# lens correction inconsistent in LR



## JHT (Aug 7, 2017)

I'm a real-estate photographer and always shoot multiple exposures of rooms. I start off with a shot using ambient light only. Then, I'll take at least one more shot of the room using flash. Later, after importing the photos into Lightroom and doing some initial editing, I'll take the two exposures into Photoshop for blending the two exposures to get the advantages of both ambient light and flash. 

The problem is that if I apply lens correction to the two exposures in LR *before *taking them into PS, I often get different corrections for the two images, and when I start blending them in PS, the two exposures are not correctly aligned with each other. Objects in the room, such as window frames, no longer line up perfectly. 

Of course, I can auto-align in PS, but I've found that's not always accurate either. Sometimes the inconsistency between the two exposures caused by LR is so great that PS can't realign them sufficiently, and blending the two exposures is a disaster.

As an alternative, I quit applying lens correction in LR before moving the photos to PS. That gave me perfect alignment in PS (because I use a very sturdy tripod), and then I would apply lens correction *after* bringing the blended photo out of PS and back into LR. The problem with this method is that the blended photo is now a TIF, and LR doesn't have a lens profile for my Rokinon 24mm tilt/shift lens once the photo is in TIF format. (Is there a way to get PS to bring the photo back into LR in DNG format?)

As a third option, I can apply manual lens correction in LR after bringing the blended TIF photo back from PS. That's okay for correcting my lens' barrel distortion, but it's a manual process that I would rather avoid. More importantly, it loses the benefits of the full Adobe lens profile, which can correct other forms of distortion in the lens.

Please understand that I'm trying to find the most efficient workflow I can so that I can process lots of photos very quickly while still getting all the benefits of applying the Adobe lens profile and producing high-quality photos for my clients. But time lost fiddling with alignment and manual workarounds equals money lost. Ideally, LR would simply apply lens correction consistently across each photo of the same subject. 

I want to know why LR is inconsistently applying lens correction. Could it be because of the different exposure levels? And is there anything I can do to get the LR lens correction to apply in exactly the same manner to every exposure of the same subject?


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## Johan Elzenga (Aug 7, 2017)

A lens profile only provides geometrical corrections and vignetting corrections, based on a certain lens. I don't see how different lighting conditions could possibly result in different lens corrections, unless one image was corrected and the other one was not. As your Rokinon lens is a fully manual lens, which doesn't provide any lens information in the metadata, that would be my first bet. You have to apply this profile manually, Lightroom can't do it automatically (because there are no lens data in the metadata). Could it be that you apply the profile to one image, then synchronize the settings, but don't realize that the profile settings aren't checked in the sync dialog?


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## JHT (Aug 7, 2017)

Thanks for responding. I really appreciate your taking the time to help

I double-checked some old photos to test that they were correctly synced. I've attached some images to show you what I did. The first attachment is a screen capture showing the lens profile in LR. (Adobe doesn't have a lens profile for my specific lens, so I chose the only 24mm profile available.) I made sure that both the ambient shot and the flash shot had the same lens profile and both were updated and in exactly the same state. Then I took them into PS and auto-aligned them. As you can see in the second attached image, the auto-alignment reveals noticeable differences between the two photos along the left, right and bottom sides. 

Next, I went back to LR and reset both photos so that neither had any processing applied. I took them both back into PS and performed auto-align again. As you can see in the third image, they align perfectly along all sides. So, in the second attachment, I assume that lens correction was not being applied consistently to the two images since lens correction was the only variable. I'm not sure how to explain the misalignment otherwise. And, since exposure is the only difference between the two photos overall, I assume that it accounts for the differences in lens correction. If you have any other explanations, I'd be very interested to hear them.


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## Johan Elzenga (Aug 7, 2017)

I think it's more likely that the auto alignment somehow goes wrong. And as you use a sturdy tripod, you shouldn't have to align in the first place. Why don't you check how well the images are aligned if you don't use auto align?


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## JHT (Aug 7, 2017)

Hi Johan,

In the attached screen capture, you can see what happens if I apply lens correction in LR but don't auto-align in PS. If you look closely, you'll see that the blending process reveals that the edges of the TV don't align. Sometimes this isn't an issue and I can just blend away one of the two edges. However, it can become really problematic in other areas of the photo where many edges come together, such as window frames. Because I have to process so many images like this, I need to find a method that consistently provides good results. That's why I'm so disappointed that LR's lens correction provides inconsistent results.

Thanks again,
John


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## Johan Elzenga (Aug 7, 2017)

Can you post the images somewhere so we can take a look at it? BTW, the idea of just using a 24mm profile that is not from this lens, sounds very odd. Each lens needs its own profile. It's not like every 24mm lens needs the same correction! Some 24mm lenses, like the Canon TS 24mm, need hardly any geometric correction at all. Other 24mm lenses need quite a bit of correction, however. It doesn't make sense to use the only 24mm profile available, just because Adobe didn't produce a profile for your lens.

Another problem is that even if you had a profile for this lens, it would still not be valid for photos where your lens was tilted or shifted. It would only be valid for photos taken with zero tilt and zero shift. That is exactly the reason why Adobe does not provide lens profiles for TS lenses.


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## Johan Elzenga (Aug 7, 2017)

By the way: could you also try the following: don't use a profile and also do not use auto align in Photoshop. Are the images perfectly aligned in this case?


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## LRList001 (Aug 7, 2017)

JHT said:


> I'm a real-estate photographer and always shoot multiple exposures of rooms.
> [snip]
> Could it be because of the different exposure levels?



Are you changing the aperture?


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## JHT (Aug 8, 2017)

The original files, in DNG format, are here: 
www.johnteaguephotography.com/images/lenscorrection/ambient-3017.dng
www.johnteaguephotography.com/images/lenscorrection/flash-3019.dng

They're about 26 MB each.

When I chose a 24mm profile, I selected a Rokinon 24mm prime profile, assuming that it would be as close as I could get to an appropriate profile for my Rokinon 24mm TS lens. However, I understand your point that Adobe would not be able to produce profiles for TS lenses, given the many variations possible with those lenses. So that means I'm limited to manual fixes for lens distortion.

As for your question about using neither a lens profile nor auto-alignment, the answer is yes, the images are perfectly aligned in PS without those processes. The problem is simply that the images often have noticeable barrel distortion, which is what I was hoping to solve with the lens profiles. I used to shoot with a Nikon 14-24mm lens for which there is a lens profile, and I saw that applying lens corrections made significant changes to the images. I was hoping to achieve the same sort of improvement with a lens profile for my Rokinon lens, but now I just have to accept that no appropriate lens profile exists for it.


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## JHT (Aug 8, 2017)

LRList001 said:


> Are you changing the aperture?



Nope, no change in aperture. I usually change the shutter speed if I want to meter for the exterior light.


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## Johan Elzenga (Aug 8, 2017)

Well, I don't know what you are doing wrong in Lightroom, but you must be doing something wrong. I've tried with and without the same lens profile that you use (I chose the Samyang 24mm one, which should be the same because Samyang makes the Rokinon lenses), and when I send both images to open as layers in Photoshop, they are perfectly aligned (without having to use Auto Align).


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## JHT (Aug 8, 2017)

JohanElzenga said:


> Well, I don't know what you are doing wrong in Lightroom, but you must be doing something wrong. I've tried with and without the same lens profile that you use (I chose the Samyang 24mm one, which should be the same because Samyang makes the Rokinon lenses), and when I send both images to open as layers in Photoshop, they are perfectly aligned (without having to use Auto Align).



Okay, thanks for taking the time to experiment with the photos. I'll have to keep doing my own experimentation to figure out what's going wrong.


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## Johan Elzenga (Aug 8, 2017)

JHT said:


> Okay, thanks for taking the time to experiment with the photos. I'll have to keep doing my own experimentation to figure out what's going wrong.



How do you apply the lens profile? Do you go to 'Lens Corrections' panel and apply it there, or did you save a Develop preset so you can apply it without leaving the Basic panel? If you saved a preset, perhaps you saved some other setting in that preset as well by mistake. I'm thinking about Auto Level in particular, because Auto Level can give slightly different results if both images have very different lighting.


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## LRList001 (Aug 8, 2017)

JHT said:


> Nope, no change in aperture. I usually change the shutter speed if I want to meter for the exterior light.



In that case I suspect that you are (somehow) applying different profiles.  The profile correction is just maths; crudely, you could apply any profile.  While any old profile won't correct the distortion (obviously), the same profile applied to the same lens settings (including focus point/distance) will always give the same results for the same sensor/image size.  There is no 'magic' to it.  However, if you are in auto, LR does fail to select the correct profile from time to time.  Make sure you are selecting the profile manually and are not applying anything like auto perspective corrections.  If you are working manually, then I can offer no explanation, it should be (has to be!!) identical.


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