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Thread: Working without Exif

  1. #1
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    Working without Exif

    Hi,

    I am doing lots of nodal point panoramas, and the stitching software wants to know the focal length of the lens used. It reads it from the Exif data. This data is not present if using a tech cam.

    When working with a tech cam, I am wondering how you can know which lens was used with which photo ? (I assume I can't recognize the lens by it's "drawing" simply by looking at the picture :-) ).

    Here are a few ideas I came up with:

    - Take notes with pencil and paper. Sounds awfully low tech :-)

    - Take a picture with the tech cam of a piece of paper (or iPhone with the notepad), on which you have written the settings. Do this each time you change lens / settings (if you want to record what aperture was used). Awful lot of Mpix used to record Exif, but you can delete those pictures once you have added the info to the Exif data in Lightroom (or something else). Advantage is that if you sort the pictures by capture time, it should be easy to sync the Exif for all the pictures you took in one go with one lens / setting. For the moment, this sounds the easiest solution.

    - Take photographic notes with the iPhone. So for example take a picture of the lens (aperture / exp time) every time you change a setting. If the digital back and iPhone have the same clock time, then you should be able to figure out which picture on the DB was taken with which setting. Maybe even importing the iPhone images into Lightroom and sorting by capture time allows to achieve the same results as the previous method.

    - If you have an IQ back, use the star system to code for the lens (e.g. 1star -> 32mm, 2 stars -> 50mm or something like that).

    - Maybe there's a way to recognize the LCC shots, which are needed ? I don't have enough experience about that to say.

    - Any other ideas ? How do you do it ?

    BTW, I found this Lightroom plugin, which seems to do what I want (modify Exif data for focal length in lightroom), once the lens is identified:
    LensTagger now with Analog Camera & Film support

    Thanks in advance !

  2. #2
    Senior Member alajuela's Avatar
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    Re: Working without Exif

    Quote Originally Posted by miska View Post
    Hi,

    I am doing lots of nodal point panoramas, and the stitching software wants to know the focal length of the lens used. It reads it from the Exif data. This data is not present if using a tech cam.

    When working with a tech cam, I am wondering how you can know which lens was used with which photo ? (I assume I can't recognize the lens by it's "drawing" simply by looking at the picture :-) ).

    Here are a few ideas I came up with:

    - Take notes with pencil and paper. Sounds awfully low tech :-)

    - Take a picture with the tech cam of a piece of paper (or iPhone with the notepad), on which you have written the settings. Do this each time you change lens / settings (if you want to record what aperture was used). Awful lot of Mpix used to record Exif, but you can delete those pictures once you have added the info to the Exif data in Lightroom (or something else). Advantage is that if you sort the pictures by capture time, it should be easy to sync the Exif for all the pictures you took in one go with one lens / setting. For the moment, this sounds the easiest solution.

    - Take photographic notes with the iPhone. So for example take a picture of the lens (aperture / exp time) every time you change a setting. If the digital back and iPhone have the same clock time, then you should be able to figure out which picture on the DB was taken with which setting. Maybe even importing the iPhone images into Lightroom and sorting by capture time allows to achieve the same results as the previous method.

    - If you have an IQ back, use the star system to code for the lens (e.g. 1star -> 32mm, 2 stars -> 50mm or something like that).

    - Maybe there's a way to recognize the LCC shots, which are needed ? I don't have enough experience about that to say.

    - Any other ideas ? How do you do it ?

    BTW, I found this Lightroom plugin, which seems to do what I want (modify Exif data for focal length in lightroom), once the lens is identified:
    LensTagger now with Analog Camera & Film support

    Thanks in advance !
    Great question - you really explained it well. - I have been using a note pad and a pen and using my watch as a time stamp. For some reason unknown to anybody but god the file number does not appear on the back - only the shot count. When I change lenses or movements I make a note of the time stamp. If tethering I bring up note pad and enter there. As an additional aid I shoot an LCC before I make a change in movements to remind me, to look at my notes

    I actually though of using a small white board and writing down the information and then taking a capture of that.

    I hope that there is great answer that I have completely over looked, preferably in C1. Also I don't know a way to to enter the Exif data in batch form - say for shots (files) at one time which have same setting.

  3. #3
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    Re: Working without Exif

    Hi Miska -

    The stitching software will work out the focal length of the lens itself (it's never what the EXIF says anyway).

    Have you tried just ignoring it, and seeing what happens? I'm pretty sure it should just stitch fine. The only thing you need to be careful of is specifying whether it's a fisheye lens or not.

    Kind regards,

    Gerald.

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    Re: Working without Exif

    Quote Originally Posted by gerald.d View Post
    Hi Miska -

    The stitching software will work out the focal length of the lens itself (it's never what the EXIF says anyway).

    Have you tried just ignoring it, and seeing what happens? I'm pretty sure it should just stitch fine. The only thing you need to be careful of is specifying whether it's a fisheye lens or not.

    Kind regards,

    Gerald.
    Interesting ! I have used, on my Canon, a Samyang 14mm lens, which doesn't tell the camera the focal lens. The stitcher (Autopano Pro) gave garbage results until I told it the lens was 14mm. BUT maybe there's an option in Autopano to just figure out the focal length and not rely at all on Exif data. I'll check. Thanks for the tip - that would simplify my workflow significantly.

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    Re: Working without Exif

    Quote Originally Posted by miska View Post
    Interesting ! I have used, on my Canon, a Samyang 14mm lens, which doesn't tell the camera the focal lens. The stitcher (Autopano Pro) gave garbage results until I told it the lens was 14mm. BUT maybe there's an option in Autopano to just figure out the focal length and not rely at all on Exif data. I'll check. Thanks for the tip - that would simplify my workflow significantly.
    I've just run a quick test, stitching 12 shots from a Mamiya 24mm FE on the FPS (so no EXIF data at all).

    Autopano Giga defaults to 50mm lens. I told it it was a fisheye, and it stitched perfectly, with a computed focal length of 14.7mm (that's in 24x36 FoV terms of course).

    I had a chat with Joost (programmer of PTGui) about this earlier in the year, as I couldn't for the life of me understand how the software can work out the focal length. Basically, it's calculated from the way the images have to be warped in order to stitch. You only need two overlapping images for the software to determine the precise focal length.

    Kind regards,

    Gerald.

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    Senior Member Pemihan's Avatar
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    Re: Working without Exif

    In my Leaf Aptus I can enter the focal length used and it will then be present i the Exif data.

    Peter
    Peter
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    Senior Member alajuela's Avatar
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    Re: Working without Exif

    Quote Originally Posted by Pemihan View Post
    In my Leaf Aptus I can enter the focal length used and it will then be present i the Exif data.

    Peter
    Hi Peter
    Can you enter it in batch form - Or you have to do each file individually?
    Thanks

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    Re: Working without Exif

    Just done another to make absolutely sure. This time 44 shots from a 32HR (these are all full 360x180 spheres I'm doing).

    Computed focal length of 20.7mm.

    Autopano Giga works just fine without any EXIF.

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    Re: Working without Exif

    Quote Originally Posted by gerald.d View Post
    Just done another to make absolutely sure. This time 44 shots from a 32HR (these are all full 360x180 spheres I'm doing).

    Computed focal length of 20.7mm.

    Autopano Giga works just fine without any EXIF.
    Excellent ! Thanks a lot for this info !

  10. #10
    Senior Member Pemihan's Avatar
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    Re: Working without Exif

    You enter it once and then the back writes it to every file until you change or delete the input.
    (I often forget all about it so all my files says it's with for instance 35mm even though it is with 120mm :-)

    Peter

    Quote Originally Posted by alajuela View Post
    Hi Peter
    Can you enter it in batch form - Or you have to do each file individually?
    Thanks
    Peter
    My website

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    Re: Working without Exif

    Another idea to keep track of what lens you are using (in case you need to do that): use a CF card per lens. So when you change lens, you also change CF card. One card per lens. Quite simple.
    It can be useful for example for newbies to remember what lens was used for what shot, to understand the results you are getting.

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    Re: Working without Exif

    I try to remember most often I do remember (thanks to low shooting volumes), sometimes I do not. I don't stitch though so it's less of a problem (no disaster if I have forgot the settings), but I do shoot LCCs, but those I can assign based on time stamp.

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