Camera Dimensions

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  1. Camera Dimensions

    #1

    One of the great features of this forum is that new users can easily ask for information on setting up their Nodal Ninja with their camera and lens.
    There is of course a wealth of information that they can be directed to, but (unless I am missing something, which is very possible) there does not seem to be a database for the two critical dimensions for the camera bodies, which could make life a lot easier.
    I am referring to the dimension from the lens flange to the 1/4" Whitworth thread and from the base plate to the centre of the lens (principal ray).
    If these dimensions were readily available it would be straight forward to calculate the rail settings for a new camera body from a different camera body with the same lens.
    For example: A recent post asks about a Nikon D7000 with a Sigma 10-20mm lens.
    I have such a lens and a couple of Nikon bodies, but do not have access to a D7000, but if I knew these dimensions calculating the settings for the D7000 and Sigma lens would be simple arithmetic.
    I have asked Nikon UK if this data is available, but was told it is not, but they might consider it for the future.
    The overall dimensions of cameras are readily available, but not these two.
    As the likes of Nikon and Canon are always bringing out new bodies but changing these dimensions it occurs to me that it may be worth keeping a database for these two values.
    I remember having a discussion with Heinz quite a long time ago and we agreed that keeping a database of camera/lens combinations was a mammoth task, but one for the recent DSLR bodies would be relatively simple to set up and maintain.
    Anyone else any thoughts on the subject?
  2. #2

    Hugh, All this was discussed a long time ago and the upshot was the wiki database at http://wiki.panotools.org/Entrance_Pupil_Database . There is also the lens data provided by Joseph Wisniewski at http://www.swissarmyfork.com/lens_table_1.htm , which uses the correct terminology and makes the difference between the entrance pupil and front nodal point very clear. I did start work on a database of my own, with entrance pupil measurements being given relative to the sensor plane (the position of which is marked on the bodies of all DSLR cameras that I have looked at). This does have the advantage that lenses available in various mounts have to be measured and listed only once. The lower rail settings are somewhat complicated by a variety of ways of mounting the camera to the upper arm, i.e. with various types of quick release systems. Giving upper and lower rail settings for a head like the M1L is also problematical, given the modular nature of the system.
    .
    The wiki database should be very useful, but it is difficult to get people to update it with their personal data. In any case, the accuracy of the information is sometimes suspect and incomplete. Nevertheless, the data is good enough to get the head setup in the right ball park. OTOH, you can do that in a few seconds just by looking into the lens and positioning the visible entrance pupil by eye.
    .
    John
  3. #3
    Users Country Flag
    Join Date: Apr 2008
    Location: Saddleworth UK
    Posts: 242

    You would think that manufacturers would publish this data themselves.
    However perhaps there is more variation between otherwise identical lenses that one might suppose.
    People here seem to come up with slight differences in settings on the same equipment, that they are very happy to use to good effect.
    So it is probably best to always find your own rotation point..
  4. #4

    Hello John and Terry,

    Thank you for your comments on my message.

    Quote Originally Posted by John Houghton View Post
    Hugh, All this was discussed a long time ago and the upshot was the wiki database at http://wiki.panotools.org/Entrance_Pupil_Database .
    The lower rail settings are somewhat complicated by a variety of ways of mounting the camera to the upper arm, i.e. with various types of quick release systems.
    The wiki database should be very useful, but it is difficult to get people to update it with their personal data.

    John
    John, it is clear I was missing something as the site:
    http://wiki.panotools.org/Entrance_Pupil_Database
    does contain the information I was looking for and looks as if it is up to date.
    I guess I was using the incorrect terms in my search .
    I take your point about the lower rail settings being complicated by the different methods of mounting the camera to the upper arm, but think that it is relatively straight forward if the camera is aimed at the observer with a light (e.g. window) behind the viewfinder so there is a small dot of light at the centre of the lens and a vertical object (e.g. plumb bob or door jamb) used to line it above the mark on the NN.
    Anyway, I have now bookmarked this site for future reference, but see my response to Terry's message.

    You would think that manufacturers would publish this data
    themselves.
    Terry, yes that was my thinking that this information should be on the manufactures specification but currently is not
    http://imaging.nikon.com/lineup/dslr/d7000/spec.htm
    and in the light of John's comment:
    In any case, the accuracy of the information is sometimes suspect and
    incomplete.
    I think that I will spend a little time lobbying the manufacturers on the subject and seeing what response I get.
    However perhaps there is more variation between otherwise identical lenses that one might suppose.
    People here seem to come up with slight differences in settings on the same equipment, that they are very happy to use to good effect.
    So it is probably best to always find your own rotation point.
    Yes, I quite agree that it is probably best for users to find their own rotation point, but it would appear from comments and questions on the forum that not everyone is OK with this.
    As a thought, I feel that the variations people get are down to the empirical determination of the rotation point rather than difference in the lenses as a few millimeters in the upper rail setting does not appear to make much difference.
    When I was making tests for using the panos with the HDS (Scanner) point clouds it was clear that it was important to get the rotation point as accurately as possible so that the geometry of the pano matched that of the point cloud, but that when I experimented by moving along the top rail by 10mm both forward and backward from the point I determined as correct for my Nikon 10.5mm fisheye I still got properly stitched panos although PTGui returned a "good" result rather than "very good" result when running the Optimizer.
    I will post any comments I get from any manufacturers.
    Best regards, Hugh.
  5. #5

    Update ...

    Following on from John and Terry's comments; at the end of March I wrote to the UK address of each of the major camera manufacturers asking if they could consider adding the three important dimensions to their specification sheets, which would be useful to new users and those changing cameras in our world of panoramic photography.

    Some might be interested to know that to-date I have received just two responses who both thanked me for my feedback and stated they would pass on my letter to the relevant departments.
    These were Nikon and Sony.
  6. #6

    Quote Originally Posted by Hugh View Post
    Yes, I quite agree that it is probably best for users to find their own rotation point, but it would appear from comments and questions on the forum that not everyone is OK with this.
    It is very easy to find the proper settings that position a camera/lens system on a particular panohead setup. On the other hand, having all possible settings for all possible combinations of camera/lens/panohead is very difficult to obtain and subsequently to maintain. Especially when new cameras and lenses and panoheads are introduced so frequently.

    And the individual variances of the actual camera/lens/panohead will always need be taken into consideration.

    There are very good tutorials showing how to do the alignment. Perhaps the focus should be on educating people to use the tutorials and perhaps good introductory tutorials educating people on terminology and techniques.

    It's a nice idea that camera alignment should be a simple matter of looking up three numbers but that is probably never going to be an actuality.
  7. #7

    Quite so DD, but the point of attempting to get the camera manufacturers to include these three dimensions on their already comprehensive specifications is so that if someone asks about their camera/lens combination (this question is posted frequently on the forum) and they have a similar rig (e.g. same lens but different body) the numbers are a quick way of giving the person who asked the question a simple response that will get them started.
    Also if someone is looking to acquire a new body for use with an existing lens (e.g. I wish to trade in a D300 for a D700 and keep my 10.5mm lens) then the differences in these dimensions is the changes I need to make on the upper and lower rails and I am ready to go.
    Also, if these dimensions and that for the lens flange to the NPP are known it is easy to calculate of a certain camera/lens combination can be accommodated by say an NN3 or whether an NN4 should be purchased.
    I was hoping that as the camera manufacturers know these dimensions that they would be willing to add them to their specifications as they have just about every other bit of information and every little bit helps.
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  8. #8
    Users Country Flag
    Join Date: Sep 2009
    Location: Los Angeles, CA
    Posts: 348

    If panoramic photography was more mainstream, manufacturers would include the numbers. Where is the financial motivation for Nikon and Canon to include the numbers? There is none. That info would not sell more cameras. Very few people (if any) base their camera purchase decision on the distance from the bottom of the camera to the center of the lens. Megapixel count, battery life, etc... are the main marketing points. Physical dimensions are not. The Sony NEX line of cameras and other similar cameras might be the exception, but not totally. I know that there are web sites that list the "flange back" (distance from the lens mounting plate back to the surface of the sensor) and others that list the camera dimensions. Even if I had the numbers, I would never do a panorama with a new lens based solely on published numbers without going through some sort of calibration exercise. One of the reasons I prefer a lens ring mount is so that I can swap out bodies without any adjustments. None of my pano heads bolt to the body. They all use a lens ring mount system.
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