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Lens Distortion Correction XT-2 + XF 10-24

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Ed Steichen

Ed Steichen

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Hello,

How is lens correction applied? I assume it occurs in-camera but does the lens also play a role?

I ask because when shooting with my XT-2 and XF 10-24 it seems like lens correction is being applied differently from one shot to another. I think.

The two images below were shot one after the other using a remote shutter release, manual focus and image stabilization turned off. I don't think I touched the camera between shots and if I did it was just to hit the playback button. Notice the sort of pincushion distortion that appears in the second image. I saw the distortion change before I imported the photos so its definitely happening in-camera. I did no editing to either image, just exported from Lr as Jpegs for upload.

This happens to me all the time and it is very frustrating. I shoot interiors and I have to composite multiple images in Photoshop and I need all the images to line up. This sort of inconsistent distortion really screws things up.

Any idea as to what is happening here? I did just notice that I had "Lens Modulation Optimizer" turned on. I wonder if that's a potential culprit?

Thanks very much for any help/advice. I really need to solve this issue.

Edit: I just noticed the focal length changes in the metadata. I did not change the focal length between shots.

Shot first
Shot first

Shot second.
Shot second.
 
Last edited:
Changes were made between shots when the camera was handled. The EXIF indicates a change in focal length which is something the camera does not accomplish on its own.

The wider the zoom is set, the greater barrel correction needed. Typically, the profile is not a 100% correction due to negative impact on IQ quality. Most raw converters allow the profile correction to be magnified beyond 100%; for instance, Capture One allows up to 20% (120% total).

To the question of how correction changes (other than physically changing the zoom perspective and distortion), all correction is done internally in processing the JPEG; your raw converter (assuming it is so equipped - as LR is) takes direction to apply the correction, but the raw file is created entirely based on what the lens provides via the optics.
 
JNR said:
Changes were made between shots when the camera was handled. The EXIF indicates a change in focal length which is something the camera does not accomplish on its own.

The wider the zoom is set, the greater barrel correction needed. Typically, the profile is not a 100% correction due to negative impact on IQ quality. Most raw converters allow the profile correction to be magnified beyond 100%; for instance, Capture One allows up to 20% (120% total).

To the question of how correction changes (other than physically changing the zoom perspective and distortion), all correction is done internally in processing the JPEG; your raw converter (assuming it is so equipped - as LR is) takes direction to apply the correction, but the raw file is created entirely based on what the lens provides via the optics.
Click to expand...
Thank you for the reply.

I never touch the lens between shots, only the playback button, and not always. There are also times when I touch the camera between shots and the distortion/focal length change never occurs. I only want a sense of what is going wrong so I can correct or avoid it. Clearly, finding a means to shoot remotely would be ideal but unfortunately, Fuji's remote app is inadequate for my needs.

I contacted Fuji support and they actually got back to me, but only with more questions for now.

Thanks again.
 
Ed Steichen said:
JNR said:
Changes were made between shots when the camera was handled. The EXIF indicates a change in focal length which is something the camera does not accomplish on its own.

The wider the zoom is set, the greater barrel correction needed. Typically, the profile is not a 100% correction due to negative impact on IQ quality. Most raw converters allow the profile correction to be magnified beyond 100%; for instance, Capture One allows up to 20% (120% total).

To the question of how correction changes (other than physically changing the zoom perspective and distortion), all correction is done internally in processing the JPEG; your raw converter (assuming it is so equipped - as LR is) takes direction to apply the correction, but the raw file is created entirely based on what the lens provides via the optics.
Click to expand...
Thank you for the reply.

I never touch the lens between shots, only the playback button, and not always. There are also times when I touch the camera between shots and the distortion/focal length change never occurs. I only want a sense of what is going wrong so I can correct or avoid it. Clearly, finding a means to shoot remotely would be ideal but unfortunately, Fuji's remote app is inadequate for my needs.

I contacted Fuji support and they actually got back to me, but only with more questions for now.

Thanks again.
Click to expand...
Unless the room is haunted or has a swirling wind, there needs to be an explanation why the EXIF indicates the focal changed and FOV was slightly altered.
 
JNR said:
JNR said:
Thanks again.
Click to expand...
Unless the room is haunted or has a swirling wind, there needs to be an explanation why the EXIF indicates the focal changed and FOV was slightly altered.
Click to expand...
I agree.

But I don't know what that exact explanation is.

I am beginning to suspect it is Lens Modulation Optimizing (LMO) being turned on.

I haven't gone over the images from today's shoot, but on site I wasn't seeing any issues on playback with having LMO turned off. Fingers crossed.

Here are two other pics from a different location where my issue arises (again, consecutive shots where I never touched the lens). And while the property was possibly haunted, given that this occurs wherever I go, all these properties must be haunted by the same ghosts of Fujis past.

e58b0aadf5ec4e168ba5afa5bb6b0c2d





b0d5325473de4efb9622b18110ee2a5e.jpg
 
I had the same problem and solved it by using the 14/2.8 witch doesn’t require software correction as it is fully optical corrected.
 
Distortion correction is applied to jpegs in camera.
For RAW files distortion correction is applied by editing software, using meta data captured in the RAW file. In LR distortion correction cannot be turned off. It can be turned off in other software (eg iridient).
Distortion corrections will depend on focal length. So the small change in focal length capture in the RAW file in your 2 shots would result in different corrections.
 
aha! you removed the lamp in the more recent set of photos. *that* is the reason!
 
Storare said:
I had the same problem and solved it by using the 14/2.8 witch doesn’t require software correction as it is fully optical corrected.
Click to expand...
Thank you for the reply and good to know I'm not alone in this.

I too own the 14/2.8 but it's not always wide enough for my needs. So today I ordered a used Samyang 12mm and hope that will solve this issue for now.
 
justin_time said:
Distortion correction is applied to jpegs in camera.
For RAW files distortion correction is applied by editing software, using meta data captured in the RAW file. In LR distortion correction cannot be turned off. It can be turned off in other software (eg iridient).
Distortion corrections will depend on focal length. So the small change in focal length capture in the RAW file in your 2 shots would result in different corrections.
Click to expand...
Thank you for the reply and clear explanation.

I think I asked the wrong question, because when I did, I didn't realize the focal length was changing (or at least the camera was being told the focal length had changed) between shots. I can see the change in distortion during playback in the camera long before it enters any software.

I suspect a communication problem between the lens and camera that may be brought on by my touching of the playback button, but who knows.

Again, thanks.
 
The Lens Modulation option toggles the lens correction profile. LMO is Fuji speak.

Since they have a couple of curves stored, it depends on focal length which curve is selected. Perhaps your focal length setting was exectly on the border of two, and my moving it just enough to trigger a different profile. I'm curious what Fuji has to say.

In CaptureOne you have more freedom to apply lens corrections. You have sliders between 0 and 120%, and for some lenses they made their own profiles, which you can choose over the embedded one.

Then you also have the Lensfun database (open source) where you have total freedom. Tools like darktable can use these profiles.

But I understand these topics go a bit beyond your question, because your lens is not supposed to change focal length between shots.
 
Ed Steichen said:
Hello,

How is lens correction applied? I assume it occurs in-camera but does the lens also play a role?

I ask because when shooting with my XT-2 and XF 10-24 it seems like lens correction is being applied differently from one shot to another. I think.

The two images below were shot one after the other using a remote shutter release, manual focus and image stabilization turned off. I don't think I touched the camera between shots and if I did it was just to hit the playback button. Notice the sort of pincushion distortion that appears in the second image. I saw the distortion change before I imported the photos so its definitely happening in-camera. I did no editing to either image, just exported from Lr as Jpegs for upload.

This happens to me all the time and it is very frustrating. I shoot interiors and I have to composite multiple images in Photoshop and I need all the images to line up. This sort of inconsistent distortion really screws things up.

Any idea as to what is happening here? I did just notice that I had "Lens Modulation Optimizer" turned on. I wonder if that's a potential culprit?

Thanks very much for any help/advice. I really need to solve this issue.

Edit: I just noticed the focal length changes in the metadata. I did not change the focal length between shots.

Shot first
Shot first

Shot second.
Shot second.
Click to expand...
OK, as you state above, these images are output by Lr from RAW files.

For RAW files, the camera does not apply lens correction. It is done by the editor (Lr) in this instance.

Therefore, in my opinion it's not the camera's lens correction that is at fault.

The problem may well be that the camera reports different focal lengths for the 2 shots, and because the distortion correction is focal length dependent, Lr applies slightly different correction to the two images.

So to me, you need to find out why the camera reports (or Lr reads) different focal lengths when you don't touch the lens in between shots.

Shoot a few images with "RAW+JPG" setting, then apply the above workflow to the RAW files and compare them to the camera JPGs, to see if there is a difference.

And then go from there.

--
Cheers,
Peter Jonas
 
sir_c said:
The Lens Modulation option toggles the lens correction profile. LMO is Fuji speak.

Since they have a couple of curves stored, it depends on focal length which curve is selected. Perhaps your focal length setting was exectly on the border of two, and my moving it just enough to trigger a different profile. I'm curious what Fuji has to say.

In CaptureOne you have more freedom to apply lens corrections. You have sliders between 0 and 120%, and for some lenses they made their own profiles, which you can choose over the embedded one.

Then you also have the Lensfun database (open source) where you have total freedom. Tools like darktable can use these profiles.

But I understand these topics go a bit beyond your question, because your lens is not supposed to change focal length between shots.
Click to expand...
Thanks for the reply.

I tried shooting with LMO turned off and the problem persisted.

Supposedly a new Fuji remote app is to be announced this week. If it's a competent app and will work with an XT-2, that may allow for shooting without touching the playback button.
 
Ed Steichen said:
sir_c said:
The Lens Modulation option toggles the lens correction profile. LMO is Fuji speak.

Since they have a couple of curves stored, it depends on focal length which curve is selected. Perhaps your focal length setting was exectly on the border of two, and my moving it just enough to trigger a different profile. I'm curious what Fuji has to say.

In CaptureOne you have more freedom to apply lens corrections. You have sliders between 0 and 120%, and for some lenses they made their own profiles, which you can choose over the embedded one.

Then you also have the Lensfun database (open source) where you have total freedom. Tools like darktable can use these profiles.

But I understand these topics go a bit beyond your question, because your lens is not supposed to change focal length between shots.
Click to expand...
Thanks for the reply.

I tried shooting with LMO turned off and the problem persisted.
Click to expand...
As stated in my previous post, Fuji's LMO function has nothing to do with your problem.

Since you are using RAW files, lens correction is applied by your processing software (I think you mentioned Lr).

The question is, why Lr uses different focal lengths for the 2 photos when you did not touch the lens between the 2 shots.

As suggested in my previous post, try shooting RAW + JPG and compare the reported focal length values for SOOC JPGS to those output by Lr.

If both report the same focal length for both your shots, then we'd have to investigate why the camera reports different values for the 2 consecutive shots.

There will be a number of possibilities then, but let's do this one thing at a time.
Ed Steichen said:
Supposedly a new Fuji remote app is to be announced this week. If it's a competent app and will work with an XT-2, that may allow for shooting without touching the playback button.
Click to expand...
Why are you touching the Playback button between 2 shots? Is it not the shutter release you are supposed to touch?

The Fuji remote app as useless as it seems, is already competent enough to take shots with the camera. You could try using it just for the sake of this test, so that you can take shots without touching the camera at all, thereby eliminating the possibility of the zoom action being nudged just a bit while taking the shot.

Using a tripod would also be able to assist you with that.
 
I think in the exif meta data you can see the reported focal length. That should give a hint I hope.

Indeed LMO is used in the embedded jpegs, but I also thought it would mark the raw file with an instruction to tools like LR to enable corrections. But apparently LR does not look at this flag and always applies the corrections.
 
Peter Jonas said:
Peter Jonas said:
I tried shooting with LMO turned off and the problem persisted.
Click to expand...
As stated in my previous post, Fuji's LMO function has nothing to do with your problem.

Since you are using RAW files, lens correction is applied by your processing software (I think you mentioned Lr).

The question is, why Lr uses different focal lengths for the 2 photos when you did not touch the lens between the 2 shots.

As suggested in my previous post, try shooting RAW + JPG and compare the reported focal length values for SOOC JPGS to those output by Lr.

If both report the same focal length for both your shots, then we'd have to investigate why the camera reports different values for the 2 consecutive shots.

There will be a number of possibilities then, but let's do this one thing at a time.
Peter Jonas said:
Supposedly a new Fuji remote app is to be announced this week. If it's a competent app and will work with an XT-2, that may allow for shooting without touching the playback button.
Click to expand...
Why are you touching the Playback button between 2 shots? Is it not the shutter release you are supposed to touch?

The Fuji remote app as useless as it seems, is already competent enough to take shots with the camera. You could try using it just for the sake of this test, so that you can take shots without touching the camera at all, thereby eliminating the possibility of the zoom action being nudged just a bit while taking the shot.

Using a tripod would also be able to assist you with that.
Click to expand...
The reason I need to check playback is because I am shooting real estate listings using the "flambient" (flash/ambient) technique where I blend flashed lit shots with ambient light shots. When I shoot the flashed frames I need to check for exposure and for various flash related problems that may need correcting. It's a more cumbersome process than working with ambient light alone, but I prefer the results. And it's all done on a sturdy tripod- I should have mentioned that earlier. In the last images I posted, you can see I was lighting one side of the room then the other with those two frames. Those two frames, along with ambient light frames, get blended together in Photoshop for the final output. But in that specific scene the distortion/focal length difference created issues I needed to work around to get an acceptable final image. In fact, none of the ambient shots for that scene aligned with the flash frames and I take two sets of ambient frames, one before I flash and one after.

As to the current Fuji remote app, it's inadequate for reviewing images while shooting on site. At least with my XT-2.

I'll try Raw+Jpeg next time and see and report.

Thank you for the help.
 
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