Mis-Reporting 35mm Equivalent Focal Length

MidlandDeltic

Hi. I'm currently trialling Smugmug, but have noticed an error on my shots. The photo linked below was taken with my Canon EOS1000D, an APS-C format camera, and my 75-300mm lens at full zoom. The 35mm equivalent should therefore be around 480mm, but the photo info tab shows it as 300mm.

Am I missing something, or is it a bug?

Regards

MidlandDeltic

https://midlanddeltic.smugmug.com/Ireland-Classes/IÉ-071-NIR-111-Classes/i-GfGcbHC/A

leftquark

Welcome to SmugMug MidlandDeltic!

It looks like something is off within the metadata of the image. We use a tool called "ExifTool", which is regarded as the best tool available to read metadata from a file, to pull the metadata from the photos. I ran your image through ExifTool and it's unable to compute the 35mm equivalent. Their documentation says that sometimes resizing the image can throw off the 35mm equivalent calculation. It looks like you exported the photo from MS Paint? It's also possible that Paint stripped some of the metadata used to properly calculate the 35mm equivalent. If you wouldn't mind uploading the original photo, I can dig deeper into whether or not this is a bug with ExifTool or with the way the photo was resized.

MidlandDeltic

Hi. I've just uploaded another new copy straight out of RAW conversion using Canon's DPP software - link below.. It's still showing as 300mm eqivalent. The image was not resized after RAW conversion. I use paint.net (not MS Paint) purely to apply the copyright text; no editing is done in that software, and the images are saved at 100% quality / no compression.

I have also uploaded a RAW conversion of a totally unedited file staraight out of the camera (no rotation, resizing, lens correction, sharpening etc) which also shows the incorrect equivalent.

I hope that helps.

Regards

Midland Deltic

Edited in DPP
https://midlanddeltic.smugmug.com/Trip-Sets-Ireland-Rail/Portlaoise-Trains-31052016/i-G5p8nWX/A

Unedited in DPP
https://midlanddeltic.smugmug.com/Trip-Sets-Ireland-Rail/Portlaoise-Trains-31052016/i-KWBRrHt/A

leftquark

I suspected that something was getting stripped from the metadata when you exported from DPP or paint.net. If you look at the Unedited photo you'll notice that we're properly detecting its 35mm equivalent ("300.0 mm (485.6 mm in 35mm)"). Moving to the other ones, which were edited, they don't show the proper focal length. It looks like DPP or paint.net is stripping the crop factor metadata from the files

MidlandDeltic

Interesting. So if I just do a jpeg conversion in DPP it's OK, but if I edit it isn't. It seems strange that this hasn't been picked up before. Anyway, not much I can do about it - just goes on the lists of pros and cons. In itself it's not an issue, but it is misleading for viewers compared to others.

Thanks for your prompt responses.

Regards

MidlandDeltic

leftquark

We have an amazing plugin for lightroom that will let you upload your photos to SmugMug straight from lightroom. You can edit your photos in Lightroom and then watermark them just before publishing to SmugMug and it won't strip the metadata. Alternatively, if you have a Portfolio or Business plan on SmugMug, you can let us watermark the photos for you.

MidlandDeltic

Thanks. Unfortunately I am on a severely limited budget, and I am generally limited to free products. I have stretched to a Power plan on here, but cannot justify the costs of Adobe Photo Cloud as well when I have a product that just works.

As I have imported my collections from from Flickr, I will be gradually replacing them with re-edited versions so I can add the info back in Windows Explorer prior to upload when copyrighting.

Thanks again for your help.

Regards

MidlandDeltic

edurant

I seem to be having the opposite problem with JPEGs exported from Lightroom for Mac (current version 6.8). I'm shooting with a full frame camera (Canon 1D X), but my focal lengths are getting multiplied by about 1.4. For example, here's one with a 135mm lens reported as 188.2mm equivalent, but it should just be 135mm. Is this a bug in Lightroom? Thanks. https://edurant.smugmug.com/MSOE/Sports/Volleyball/2017-03-08-MSOE-Men-v-Cardinal-Stritch/i-nWmmbRM