Recently getting blur/softness with Z9 while using strobes

[SCoombs]

All of this seems to be contradicted by the fact that my physical technique and approach to setting the camera and flash has remained unchanged from previous shoots where I did not experience these problems.

This is likely not the case. You’re just missing what you’ve changed (or what your gear has changed for you).

Well, yes, that's mostly the assumption and the point of the post is to try to figure out what may have changed. What I was saying was contradicted was the thought that the problem was the flash power or the use of standard sync speed vs. HSS because these are definitely things that haven't changed or about which there were already examples of doing differently where the problem persists (eg, I always used the regular sync speed indoors and never had an issue with it and I almost always have used HSS outdoors and had also never seen the problem in that situation until the last few weeks).

 

[LukeP_Photo]

It’s definitely a curious issue. I’m not sure what it could be but I do some have questions out of curiosity.

1) At any point in recent memory, have you switched to rear sync for the flash for something else other than portraits? I’m asking only since that’s a setting that doesn’t reset every time you power up the Z9 with the banks UI. From what I’ve seen you’re very detail oriented but a change like that can get overlooked if it’s an adjustment you don’t regularly do.

2) Have there been any firmware updates for your strobes that you’ve done recently? The last firmware update for the Z9 was before the summer so that couldn’t be a culprit unless you recently updated the camera

3) This is an obvious question, but I just want to reaffirm this, you are strictly shooting handheld correct? I know this has been your standard method and there shouldn’t be anything wrong with it for these situations. However, have you experimented with shooting on a tripod for comparison?

 

[arniebook]

Here are some more of the 24-70 with flash, this time a speedlight bounced off the ceiling. You can certainly see some places where the falloff of the depth of field is noticeable, but leaving that aside there isn't really anything more to be desired with the sharpness.

My first thought was ambient light "ghosting", and I'm mentioning it here without reading the remainder of the replies, (in case someone else has) because the kitty shots are tac sharp and are obviously shot in a darker environment.

I experienced this way back in film days. I would always use a shutter sync speed and aperture that would make a dark (underexposed) picture if shot without flash. But, one time I was shooting an event in a fairly well lit building, and turned the flash off for some special shots without flash. I slowed the shutter speed and opened the aperture for those particular "available light" shots. I then turned the flash back on and continued shooting the event ... yep ... I got distracted, and forgot to change the shutter and aperture back to the flash settings. I caught it after a few shots, simply because of a habit of occasionally checking settings. When the pictures were developed, I could see the ghosting and softness in those few shots. I don't think anyone else noticed.

So here is my question to you ... could it be that the blurry shots were taken in a "brighter" environment than usual??? A flash duration is very short, but is enough to properly expose the subject and freeze any camera or subject motion. But, if the ambient light is also enough to make an exposure under the camera's exposure setting (shutter, aperture, ISO) ... and ... there is even just a little motion in the subject or camera, ghosting can occur.

I'm certainly not saying that is for sure the problem. Having no physical shutter, the Z8 is very different from film cameras, and even DSLR's, and I haven't done any flash event shooting with my Z8, other than to see if my old SB800 worked with it (it does). I am suggesting that if no other reason can be determined, that you do some experimental shooting to reproduce the less than desirable results, and then, if you find "ghosting" is the problem, you can determine a camera setting solution.

Arnold

--
What we spend on this stuff is equal to the depth of our pockets squared ($²) times what we (j)ustify in our minds as to what we expect to do with our pictures plus (+) the (e)njoyment we experience from using our stuff and sharing the result ... $xxxx=$²(j+e )

 

[Leonard Shepherd]

but in practice I pay extremely close attention to what the AF box does when composing and shooting and it was definitely not on the ball in this case.

In reality, the sharpness detail in the image clarifies that the auto focus selected the area around the ball as the intended subject :-(

There are several potential reasons why AF might prefer the ball - it is close to the camera with good contrast making the ball a reasonably good "first camera choice" AF subject.

If your eyesight is good enough to read the smallest print on an opticians reading test chart – not everybody's is – then I find this amount of focus differential can be seen in the viewfinder, providing an opportunity to adjust the auto focus perameters to achieve the result you wanted.



--
Leonard Shepherd
In lots of ways good photography is similar to learning to play a piano - it takes practice to develop skill in either activity.

 

[SCoombs]

but in practice I pay extremely close attention to what the AF box does when composing and shooting and it was definitely not on the ball in this case.

In reality, the sharpness detail in the image clarifies that the auto focus selected the area around the ball as the intended subject :-(

There are several potential reasons why AF might prefer the ball - it is close to the camera with good contrast making the ball a reasonably good "first camera choice" AF subject.

If your eyesight is good enough to read the smallest print on an opticians reading test chart – not everybody's is – then I find this amount of focus differential can be seen in the viewfinder, providing an opportunity to adjust the auto focus perameters to achieve the result you wanted.

Part of the potential question here is whether or not this is happening in some way because of the flash. When I and others were discussing another issue with focus accuracy with flash use during event photography sometime last year, Thom Hogan chimed in something to the effect that we might try shooting in manual rather than TTL flash, and this evolved into the idea of shooting in AF-S instead of AF-C. The idea was that even though we're talking about milliseconds that there was a disconnect between what the camera was focusing on at the moment of the shutter release vs. what it needed to be focused on during the period when the flash was illuminating things.

Now this seems relevant here because you are correct that it is generally possible to observe whether or not the subject is focused properly in the viewfinder. I keep an eye on this when shooting. I keep an eye not only on the AF box that is on the subject in the viewfinder, where it moves to when shooting in some kind of subject detect mode, whether the indicator is red, yellow, or green, etc., but also what the image ACTUALLY looks like to my eye: if it is in focus or not.

In fact - and I do hope people will believe me here because this really is true - I specifically remember double checking what looked in focus when taking the shot with this particular photo because it was one of the few from that day where the ball was out in the forefront and on a very different plane of focus like this. I was trying to make sure it was not stealing the focus, and when I pressed the shutter it wasn't. But, did the focus shift when the flashed fired, as we had discussed happening when shooting with the speedlight at events? That is part of the question here.

 

[jlafferty]

All of this seems to be contradicted by the fact that my physical technique and approach to setting the camera and flash has remained unchanged from previous shoots where I did not experience these problems.

This is likely not the case. You’re just missing what you’ve changed (or what your gear has changed for you).

Well, yes, that's mostly the assumption and the point of the post is to try to figure out what may have changed.

Anecdotally I’ve never shot TTL, and never will, and have no focus issues shooting AF-C with the AD600 Pros in a variety of conditions/sync speeds/etc. I’m shooting a lot now with Z series cameras, subject detect sometimes, and switching between that and 3D tracking, and I’ve never had my camera jump from a face to another detail without it being very obvious. This is across the Z6, Z6III, Z8 and Z9, always using the R2ProII trigger. I’m trying to recall the last time I took these cameras out of AF-C and into AF-S and it’s a struggle - AF-C has gotten so good, which wasn’t necessarily the case for the D700/D810 which I shot for years.

Curious how the camera “feels” as you shoot these things - instantly responsive and snappy, or lagging and spongey. I get the spongey feeling when my camera is struggling in low contrast, or I’ve tried a setting like Rear Curtain and there’s a palpable delay between focus acquisition and firing.

Also curious what your AF-C vs AF-S priority settings are. Years ago I read a Nikon “best AF settings for action” article which advised AF-C set to “focus” and AF-S set to “release.” I’ve heard other people advise to the contrary, but I’ve been shooting this way for ~14 years without issue.

I may have said it before but TBH I would do a factory reset on camera, trigger and strobe and rebuild my workflow if I were in your shoes. Good luck.

 

[SCoombs]

All of this seems to be contradicted by the fact that my physical technique and approach to setting the camera and flash has remained unchanged from previous shoots where I did not experience these problems.

This is likely not the case. You’re just missing what you’ve changed (or what your gear has changed for you).

Well, yes, that's mostly the assumption and the point of the post is to try to figure out what may have changed.

Anecdotally I’ve never shot TTL, and never will, and have no focus issues shooting AF-C with the AD600 Pros in a variety of conditions/sync speeds/etc. I’m shooting a lot now with Z series cameras, subject detect sometimes, and switching between that and 3D tracking, and I’ve never had my camera jump from a face to another detail without it being very obvious. This is across the Z6, Z6III, Z8 and Z9, always using the R2ProII trigger. I’m trying to recall the last time I took these cameras out of AF-C and into AF-S and it’s a struggle - AF-C has gotten so good, which wasn’t necessarily the case for the D700/D810 which I shot for years.

I have mainly done without TTL. When I have used it, it does yield a pretty good exposure most of the time. A lot of event pros on this forum and elsewhere insist it's essential and I understand why. There are ways to work without it but there's no question that these are an extra mental load during an already hectic job and they absolutely slow you down a bit, meaning that you can miss things. I work without it because on the Z system it definitely causes some issues when shooting in AF-C, which is what you're primarily in for event stuff. It may be that for some use cases it will still work, but most of the things I would use it for involve processions of people walking towards the camera and with the plane of focus moving towards the camera it was back focusing on almost every shot in TTL. Swapping to manual flash mode eliminates that problem instantly, so it is definitely something with TTL.

With the AD-600s, I had shot them primarily in AF-C with no problems until the past few weeks. That is why I started in AF-C on those volleyball photos before swapping into AF-S.

Curious how the camera “feels” as you shoot these things - instantly responsive and snappy, or lagging and spongey. I get the spongey feeling when my camera is struggling in low contrast, or I’ve tried a setting like Rear Curtain and there’s a palpable delay between focus acquisition and firing.

It's pretty snappy unless I am in fairly low lighting conditions - much lower than any of the portraits I do would be done in.

Also curious what your AF-C vs AF-S priority settings are. Years ago I read a Nikon “best AF settings for action” article which advised AF-C set to “focus” and AF-S set to “release.” I’ve heard other people advise to the contrary, but I’ve been shooting this way for ~14 years without issue.

Honestly, without looking I don't know because I have tested all the possible combinations of that for different use cases and never really found it made a difference. To me that is consistent with the idea that half the people say it is better one way and half say it is better the other way. If there really isn't much if any difference, you'd expect to get people recommending both.

 

[SCoombs]

Here are some more of the 24-70 with flash, this time a speedlight bounced off the ceiling. You can certainly see some places where the falloff of the depth of field is noticeable, but leaving that aside there isn't really anything more to be desired with the sharpness.

My first thought was ambient light "ghosting", and I'm mentioning it here without reading the remainder of the replies, (in case someone else has) because the kitty shots are tac sharp and are obviously shot in a darker environment.

I experienced this way back in film days. I would always use a shutter sync speed and aperture that would make a dark (underexposed) picture if shot without flash. But, one time I was shooting an event in a fairly well lit building, and turned the flash off for some special shots without flash. I slowed the shutter speed and opened the aperture for those particular "available light" shots. I then turned the flash back on and continued shooting the event ... yep ... I got distracted, and forgot to change the shutter and aperture back to the flash settings. I caught it after a few shots, simply because of a habit of occasionally checking settings. When the pictures were developed, I could see the ghosting and softness in those few shots. I don't think anyone else noticed.

So here is my question to you ... could it be that the blurry shots were taken in a "brighter" environment than usual??? A flash duration is very short, but is enough to properly expose the subject and freeze any camera or subject motion. But, if the ambient light is also enough to make an exposure under the camera's exposure setting (shutter, aperture, ISO) ... and ... there is even just a little motion in the subject or camera, ghosting can occur.

I'm certainly not saying that is for sure the problem. Having no physical shutter, the Z8 is very different from film cameras, and even DSLR's, and I haven't done any flash event shooting with my Z8, other than to see if my old SB800 worked with it (it does). I am suggesting that if no other reason can be determined, that you do some experimental shooting to reproduce the less than desirable results, and then, if you find "ghosting" is the problem, you can determine a camera setting solution.

Arnold

Ghosting was one of the first things I thought of. I don't think it's that, but I am continuing to consider it and try to check for it. I'd never had this issue in the same lighting conditions with the same sorts of settings before, and checking for it a few times so now I haven't really found any evidence that it is the issue.

 

[jlafferty]

One of the things that’s difficult in trying to help you here is that you keep jumping outside of this specific issue to discuss other things that have seemingly no bearing on your current problem, and it’s easy for people replying to get lost. For example: relating your experiences shooting events or processions only serve to confuse the issue in the context of static portrait shots. You talk about TTL definitely being problematic, but then when you switch in the next paragraph talking about AF-C, you don’t say whether or why you’d shoot in TTL for the volleyball stuff.

To put it simply: with these portraits are you shooting TTL or not? Is the problem consistently an issue with TTL in these portraits, or does it stop when you’re out of TTL? (IMO for the portraits you’ve shared, TTL is absolutely irrelevant and I’m unclear as to why it’s part of the conversation.) Does it only happen in AF-C, or AF-S as well? Are you shooting back button focus or shutter release+focus? What trigger are you using? Is the trigger on the latest firmware? Are your cameras on their latest firmware? Are your lights on their latest firmware?

Given that we’ve identified that it’s an interaction between your new lens, TTL (maybe?), and the strobes, I would take a moment to think about all of the settings along the chain of that process and do A/B scenarios turning them on/off and running through the issue. Off the top of my head at a minimum you’ve got:

AF-C vs AF-S priority

AF area mode- tracking or not

Subject detect on or off

Back button focus or not

Curtain sync mode: first vs rear

HSS or not

If in HSS are you shooting too close to normal sync (e.g. 1/500) - this is problematic in my experience and I push to 1/800 or faster in HSS to clear it up

TTL or not

Strobe output power setting and related flash duration

AF release/focus priority

Trigger sub-settings: various modes, are they in conflict with the camera

I can’t recall offhand what this is what it’s called on the Z bodies but Auto-FP, setting the upper limit of flash sync and shutter behavior

Lens custom behaviors

I know you’ve answered some of these above but I’m just giving you a run off of stuff I’d check. Definitely not needing your replies to each, it’s just a reference for you to consider. So for example when you write things like “it’s definitely something with TTL” there are so many things that interact with TTL, it might be more accurate to assign blame to another thing, and recognize that it only becomes apparent in TTL (it could be release priority for example).

All of this seems to be contradicted by the fact that my physical technique and approach to setting the camera and flash has remained unchanged from previous shoots where I did not experience these problems.

This is likely not the case. You’re just missing what you’ve changed (or what your gear has changed for you).

Well, yes, that's mostly the assumption and the point of the post is to try to figure out what may have changed.

Anecdotally I’ve never shot TTL, and never will, and have no focus issues shooting AF-C with the AD600 Pros in a variety of conditions/sync speeds/etc. I’m shooting a lot now with Z series cameras, subject detect sometimes, and switching between that and 3D tracking, and I’ve never had my camera jump from a face to another detail without it being very obvious. This is across the Z6, Z6III, Z8 and Z9, always using the R2ProII trigger. I’m trying to recall the last time I took these cameras out of AF-C and into AF-S and it’s a struggle - AF-C has gotten so good, which wasn’t necessarily the case for the D700/D810 which I shot for years.

I have mainly done without TTL. When I have used it, it does yield a pretty good exposure most of the time. A lot of event pros on this forum and elsewhere insist it's essential and I understand why. There are ways to work without it but there's no question that these are an extra mental load during an already hectic job and they absolutely slow you down a bit, meaning that you can miss things. I work without it because on the Z system it definitely causes some issues when shooting in AF-C, which is what you're primarily in for event stuff. It may be that for some use cases it will still work, but most of the things I would use it for involve processions of people walking towards the camera and with the plane of focus moving towards the camera it was back focusing on almost every shot in TTL. Swapping to manual flash mode eliminates that problem instantly, so it is definitely something with TTL.

With the AD-600s, I had shot them primarily in AF-C with no problems until the past few weeks. That is why I started in AF-C on those volleyball photos before swapping into AF-S.

Curious how the camera “feels” as you shoot these things - instantly responsive and snappy, or lagging and spongey. I get the spongey feeling when my camera is struggling in low contrast, or I’ve tried a setting like Rear Curtain and there’s a palpable delay between focus acquisition and firing.

It's pretty snappy unless I am in fairly low lighting conditions - much lower than any of the portraits I do would be done in.

Also curious what your AF-C vs AF-S priority settings are. Years ago I read a Nikon “best AF settings for action” article which advised AF-C set to “focus” and AF-S set to “release.” I’ve heard other people advise to the contrary, but I’ve been shooting this way for ~14 years without issue.

Honestly, without looking I don't know because I have tested all the possible combinations of that for different use cases and never really found it made a difference. To me that is consistent with the idea that half the people say it is better one way and half say it is better the other way. If there really isn't much if any difference, you'd expect to get people recommending both.

--
http://jimlafferty.com
Evocative beats academic.

 

[SCoombs]

One of the things that’s difficult in trying to help you here is that you keep jumping outside of this specific issue to discuss other things that have seemingly no bearing on your current problem, and it’s easy for people replying to get lost. For example: relating your experiences shooting events or processions only serve to confuse the issue in the context of static portrait shots. You talk about TTL definitely being problematic, but then when you switch in the next paragraph talking about AF-C, you don’t say whether or why you’d shoot in TTL for the volleyball stuff.

To put it simply: with these portraits are you shooting TTL or not? Is the problem consistently an issue with TTL in these portraits, or does it stop when you’re out of TTL? (IMO for the portraits you’ve shared, TTL is absolutely irrelevant and I’m unclear as to why it’s part of the conversation.) Does it only happen in AF-C, or AF-S as well? Are you shooting back button focus or shutter release+focus? What trigger are you using? Is the trigger on the latest firmware? Are your cameras on their latest firmware? Are your lights on their latest firmware?

Given that we’ve identified that it’s an interaction between your new lens, TTL (maybe?), and the strobes, I would take a moment to think about all of the settings along the chain of that process and do A/B scenarios turning them on/off and running through the issue. Off the top of my head at a minimum you’ve got:

AF-C vs AF-S priority

AF area mode- tracking or not

Subject detect on or off

Back button focus or not

Curtain sync mode: first vs rear

HSS or not

If in HSS are you shooting too close to normal sync (e.g. 1/500) - this is problematic in my experience and I push to 1/800 or faster in HSS to clear it up

TTL or not

Strobe output power setting and related flash duration

AF release/focus priority

Trigger sub-settings: various modes, are they in conflict with the camera

I can’t recall offhand what this is what it’s called on the Z bodies but Auto-FP, setting the upper limit of flash sync and shutter behavior

Lens custom behaviors

I know you’ve answered some of these above but I’m just giving you a run off of stuff I’d check. Definitely not needing your replies to each, it’s just a reference for you to consider. So for example when you write things like “it’s definitely something with TTL” there are so many things that interact with TTL, it might be more accurate to assign blame to another thing, and recognize that it only becomes apparent in TTL (it could be release priority for example).

All of this seems to be contradicted by the fact that my physical technique and approach to setting the camera and flash has remained unchanged from previous shoots where I did not experience these problems.

This is likely not the case. You’re just missing what you’ve changed (or what your gear has changed for you).

Well, yes, that's mostly the assumption and the point of the post is to try to figure out what may have changed.

Anecdotally I’ve never shot TTL, and never will, and have no focus issues shooting AF-C with the AD600 Pros in a variety of conditions/sync speeds/etc. I’m shooting a lot now with Z series cameras, subject detect sometimes, and switching between that and 3D tracking, and I’ve never had my camera jump from a face to another detail without it being very obvious. This is across the Z6, Z6III, Z8 and Z9, always using the R2ProII trigger. I’m trying to recall the last time I took these cameras out of AF-C and into AF-S and it’s a struggle - AF-C has gotten so good, which wasn’t necessarily the case for the D700/D810 which I shot for years.

I have mainly done without TTL. When I have used it, it does yield a pretty good exposure most of the time. A lot of event pros on this forum and elsewhere insist it's essential and I understand why. There are ways to work without it but there's no question that these are an extra mental load during an already hectic job and they absolutely slow you down a bit, meaning that you can miss things. I work without it because on the Z system it definitely causes some issues when shooting in AF-C, which is what you're primarily in for event stuff. It may be that for some use cases it will still work, but most of the things I would use it for involve processions of people walking towards the camera and with the plane of focus moving towards the camera it was back focusing on almost every shot in TTL. Swapping to manual flash mode eliminates that problem instantly, so it is definitely something with TTL.

With the AD-600s, I had shot them primarily in AF-C with no problems until the past few weeks. That is why I started in AF-C on those volleyball photos before swapping into AF-S.

Curious how the camera “feels” as you shoot these things - instantly responsive and snappy, or lagging and spongey. I get the spongey feeling when my camera is struggling in low contrast, or I’ve tried a setting like Rear Curtain and there’s a palpable delay between focus acquisition and firing.

It's pretty snappy unless I am in fairly low lighting conditions - much lower than any of the portraits I do would be done in.

Also curious what your AF-C vs AF-S priority settings are. Years ago I read a Nikon “best AF settings for action” article which advised AF-C set to “focus” and AF-S set to “release.” I’ve heard other people advise to the contrary, but I’ve been shooting this way for ~14 years without issue.

Honestly, without looking I don't know because I have tested all the possible combinations of that for different use cases and never really found it made a difference. To me that is consistent with the idea that half the people say it is better one way and half say it is better the other way. If there really isn't much if any difference, you'd expect to get people recommending both.

I never said it had anything to do with TTL. I do not use TTL. I've said I don't use TTL. I only commented about TTL in my recent post as a reply to your prior comment.


When I first listed the troubleshooting steps I had already taken and said that this included switching into AF-S I may have very briefly mentioned that I thought about this step because of a previous discussion about AF-C and TTL, but beyond that I haven't said anything about TTL.

 

[Horshack]

The only reliable way to arrive at the cause is to do a controlled test, where you compare flash vs no flash using the same subject, focal length, and aperture. I think that effort will be a much more productive use of your time compared to making and fielding speculations.

 

[SCoombs]

The only reliable way to arrive at the cause is to do a controlled test, where you compare flash vs no flash using the same subject, focal length, and aperture. I think that effort will be a much more productive use of your time compared to making and fielding speculations.

Horshack, after trying a few things my current best theory is that this lens is in some way substantially more susceptible to camera shake than other short focal length lenses I have used. I seem to be able to generally avoid this problem by being extraordinarily cautious about camera movement - far, far more than I have needed to be using other lenses. I always aim to keep my hands steady, but with this I am needing to approach it like I would when trying to do a longer exposure in low light without the use of a tripod. Moreover, the problem persists even using flash with shorter duration or even combining flash with a fast shutter speed like 1/2000. Still, it's the extreme approach to steadying the camera that is giving me sharper results.

Any thoughts on how to test this theory out, compare to other lenses, etc.?

 

[kamiel2]

If you pull the raw image in nx studio, you can bring back the red square, and see where it actually focused (It works for z6iii). Or is that not reliable ? Or maybe not available on z9 ?

 

[SCoombs]

If you pull the raw image in nx studio, you can bring back the red square, and see where it actually focused (It works for z6iii). Or is that not reliable ? Or maybe not available on z9 ?

You can do this and I think it's generally reliable enough. A lot of people will say that it is not necessarily reliable, so it won't always convince people of what the focus was really doing. I've never noticed it to be different from what I saw in the EVF, so I trust it for the most part.

 

[Leonard Shepherd]

AF-S as a work-around first.

Focus seems several inches forward of where intended.

With a static pose like this yours and AF-S on the face and the way you are holding the camera should limit movement to no more than an inch - better focus without an explanation as to what is going wrong in AF-C.

my current best theory is that this lens is in some way substantially more susceptible to camera shake than other short focal length lenses I have used. I seem to be able to generally avoid this problem by being extraordinarily cautious about camera movement - far, far more than I have needed to be using other lenses. I always aim to keep my hands steady, but with this I am needing to approach it like I would when trying to do a longer exposure in low light without the use of a tripod. Moreover, the problem persists even using flash with shorter duration or even combining flash with a fast shutter speed like 1/2000. Still, it's the extreme approach to steadying the camera that is giving me sharper results.

My view is the steps you are taking should not be normally be necessary.

Sometimes carefully cleaning the lens contacts resolves an otherwise un-explained focus problem.

Otherwise maybe this specific lens needs a Nikon service.

 

[kamiel2]

So that could be used to know whether the softness comes from the camera focussing on an unexpected point of not ....

 

[SCoombs]

So that could be used to know whether the softness comes from the camera focussing on an unexpected point of not ....

I think that that is true, yes. The only reason I haven't posted any examples of this is because I know there are enough people on this forum who aren't confident in what NX Studio says and would say that it is not always accurate.

That said, here it is for the curious:



(By the way, I notice that this says auto-ISO, which is definitely a mistake on my part. I never use auto-ISO when shooting with a flash).

 

[Leonard Shepherd]

So that could be used to know whether the softness comes from the camera focussing on an unexpected point of not ....

I think that that is true, yes. The only reason I haven't posted any examples of this is because I know there are enough people on this forum who aren't confident in what NX Studio says and would say that it is not always accurate.

That said, here it is for the curious:

Perhaps the equipment needs a visit to Nikon to advance the issue?

Traditionally in the DSLR era Nikon used to caution that the auto focus rectangle could illuminate (not on something as small as an eye back then) even though the detail under it was not good enough for accurate auto focus.

There is usually a difference between insufficient detail under the AF point for good AF, and decent AF some place else.

A have not encountered any example of the wrong AF area being illuminated post capture, in my photography using your practice of checking the viewfinder to ensure the area under the AF point looks visually sharp.

This is not the same as saying it cannot occasionally happen.

You imply this does not happen with other similar wide angle lenses - strongly indicating a probable issue with this specific lens.

--
Leonard Shepherd
In lots of ways good photography is similar to learning to play a piano - it takes practice to develop skill in either activity.

 

[SCoombs]

So that could be used to know whether the softness comes from the camera focussing on an unexpected point of not ....

I think that that is true, yes. The only reason I haven't posted any examples of this is because I know there are enough people on this forum who aren't confident in what NX Studio says and would say that it is not always accurate.

That said, here it is for the curious:

Perhaps the equipment needs a visit to Nikon to advance the issue?

Traditionally in the DSLR era Nikon used to caution that the auto focus rectangle could illuminate (not on something as small as an eye back then) even though the detail under it was not good enough for accurate auto focus.

There is usually a difference between insufficient detail under the AF point for good AF, and decent AF some place else.

A have not encountered any example of the wrong AF area being illuminated post capture, in my photography using your practice of checking the viewfinder to ensure the area under the AF point looks visually sharp.

This is not the same as saying it cannot occasionally happen.

You imply this does not happen with other similar wide angle lenses - strongly indicating a probable issue with this specific lens.

If it were one lens vs others, I doubt I'd even have posted about it and it would be relatively obvious what the problem was. I'll reiterate in case you didn't see above that the lens itself when using natural light can be seen to be extremely sharp and to acquire very accurate focus. It is only when paired with the off camera flash that these results manifest. YET, other lenses paired with the same lighting equipment also function well. I have so far only observed this to happen when this specific lens is paired with the lighting equipment. Either the lens or the lighting when used with other equipment function normally.

That is why I shared the question. It is quite an odd thing indeed that it is only this specific combination that seems to do this.

 

[Horshack]

The only reliable way to arrive at the cause is to do a controlled test, where you compare flash vs no flash using the same subject, focal length, and aperture. I think that effort will be a much more productive use of your time compared to making and fielding speculations.

Horshack, after trying a few things my current best theory is that this lens is in some way substantially more susceptible to camera shake than other short focal length lenses I have used. I seem to be able to generally avoid this problem by being extraordinarily cautious about camera movement - far, far more than I have needed to be using other lenses. I always aim to keep my hands steady, but with this I am needing to approach it like I would when trying to do a longer exposure in low light without the use of a tripod. Moreover, the problem persists even using flash with shorter duration or even combining flash with a fast shutter speed like 1/2000. Still, it's the extreme approach to steadying the camera that is giving me sharper results.

Any thoughts on how to test this theory out, compare to other lenses, etc.?

Write up a matrix with the following configuration parameters:

• Focus Locked for all shots in a series vs Focus Acquired for each shot in a series
• IBIS/VR On vs IBIS/VR Off
• Flash On vs Flash Off

Using a fixed, detailed subject that doesn't move, shoot 10 shots in a series for each combination of the above matrix. The total number of shots should be 200, ie there are 20 combinations of the above parameters x 10 photos in the series per combination.

Use the identical aperture, shutter speed, and focal length for all shots. Use a scene where there are depth cues in front of and behind the subject you're focusing on, so that it's easy to determine where the plane of focus is from the resulting photographs.