I recently took some HDR shots and am fairly new at this. Three images are shot. My problem is my Canon T1i doesn't really differentiate them from one-shot shots (same numbering scheme). Is there something I am missing that would help me filter these tri-shots out so I don't end up deleting one of the set when pruning the day's shots (besides being more mindful)? Like an EXIF attribute? What is your work flow from camera to just before you open an HDR program to process them?
I also shoot with a T1i, but I'm not really understanding the issue you're having.
EDIT: Re-read it a few times, and now I think I'm understanding.
If you're talking about the file name number system IMG_XXXX, then I think you're stuck with it. Like you said, you'll need to be more mindful of what you're deleting, and it's probably best that you don't do it on the camera, but on your computer.
The only possible giveaway (and I'm not 100% sure about this, and don't have immediate access to my camera at the moment) might be info in the EXIF that identifies +/-EV. If that's recorded, then you can identify where each shot belongs in the series, so long as you remember how many shots you took. (On second thought, this information must be recorded somewhere, because it appears when you review pictures on the camera's LCD. Still though, I wouldn't suggest pruning on the camera.)
My process: Usually, at the end of the day, I'll import everything into iPhoto, delete what I don't want, and then format the card using my camera. From there, I'll export the RAW files to a folder, and dump them straight into Photomatix or Photoshop to make the HDR comp.
From looking at the exif data from a few sets (three shots), two exif values seem to change (while most others remain the same): exposure time and exposure bias. The exposure bias seems to be most obvious clue, being something like 0, -1, 1 or 0, -2, 2 in the first, second, and third shot. If the ISO speed, f-stop, and lets say the focal length are the same, I'm guessing we could assume it's likely there are three shots that can make a HDR image.
I'm obviously a computer programmer who's wanting to automate this process of grouping each set of three shots into a group, and then later process them into an HDR image. Leading back to me asking what are the similarities/differences between the three shots.
@jeancarl I think you're on the right track, and I think this is a pretty awesome idea! I would love something like this to be built into iPhoto or Lightroom, but I haven't seen anything like it yet.
Like you said, the exposure bias should be available in the EXIF, and the shutter speed is the only variable setting -- so long as you're using AEB and shooting in manual or aperture priority mode.
You might also want to consider finding a way to group shots with more than three exposures. Maybe all the way from -4 to +4, since that's the highest you can go on the T1i -- and probably the highest you should ever really need to go.
I've seen a tip that before you shoot a set of HDR or panorama shots, take a picture of your hand before and after. Then you know that between the shots of your hand are a set you need to combine.
@jeancarl I do not think the camera records any data that says "this is a part of group 'x'" You could potentially write a routine which reads the exposure compensation in the exif info. If it finds an ev that is +or- it would then read adjacent shots within a specified time differential and group these. Not foolproof, though.
I copy all my photos at the end of shooting into folders dated and named. If there is any subgrouping, I create sub folders, such as HDR to process.
@mikew I've done that a couple of times, but it just adds complexity and you have to remember to do it and delete those extra shots (which uses disk space!). ;-)
@lilbudhha getting a little technical here, I look at the combination of f-stop, iso, and focal length to group adjacent images together. They have remained constant for all the test shots I did. For my use, I look at the adjacent neighbors to see if they have three different exposure bias values.
Some issues:
- @gurry mentioned more than three images can be created. Haven't looked at when that happens, but a good corner case to keep in mind.
- the exposure bias can actually be all >= 0 or all /
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EDIT: Re-read it a few times, and now I think I'm understanding.
If you're talking about the file name number system IMG_XXXX, then I think you're stuck with it. Like you said, you'll need to be more mindful of what you're deleting, and it's probably best that you don't do it on the camera, but on your computer.
The only possible giveaway (and I'm not 100% sure about this, and don't have immediate access to my camera at the moment) might be info in the EXIF that identifies +/-EV. If that's recorded, then you can identify where each shot belongs in the series, so long as you remember how many shots you took. (On second thought, this information must be recorded somewhere, because it appears when you review pictures on the camera's LCD. Still though, I wouldn't suggest pruning on the camera.)
My process: Usually, at the end of the day, I'll import everything into iPhoto, delete what I don't want, and then format the card using my camera. From there, I'll export the RAW files to a folder, and dump them straight into Photomatix or Photoshop to make the HDR comp.
Hope that helps.
From looking at the exif data from a few sets (three shots), two exif values seem to change (while most others remain the same): exposure time and exposure bias. The exposure bias seems to be most obvious clue, being something like 0, -1, 1 or 0, -2, 2 in the first, second, and third shot. If the ISO speed, f-stop, and lets say the focal length are the same, I'm guessing we could assume it's likely there are three shots that can make a HDR image.
I'm obviously a computer programmer who's wanting to automate this process of grouping each set of three shots into a group, and then later process them into an HDR image. Leading back to me asking what are the similarities/differences between the three shots.
Like you said, the exposure bias should be available in the EXIF, and the shutter speed is the only variable setting -- so long as you're using AEB and shooting in manual or aperture priority mode.
You might also want to consider finding a way to group shots with more than three exposures. Maybe all the way from -4 to +4, since that's the highest you can go on the T1i -- and probably the highest you should ever really need to go.
I copy all my photos at the end of shooting into folders dated and named. If there is any subgrouping, I create sub folders, such as HDR to process.
@lilbudhha getting a little technical here, I look at the combination of f-stop, iso, and focal length to group adjacent images together. They have remained constant for all the test shots I did. For my use, I look at the adjacent neighbors to see if they have three different exposure bias values.
Some issues:
- @gurry mentioned more than three images can be created. Haven't looked at when that happens, but a good corner case to keep in mind.
- the exposure bias can actually be all >= 0 or all /