done this a dozen times, and i get the same results on the K3.
from -10 to +10 the images look nearly identical.
Yet doing this on the K5IIs the images are definitely different for each shot.
Could the shake reduction on the K3 be damaged ? since it does move the sensor, could it have gotten stuck or stopped responding ?
I am assuming the AF fine tune adjusts the position of the sensor and thus might be affected my the SR.
Yes, I know this is not a test chart, but the same results happen with one.

Shots were on a tripod, out of any wind, SR off, critical focus in live view with focus peaking, then shot out of live view with a 2 sec timer
Lens is a Pentax DA* 300mm F4, shot at F4.5 as F4 is soft on everything. It's 7 years old, the camera about 5 I think. and both have had a lot of use
and bumped but never dropped.

There seems to be slight haze on the front element, but very slight. Have tried this with the built in SDM motor as well as the camera's af motor


Shots are as labeled minus 10 , zero, and plus 10.
all of the images are just as identical to my eyes.

I suspect the lens being the issue as using the sdm, it will not lock on a target with a confermation dot when focusing in from a distance,
but always locks when focusing the opposite direction.

Puzzled


Thanks for any help.

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Last edited by dewolf; 12-31-2021 at 11:54 AM. Reason: addition

[BigMackCam]

done this a dozen times, and i get the same results on the K3.
from -10 to +10 the images look nearly identical.
Yet doing this on the K5IIs the images are definitely different for each shot.
Could the shake reduction on the K3 be damaged ? since it does move the sensor, could it have gotten stuck or stopped responding ?
I am assuming the AF fine tune adjusts the position of the sensor and thus might be affected my the SR.
Yes, I know this is not a test chart, but the same results happen with one.

Shots were on a tripod, out of any wind, SR off, critical focus in live view with focus peaking, then shot out of live view with a 2 sec timer

Shots are as labeled minus 10 , zero, and plus 10.
all of the images are just as identical to my eyes.

Thanks for any help.

AF fine tuning only affects phase detect auto-focus (PDAF), the method used when viewing images through the viewfinder, and it does so by adding or subtracting an offset to the measurements from the PDAF sensors, changing the point at which the PDAF algorithm thinks the image is correctly focused. It doesn't move the sensor. In Live View, sensor-based contrast detect auto-focusing is used. This will always be accurate - or, at least, as accurate as possible using the camera's CDAF algorithms and a suitable target - since the focusing is determined directly on the imaging sensor where the image is projected. AF fine tuning has no effect on contrast detect focusing, which is why you're seeing identical results in each shot.

Hope this helps

[stevebrot]

I am assuming the AF fine tune adjusts the position of the sensor and thus might be affected my the SR.

That is not how it works.

critical focus in live view with focus peaking

AF fine adjust does not work in life view and switching out while still set to manual focus will leave everything as it was when you did the critical focus.


Steve

[c.a.m]

Shots were on a tripod, out of any wind, SR off, critical focus in live view with focus peaking, then shot out of live view with a 2 sec timer

Seems that you have several important elements covered -- tripod, SR off, good lighting (I presume).

I'm confused on your process. Here's my understanding: you focused while in Live View, then exited Live View to take shots in 'viewfinder mode', changing the AF Fine Adjust setting between shots and using the 2-second timer. Did you re-focus the lens before each shot? I'm not understanding the purpose of the "critical focus in live view."

I am assuming the AF fine tune adjusts the position of the sensor and thus might be affected my the SR.

Actually, the camera's AF algorithm uses the AF Fine Adjust setting as a virtual 'offset' in the determination of the alignment of two phase channels. I don't believe that the AF process involves any physical movement of the imaging sensor or AF sensor.

Lens is a Pentax DA* 300mm F4, shot at F4.5 as F4 is soft on everything. It's 7 years old, the camera about 5 I think. and both have had a lot of useand bumped but never dropped.

I'm wondering whether your lens has experienced some physical damage or wear. My DA* 300/4 is fairly sharp at f/4, certainly not soft. However, it might depend on one's definition of 'sharp' and 'soft.'


- Craig

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Last edited by c.a.m; 12-31-2021 at 12:42 PM.

[UncleVanya]

Yet doing this on the K5IIs the images are definitely different for each shot.
Could the shake reduction on the K3 be damaged ? since it does move the sensor, could it have gotten stuck or stopped responding ?
I am assuming the AF fine tune adjusts the position of the sensor and thus might be affected my the SR.
Yes, I know this is not a test chart, but the same results happen with one.

Shots were on a tripod, out of any wind, SR off, critical focus in live view with focus peaking, then shot out of live view with a 2 sec timer
Lens is a Pentax DA* 300mm F4, shot at F4.5 as F4 is soft on everything. It's 7 years old, the camera about 5 I think. and both have had a lot of use
and bumped but never dropped.

There seems to be slight haze on the front element, but very slight. Have tried this with the built in SDM motor as well as the camera's af motor


Shots are as labeled minus 10 , zero, and plus 10.
all of the images are just as identical to my eyes.

I suspect the lens being the issue as using the sdm, it will not lock on a target with a confermation dot when focusing in from a distance,
but always locks when focusing the opposite direction.

Puzzled


Thanks for any help.

First I assume you know how to do an sdm conversion based on the info above. Second failing sdm often fails to lock focus before it gives up focusing altogether so conversion is the correct step.

Next, as others said Liveview doesn’t use af fine tuning. So no surprise that this gives the same results over and over. Additionally the sensor shake reduction isn’t involved in af fine adjustment. Dslr cameras have a PDAF focus system that operates in viewfinder mode - this is what you adjust with fine focusing. It isn’t a physical change but an electronic one.

However this begs the question- how did this process differ when you used the k5iis? Perhaps you misremembered the process or misrecalled the results? The two cameras both work the same way.

As for the lens haze - this may impact accuracy focus potentially and may reduce sharpness even when correctly focused - the degree is unknown. I suggest a CLA of the lens by a competent technician. Or perhaps a trip to Precision and an sdm replacement along with element haze cleaning. Personally I don’t mind screwdrive enough to pay for sdm replacement.

First I assume you know how to do an sdm conversion based on the info above. Second failing sdm often fails to lock focus before it gives up focusing altogether so conversion is the correct step.

Next, as others said Liveview doesn’t use af fine tuning. So no surprise that this gives the same results over and over. Additionally the sensor shake reduction isn’t involved in af fine adjustment. Dslr cameras have a PDAF focus system that operates in viewfinder mode - this is what you adjust with fine focusing. It isn’t a physical change but an electronic one.

However this begs the question- how did this process differ when you used the k5iis? Perhaps you misremembered the process or misrecalled the results? The two cameras both work the same way.

As for the lens haze - this may impact accuracy focus potentially and may reduce sharpness even when correctly focused - the degree is unknown. I suggest a CLA of the lens by a competent technician. Or perhaps a trip to Precision and an sdm replacement along with element haze cleaning. Personally I don’t mind screwdrive enough to pay for sdm replacement.

Well I wasn't actually taking the photographs in live view. I was using live view to be able to tell if I was properly manually focused on the target because there's no way for me to tell if I'm perfectly critically focused using just the viewfinder and so the directions I had read said to use live view to get your critical focus and then exit live view and begin taking your shots. So if that is incorrect then I'm at a loss to know how I'm supposed to focus and get a critical focus through the viewfinder because that is very very tiny and 90% of what you all have said is so far over my head. I would have to hire an astronaut to get a grasp:-) lol. Sorry but I am not that technical. I was just following some basic they were for Dot tune or some other process. So yeah, how do I take and get a critical focus without using live view and magnifying that to see if I'm perfectly focused? None of the shots were taken in live view they were taken through the viewfinder like any other image I would take and then I would simply adjust the AF fine tune one step up each time on the k5ii. That seems to make quite a noticeable difference on the k3 it makes no difference whatsoever.
all I am attempting to do is tune the lens better for the camera. lens in manual focus mode as instructed by dot tune

[UncleVanya]

Well I wasn't actually taking the photographs in live view. I was using live view to be able to tell if I was properly manually focused on the target because there's no way for me to tell if I'm perfectly critically focused using just the viewfinder and so the directions I had read said to use live view to get your critical focus and then exit live view and begin taking your shots. So if that is incorrect then I'm at a loss to know how I'm supposed to focus and get a critical focus through the viewfinder because that is very very tiny and 90% of what you all have said is so far over my head. I would have to hire an astronaut to get a grasp:-) lol. Sorry but I am not that technical. I was just following some basic they were for Dot tune or some other process. So yeah, how do I take and get a critical focus without using live view and magnifying that to see if I'm perfectly focused? None of the shots were taken in live view they were taken through the viewfinder like any other image I would take and then I would simply adjust the AF fine tune one step up each time on the k5ii. That seems to make quite a noticeable difference on the k3 it makes no difference whatsoever.
all I am attempting to do is tune the lens better for the camera. lens in manual focus mode as instructed by dot tune

Ahhh. Ok. Let’s take this slow. If you first focus on live view the dot tune method leaves you in manual focus but you use the viewfinder to see what the resulting focus indicator does.

Essentially this is what I did when using that method:

0) Print a focus target. You need a good target to use for this. See attached - don’t use this image but get a similar target online.

1) Using a tripod and setup 20-50x distance of the focal length of the lens from the target; focus in magnified live view in manual focus mode.

2) Switch to OVF and press focus button while looking in the viewfinder. See if the green hexagon comes on quickly and is solid. Even if it does not, pick a direction - or + and change the offset one step at a time checking each time. I found turning the camera off between adjust helped with “focus confirmation stickiness” but I also found holding a greeting card up to break focus worked as well. Note each success. Note each failure. The successes should be contiguous so if it first was solid at -2 and -3, -4, -5 were all solid but -1 and -6 fluttered and 0 and -7 did not light up the green hexagon then you would pick -2 or -3 to be in the middle of that range. At no time during these tests at this point do you take a photo. You wait until you have picked your value and then try it with a photo.

Essentially you are mapping out all the focus adjustments that give you a focus confirmation then setting it to the middle of that range. To be complete you do this multiple times confirming the range over several trials. Additionally you need adequate light and you need to test at multiple focal lengths (if a zoom) or the main focal lengths that you expect to use. When mapping zooms the best advice is to find something that is in focus across all of the focal or pick the range that is most critical. So if at 18 you had a range of 0, +1, +2, +3, +4 and at 55 it was -3, -2, -1, 0, +1 you would pick 0 or +1 to be in acceptable focus at both ranges.

Once a lens is completely tested and you have assigned a value switch focus back on and focus with the ovf on a few objects. Critically examine them. If they look good you’re done. If not try a different value in the range you derived earlier.

You may also want to test at different distances but that’s not typically necessary.

There are more nuances but this seems to work for me.

Ahhh. Ok. Let’s take this slow. If you first focus on live view the dot tune method leaves you in manual focus but you use the viewfinder to see what the resulting focus indicator does.

Essentially this is what I did when using that method:

0) Print a focus target. You need a good target to use for this. See attached - don’t use this image but get a similar target online.

1) Using a tripod and setup 20-50x distance of the focal length of the lens from the target; focus in magnified live view in manual focus mode.

2) Switch to OVF and press focus button while looking in the viewfinder. See if the green hexagon comes on quickly and is solid. Even if it does not, pick a direction - or + and change the offset one step at a time checking each time. I found turning the camera off between adjust helped with “focus confirmation stickiness” but I also found holding a greeting card up to break focus worked as well. Note each success. Note each failure. The successes should be contiguous so if it first was solid at -2 and -3, -4, -5 were all solid but -1 and -6 fluttered and 0 and -7 did not light up the green hexagon then you would pick -2 or -3 to be in the middle of that range. At no time during these tests at this point do you take a photo. You wait until you have picked your value and then try it with a photo.

Essentially you are mapping out all the focus adjustments that give you a focus confirmation then setting it to the middle of that range. To be complete you do this multiple times confirming the range over several trials. Additionally you need adequate light and you need to test at multiple focal lengths (if a zoom) or the main focal lengths that you expect to use. When mapping zooms the best advice is to find something that is in focus across all of the focal or pick the range that is most critical. So if at 18 you had a range of 0, +1, +2, +3, +4 and at 55 it was -3, -2, -1, 0, +1 you would pick 0 or +1 to be in acceptable focus at both ranges.

Once a lens is completely tested and you have assigned a value switch focus back on and focus with the ovf on a few objects. Critically examine them. If they look good you’re done. If not try a different value in the range you derived earlier.

You may also want to test at different distances but that’s not typically necessary.

There are more nuances but this seems to work for me.

and that is exactly what I had done, leaving me with a setting between +2 and +3 at 25 ft distance. at 50 ft distance it was between +3 and +4. and thus I chose +3 as a middle setting for both.
But, say after all this, I chose to just set the af fine tune to -10, wouldn't you think the focus would be considerably different ? wouldn't you expect it to be less sharp ?
sane as of I had chose +10 ? That's what confuses me, all the images shot at different af fine tune points look the same, whereas I would think they would fade off focus as you go to the extremes.
So, what am I not understanding. lol, look, I know I am a bit thick, have mercy lol.

I have tried other distances as well. up to 100 ft, and I can not make those images sharp as they used to be no matter what.
As posted in another topic, I live in a hot humid climate, It's and old lens, and it has taken perhaps 400,000 images between 3 camera bodies ,and I am afraid haze may be making the long distance shots soft. well making it more apparent anyway as the resolution gets thin. Thus I am trying to get the best out of it before it is no longer usable for the shots I take.
limited SSI income leaves me without a lens for 18 months should I choose to save up for the 150-450. Half that time to replace this one with the same model.
I could use a tad more reach, and certainly faster af, but this lens has always stunned me with it's sharpness..at F4.5 and up it has been a dream.
Many of my friends with 4 thousand dollar rigs are awed by how sharp this lens is. Just trying to baby it along till I can get a replacement.
In 18 months I may not be able to even shoot, hence my attempts (parkinson's) I dearly love photography, almost as much as my dear Golden retriever
perhaps, as much. I live for going out and shooting

Well at least I know I did the Dot Tune correctly. BTW using the card to break the focus is something I had thought of, then realized my hand would do that
even without pressing the shutter, it flickers when I get close to what the camera wants.

Thanks SO much for yer help mates crop from raw attached taken today approx 70 ft distance F 6.3