p.1 #1 · AF-S front focus issue with XF 70-300 + X-T5
Wondering if anyone else has seen this behavior. I just acquired a Fuji XF 70-300 last week for my x-t5 camera. I test my lenses extensively now since having some issues in the past I discovered past warranty. I'm having an issue with focusing this lens specifically in AF-S mode. The lens will consistently front focus ever so slightly. This is most noticeable at the long end of the zoom causing my photos to look soft.
For example, if I place two bottles down about 20ft away from me with one bottle 2 inches in front of the other, zoom into 300mm, and focus on the back bottle, the front bottle will be in sharper focus! This hold true at practically every distance. I've tested this with numerous subjects indoors and outdoors only to find the same result. The lens will focus ever so slightly in front of the subject. This happens to be most noticeable with the lens stopped down to its sharpest aperture of f8.
This issue occurs with image stabilization on or off and I've been testing it on a tripod. Using different size focus points also don't seem to matter. Firmware on camera and lens are up to date.
Now if I manually focus, I can overcome this issue. More interestingly, this problem does not occur with AF-C! I can nail sharp focus ever time using AF-C, even on still subjects with my focus point set to the smallest size.
I'm guessing this is a camera issue where the focus algorithm is confirming focus too soon without rechecking? But this is going to make using the lens annoying for landscape and architecture work where I am working in low light on a tripod. AF-C doesn't work with self-timer and using manual focus on a digital camera isn't always the best experience. Not to mention issues using focus and recompose techniques.
If this is happening to others, I wonder if it contributes to people's complaints about softness at 300mm. Yeah the lens is def softer there in midframe and edges, but the slight focus shift in the center makes a huge difference!
p.1 #2 · AF-S front focus issue with XF 70-300 + X-T5
This may have something to do with how the camera determines which object to focus on (the nearest). The focus field that shows in the EVF is smaller than the area of focusing points the camera actually uses. So it may well happen that those focus points outside the focus area indicated in the EVF detect an object that is nearer than the object that you want focus on. I would try with the smallest focus point. And if that doesn't work, you may have to just dial in focus manually. For landscape and architecture, I'd be more concerned about the cameras tendency to focus beyond infinity.
p.1 #3 · AF-S front focus issue with XF 70-300 + X-T5
No to discount what you are saying, but this also happens when shooting things like a flat wall or fenc. AF-S will always slightly miss focus. There isn't really anything else for focus to accidentally grab onto. Switching to manual or AF-C will yield a sharper result.
p.1 #4 · AF-S front focus issue with XF 70-300 + X-T5
cirwin2010 wrote:
Wondering if anyone else has seen this behavior. I just acquired a Fuji XF 70-300 last week for my x-t5 camera. I test my lenses extensively now since having some issues in the past I discovered past warranty. I'm having an issue with focusing this lens specifically in AF-S mode. The lens will consistently front focus ever so slightly. This is most noticeable at the long end of the zoom causing my photos to look soft.
For example, if I place two bottles down about 20ft away from me with one bottle 2 inches in front of the other, zoom into 300mm, and focus on the back bottle, the front bottle will be in sharper focus! This hold true at practically every distance. I've tested this with numerous subjects indoors and outdoors only to find the same result. The lens will focus ever so slightly in front of the subject. This happens to be most noticeable with the lens stopped down to its sharpest aperture of f8.
This issue occurs with image stabilization on or off and I've been testing it on a tripod. Using different size focus points also don't seem to matter. Firmware on camera and lens are up to date.
Now if I manually focus, I can overcome this issue. More interestingly, this problem does not occur with AF-C! I can nail sharp focus ever time using AF-C, even on still subjects with my focus point set to the smallest size.
I'm guessing this is a camera issue where the focus algorithm is confirming focus too soon without rechecking? But this is going to make using the lens annoying for landscape and architecture work where I am working in low light on a tripod. AF-C doesn't work with self-timer and using manual focus on a digital camera isn't always the best experience. Not to mention issues using focus and recompose techniques.
If this is happening to others, I wonder if it contributes to people's complaints about softness at 300mm. Yeah the lens is def softer there in midframe and edges, but the slight focus shift in the center makes a huge difference! ...Show more →
Are both bottles in the focus box?
2 inches at 20feet is less than 1%, what accuracy do you expect from A F, Is any quoted? Can you do better with MF?
What aperture what's the DoF?
First reaction is you are looking too closely and expecting too much.
p.1 #5 · AF-S front focus issue with XF 70-300 + X-T5
I feel like my post wasn't read very carefully which is a bit frustrating.
In the stated example I am focusing on the rear bottle. For specifics, the focus box is only on the high contrast text of the rear bottle. Focus with AF-S ALWAYS will front focus a little. The front bottle is in focus, the read bottle is not in acceptably sharp focus.
As stated I do not have this problem manually focusing. I am consistently getting better focus using manual focus than with AF-S. I don't think it is unreasonable to expect AF-S to nail focus when AF-C is able to do so no problem every single time. I don't think it is unreasonable to expect the lens to nail focus when it will be used by bird and wildlife photographers who photograph small animals and crop heavily.
As stated this is most noticeable when stopped down to f8. As stated this happens at any distance so the DOF will be variable . I've tested things such as those bottles at about 20ft, to a fence at about 60 feet, to a house across the way at about 200ft. The area of acceptable focus is always slightly forward of the subject when using AF-S.
For a CoC of 0.006mm (which is worst case scenario for a largish print under close inspection), focusing at 200ft (~60m) with a focal length of 300mm and aperture of f8 gives a DoF of about 12ft (3.75m). That is more than enough to get the chimney I selected in focus. But that 12ft of DoF was instead moved just forward of the chimney and instead brought some shrubs into focus instead.
And yes, AF-C did get the chimney in focus, as did my manual focus.
p.1 #6 · AF-S front focus issue with XF 70-300 + X-T5
cirwin2010 wrote:
I feel like my post wasn't read very carefully which is a bit frustrating.
In the stated example I am focusing on the rear bottle. For specifics, the focus box is only on the high contrast text of the rear bottle. Focus with AF-S ALWAYS will front focus a little. The front bottle is in focus, the read bottle is not in acceptably sharp focus.
As stated I do not have this problem manually focusing. I am consistently getting better focus using manual focus than with AF-S. I don't think it is unreasonable to expect AF-S to nail focus when AF-C is able to do so no problem every single time. I don't think it is unreasonable to expect the lens to nail focus when it will be used by bird and wildlife photographers who photograph small animals and crop heavily.
As stated this is most noticeable when stopped down to f8. As stated this happens at any distance so the DOF will be variable . I've tested things such as those bottles at about 20ft, to a fence at about 60 feet, to a house across the way at about 200ft. The area of acceptable focus is always slightly forward of the subject when using AF-S.
For a CoC of 0.006mm (which is worst case scenario for a largish print under close inspection), focusing at 200ft (~60m) with a focal length of 300mm and aperture of f8 gives a DoF of about 12ft (3.75m). That is more than enough to get the chimney I selected in focus. But that 12ft of DoF was instead moved just forward of the chimney and instead brought some shrubs into focus instead.
And yes, AF-C did get the chimney in focus, as did my manual focus. ...Show more →
You are using generalisations. 'Nail focus', all systems have tolerances, no manufacturer seems willing to publicise what they are, also using jargon like pin point
Your test methods are too vague, did the label fill the focus box or was there background in it, for instance. Af-c 'nailing it' may just be chance.
2 inches is about 0.8% at 20 feet. I would think that pretty good, and certainly within DoF as properly defined. You can't alter the spec for DoF to suit a large print closely inspected, that is not within the definition of depth of field, the illusion only works at normal viewing distance, enough to view the whole image. If you enlarge or inspect closely as you have found there is only one plane of sharp focus, if you want to change CoC and viewing distance you will need to define the magnification.
You are looking for unreasonable standards of no bearing to actual production of images to be viewed. A pointless technical exercise.
p.1 #7 · AF-S front focus issue with XF 70-300 + X-T5
Your response is dismissive and attempting to undermine my efforts and testing methodology. You are shifting the focus from a constructive discussion to declaring the entire exercise worthless. Just because there isn't a manufacturing spec for tolerances that doesn't invalidate what I am seeing with my own eyes!
AF-C IS achieving more precise focus, yielding better sharpness and detail retention than AF-S CONSISTENTLY. I have tested this many times, with many subjects, with many different setting, lighting, etc over the course of 2 days. No I don't have tolerance specs, but I don't need them to tell you that I am getting subpar results using Autofocus single mode IN COMPARISON to Autofocus continuous mode. I'm not comparing to another system, some spec, or other expectation. I am comparing the system as a whole... to itself.
Sure a slight misfocus may not matter for some applications, but it sure as heck can for others. But that isn't the point! The point is that the behavior changes between AF-S and AF-C.
And I don't need to define "nailing focus" or "sharp" or anything like that. These are widely used terms in the community where with the addition the context of what I am saying should be enough. You can infer that when I say "nailing focus" I mean that I am achieving a better result than the alternative method presented.
And don't give me the by "chance" stuff either. Have some trust that I am repeating my tests where I can make a claim with a level of certainty that it isn't left to chance. Heck, for better constructive feeback you could ask if it is repeatable or how repeatable.
It's one thing to say there may be some wiggle room in manufacturing tolerances, but its another to come in here and say my experience is wrong. Stop that.
p.1 #8 · AF-S front focus issue with XF 70-300 + X-T5
cirwin2010 wrote:
Your response is dismissive and attempting to undermine my efforts and testing methodology. You are shifting the focus from a constructive discussion to declaring the entire exercise worthless. Just because there isn't a manufacturing spec for tolerances that doesn't invalidate what I am seeing with my own eyes!
AF-C IS achieving more precise focus, yielding better sharpness and detail retention than AF-S CONSISTENTLY. I have tested this many times, with many subjects, with many different setting, lighting, etc over the course of 2 days. No I don't have tolerance specs, but I don't need them to tell you that I am getting subpar results using Autofocus single mode IN COMPARISON to Autofocus continuous mode. I'm not comparing to another system, some spec, or other expectation. I am comparing the system as a whole... to itself.
Sure a slight misfocus may not matter for some applications, but it sure as heck can for others. But that isn't the point! The point is that the behavior changes between AF-S and AF-C.
And I don't need to define "nailing focus" or "sharp" or anything like that. These are widely used terms in the community where with the addition the context of what I am saying should be enough. You can infer that when I say "nailing focus" I mean that I am achieving a better result than the alternative method presented.
And don't give me the by "chance" stuff either. Have some trust that I am repeating my tests where I can make a claim with a level of certainty that it isn't left to chance. Heck, for better constructive feeback you could ask if it is repeatable or how repeatable.
It's one thing to say there may be some wiggle room in manufacturing tolerances, but its another to come in here and say my experience is wrong. Stop that. ...Show more →
I'm not saying yourexperience is wrong, I don't doubt what you are seeing, just that it doesn't matter in the real world. Of taking satisfactory photos with the kit. I don't doubt a faster lens might be more accurate, especially if it has more contrast.
You are exploring the boundaries of what the system can do, to tolerances that are meaningless in the use of the equipment for it's normal task its designed for.
p.1 #9 · AF-S front focus issue with XF 70-300 + X-T5
I'd send/take that 70-300 back to where it was purchased and ask for it to be tested and calibrated by the service organisation in your area.
If your other lenses work properly in the same situation, it suggests there is a fault with your 70-300 lens.
p.1 #11 · AF-S front focus issue with XF 70-300 + X-T5
pw-pix wrote:
I'd send/take that 70-300 back to where it was purchased and ask for it to be tested and calibrated by the service organisation in your area.
If your other lenses work properly in the same situation, it suggests there is a fault with your 70-300 lens.
I don't have this issue with my other lenses and the Fuji 150-609 set to same focal length also focuses fine. Still feels like some sort of software thing where it isn't double checking focus, but you may be right. Problem is I got it at Bestbuy (I know, shameful, but it was on sale for $750) so we shall see how that goes...
p.1 #12 · AF-S front focus issue with XF 70-300 + X-T5
gyoung143 wrote:
I'm not saying yourexperience is wrong, I don't doubt what you are seeing, just that it doesn't matter in the real world. Of taking satisfactory photos with the kit. I don't doubt a faster lens might be more accurate, especially if it has more contrast.
You are exploring the boundaries of what the system can do, to tolerances that are meaningless in the use of the equipment for it's normal task its designed for.
Disagree. with todays high res sensors, the point is to be able to crop up to 2.5 times (I can do 3 times with excellent results with my a7cR and RX100RMkIII. And then it really matters that critical focus is where it is supposed to be.
The issue doesn't seem be a lens issue but rather a camera issue since the focus works in AF-C mode.
p.1 #13 · AF-S front focus issue with XF 70-300 + X-T5
Less than 1% inaccuracy is a wonderful achievement. I can't think of any focus system that would even approach that, and the difference in plane of focus is minute, easily covered by DoF in practical use. Another 'issue' only revealed by unreasonable magnification when viewing.
