Welcome, Guest. Please Login or Register
Home Help Search Login Register
Page Index Toggle Pages: 1
Send Topic Print
Fixing Exposure Time Metadata (Exif) in Canon Bulb-Mode (Read 5292 times)
Peter Ruschel
Ex Member


Fixing Exposure Time Metadata (Exif) in Canon Bulb-Mode
08/10/12 at 08:54:40
 
Hey Friends,
I was wondering if you know of a good way to fix/edit/manipulate the Exif-Information in the RAW-Files that come from my Canon 5D classic (.CR2)
I run into the comnon problem of shooting an HDR-Bracket-Sequence in Bulb-Mode but the 5D only records roughly rounded exposure times above one second (> 1 sec.)
E.g. for a sequence that is timed at 0.1, 0.2, 0.4, 0.8, 1.6 etc  I get Metadata of  1.0, 1.0, 1.0, 1.0, 2.0 etc.
Meaning, everything unter a second gets rounded to a second and everything above gets rounded to the next integer as well...

Anyways, anybody know a good solution for cheating the values in manually later, so that the HDR-stacking has proper EV-data to work properly??

Best regards, Peter
Back to top
 
 
IP Logged
 
davidb
Ex Member


Re: Fixing Exposure Time Metadata (Exif) in Canon Bulb-Mode
Reply #1 - 08/10/12 at 10:26:52
 
I would probably leave my raw files alone and convert to 16 bit tiff with something like dcraw, then use exiftool to change the metadata.

exiftool might be able to work on the raw files directly, but I have never tried that as I prefer to leave the originals alone.
Back to top
 
 
IP Logged
 
Peter Ruschel
Ex Member


Re: Fixing Exposure Time Metadata (Exif) in Canon Bulb-Mode
Reply #2 - 08/10/12 at 12:04:43
 
Thanks for the hint - i'll try that today.
You're propably right about leaving the Raw file alone..

About converting in Cdraw: Are you using a particular setting and is it a 16bit float or INT format?
Back to top
 
 
IP Logged
 
davidb
Ex Member


Re: Fixing Exposure Time Metadata (Exif) in Canon Bulb-Mode
Reply #3 - 08/10/12 at 12:13:23
 
I think the command line you need is

dcraw -w -W -t -6 FILE

-w tells it to use camera white balance
-W tells it not to do histogram modification
-t tells it to output tiff
-6 asks for 16 bit.

You should get a 16 bit integer tiff.
Back to top
 
 
IP Logged
 
Peter Ruschel
Ex Member


Re: Fixing Exposure Time Metadata (Exif) in Canon Bulb-Mode
Reply #4 - 08/11/12 at 15:47:11
 
Thanks for the directions, David. It worked fine so far.

Figuring out how to get exiftool to edit the shutter speed was another little adventure. But it also works now:

After testing with tiff and RAW (.CR2) i'm going for the route of editing the shutter speed in the Raw right away (keeping a backup - exiftool makes backups automatically)

Looking at this setup now, it seems very tedious to hack in all the proper values after shooting... i'm currently also looking into using gPhoto2 to do the shooting instead of the remote (Phottix Aion), but I must still figure out if i can speed up the shooting process with a more tricked out batch-script for gPhoto2.

I'll post some results it i find them.

Thanks again,
peter



Back to top
 
 
IP Logged
 
Blochi
Administrator
*****
Offline



Posts: 1726
Hollywood
Re: Fixing Exposure Time Metadata (Exif) in Canon Bulb-Mode
Reply #5 - 08/12/12 at 23:25:21
 
Well, Lightroom 4 also has the ability to edit EXIF data. I would think if you adjust the window width to show exactly one exposure bracket per row, you can rather quickly mass-apply such edits to a column selection or just use the metadata spray can.
Back to top
 
WWW  
IP Logged
 
gvjump
Ex Member


Re: Fixing Exposure Time Metadata (Exif) in Canon Bulb-Mode
Reply #6 - 07/04/13 at 04:36:40
 
thank you for giving software that is so powerful. i'd like to adjust the width and height of the image
Back to top
 
 
IP Logged
 
arronlee
Ex Member


Re: Fixing Exposure Time Metadata (Exif) in Canon Bulb-Mode
Reply #7 - 07/24/13 at 09:22:38
 
Hi, gvjump.
I have never used the tool you mentioned above brfore? Could you give us more details aboiut its processing? As for myself, I used to process images with the help of another
image processing SDK
. It is just one of many but I do appreciate its simple way of processing. Even though I only tried its free trial package to adjust the width and height of the image and didn′t check the cost and licensing conditions, it worked great for me. Besides, this site gives a lot of
tutoials
for processing different kinds of document and image formats using VB.NET. Share with you. And I hope you success. Good luck.



Best regards,
Arron
Back to top
 
 
IP Logged
 
Page Index Toggle Pages: 1
Send Topic Print