I received the following email:

Hi Mr. Mills,

Some time ago, I contacted a developer of your cousin project exiftool, because I had managed to decode some private Nikon data when using a radio flash trigger, showing some settings for each group. This person completed my findings, asking for images with certain combinations of settings, and added the result to their project.

In the meanwhile, I'm using only darktable which is based on exiv2, where this information is not available.

Is there any possibility to get Exif.Nikon3.FlashInfo also decoded in exiv2?

Thanks

Christoph

Here is my reply:

Christoph

Thank You for your email. Exiv2 has a good and friendly working relationship with Phil Harvey. An excellent engineer and very nice person.

In June, I retired from Exiv2 and will leave it to others to support and develop Exiv2 in future. I volunteered to be the release engineer for v0.27.5 which is scheduled for release on 2021-10-22. I released Exiv2 v0.27.5 RC3 today. So, I’m almost out of the project.

I recommend that you open a new issue on https://github.com/exiv2/exiv2 requesting these features. Please attach your sample files. Any information you have concerning Nikon3.FlashInfo will be appreciated. Phil has probably documented this on his web-site.

The tag is known to Exiv2:

580 rmills@rmillsmm-local:~/gnu/exiv2/team $ taglist ALL | grep Exif.Nikon3.FlashInfo Nikon3.FlashInfo,168,0x00a8,Nikon3,Exif.Nikon3.FlashInfo,Undefined,"Flash info" 581 rmills@rmillsmm-local:~/gnu/exiv2/team $ 

We don’t decode it. Here’s an example with my D5300:

584 rmills@rmillsmm-local:~/gnu/github/exiv2/0.27-maintenance $ exiv2 -g FlashInfo ~/Stonehenge.jpg Exif.Nikon3.FlashInfo Undefined 49 48 49 48 54 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 585 rmills@rmillsmm-local:~/gnu/github/exiv2/0.27-maintenance $ 

So there are 49 bytes which are "0106\0......\0". I know the flash was not used on that photo. I see there are notes relating to this tag here: https://exiftool.org/TagNames/Nikon.html#FlashInfo0106

I hope the people working on Exiv2 will help you. Please remember they are all volunteers with jobs, family and other demands on their time. In anticipation of retirement, I spent 6 months last year writing a book: Image Metadata and Exiv2 Architecture https://exiv2.org/book/index.html So how to deal with this is documented and I am willing to mentor/assist anybody who volunteers.

If you have good C++ skills, you may enjoy the challenge to bring this feature to life by joining Team Exiv2. I assure you of my support and assistance.

Robin

Christoph replied and declined my invitation to undertake this work. He didn't want to open an issue as he knows nothing about git. So, I offered to open this issue.