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05-29-2014, 08:12 AM   #1
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Focus peaking with manual lens

Hi,

I have a K5 and i like to use old lens. They are cheap and have great quality.

I just bought a Tokina RMC 300mm 1:5,6 after reading the good reviews it has. I've tried it with my camera and I was not happy with the results. Was I doing something wrong or I had a bad lens?

I thought about testing the reliability of the focus peaking and took some photos.

All photos were taken in a tripod and with the camera shake off and using the center focus point.

So, the problem is all the photos taken with the focus peaking green light on (focus achieved) and the beeping signal of confirmation are a little bit off (photos A1, A2, A3 and A4), and when I take the photo with no confirmation at all, relying only in what I see, there seems to be a great improvement (photos B1, B2, B3 and B4).

So, my questions are:

1 - What is wrong here, the lens or the camera?

2 - Can this be corrected with the lens correction function in the K5?

3 - If not, is there any way to turn off focus peaking (the green light and the beeping)?

Here are the samples:

A1


A2


B1


B2


C1


C2


D1 Here, it looks like it is focusing in the second battery cell and not in the third


D2


Thank you in advance

05-29-2014, 08:28 AM   #2
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The K5 does not have focus peaking...
05-29-2014, 08:37 AM - 1 Like   #3
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This beep and focus confirmation are all depends on how your focusing system is calibrated with each particular lens. You are fortunate to have K5 which as far as I know has ability to store more than 1 AF correction setting - my K10D does that only globally for all the lenses I have. Basically many Pentax cameras are required to have focusing calibrated - especially true for older K10D/K20D and similar cameras as well as when you are using some off-branded lenses. AF confirmation is easy to calibrate - just check the forums for further info ( as I don't own a K5 so cannot help here ) but the good news is that your focusing screen seems to be well calibrated - which manifests itself in the fact that you achieve a good focus when relying on what you see.

And so called 'focusing peeking ' is not that beep or hexagon in the viewfinder - but way that camera in some cases ( like K-01 ) marks the area of greatest contrast ( an presumably sharpness ) in your live view. Again I don't have the K5 so cannot confirm whether you have it there or not - I assume it's not there if the camera cannot do videos - if it can then I assume the focus peeking would be reasonable ).
,,,
' >' manntax
05-29-2014, 08:38 AM   #4
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Thank you blackcloudbrew,

then I'm mistaken and making some confusion about the name of this functionality!

What I mean is, when the focus is achieved, there is a green light that goes on and the camera beeps (that is what I was wrongly calling focus peaking).

---------- Post added 05-29-14 at 04:43 PM ----------

Thank you manntax,

I will try to calibrate the auto focus confirmation has you suggest.

05-29-2014, 09:49 AM - 1 Like   #5
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looks like you have a little of front-focus FF on the k-5 AF system. Perhaps you can try using the AF fine adjustment feature (C.26) to correct it, by turning the option ON and then apply somewhere around -5 or so. You may have to try a few times using the 'battery' testing method to get it right.

By the way, you can turn off the beep sound by changing the camera configuration setting (the one with wrench symbol).
05-29-2014, 09:52 AM - 1 Like   #6
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QuoteOriginally posted by Sevandija Quote
then I'm mistaken and making some confusion about the name of this functionality!

What I mean is, when the focus is achieved, there is a green light that goes on and the camera beeps (that is what I was wrongly calling focus peaking).
With a non-AF lens, the AF system provides what is called "focus confirmation". Focus confirmation has all the strengths and also all the weaknesses of the AF system. I find it useful, but not adequate for fine focus with faster lenses.

Focus peaking, on the other hand, is something you would see in live view and is very cool.

As for lens correction with non-AF lenses...you cannot assign a custom correction factor for your Tokina only. It is incapable of providing identity information back to the camera. Any adjustment you might make using C-26 will apply to all lenses. This is probably not a good thing. If find at some point that you are having trouble with manual focus, I would suggest a quality aftermarket focus screen.


Steve

Last edited by stevebrot; 05-29-2014 at 10:07 AM.
05-29-2014, 02:35 PM - 1 Like   #7
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QuoteOriginally posted by stevebrot Quote

As for lens correction with non-AF lenses...you cannot assign a custom correction factor for your Tokina only. It is incapable of providing identity information back to the camera. Any adjustment you might make using C-26 will apply to all lenses. This is probably not a good thing. If find at some point that you are having trouble with manual focus, I would suggest a quality aftermarket focus screen.


Steve
I am not sure if that is true.. with AF lens, the camera will likely identify them and adjust accordingly, therefore, the 'general' setting does not affect the other AF lenses. However, just to be safe that it will not affect the other lenses, the best way to do it is to assign a 'USER' setting with C.26 adjusted just for manual focus lenses.
05-29-2014, 04:19 PM - 1 Like   #8
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Can't really solve your problem, but can reaffirm that you are not the only one. On my K-r (haven't tried on other bodies) my MF lenses produce the same results. If I focus my M50 or A28 lenses and wait for the green hexagon confirmation, I know my focus will be off. I just give it a little turn back and it is spot on. Never bothered to ask why, just dealt with it. Hopefully we both get an answer!

05-29-2014, 06:15 PM - 2 Likes   #9
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QuoteOriginally posted by aleonx3 Quote
I am not sure if that is true.. with AF lens, the camera will likely identify them and adjust accordingly, therefore, the 'general' setting does not affect the other AF lenses.
Hard to say. The manual for my K-3 indicates that "general" affects all lenses, which I took to mean that you are adjusting the universal baseline. What you say makes good sense, though since it is well within the capacity of the camera do do what you describe. At the very least the "general" adjustment will effect all non-AF lenses used by the camera which is not a good thing either. FWIW, I have not been following the focus tuning discussions all too closely since I use mostly manual focus lenses with the optical system or focus peaking and generally do my best to ignore the focus confirmation. In fact, it has only been in the last couple of weeks that I have actually owned a system with user-tunable AF. My K10D lacks the feature* and fortunately enough, none of my AF lenses I show consistent front/back focus.

As for having a User setting just for manual focus lenses, I am not sure that would work either. Front/back focus bias in the AF system with manual focus lenses is as individual as with AF glass. One size does not fit all.


Steve

* To head off the chorus of "...but what about...!", I am aware of the debug hacks to impose an adjustment, but don't consider those to be a stable or advisable solution.

---------- Post added 05-29-14 at 06:24 PM ----------

QuoteOriginally posted by calculator01 Quote
Can't really solve your problem, but can reaffirm that you are not the only one. On my K-r (haven't tried on other bodies) my MF lenses produce the same results. If I focus my M50 or A28 lenses and wait for the green hexagon confirmation, I know my focus will be off. I just give it a little turn back and it is spot on. Never bothered to ask why, just dealt with it. Hopefully we both get an answer!
Your experience with the K-r is pretty much what you would expect. The AF system has a functional precision (i.e. consistently getting the same focus point) equivalent to an aperture of f/5.6.* This is the case regardless of the maximum aperture of the lens mounted. Most of the time this is quite adequate, but the slop in the system starts to show when you are doing critical focus with fast manual focus lenses.


Steve

* This has been improved on the K-3 and to a lesser extent on the K-5IIs (and K-5II as well, I think) by the addition of one or more f/2.8-capable AF points at center.

Last edited by stevebrot; 05-29-2014 at 06:27 PM.
05-29-2014, 07:10 PM - 1 Like   #10
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QuoteOriginally posted by stevebrot Quote
Hard to say. The manual for my K-3 indicates that "general" affects all lenses, which I took to mean that you are adjusting the universal baseline. What you say makes good sense, though since it is well within the capacity of the camera do do what you describe. At the very least the "general" adjustment will effect all non-AF lenses used by the camera which is not a good thing either. FWIW, I have not been following the focus tuning discussions all too closely since I use mostly manual focus lenses with the optical system or focus peaking and generally do my best to ignore the focus confirmation. In fact, it has only been in the last couple of weeks that I have actually owned a system with user-tunable AF. My K10D lacks the feature* and fortunately enough, none of my AF lenses I show consistent front/back focus.

As for having a User setting just for manual focus lenses, I am not sure that would work either. Front/back focus bias in the AF system with manual focus lenses is as individual as with AF glass. One size does not fit all.

.
I am no expert in this (and YMMV of course) but I know it works for me on both my K-5 and K-5IIs. And I think the tricky part may be the third party (Tamron, Sigma) AF lenses which I don't know under which setting it should be. The other point is why would there be a 'general' setting as well as "per lens" setting in AF Fine adjustment. Anyway, all my A/K/M and Chinon/Topcon lenses works just fine on both my k-5/IIs cameras. I don't have good eyesight and I rely on the camera AF mechanism to help me nail the focus.
05-29-2014, 09:09 PM - 1 Like   #11
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QuoteOriginally posted by Sevandija Quote

What I mean is, when the focus is achieved, there is a green light that goes on and the camera beeps
It just means AF thinks it's in focus, Sevandija!

The experienced Macro guys don't trust it, for example.

Without Live View focus peaking, you might find replacing the stock focus screen an advantage.
05-31-2014, 12:35 PM   #12
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Thank you all for your answers. I'll see what I can do with some use and habit. If it continues to be a problem, maybe I adopt the focus screen solution.
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