Invalid Focal Length calculation
Allen
Registered Users Posts: 10,013 Major grins
This is a very popular 1.6 crop camera, how come the Focal Length can not be calculated correctly?
Please remove the "(xxx mm in 35mm)" part as it is not working and useless.
Thanks
Camera Info Camera Canon EOS 7D Mark II Lens EF100-400mm f/4.5-5.6L IS USM Focal Length 285.0 mm (285.0 mm in 35mm)
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Hello?
If Smug can not get this to show correct info please remove (700.0 mm in 35mm) part.
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Hi Allen,
Can you include a link to a specific photo that you see this for (for each lens separately)?
We use the industry standard tool called EXIFTool for handling metadata and to report this to the developer, we may need to pass on your original photo to the developer for inspection. Would this be okay for you?
If you don't wish to share the links to the photos here, you may send us the details on our HelpDesk.
SmugMug Support Hero
Here's two different lens on three different cameras.
https://www.photosbyat.com/Birds/2020-Birding/Birding-2020-October/2020-10-10-RMBS-CBCA/i-w2vgmpH
Camera Canon EOS 7D Mark II
Lens EF500mm f/4L IS USM +2x III
Focal Length 1000.0 mm (1000.0 mm in 35mm)
7D5B1725_7DII4-0.jpg (7D No.4 Photo 01725)
https://www.photosbyat.com/Birds/2020-Birding/Birding-2020-October/2020-October-Yardbirds/i-jBG868Z
Camera Canon EOS 7D Mark II
Lens EF500mm f/4L IS USM +1.4x III
Focal Length 700.0 mm (700.0 mm in 35mm)
7D5B1944_7DII4-0.jpg (7D No.4 Photo 01944)
https://www.photosbyat.com/Birds/2020-Birding/Birding-2020-May/2020-05-26-Western-Kingbirds-WEKI/i-vHvnkHk
Camera Canon EOS 7D Mark II
Lens EF100-400mm f/4.5-5.6L IS USM +1.4x III
Focal Length 560.0 mm (560.0 mm in 35mm)
7D5A3281_7D3-2.jpg (7D No.3 Photo 23282)
https://www.photosbyat.com/Birds/2020-Birding/Birding-2020-June/2020-06-15-Creve-Couer-Marsh/i-WNSNtqc
Camera Canon EOS 7D Mark II
Lens EF500mm f/4L IS USM +2x III
Focal Length 1000.0 mm (1000.0 mm in 35mm)
7D5A3981_7D3-2.jpg (7D No.3 Photo 23981)
https://www.photosbyat.com/Birds/2019-Birding/Birding-2019-December/2019-December-Yardbirds/i-MN8tfP4
Camera Canon EOS 7D
Lens EF100-400mm f/4.5-5.6L IS USM
Focal Length 400.0 mm (628.1 mm in 35mm)
IMG_2063_7D1-6.jpg (7D No. 1 Photo 62063)
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Hi Allen,
Thanks for the details. Could you also update your post with what the 35mm equivalent should be for the specific photo so we're on the same page when reporting this?
SmugMug Support Hero
Canon APS-C dSLRs are a crop factor of 1.6x, so a native focal length should be multiplied by 1.6.
In Allen's examples:
"(1600.0 mm in 35mm)" is the proper and desired reporting result.
"(1120.0 mm in 35mm)"
"(896.0 mm in 35mm)"
"(1600.0 mm in 35mm)"
The Canon 7D appears to be properly reporting oddly but closer to correct. I believe that 640.0 mm is the correct (... at least generally accepted) Full-Frame equivalence.
Moderator of the Cameras and Accessories forums
I reported this in 2016 ( https://dgrin.com/discussion/258227/mis-reporting-35mm-equivalent-focal-length ), and was basically told it was something in my workflow that was creating the issue. Since then I've changed camera, software (to Affinity Photo) and workflow yet the issue still exists. I really cannot see why a simple look-up table and multiplier is not used - after all it is known what crop multipiers apply to each camera.
I'm pretty sure SmugMug is just passing on what ExifTool reports. You can get Exiftool for your computer at https://exiftool.org/. It's not in anyway connected with SmugMug. It looks to me like ExifTool looks just reports on metadata that's already in the file, but I guess there could be a look-up table for crop factors in there. If it's not there, the crop factor or equivalent focal length calculation would have to come from the camera. In any case, you can check what ExifTool reports on your own images as they come out of the camera, as they get walk through software processing, and in the files that get sent off to SmugMug ... and see for yourself if anything changed along the way.
ExifTool by itself is not the friendliest thing to use, but in a Windows environment there's a GUI front end, ExifToolGUI, at https://exiftool.org/gui/ that works well. To show the 35mm equivalent focal length in ExifToolGUI, you will need to check "Show Composite tags in view ALL" in the Options menu, and then go looking for the FocalLength35efl tag toward the bottom of the list on the "ALL" tab at the right for a given file. (The left side of ExifToolGUI has a file-manager-like interface to point at an image; the right side has various partial metadata displays and one complete one labeled ALL.)