calibrate each lens to each body.
> 
> On Thu, Mar 17, 2016 at 7:03 PM, Larry Colen wrote:
> 
>> I have been thinking of posting a related question.  When you determine the
>> per lens focus adjustment for a lens on one camera, does that number tend to
>> work on another camera, perhaps with a slight offset.
>> 
>> For example if on camera 1 you have
>> lens A  +5
>> lens B  +2
>> lens C  -1
>> 
>> would you use the same numbers? Or if lens A works out to be +4, could you
>> assume that the corrections would be
>> lens A  +4
>> lens B  +1
>> lens C  -2
>> 
>> Or do they end up just being totally random?
> 
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Re: An odd K-5 problem

[John]

On 3/18/2016 8:23 AM, Bill wrote:

On 3/18/2016 9:01 AM, Mark Roberts wrote:

David J Brooks wrote:


On Thu, Mar 17, 2016 at 11:36 PM, Bill 
wrote:

Gentlemen, remember that with the K5, the AF accuracy can be thrown off
tremendously by the colour of the subject.


Sort of the Donald Trump of cameras then


Mark!
;-)




Can we please leave that person out of it?



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Re: An odd K-5 problem

[Mark Roberts]

David J Brooks wrote:

>On Thu, Mar 17, 2016 at 11:36 PM, Bill  wrote:
>> Gentlemen, remember that with the K5, the AF accuracy can be thrown off
>> tremendously by the colour of the subject.
>
>Sort of the Donald Trump of cameras then

Mark!
;-)
 
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