Lightroom Mobile: Double tap for accurate 100% zoom on iPad Pro

Zoom resolution will depend on how the photos got to the device. If they were uploaded through Lightroom Classic, the full size originals aren't available. Those are only 2560px long edge, with 100% being 100% of that. If they were uploaded through any Lightroom CC app, then they should be a true 100%.

Hi Victoria, thanks for the response. Yes, I am aware of this. My images are full size originals uploaded direct from camera to iPad Pro and then added directly to albums in Lightroom Mobile. File information in Lightroom CC mobile confirms full resolution original files, yet I am unable to achieve a true 100% zoom. All my files are stored in cache on the iPad. I have changed settings to locally store original files, but that makes no difference to this issue. I have seen same subject being discussed in other postings with same answers being offered and that's where discussion seems to end with no resolution. Any ideas?

Hmmm. Can we get some screenshots of the different stages then? That might offer some clues.

Yes, I'll try to do that tonight. In meantime here are some additional details:

All my image files are synced with Lightroom Classic on my desktop, but just to underscore I have originally imported files to iPad and then used Lightroom Mobile to add files to Lightroom Mobile albums. The process is entirely managed on the iPad. Fact that I am then syncing images to Lightroom Classic on my desktop is secondary and should not affect anything.

Also to clarify what I regard as true 100% zoom. If we take my D850 full res images as an example. These images are 8256 pixels long. The 13" iPad Pro screen resolution is 2732 pixels on long axis. This means that at 100% zoom apprx 1/3rd of image should be displayed over the full screen on the long axis. This is never the case. Initially when opening an image and double tapping ~2/3rd's of the image is displayed along the long axis implying around 50% zoom factor. When repeatedly double tapping same image it eventually jumps to higher zoom where apprx 1/6th of image is displayed along long axis. This implies ~200% zoom factor. For true 100% zoom apprx 1/3rd of my D850 image files should be displayed along long axis, right?

Another point is I have same problem with files from my D500, but first zoom ratio is different. With D500 on first opening image and double tapping, again apprx. 2/3rd's of image is displayed on long axis. This time though this implies a 75% zoom factor due to the lower sensor resolution of the D500. When repeatedly double tapping I will again see zoom factor suddenly jump and with D500 files this time with apprx. 1/4 of image displayed along long axis. This corresponds to 200% zoom factor which is same as with D850 files.

So basically 1) when first opening an image and double tapping to zoom, the zoom factor will vary depending on image file resolution, in this case 50% zoom for D850 and 75% zoom for D500 full res. images, and 2) when repeatedly double tapping zoom factor will eventually pop in displaying apprx. 200% zoom factor for both D850 and D500 files.

Regarding process for importing files to iPad and then to Lightroom mobile, here are my steps:

1) Connect XQD card from camera via card reader to iPad Pro
2) iOS Auto import window pops up
3) Select images to be imported and import
4) Open Lightroom CC Mobile on iPad Pro
5) Create new album in Lightroom Mobile
6) Select add photos to album
7) Select images from iOS "last import" and add images to Lightroom album
8) Once images are in Lightroom Mobile album I delete images in the iOS "last import" to prevent uneccessary iCloud storage space use
9) That's it, and then Lightroom Mobile proceeds to upload image files to Adobe Creative Cloud. I am allowing unlimited cache size to maintain local copies on iPad Pro. I have never performed clear cache.

When I then review images in Lightroom mobile I initially see message "Smart Preview" in the file information display and after few seconds changes to "original". Full image resolution information is available and displayed correctly. However zoom function is as described above.

Hi again Victoria. I’ve given a detailed verbal description above. What specific information would you like me to capture in screenshots to help along a resolution? Thanks.

Hi Victoria, here is a selection of screenshots. I wasn’t really sure what information to show you. I just updated to version 4.1 and zooming behavior is unchanged.

1) Processed RAW (NEF) file shot on my D850 and imported to Lightroom mobile as described above. As you can see it is original file at full resolution.

I am trying to upload additional images but getting an internal server error. Presumably files exceed 2MB. Not actually sure what additional info I can provide to prove this zooming behavior? I am following a standard approach to get my image files from the camera to Lightroom mobile on the iPad.

Thanks for the detailed feedback, Roy. I've put your thread in front of the Lightroom CC for iOS team for review.  You don't need to upload the additional screenshots that Victoria requested. (unless she really wants to see them...)

Thanks Rikk. Couple of additional observations. I need to check but seems as if initial zoom factor may have changed a bit with the new v4.1? Slightly higher zoom factor >50% but still definitely not 100%. Repeated double tapping still results in 200% zoom. Thing is number of double taps to get to 200% zoom is inconsistent. It can happen quite quickly with some images, but may require multiple double taps in other cases. Once it starts though double tapping will consistently result in 200% zoom. Only way to stop this is to select a new image and go back to previous image again. Then process repeats. I also use Apple Pencil and I think the jump to 200% zoom occurs more readily with that rather than finger tapping. Although behavior also occurs with finger tapping might be less frequent. Either way the initial zoom factor is never a true 100%

Perhaps this is more of a feature request than a problem, but I agree it would be a great feature for “pixel peeping”. Having Lightroom perform consistently / predictably no matter which camera is being used, is a boon. Programmatically it’s actually more complex to adapt to / vary based on camera, than having a basic 100% zoom.

I initially entitled my thread with wording "feature request", but an administrator must have removed that wording. Point is true 100% zoom is supposed to be a supported feature with Lightroom Mobile already, so in that sense it was correct to call this a "problem".

So, I have compared zoom behavior of original files directly uploaded to my iPad from camera to Lightroom mobile with smart previews originally uploaded to my desktop and synced via Lightroom Classic, and the zooming behavior is identical. In Lightroom Mobile on iPad (and in this case with D500 NEF files) double tapping on a newly opened image shows about 2/3rd’s of image along the long axis. On 13” iPad Pro this is a zoom factor of approximately 75% give or take. This zoom factor remains the same regardless of whether I am reviewing original images or smart previews. Repeated double tapping will, as discussed above, eventually result in a significantly higher zoom factor of about 200%. Once again I see exactly same behavior with both smart previews and original files. No difference.

Odd, it sounds as if you’re getting more than two zoom levels upon double-tapping repeatedly. However, I only get two, “fit” and then something that I thought was greater than 100% before, but in hindsight realize it was the smart preview. Upon downloading the original I saw it’s probably 100% . Repeated double-tapping just causes it to go back and forth between “fit” and what I assume now is 100%.

I am using the new iPad Pro 11”, on the latest Developer Beta of iOS, and the iPhone 7 also on the latest Developer Beta. Behavior is the same for both devices, only two zoom levels. I do not use Lightroom Classic and never have. So it causes me to wonder if although the files originated from iOS import, something about Lightroom Classic is mucking up the zoom levels.

I’ve been on the road a few times and uploaded images directly to my iPad from camera and prior to images being synced with Lightroom Classic have exhibited same zoom behavior I have described above. So don’t think the sync to Classic is responsible for the issue. Yes, the normal behavior should be as you describe, but in my case I am indeed getting two different zoom levels.


I’ll clearly summarize how all different types of image tapping options behave for me:


1) Single tap on image toggles between regular view (with menus) and full screen fit - this works fine


Rest below assumes full screen mode as starting point:


2) First time double tapping on newly opened image (two taps in very quick succession) yields a zoom factor < 100% and depends on image file resolution, e.g., in my case with 13” iPad Pro zoom factor is 75% for D500 and 50% for D850 full resolution NEF files respectively. This is the main issue. According to Lightroom Mobile documentation this should provide a true 100% view, but it does not.


3) Repeat double tapping after zooming in returns image to full screen viewing size


4) If I then repeat double tapping to zoom in and out multiple times the zoom factor will eventually pop to 200%. Behavior is same regardless of image file resolution. I will see 200% zoom factor on both D500 and D850 NEF files. The big variable here is there is no consistency in number of repeated double taps for zoom factor to jump to 200%. Sometimes it happens quite quickly, other time I have to repeat double tap many times to get it to happen. However once zoom factor has jumped to 200% then further double tapping will always toggle between full screen view and 200% zoom, never the lower zoom factor that occurs initially. Also seems that jump to 200% zoom happens more readily with Apple Pencil rather than with finger tapping, but can also be induced with finger tapping.

The resolution of my files are 24mp (6000x4000) Leica DNG, and 12mp (4032x3024) Lightroom DNG (taken with my iPhone). On the 11" iPad with a resolution of 2388x1668, 100% zoom on the 24mp image would be 39.8% of the image displayed. It came to mind that I could use Lightroom's 100% calculation behavior itself to trigger the glitch, by forcing it to calculate while changing the orientation of the device. I was able to successfully get the 200% zoom to trigger, and narrowed the steps down to:

1. With Lightroom CC on iPad completely exited from the open tasks, I opened Lightroom CC while holding the iPad in landscape orientation. If Lightroom hasn't been completely closed yet, open an image ... and make sure to close any open panels. Exit the image to get back to grid view. Then completely close the app from the task switcher while you're in grid view, and open it again.
   
   
2. With LR open, I opened one of the 24mp landscape images using a single click. The photo opened in "fit" mode.
   
   
3. Double-tapping the photo caused it to zoom in so that the 1/2 of the image could be seen at once (which is actually less than true 100% zoom).
   
   
4. Double-tapping the photo again causes the image to zoom out to "fit". Subsequent double-taps just cause it to go back and forth between zoomed-in and fit.
   
   
5. While the image was zoomed-in I rotated the iPad to portrait orientation.
   
   
6. While the iPad was in portrait orientation I opened the info panel with the image zoomed-in.
   
   
7. With the info panel open, double-tapping the photo resulted in it zooming out to "fit".
   
   
8. Double-tapping it again causes the image to zoom to 1/4 of the photo's width.
   
   
9. Double-tapping it again causes it to zoom out to "fit".
   
   
10. I closed the info panel while the image was in "fit" and the iPad is held in portrait orientation.
    
    
11. Double-tapping the photo again causes the zoom behavior to break. In my case the zoom showed 1/8 of the image or double the previous 1/4 it was giving. Thus becoming a 200% zoom (not a true 200%, just 200% relative to the previous 100%).
    
    
12. Once the zoom behavior breaks it stays that way, whether the iPad is held in portrait orientation or landscape. It consistently goes back and forth between 200% and "fit".

Those steps do not always trigger the break, but it does it consistently enough for me to call it reproducible. If those steps do not work, exit the app completely and try it again. Or just add rotation to the double tapping to increase the probability of triggering the break. The opening of the panel introduces another level of complexity in calculating the position while calculating the zoom level, further increasing the chance of a break.

Point is, it's reproducible despite having never used Lightroom Classic.

My previous assumption that it was doing a 100% zoom is because I was eyeballing the lower resolution images on a smaller screen rather than actually measuring it. But having measured it I see that at no point was the 100% zoom truly 100%.

I imagine the zoom calculation is taking ppi into account, causing the 100% zoom to be incorrect due to the variance of ppi in displays (that or doing something like dpi to ppi math). If the math were based purely on resolution, I doubt there would be room for glitching.