# "unable to merge photos . . ."



## robert_g

I took 12 sets of "bracketed "photos of the solar eclipse at totality; each consisting of 3 shots. But, when I try to use Photomerge, I get the message: "unable to merge photos not enough matching photos for merging"
I've tried just merging two (2)  photos and all 36, and I get the same message.

Each photo looks pretty good on its own; showing some good detail of the solar corona. I was very much looking forward to getting the HDR look. 

I am using the stand alone version of Lightroom 6.12. My photos were taken with a Canon Rebel T2i  in RAW

I am essentially a relatively naive photographer trying to upgrade my competence from the "point and shoot" mode. I apologize if this question has been asked and answered previously, but I did try searching the forums for an answer before posting, without luck .

Any suggestions will be appreciated.


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## Cerianthus

Handheld or on a tripod ?  If it is just the sun in the pictures, there might not be enough overlap if it was handheld.


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## Johan Elzenga

The problem with these kinds of photos is that there is very little information that can be used to align the images. A black circle, and some brighter pixels around it that are different in different photos. For us, these are photos of a solar eclipse, so for us this is pretty easy. For Photoshop or Lightroom these are just a bunch of pixels, with no clearly matching patterns. That means you may have to stack them into layers and align the layers manually.


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## robert_g

Cerianthus said:


> Handheld or on a tripod ?  If it is just the sun in the pictures, there might not be enough overlap if it was handheld.



I used a tripod and a remote release. 
The lens was a Canon zoom EF 75-300 f/4-5.6, zoomed out. 
The photos were shot at 270 mm f/8.0;exposure bracketed at 1/15, 1/30, and 1/60 ; ISO 200


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## Johan Elzenga

robert_g said:


> I used a tripod and a remote release.
> The lens was a Canon zoom EF 75-300 f/4-5.6, zoomed out.
> The photos were shot at 270 mm f/8.0;exposure bracketed at 1/15, 1/30, and 1/60 ; ISO 200



Overlap is not an issue anyway. That only concerns panoramas, not HDR.


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## robert_g

JohanElzenga said:


> The problem with these kinds of photos is that there is very little information that can be used to align the images. A black circle, and some brighter pixels around it that are different in different photos. For us, these are photos of a solar eclipse, so for us this is pretty easy. For Photoshop or Lightroom these are just a bunch of pixels, with no clearly matching patterns. That means you may have to stack them into layers and align the layers manually.



A similar thought occurred to me. Perhaps Lightroom was overwhelmed with the number of black pixels. I was wondering if I should crop to around the sun where the "action is", enlarge (or vice versa), and then try to merge. I am guessing Lightroom actually numbers the pixels with a "grid" address. That being the case, I was thinking that when I crop, I should use the grid tool to help keep the same pixels in the same relative place on the cropped photos (or would that be unnecessary?)

Or perhaps try to give Lightroom more to work with by further under exposing the underexposed shot and further over exposing the overexposed shot, and then merge.

Or, follow your advice: bite the bullet, dive in and learn how to stack


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## Johan Elzenga

Cropping in Lightroom is non-destructive, so it would not make any difference.


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## robert_g

JohanElzenga said:


> Cropping in Lightroom is non-destructive, so it would not make any difference.



understood, but if I cropped and then used those cropped photos, wouldn't that give Lightroom a smaller arena--focused more precisely on where the differential action is--so Photomerge can do its thing rather than being overwhelmed with irrelevant pixels.

Or would Lightroom "remember" all the pre-cropped info and want to use it for merging, and therefore still be confused.

BTW: can you refer me to any Adobe source information on the "unable to merge . . ."  message?


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## Cerianthus

JohanElzenga said:


> Overlap is not an issue anyway. That only concerns panoramas, not HDR.



You have to have overlap in HDR, otherwise the whole photo is part of the ghosting. That is the alligning bit is it not ? If there are no similarities, it cannot allign.  I cant HDR pictures with a different subject, but LR accepted some pictures that I would consider as a different viewpoint. Would it help if you unchecked the auto align and and deghosting at none ?


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## Johan Elzenga

Cerianthus said:


> You have to have overlap in HDR, otherwise the whole photo is part of the ghosting. That is the alligning bit is it not ? If there are no similarities, it cannot allign.  I cant HDR pictures with a different subject, but LR accepted some pictures that I would consider as a different viewpoint. Would it help if you unchecked the auto align and and deghosting at none ?



Maybe I was not making myself clear. In panoramas you need about 25% overlap, or else they can't be stitched correctly. In HDR you normally have (close to) 100% overlap, so 'enough overlap' should never be an issue. You can turn off Auto Align, but because Lightroom creates a non-layered HDR DNG, that will probably not work either. Because of the rotation of the earth, your solar eclipse photos will not align perfectly, even when they were shot from a tripod.


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## robert_g

Re: Johan E and Cerianthus overlap comments:

I can assure you, the photos are *essentially identical* except w/r/t exposure. Each bracketed set was taken within a few (<5) seconds. The diurnal rotation of the earth and its annual revolution about the sun were completely insignificant. I was following instructions as laid out by an experienced astrophotographer (including multiple solar eclipses) published in _Sky and Telescope._ Among other things, he mentioned that given the speed of modern DSLRs tracking mounts were unnecessary. Also, please note that the totality, itself, only lasted for 1-2 minutes. The overlap is essentially 100% 

My original question still stands. Why does Lightroom tell me: "unable to merge photos; *not enough matching photos* for merging?" 
Shouldn't 3 be enough? If not, how about 36 !!! ? 
How many photos does Lightroom need?

Thanks for your help


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## Cerianthus

It would only need two for a HDR image. It clearly is not working and if you tried all the options, nothing we can do will make it work. I would try if you could do it with any of the free HDR programs available. Best Free High Dynamic Range (HDR) Software apparantly, Hugin does HDR as well. Although not free, the enfuse plugin might be some use as that was used before LR had HDR. LR/Enfuse - Blend Multiple Exposures Together in Adobe Lightroom


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## Roelof Moorlag

Is this information from Rikk Flohr helpfull? https://www.lightroomqueen.com/community/threads/hdr-in-lr-6-without-base-exposure.25424/#post-1205332


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## Johan Elzenga

robert_g said:


> The diurnal rotation of the earth and its annual revolution about the sun were completely insignificant.



The latter obviously is insignificant, the diurnal rotation is significant depending on the focal length and the shutter speed and the time between the shots. When I shot the full eclipse in Egypt in 2006, I found I had to adjust my camera angle several times during the eclipse (which lasted 5 minutes, though). 

Anyway, I don't think that's the problem. Just three shots is also not the problem. I use that all the time. I think the problem is that Lightroom does not understand a photo that is basically 95% black pixels and 5% white pixels with very little in between. It's looking for a 'base exposure' but doesn't recognize one. Did this experienced astrophotographer use Lightroom to create the HDR, or did he use Photoshops 'Merge to HDR Pro'? These are very different things, so it could well be that Lightroom fails where Merge to HDR Pro succeeds.


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## RikkFlohr

I am seeing it too on my Eclipse Brackets. I have asked the team to chime in.


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## robert_g

Gerard--Thank you for the alternative HDR program links. I'll keep them in mind as I wait a bit to see if any other suggestions solve the issue directly in Lightroom

Roelf--Good info.  Especially the 3 stop or less rule and the fact that Lightroom ignores the crops as I mentioned up-thread

Johan--Wow; five minutes!!  The photographer is Dennis di Cicco. I have no idea what he uses to merge his photos. As discussed above, I agree with you w/r/t the number of black pixels confusing LR. That is why I was thinking about using cropped photos, but--as per the Rikk Flohr article--LR ignores crops in merge

Rikk--Thanks for your help. Sorry to hear you you are having the same problem. I'll look forward to the "team's" response.


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## RikkFlohr

robert_g said:


> Rikk--Thanks for your help. Sorry to hear you you are having the same problem. I'll look forward to the "team's" response.



Turns out that HDR is not my preferred method for coronal images. I used an 8 Image Stack (normal exposures) blended using the Mean Stacking mode in Photoshop. It was superior to the HDR Tone-mapped version.


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