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09-14-2016, 05:56 PM   #1
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Batch EXIF extraction or analysis?

Is anyone aware of a tool or method to do an extraction of EXIF data from a batch of photos?

I took some photos at an engagement party held inside a house. I ended up using a number of lenses that spanned similar focal lengths. Using exposure plot I can get a histogram of the focal lengths I used (as well as shutter speed and aperture although the ISO data seems lost). But what I also wanted to do is get a histogram of the number of shots taken with each of the lenses. Any suggestions on how to do this, either by batch extracting EXIF data from the raw files into a large table, or some other analysis tool?

09-14-2016, 06:04 PM - 1 Like   #2
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You could probably do what you want with ExifTool. I don't use it enough though to help you out.

ExifTool by Phil Harvey

Last edited by Not a Number; 09-14-2016 at 06:16 PM.
09-14-2016, 07:32 PM - 1 Like   #3
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QuoteOriginally posted by Not a Number Quote
You could probably do what you want with ExifTool. I don't use it enough though to help you out.

ExifTool by Phil Harvey
More specifically, you can use the -csv or -T flags to create a comma- or tab-delimited list and output as a text file which you can then use as your source data for the plot/graph utility of your choice. This will also allow you to include ISO if you so desire, or any of the other metadata in the files. For more info, check the FAQ, item #12, on exporting to a database:

ExifTool FAQ

--Steve
09-14-2016, 07:42 PM   #4
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Thank you @ashurbanipal and @not_a_number as I wasn't aware of this tool. Now I just need to figure out how to insert command line options into the windows executable version but I"m sure this is in the faq.

Ok, mostly figured it out, except the -csv tag to get a single output file rather than .txt files for every image!

---------- Post added 09-14-16 at 11:17 PM ----------

Sweet - figured it out using a command prompt window (only way to do it). Now it is a matter of filtering the massive amount of data it has extracted or to get more clever with the options I pick.


Last edited by MSL; 09-14-2016 at 07:57 PM.
09-14-2016, 08:22 PM   #5
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Glad you figured it out! Once you have your options figured out, you might consider setting up a script for those options. I have a few scripts that I use (sometimes I want ISO, sometimes I don't; sometimes I need to see the flash settings, but usually I don't--you get the idea). Not sure how you do that on Windows these days--I used to use old-school batch files but that was on XP. Probably still work, but I would think newer versions of Windows have better options.
09-14-2016, 08:28 PM   #6
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Any kind of plotting has so many variables and makes it time-consuming and inconclusive - at least in my experience. Do you count all marginal images, or just the top 10 or 20% ? If you shoot bursts to cover the shot, should those be counted as one, etc.

In the past, I used the Pentax software to save the exif into a database. The software does not play well with others, so I have switched to Breeze Browser. It exports each image into its own file, or all into one. I do have to rename that txt file as csv to import into the Open Office spreadsheet and all is well - after adding an apostrophe before the shutter speed because the spreadsheet wants to do some math on it.
09-14-2016, 08:42 PM   #7
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Well I hear what you are saying, but in this case I was trying to answer a couple of questions. For background I used 3 lenses - 50/1.7, 18-55 WR and Tamron 28-75/2.8. I am curious whether I used the 18-55 or 28-75 more, and how many photos were taken around 35mm, since I keep trying to talk myself into the DA35/2.4. I took about 215 shots that night, of which 200 were good enough that I put them on a disk for one of the families to use as they like, and 40 of which made it into a photo book I put together for the couple. I didn't take any bursts. So my histogram analysis is based on the 200 shots I was willing to share even if they aren't all great.

Exposure plot very quickly told me how few photos I took at 35mm, so for a venue like this one it won't be a critical lens to have (the 50 is too long and didn't get used beyond the first few photos I took that night).
The other thing I will do, time permitting, is look at which lens was used for the 40 "best" shots that made the photo book. I still have mixed thoughts about the Tamron lens and whether I want to keep it.
09-14-2016, 11:43 PM - 1 Like   #8
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Time sequence relative to focal length is important. If you took 33% of the shots at 35mm but changed focal length every other shot, then a 35mm fixed focal length may not fit. On the other hand if you shot 20% with a lens that you use in short spurts is more practical to replace with a fixed focal length lens.

09-15-2016, 07:37 AM   #9
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QuoteOriginally posted by UncleVanya Quote
Time sequence relative to focal length is important. If you took 33% of the shots at 35mm but changed focal length every other shot, then a 35mm fixed focal length may not fit. On the other hand if you shot 20% with a lens that you use in short spurts is more practical to replace with a fixed focal length lens.
That too is a good point and I should do a sequence plot.

What I have found is that about 15% of the shots were taken at 18mm (lower limit of one lens) and 20% at 28mm (lower limit of the other lens, although some may have been taken using the 18-55).
Very few shots were taken at 35, but quite a few at 33 or 37 (14% in total across the 3 focal lengths).

Lots to ponder should I ever have money for significant lens purchases
Thanks.
09-15-2016, 08:34 AM   #10
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QuoteOriginally posted by MSL Quote
What I have found is that about 15% of the shots were taken at 18mm (lower limit of one lens) and 20% at 28mm (lower limit of the other lens, although some may have been taken using the 18-55).
I think this is a typical usage; a lot of shots taken as wide as you can get, presumably because you might have liked to get wider, but had reached the limit of that lens.
09-15-2016, 08:43 AM   #11
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If I had a CSV file, I'd probably utilize Excel to sort, filter, review, plot, etc. the data.

In my own mind, if I was concerned with 35 mm, I'd count 33 and 37 as being essentially 35. Many zoom lenses are not exact at how they identify focal lengths that are not at the extremes. I had noted that one zoom I had would report focal lengths on 4 mm spacing. I don't remember which, but when I plotted over a large range of photos, the photos dropped on specific points rather than smoothly. It makes sense, but if you have a lens that may only report 33 and 37 mm, then 35 may not be a possible reporting point.

Just something to keep in mind if you really need to statistically show you need a 35 mm lens. Plus, if you had a 35 mm lens on the camera, you would just step back or forward a step or two to frame the shot you would have had for those that are actually at 33 or 37 mm (or even a bit more or less).

Aside, I tried to do something similar to justify getting the 31/1.8. When I looked at the statistics, I rarely shot at that focal length. I still wanted the lens, so I got it. I now mostly shoot with that lens. I just use my feet more, and I actually think I compose my images better. Never-mind that shooting at apertures faster than 2.8 with that lens is just fantastic.... sorry for digressing.
09-16-2016, 05:21 AM   #12
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QuoteOriginally posted by emalvick Quote
Plus, if you had a 35 mm lens on the camera, you would just step back or forward a step or two to frame the shot you would have had for those that are actually at 33 or 37 mm (or even a bit more or less).
Well yes and no. This was a very crowded house setting. I often couldn't move back further due to lack of space or because I'd have to step on people or move them aside to get the shot.

I'm not overly fretting the specifics any one focal length. (Nor am I dreaming of a day where I might shoot with a 31/1.8 or some other gem of a lens.) But I can see doing more events like this one, and I've been wondering whether to keep the Tamron or not, so in that context I wanted to do some basic analysis, which I've started. For example, I didn't even know if I'd used the Tamron or 18-55 more over the 3+ hours I was there, and also how much I used the Tamron at focal lengths above 50 or 55 (which might point to getting a better lens in the 16-50 range).

Thanks for the helpful suggestions.
09-16-2016, 08:38 AM   #13
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QuoteOriginally posted by MSL Quote
Well yes and no. This was a very crowded house setting. I often couldn't move back further due to lack of space or because I'd have to step on people or move them aside to get the shot.

I'm not overly fretting the specifics any one focal length. (Nor am I dreaming of a day where I might shoot with a 31/1.8 or some other gem of a lens.) But I can see doing more events like this one, and I've been wondering whether to keep the Tamron or not, so in that context I wanted to do some basic analysis, which I've started. For example, I didn't even know if I'd used the Tamron or 18-55 more over the 3+ hours I was there, and also how much I used the Tamron at focal lengths above 50 or 55 (which might point to getting a better lens in the 16-50 range).

Thanks for the helpful suggestions.
My point was more in the accuracy of how the focal lengths are reported. When you zoom a lens in and out, it isn't like there are obvious stopping points at each focal length. The camera and lens have to interpret a focal length. My comment was just that some of those 33 mm or 37 mm could be in reality 35 mm shots.

Frankly, if you are shooting indoors, I can understand needing wider, in which case I'd stick with the zoom lens. But, I would caution that as you shoot wider, be aware that people can get distorted funny, especially when you are wider than 20 mm. My Tamron 17-50 has generally been ok at the 17 mm end, but I've had to work hard in some situations to undo distortion making people look a bit shorter than they are. Anyway, it's just a suggested awareness.

Finally, while the 31 mm may be out of reach, I have found that focal length to be great for indoor shots of people. It isn't always wide enough, but I find that it does a better job of capturing the moment than having a wider angle does. In that regard, you might consider investigating the potential for something like a 30 mm (Sigma has one) or even an older 28 mm, if you are looking for a prime lens.
09-16-2016, 09:46 AM   #14
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QuoteOriginally posted by emalvick Quote
My point was more in the accuracy of how the focal lengths are reported.
Funny you mention this. I haven't dug deeply into the data, but there are cases where the recorded FL and the recorded FL for SR purposes differ a bit. Not sure which value should be thought of as the accurate one.

I wouldn't shoot a single person at 18mm, but for 2-3 people it was definitely helpful, and I think I was far enough away to reduce the distorted effects. Of course, if I wanted to go down that road, there is the 10-17 mm fisheye
09-16-2016, 11:25 AM   #15
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QuoteOriginally posted by emalvick Quote
My point was more in the accuracy of how the focal lengths are reported. When you zoom a lens in and out, it isn't like there are obvious stopping points at each focal length. The camera and lens have to interpret a focal length. My comment was just that some of those 33 mm or 37 mm could be in reality 35 mm shots.
The EXIF record is based on the value the lens sends. ADDENDUM: For some lenses the steps are fairly course. For others, fairly fine.


Steve

Last edited by stevebrot; 09-16-2016 at 11:43 AM.
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