AF fine-tune conundrum

FA 77mm Limited...

I was finding it rather too soft, even at f2.8. So thought some AF fine-tuning might help.

I took various scenes, at f2.8, and each without multiple distances near the AF point - which might otherwise confuse it. Infinity was a tree on the horizon, above sky, no AF found, then moving the AF point slightly down onto the tree, AF found, etc. Closer subjects were barn walls, essentially flat.

These were the required adjustments, negative values means the focus is pushed further back than the default 0. I did find AF missed a few times, so I discounted those.

Infinity, -8

Middle distance, -6

Close, -2 (-4 for sides of the frame).

Unfortunately the results change, but do follow a predicable change, though I have to choose one value!

Ok, if I only shot close subjects I'd know which to choose, but I don't, with all my lenses I shoot a variety of distances. What would you do?

At times like these, my dislike of mirror-less cameras and their EVFs, lessens. But despite their confidence building bang-on focusing, an EVF isn't an OVF!

And for the critical shooting you can always switch to LV .

left eye said:

FA 77mm Limited...

I was finding it rather too soft, even at f2.8. So thought some AF fine-tuning might help.

I took various scenes, at f2.8, and each without multiple distances near the AF point - which might otherwise confuse it. Infinity was a tree on the horizon, above sky, no AF found, then moving the AF point slightly down onto the tree, AF found, etc. Closer subjects were barn walls, essentially flat.

These were the required adjustments, negative values means the focus is pushed further back than the default 0. I did find AF missed a few times, so I discounted those.

Infinity, -8

Middle distance, -6

Close, -2 (-4 for sides of the frame).

Unfortunately the results change, but do follow a predicable change, though I have to choose one value!

Ok, if I only shot close subjects I'd know which to choose, but I don't, with all my lenses I shoot a variety of distances. What would you do?

At times like these, my dislike of mirror-less cameras and their EVFs, lessens. But despite their confidence building bang-on focusing, an EVF isn't an OVF!

Click to expand...

Yeah, that drove me batty too! And it is even worse with variable light, from natural light vs/incandescent, etc. It's all over the map. With high res sensors like the K1, or even the K3 III with high density that we have now, these things start to matter.

With my FA77 I set up a yard stick at about 8ft leaning at a 45 deg angle in natural light, the average I thought I'd use for portraits wide open, and set fine AF there on the 18" mark and my DOF on the 1/16" marks being equally in focus to out of focus to the front and back of the 18" mark, giving me the best shot at getting the subject in the focal plane. Also have to make sure your camera is level to the target, so you don't induce any parallax into your AF adjustment.

I would shoot multiple series to confirm what I saw, turning the camera off/on and making the lens focus on my hand, then back to the 18" mark, so any "slop" or creep in the system was averaged out to make sure I had a consistent bang-on focus to the target. I think some of the inconsistencies could be related to maybe some slack in the older screw drive type lenses.

My FA*85 was even trickier to get fine AF set properly because of F 1.4, so yeah, I feel your pain.

--
"You maniacs! You almost blew DPR up! Damn you!"
EricV

TBLF said:

left eye said:

FA 77mm Limited...

I was finding it rather too soft, even at f2.8. So thought some AF fine-tuning might help.

I took various scenes, at f2.8, and each without multiple distances near the AF point - which might otherwise confuse it. Infinity was a tree on the horizon, above sky, no AF found, then moving the AF point slightly down onto the tree, AF found, etc. Closer subjects were barn walls, essentially flat.

These were the required adjustments, negative values means the focus is pushed further back than the default 0. I did find AF missed a few times, so I discounted those.

Infinity, -8

Middle distance, -6

Close, -2 (-4 for sides of the frame).

Unfortunately the results change, but do follow a predicable change, though I have to choose one value!

Ok, if I only shot close subjects I'd know which to choose, but I don't, with all my lenses I shoot a variety of distances. What would you do?

At times like these, my dislike of mirror-less cameras and their EVFs, lessens. But despite their confidence building bang-on focusing, an EVF isn't an OVF!

Click to expand...

Yeah, that drove me batty too! And it is even worse with variable light, from natural light vs/incandescent, etc. It's all over the map. With high res sensors like the K1, or even the K3 III with high density that we have now, these things start to matter.

With my FA77 I set up a yard stick at about 8ft leaning at a 45 deg angle in natural light, the average I thought I'd use for portraits wide open, and set fine AF there on the 18" mark and my DOF on the 1/16" marks being equally in focus to out of focus to the front and back of the 18" mark, giving me the best shot at getting the subject in the focal plane. Also have to make sure your camera is level to the target, so you don't induce any parallax into your AF adjustment.

I would shoot multiple series to confirm what I saw, turning the camera off/on and making the lens focus on my hand, then back to the 18" mark, so any "slop" or creep in the system was averaged out to make sure I had a consistent bang-on focus to the target. I think some of the inconsistencies could be related to maybe some slack in the older screw drive type lenses.

Click to expand...

...yes did all that, the refocusing etc, and double checking, taking multiple shots with same AF adjustment etc, and arrived at -

Infinity, -8

Middle distance, -6

Close, -2 (-4 for sides of the frame).

your 8ft stick would equate to my close distance. BUT that's not the whole story, AF disparity changes with focus distance. That's the tricky bit.

And BTW I've found slanted targets to give erroneous results, as the AF point/box which you think is where you think it is, the camera often has other ideas, and find focus just before or after it. Slanted targets just don't work that well despite what you read on the net about printed rulers on tables.

Main issue is that the adjustment changes radically due to distance.

TBLF said:

My FA*85 was even trickier to get fine AF set properly because of F 1.4, so yeah, I feel your pain.

Click to expand...

flektogon said:

And for the critical shooting you can always switch to LV .

Click to expand...

That's a horrible experience, especially outdoors, and it why I want to use an OVF.

If I need bang-on focus yes I can use my Fujifilm GFX,

...but I want to use an OVF.

left eye said:

TBLF said:

left eye said:

FA 77mm Limited...

I was finding it rather too soft, even at f2.8. So thought some AF fine-tuning might help.

I took various scenes, at f2.8, and each without multiple distances near the AF point - which might otherwise confuse it. Infinity was a tree on the horizon, above sky, no AF found, then moving the AF point slightly down onto the tree, AF found, etc. Closer subjects were barn walls, essentially flat.

These were the required adjustments, negative values means the focus is pushed further back than the default 0. I did find AF missed a few times, so I discounted those.

Infinity, -8

Middle distance, -6

Close, -2 (-4 for sides of the frame).

Unfortunately the results change, but do follow a predicable change, though I have to choose one value!

Ok, if I only shot close subjects I'd know which to choose, but I don't, with all my lenses I shoot a variety of distances. What would you do?

At times like these, my dislike of mirror-less cameras and their EVFs, lessens. But despite their confidence building bang-on focusing, an EVF isn't an OVF!

Click to expand...

Yeah, that drove me batty too! And it is even worse with variable light, from natural light vs/incandescent, etc. It's all over the map. With high res sensors like the K1, or even the K3 III with high density that we have now, these things start to matter.

With my FA77 I set up a yard stick at about 8ft leaning at a 45 deg angle in natural light, the average I thought I'd use for portraits wide open, and set fine AF there on the 18" mark and my DOF on the 1/16" marks being equally in focus to out of focus to the front and back of the 18" mark, giving me the best shot at getting the subject in the focal plane. Also have to make sure your camera is level to the target, so you don't induce any parallax into your AF adjustment.

I would shoot multiple series to confirm what I saw, turning the camera off/on and making the lens focus on my hand, then back to the 18" mark, so any "slop" or creep in the system was averaged out to make sure I had a consistent bang-on focus to the target. I think some of the inconsistencies could be related to maybe some slack in the older screw drive type lenses.

Click to expand...

...yes did all that, the refocusing etc, and double checking, taking multiple shots with same AF adjustment etc, and arrived at -

Infinity, -8

Middle distance, -6

Close, -2 (-4 for sides of the frame).

your 8ft stick would equate to my close distance. BUT that's not the whole story, AF disparity changes with focus distance. That's the tricky bit.

And BTW I've found slanted targets to give erroneous results, as the AF point/box which you think is where you think it is, the camera often has other ideas, and find focus just before or after it. Slanted targets just don't work that well despite what you read on the net about printed rulers on tables.

Main issue is that the adjustment changes radically due to distance.

left eye said:

My FA*85 was even trickier to get fine AF set properly because of F 1.4, so yeah, I feel your pain.

Click to expand...

Click to expand...

Ricoh/Pentax recommends calibrating at 30 - 40x the focal length, so between 2.3m and 3.2m for the FA77.

https://www.ricoh-imaging.co.jp/english/explore/technic/001/

If focused at distance you do benefit from a greater DoF.

Doug

left eye said:

TBLF said:

left eye said:

FA 77mm Limited...

I was finding it rather too soft, even at f2.8. So thought some AF fine-tuning might help.

I took various scenes, at f2.8, and each without multiple distances near the AF point - which might otherwise confuse it. Infinity was a tree on the horizon, above sky, no AF found, then moving the AF point slightly down onto the tree, AF found, etc. Closer subjects were barn walls, essentially flat.

These were the required adjustments, negative values means the focus is pushed further back than the default 0. I did find AF missed a few times, so I discounted those.

Infinity, -8

Middle distance, -6

Close, -2 (-4 for sides of the frame).

Unfortunately the results change, but do follow a predicable change, though I have to choose one value!

Ok, if I only shot close subjects I'd know which to choose, but I don't, with all my lenses I shoot a variety of distances. What would you do?

At times like these, my dislike of mirror-less cameras and their EVFs, lessens. But despite their confidence building bang-on focusing, an EVF isn't an OVF!

Click to expand...

Yeah, that drove me batty too! And it is even worse with variable light, from natural light vs/incandescent, etc. It's all over the map. With high res sensors like the K1, or even the K3 III with high density that we have now, these things start to matter.

With my FA77 I set up a yard stick at about 8ft leaning at a 45 deg angle in natural light, the average I thought I'd use for portraits wide open, and set fine AF there on the 18" mark and my DOF on the 1/16" marks being equally in focus to out of focus to the front and back of the 18" mark, giving me the best shot at getting the subject in the focal plane. Also have to make sure your camera is level to the target, so you don't induce any parallax into your AF adjustment.

I would shoot multiple series to confirm what I saw, turning the camera off/on and making the lens focus on my hand, then back to the 18" mark, so any "slop" or creep in the system was averaged out to make sure I had a consistent bang-on focus to the target. I think some of the inconsistencies could be related to maybe some slack in the older screw drive type lenses.

Click to expand...

...yes did all that, the refocusing etc, and double checking, taking multiple shots with same AF adjustment etc, and arrived at -

Infinity, -8

Middle distance, -6

Close, -2 (-4 for sides of the frame).

your 8ft stick would equate to my close distance. BUT that's not the whole story, AF disparity changes with focus distance. That's the tricky bit.

And BTW I've found slanted targets to give erroneous results, as the AF point/box which you think is where you think it is, the camera often has other ideas, and find focus just before or after it. Slanted targets just don't work that well despite what you read on the net about printed rulers on tables.

Main issue is that the adjustment changes radically due to distance.

left eye said:

My FA*85 was even trickier to get fine AF set properly because of F 1.4, so yeah, I feel your pain.

Click to expand...

Click to expand...

I completely agree and had a longer reply which got into the weeds, so I deleted most of it and left it with what you got, because I didn't want to ruffle any feathers.

Bottom line - I totally 100% agree with you and experienced the same. I just worked around it by using the FA77 in this case, at close range mostly for portraits, I didn't use it for landscapes because it's not great for CA in bright light anyways, and if I did use it at longer distances, the lens would be stopped down a lot more and AF accuracy didn't matter as much.

My DFA 150-450mm had to be Fine AF'd for long distances, and I did it in the field in real use conditions, stopping and zooming in with a pocket loop looking at fine AF to confirm the changes I made for BIF.

This frustrated me no end. I don't bring it up if possible, on this forum because I find it tacky and crass, but since you kinda pushed me a little on this with your reply, I'm going to suffice it to say, just look at my gear profile below my post to see what my solution was. I haven't had to do any Fine A/F adjustments ever since and hope I never have to again. I still have plenty of Pentax gear, I use for other casual stuff and manual focus with my old M42 lens collection via adapters, but when I want accurate fast AF and CAF, I found other solutions. Still love my old Pentax glass though.

flektogon said:

And for the critical shooting you can always switch to LV .

Click to expand...

Pentax LV AF is perfectly capable to miss completely. That algorithm is very strange and does not do iterations in steps, but in many cases it simply sends the lens to wrong position while claiming, that AF is finished. And with fast F1.4-F1.8 lenses, this is one order of magnitude worse thanks to shallow depth of field.
I would really like to see some AF method selector to select if I want to use standard method which mostly works with lenses like 18-135WR, 18-55WR etc. And then slow but stepping version, that might finally be capable to achieve reliable focus lock on 70-200/2.8, 50/1.4 etc. Not to mention various 3rd party lenses where it either fails completely or is very moody and unreliable.

Btw K-5 had that nice feature, that it enlarged the selected area while focusing. No other Pentax cameras introduced later does that. And that is sad. Because I was at least able to see how misfocused it is in detail and do something, while on K3 and more modern ones, you only see the full view and then enlarge manually to check.

--
http://pentax.xf.cz/ - Personal page about my favourite system.

xmeda said:

flektogon said:

And for the critical shooting you can always switch to LV .

Click to expand...

Pentax LV AF is perfectly capable to miss completely. That algorithm is very strange and does not do iterations in steps, but in many cases it simply sends the lens to wrong position while claiming, that AF is finished. And with fast F1.4-F1.8 lenses, this is one order of magnitude worse thanks to shallow depth of field.
I would really like to see some AF method selector to select if I want to use standard method which mostly works with lenses like 18-135WR, 18-55WR etc. And then slow but stepping version, that might finally be capable to achieve reliable focus lock on 70-200/2.8, 50/1.4 etc. Not to mention various 3rd party lenses where it either fails completely or is very moody and unreliable.

Btw K-5 had that nice feature, that it enlarged the selected area while focusing. No other Pentax cameras introduced later does that.

Click to expand...

Enlarge/magnify the screen in LV while focussing? My KP does it. My K-3iii does it.

Or are you talking about something else?

Doug

xmeda said:

And that is sad. Because I was at least able to see how misfocused it is in detail and do something, while on K3 and more modern ones, you only see the full view and then enlarge manually to check.

Click to expand...

DougOB said:

left eye said:

TBLF said:

left eye said:

FA 77mm Limited...

I was finding it rather too soft, even at f2.8. So thought some AF fine-tuning might help.

I took various scenes, at f2.8, and each without multiple distances near the AF point - which might otherwise confuse it. Infinity was a tree on the horizon, above sky, no AF found, then moving the AF point slightly down onto the tree, AF found, etc. Closer subjects were barn walls, essentially flat.

These were the required adjustments, negative values means the focus is pushed further back than the default 0. I did find AF missed a few times, so I discounted those.

Infinity, -8

Middle distance, -6

Close, -2 (-4 for sides of the frame).

Unfortunately the results change, but do follow a predicable change, though I have to choose one value!

Ok, if I only shot close subjects I'd know which to choose, but I don't, with all my lenses I shoot a variety of distances. What would you do?

At times like these, my dislike of mirror-less cameras and their EVFs, lessens. But despite their confidence building bang-on focusing, an EVF isn't an OVF!

Click to expand...

Yeah, that drove me batty too! And it is even worse with variable light, from natural light vs/incandescent, etc. It's all over the map. With high res sensors like the K1, or even the K3 III with high density that we have now, these things start to matter.

With my FA77 I set up a yard stick at about 8ft leaning at a 45 deg angle in natural light, the average I thought I'd use for portraits wide open, and set fine AF there on the 18" mark and my DOF on the 1/16" marks being equally in focus to out of focus to the front and back of the 18" mark, giving me the best shot at getting the subject in the focal plane. Also have to make sure your camera is level to the target, so you don't induce any parallax into your AF adjustment.

I would shoot multiple series to confirm what I saw, turning the camera off/on and making the lens focus on my hand, then back to the 18" mark, so any "slop" or creep in the system was averaged out to make sure I had a consistent bang-on focus to the target. I think some of the inconsistencies could be related to maybe some slack in the older screw drive type lenses.

Click to expand...

...yes did all that, the refocusing etc, and double checking, taking multiple shots with same AF adjustment etc, and arrived at -

Infinity, -8

Middle distance, -6

Close, -2 (-4 for sides of the frame).

your 8ft stick would equate to my close distance. BUT that's not the whole story, AF disparity changes with focus distance. That's the tricky bit.

And BTW I've found slanted targets to give erroneous results, as the AF point/box which you think is where you think it is, the camera often has other ideas, and find focus just before or after it. Slanted targets just don't work that well despite what you read on the net about printed rulers on tables.

Main issue is that the adjustment changes radically due to distance.

DougOB said:

My FA*85 was even trickier to get fine AF set properly because of F 1.4, so yeah, I feel your pain.

Click to expand...

Click to expand...

Ricoh/Pentax recommends calibrating at 30 - 40x the focal length, so between 2.3m and 3.2m for the FA77.

Click to expand...

Ok I did that, but calibration is then out for longer distances.

DougOB said:

https://www.ricoh-imaging.co.jp/english/explore/technic/001/

If focused at distance you do benefit from a greater DoF.

Click to expand...

so the calibration offset should be less, as DOF helps, but calibration required at distance is more, as per my original post and offset values.

The recommendations unfortunately don’t help.

DougOB said:

Doug

Click to expand...

xmeda said:

flektogon said:

And for the critical shooting you can always switch to LV .

Click to expand...

Pentax LV AF is perfectly capable to miss completely. That algorithm is very strange and does not do iterations in steps, but in many cases it simply sends the lens to wrong position while claiming, that AF is finished. And with fast F1.4-F1.8 lenses, this is one order of magnitude worse thanks to shallow depth of field.
I would really like to see some AF method selector to select if I want to use standard method which mostly works with lenses like 18-135WR, 18-55WR etc. And then slow but stepping version, that might finally be capable to achieve reliable focus lock on 70-200/2.8, 50/1.4 etc. Not to mention various 3rd party lenses where it either fails completely or is very moody and unreliable.

Btw K-5 had that nice feature, that it enlarged the selected area while focusing. No other Pentax cameras introduced later does that. And that is sad. Because I was at least able to see how misfocused it is in detail and do something, while on K3 and more modern ones, you only see the full view and then enlarge manually to check.

Click to expand...

Well, what I found is that the LV AF performance depends on the used lens. A lens with a short "lift", like the DA 21/3.2 has absolutely no problems with focusing. The camera always turns it into infinity, and only then actually it starts the focusing process. And it nails the focus perfectly, at least the K-01 and the mentioned lens. Something else is the DA 35/2.8 Macro Ltd for example. The camera (I tested it right the way) wants again to turn it towards the infinity, but often it fails and moves this lens in the opposite direction, and then (but not always!) rotates it towards the infinity. Once the lens is at the infinity, then the correct focus is achieved pretty quickly and always precisely. That's my experience with LV AF.

--
Regards,
Peter

left eye said:

FA 77mm Limited...

I was finding it rather too soft, even at f2.8. So thought some AF fine-tuning might help.

I took various scenes, at f2.8, and each without multiple distances near the AF point - which might otherwise confuse it. Infinity was a tree on the horizon, above sky, no AF found, then moving the AF point slightly down onto the tree, AF found, etc. Closer subjects were barn walls, essentially flat.

These were the required adjustments, negative values means the focus is pushed further back than the default 0. I did find AF missed a few times, so I discounted those.

Infinity, -8

Middle distance, -6

Close, -2 (-4 for sides of the frame).

Unfortunately the results change, but do follow a predicable change, though I have to choose one value!

Ok, if I only shot close subjects I'd know which to choose, but I don't, with all my lenses I shoot a variety of distances. What would you do?

Click to expand...

Here is one of the problems

Some manufactures have a profile that is built around how this focus shift happens throughout the range of the lenses uses but this feature is not always found in all cameras but the more expansive bodies and lenses.

some lens manufactures allow the user to create this profile and upload it to the lens

while some camera manufactures allow 2 spectate values to be stored the camera.

left eye said:

At times like these, my dislike of mirror-less cameras and their EVFs, lessens. But despite their confidence building bang-on focusing, an EVF isn't an OVF!

Click to expand...

@left eye

What is the most common f-stop you use? For myself I do not use the widest aperture. Normally I would stop down 1 or 2 stops.

And so I decided to adjust the AF using those settings, mainly for 2 reasons.

1. Priority reason - some of my lenses have quite bad focus shift when stopped down. I don't want to be adjusting the AF for the incorrect f-stop.

2. The greater depth of field helps to negate some of the AF shifts when shooting at different distances and zoom settings.

3. Off topic but, I had 2 lenses, a 1st gen DFA100mm Macro and a new 16-85mm zoom, that misfocused badly in LV. I sold the macro lens cheaply and returned the 16-85mm for an exchange. So it may not be true that the LV contrast detect AF is the most accurate. It varies with individual lenses. But the LV AF error was consistent. It missed focus by exactly the same amount every time.

Seahbc said:

@left eye

What is the most common f-stop you use? For myself I do not use the widest aperture. Normally I would stop down 1 or 2 stops.

Click to expand...

for the f1.8 or f1.7 lenses I sometimes use f2 if I want maximum background defocus, otherwise I go for f2.8.

For more in focus I choose f5.6 or f6.4 and sometimes f8.

So I don't have no common f-stop, I use a range as required.

Seahbc said:

And so I decided to adjust the AF using those settings, mainly for 2 reasons.

1. Priority reason - some of my lenses have quite bad focus shift when stopped down. I don't want to be adjusting the AF for the incorrect f-stop.

Click to expand...

I've just tried my four full-frame Pentax lenses, their AF results all jump around at f2.8. I haven't even explored other f-stops. If f2.8 is jumping around, I'm not going to retest at f5.6 and f8 as well. For sure f8 will be more forgiving, but generally I wouldn't calibrate at f8.

Seahbc said:

2. The greater depth of field helps to negate some of the AF shifts when shooting at different distances and zoom settings.

Click to expand...

Not enough in my case, but does help. These results are far worse than I was expecting of a relatively modern dSLR. Makes me realise what a game changer all my mirrorless gear is, but I don't like EVFs.

Seahbc said:

3. Off topic but, I had 2 lenses, a 1st gen DFA100mm Macro and a new 16-85mm zoom, that misfocused badly in LV. I sold the macro lens cheaply and returned the 16-85mm for an exchange. So it may not be true that the LV contrast detect AF is the most accurate. It varies with individual lenses. But the LV AF error was consistent. It missed focus by exactly the same amount every time.

Click to expand...

- that doesn't build my confidence!

flektogon said:

Well, what I found is that the LV AF performance depends on the used lens. A lens with a short "lift", like the DA 21/3.2 has absolutely no problems with focusing. The camera always turns it into infinity, and only then actually it starts the focusing process. And it nails the focus perfectly, at least the K-01 and the mentioned lens. Something else is the DA 35/2.8 Macro Ltd for example. The camera (I tested it right the way) wants again to turn it towards the infinity, but often it fails and moves this lens in the opposite direction, and then (but not always!) rotates it towards the infinity. Once the lens is at the infinity, then the correct focus is achieved pretty quickly and always precisely. That's my experience with LV AF.

Click to expand...

Oh yes, that is another point. LV-AF with lenses like SMC DA55-300, DFA100/2.8WR and similar long screws is... unusable unless camera is on tripod and subject fixed.

Live view AF simply is still years behind all the competition. And we are not talking about 1-2 years, rather a decade. Same like video.

I've been re-testing and re-testing.

On finding out that even a fracton of a mm on the camera's lens mount, can make a big difference to wide angle lenses (being able to achieve infinity - if they are not), I checked the tightness of the K-1 mount. With a gentle turn the screws did move a degree or two, to nipped tight. Maybe over the past years the paint underneath has compressed, or the screws just loosened a tad. Anyway thought they were worth checking.

So after all this, and weeding out misfocused-AF shots, adjustment has settled down a touch, and is less than before, averaging -4 rather than -6 (maybe due to tightening the lens mount).

77mm, infinity -6 -5 -4, close -6 to 0, so using -4.

31mm, infinity -8 -7 -6, close - 6, -5, -4, so using -6.

50mm, infinity -8 -7 -6 -5 -4, close -4, so using -4.

100mm, infinity -6 -5 -4, close -4 -2 0, so using -4.

-4 does seem to be a common sweet spot, thought there's quite a lot of mis-focused shots in the mix which do confuse results. I'm going to draw a line under my AF calibration of these lenses and call it a done job, otherwise I'll be endlessly calibrating and chasing around mis-focused shots, though it was worth it.

While all the lenses quickly achieve focus confirmation, I'm finding the 31mm Limited often doesn't, the AF confirmation light flashing even when the AF point is over an obvious contrasty edge - in bright daylight, usually at infinity or at distance (that causes no issues for the other lenses). Strange, I've never come across this issue before.

Have you? - with the 31mm Limited.

Just one comment, if (almost) all lenses require a similar adjustment (-4), you can apply this correction as a default (well, check the manual hoe\w to do so) camera correction, instead of setting correction for the individual lenses.

When shooting a subject with a DSLR that requires critically accurate focus, such as when shooting wide open, I rely 100% on live view only. I just do not trust viewfinder AF when focus accuracy needs to be precise. When I want to shoot wide open without a stressing about it, I greatly prefer using a mirrorless system. When I'm out shooting landscapes at f8, my DSLR provides a much better experience. I do more of the latter than the former, so Pentax remains in my kit.

flektogon said:

Just one comment, if (almost) all lenses require a similar adjustment (-4), you can apply this correction as a default (well, check the manual hoe\w to do so) camera correction, instead of setting correction for the individual lenses.

Click to expand...

...that option is an either or though isn't it?

I've already got a different adjustment for the 31mm (-6), and may wish to tweak some of the other lenses in the future.

Or is the 'Apply One' option in addition to the individual lens calibration values? - i.e. can I set the 'Apply One' to -4 then the 31mm to -2 (to make -6)?

Gary Martin said:

When shooting a subject with a DSLR that requires critically accurate focus, such as when shooting wide open, I rely 100% on live view only. I just do not trust viewfinder AF when focus accuracy needs to be precise. When I want to shoot wide open without a stressing about it, I greatly prefer using a mirrorless system. When I'm out shooting landscapes at f8, my DSLR provides a much better experience. I do more of the latter than the former, so Pentax remains in my kit.

Click to expand...

...yes, I'm coming to this hard cold realisation.

I only use rear-screen live-view in the studio, though even then with mirrorless I'd finalise with the EVF (or just use the EVF).

Anyway, with dSLRs, use the OVF and stop down to near f8, or shoot layered subjects where critical focus is not an issue, or use mirrorless and get that bang-on focus with a shallow DOF.

As I have a GFX 50S and now a K-1, I wonder which I'll use more. I got the K-1 for the OVF, I'm not keen on EVF's - though can get by with them (with a few extra batteries to hand!).