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Author Topic: Changing capture time and other date fields in CR2 and NEF Raw Files  (Read 12350 times)
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« on: February 25, 2010, 10:35:07 AM »


In a recent vacation, I set my camera to UTC time to make life easier later down the road if I want to geotag. I did that and now I find myself in a situation where I need to change the capture time and other date fields in the CR2 and NEF files that I got. The problem is that I'm not sure which is the best tool to do this. I've been asking a lot of questions lately, but I'm still not convinced the method is the right one to go. I'm mainly afraid of corrupting the files that I got.

One of the tools that I was told to use is ExifTool. I've contacted the programmer, Phil Harvey, and he was very helpful, but he can't provide any guarantees that his tool will not corrupt the RAW files that I have. Because I have literally thousands of photos, he told me to use the following command line to change the dates (directory will be different obviously)

exiftool -overwrite_original " -alldates+=8 -ext nef c:\images

Has anyone here used ExifTool to change the date fields in CR2 and NEF files before? What if some of my pictures were taken at 22:00. If I add 8 hours, then clearly that's a new day. Will ExifTool be smart enough to fast forward one day for the pictures that were taken from 14:00 (UTC) and onward?Any comments on the reliability of the program? How many date fields are there in CR2 and NEF files? I got the impression from Phil that CR2 and NEF files have the exact 3 date fields. I need to change it all to as if I set the date and time correctly in the first place. Does anyone here understand exactly what I want to do?

I realize that LR2 can change the capture dates, but I'm currently in the middle of organizing my files. My goal is to fix the date problems of the CR2 and NEF files, then convert and embed the originals to DNGs, before I catalog them with LR2. One last thing and that is I don't want to create any XMP sidecar files! I can't stress that enough. I'm sure the whole XMP sidecar pros and cons have been debated to death and I don't want to get into it. One of the reasons why I want to go down the road of using DNS is because I don't have to deal with sidecar files. I want to permanately change the date fields of my RAW files in a standard compliant way without corrupting the Raw files. What this ultimately means is that regardless of which program I use, the correct time and date will be displayed. I hope everyone here understands the point of my post and help me resolve my problem. Thx!
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« Reply #1 on: March 02, 2010, 05:11:29 PM »

Hello lsquare,

I have great confidence in Phil's ExifTool -- he is a very conscientious developer. I have used it personally, and since Geotagalog uses it internally to losslessly change metadata (and even specifically sets one of the time fields using it), I know many customers have used it successfully as well. And both CR2 and NEF are quite common RAW formats and any problems with something basic like timestamps are very likely to have been found by now. Of course, you should always have backups anyway. (And in the upcoming version of my software I mentioned, when I overwrite originals I have it double check the results before removing a temporary backup - just to be extra paranoid.)

The -AllDates+=8 option will properly adjust the dates across days like you ask. The one thing I might personally disagree with is changing all the dates. I prefer to change just DateTimeOriginal and leave the others as they were in camera (eg -DateTimeOriginal+=8 instead of -AllDates+=8, which would also change CreateDate and ModifyDate). Among other reasons, if I pick the wrong timezone adjustment for any of them I can more confidently re-adjust them. You'd want to test this, but most apps use the EXIF "original" date for display and sorting, so you would have both the original UTC date available but you would be using your photos in the local timezone you want.

hope this helps,
Nathan V.W.
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« Reply #2 on: March 05, 2010, 10:16:02 PM »

lsquare (please sign your post, per forum rules),
I suggest you do that with Lightroom. You can do it with a catalog that you use and then throw away, of you wish, or use that catalog to convert the files to DNG.
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