Microfocus Adjustment: Not a One Time Thing

[Mike Buckley]

So it is a very fine adjustment. Quite possibly one that only the most critical photographers may even notice.

It would also not be noticed by photographers doing only the kinds of photography in which razor-thin depths of field are never used.

[John 2]

Terri, a very nice set of images which to my eye and with the possible exception of no.4, are acceptably sharp. I use the word "acceptably" because IMHO, I don't think a good image ever suffers because it isn't absolutely tack sharp. Being significantly OOF is a different matter of course.

As to tweaking lenses, does anybody know if the "tweak" is necessarily effective over a whole zoom range? I genuinely don't know but I wondered when I considered seeing whether my Tamron 150 - 600 would benefit from adjustment. I would hate to find that an improvement at one end of the range caused a deterioration at the other; particularly if it destroyed what might have been the best compromise.

[Loose Canon]

Microfocus adjustment is a function of aperture rather than focal length John.

You can only apply one adjustment for a lens. So you can’t have an adjustment for it wide and another for it racked. Canon recommends you zoom to maximum telephoto length and of course wide open aperture to evaluate/adjust.

It is not a hugely technically involved process to make these adjustments if needed. If you don't like the results its easy to go back to where you started.

[selig1656]

Great thread ,a lot of information on a subject that I have little knowledge on. Thank you to all that participated. BTW great photos and amazing sharpness.

[JR1]

Nikon

https://nikoneurope-en.custhelp.com/...-tune-function

[John 2]

Microfocus adjustment is a function of aperture rather than focal length John.

You can only apply one adjustment for a lens. So you can’t have an adjustment for it wide and another for it racked. Canon recommends you zoom to maximum telephoto length and of course wide open aperture to evaluate/adjust.

It is not a hugely technically involved process to make these adjustments if needed. If you don't like the results its easy to go back to where you started.

That makes sense. Thanks Terry.

[Brownbear]

Thanks for starting this thread Terri...

I'm pretty sure that Chauncey's comment is directed at me as last summer he recommended that I try this because I was having difficulty capturing a head on shot of a goose in flight. I've managed sharp images of head on pelicans in flight (better light/without a 1.7 extender on my 300 mm but I have yet to capture a goose.) I'm of the mind that it is because of the low light and extender but perhaps not.

All that said, yes I've avoided trying it all this time likely because of a fear that I might do something wrong. My intent was to wait until I needed to take my camera in for a cleaning and have it professionally done.

I will give it a try sometime in the next couple of weeks.

[NorthernFocus]

...what happens to/with cameras that can not be adjusted like this

All but the entry level cameras in the Nikon line have AF adjust. I suspect the average owners of those bodies don't attach them to wide aperture lenses and/or simply aren't experienced enough to recognize if there is an issue.

[Loose Canon]

Thanks for starting this thread Terri...

I'm pretty sure that Chauncey's comment is directed at me as last summer he recommended that I try this because I was having difficulty capturing a head on shot of a goose in flight. I've managed sharp images of head on pelicans in flight (better light/without a 1.7 extender on my 300 mm but I have yet to capture a goose.) I'm of the mind that it is because of the low light and extender but perhaps not.

All that said, yes I've avoided trying it all this time likely because of a fear that I might do something wrong. My intent was to wait until I needed to take my camera in for a cleaning and have it professionally done.

I will give it a try sometime in the next couple of weeks.

Christina, when you make these adjustments it is done in one-shot mode and manually set to center point focus with all other focus point expansion disabled. Shooting a still target (3-D so you can assess DoF limits) in adequate light on a tripod.

In other words if you were shooting your GiF in say, AI Servo, and with multiple focus points enabled, and set to “run-and-gun” (burst), which would stand to reason with that subject matter, there are way too many variables that come into play to accurately assess that the problem lies with a microfocus adjustment.

Microfocus has to do with DoF (focal plane) and where it lands relative to the focus point. Either more forward or more backward of the existing focus point. That’s all it does. It does not necessarily improve overall focus generically or necessarily make moving targets easier to acquire. The above mentioned caveats are the only way to accurately assess if an adjustment is needed.

Of course it’s not hard to assess and won’t hurt, but it won’t necessarily improve your focus with moving targets.

For the majority of shooters it is a non-issue.

[AlwaysOnAuto]

As to tweaking lenses, does anybody know if the "tweak" is necessarily effective over a whole zoom range? I genuinely don't know but I wondered when I considered seeing whether my Tamron 150 - 600 would benefit from adjustment. I would hate to find that an improvement at one end of the range caused a deterioration at the other; particularly if it destroyed what might have been the best compromise.

John - I've done some experimenting with my zooms, nothing really scientific mind you, and I've found that some of them change focus point as you zoom.
I'd recommend you take a look at the Nikon link jr1 posted and set up that kind of 'system' to check your lens at different FL's. It'll give you a good idea as to what the lens is doing as you zoom. All you need to do is set it up for one FL, take the shot, then zoom to the whatever FL you're interested in and take another shot without changing the focus. Pretty simple really. You don't need to change any setting to try it either, ie make an adjustment.
You might be surprised by what you see.

[Brownbear]

Thank you Terry. Your explanation is very helpful. I use single point auto focus aimed at the eye of the bird. And of course it is hard to tell with missed shots if it is me, or not. I will try it for the learning experience and see if it makes a difference.

Christina, when you make these adjustments it is done in one-shot mode and manually set to center point focus with all other focus point expansion disabled. Shooting a still target (3-D so you can assess DoF limits) in adequate light on a tripod.

In other words if you were shooting your GiF in say, AI Servo, and with multiple focus points enabled, and set to “run-and-gun” (burst), which would stand to reason with that subject matter, there are way too many variables that come into play to accurately assess that the problem lies with a microfocus adjustment.

Microfocus has to do with DoF (focal plane) and where it lands relative to the focus point. Either more forward or more backward of the existing focus point. That’s all it does. It does not necessarily improve overall focus generically or necessarily make moving targets easier to acquire. The above mentioned caveats are the only way to accurately assess if an adjustment is needed.

Of course it’s not hard to assess and won’t hurt, but it won’t necessarily improve your focus with moving targets.

For the majority of shooters it is a non-issue.

[Mike Buckley]

If there is a problem it can also be a problem in manual focus.

How? I ask because if I am using manual focus I turn the focus ring until the part of the image that I want to be in focus is indeed in focus. It doesn't matter to me whether the part that is in focus is supposed to be in focus when the focus ring is in that particular position.

[John 2]

How? I ask because if I am using manual focus I turn the focus ring until the part of the image that I want to be in focus is indeed in focus. It doesn't matter to me whether the part that is in focus is supposed to be in focus when the focus ring is in that particular position.

Mike, I think it might be that if what you see as in focus via the mirror isn't what the sensor is seeing due to a mismatch in the two optical paths, you would have a problem. Not a problem with mirrorless of course.

[NorthernFocus]

How? I ask because if I am using manual focus I turn the focus ring until the part of the image that I want to be in focus is indeed in focus. It doesn't matter to me whether the part that is in focus is supposed to be in focus when the focus ring is in that particular position.

Mike, I suspect some people use the camera's focus lock indicator in manual mode. In such a case the AF system is still in the equation. Clearly if focus is being achieved purely visually, it SHOULDN'T matter. That assumes of course that the internal geometry of the camera is correct and that viewfinder and sensor plane are properly aligned

[Mike Buckley]

If I'm manually focusing using Live View, the mirror is raised (not being used to reflect the image). Is there still potential for something being in focus in the LCD's display of the scene that is not in focus in the image file?

[Rita]

This is turning into an educational thread. I had heard about micro adjusting but like Christina and Izzie I have felt hesitant. Good to know that you can't go wrong and if you do the settings can be easily put back to the original. Think I will be bookmarking this thread for when I get my zoom.

[NorthernFocus]

If I'm manually focusing using Live View, the mirror is raised (not being used to reflect the image). Is there still potential for something being in focus in the LCD's display of the scene that is not in focus in the image file?

It is amazing how different our various styles, techniques, subject matter, etc. can be. I don't use LV so it never occurs to me. As a matter of fact the only time I've ever used it is for fiddling with checking focus.

However, AS I UNDERSTAND IT, when in LV the image displayed is coming straight off of the image sensor. Therefore if you manually focus until the displayed image is sharp, then by definition the image is in focus. Assuming, of course, that your eyes are good

One reason I always use AF is that I wear glasses but don't typically use them when shooting. It's a crazy, complicated world of photography...

[AlwaysOnAuto]

I'm the same way Dan. AF has been a real blessing to me as I could never get things in focus. When I was younger I was too far sighted to use the frensel screen in my Mamiya 1000 DTL. Never got a good picture with that camera because of it. Fast forward to the split screen of my FE and things were pretty good, but not perfect by any means. Now with AF in my D7k, it is almost picture perfect every time, well, it was once I figured out HOW the AF worked. Knowing how it works makes all the difference in the world.

[John 2]

If I'm manually focusing using Live View, the mirror is raised (not being used to reflect the image). Is there still potential for something being in focus in the LCD's display of the scene that is not in focus in the image file?

I suspect not Mike. One of the methods for fine tuning that I found on the internet (stored but not yet tried) seems to rely on focussing the camera on a target using live view and then adjusting the focus incrementally using the built in menu function, with the mirror down. I haven't tried it yet because the recommended distance between camera and target for a 600mm lens needs an outdoor location and good weather; both of which are in short supply at the moment.

[chauncey]

recommended distance between camera and target for a 600mm lens needs an outdoor location

I know that's what they recommend John but, I haven't found that to be necessary
as I do it all inside my home.

I MF'd my 300mm with/without a 2X TC at a distance of 15 yards...placed a box
with wall tile mirror taped to it (to align parallax with camera), then taped my
printed target to that mirror with a pencil jutting out from the box at the center
point of the target on which I leaned a yardstick.

Then it's an easy task to shoot tethered and see, in real time, the effect of each
micro focus adjustment by focusing on the target center point and watching the
movement on the yardstick.

It works great, for me, whether the target is ten feet or 200 yards away,
as illustrated here...I could not believe this