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
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    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
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    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.
  9. #9

    Thank you for your input Dennis, I would like to comment as follows:

    Quote Originally Posted by DennisS View Post
    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.
    Does there aways need to be a financial implication for doing something? My experience with the camera industry, especially Nikon, is that they have been willing to listen to Customer feedback and occasionally do things to encourage the more unusual applications. Back in the early 1908s when we started using "off the shelf" cameras for photogrammetry lobbying the camera manufacturers resulted in useful innovations. Some (e.g. Rollie) even went as far as manufacturing metric versions of their "off the shelf" models for a very limited market. The cost of adding these dimensions to their already comprehensive specifications is minuscule. The dimensions are "knowns" and are an integral part of the camera design and "drawings". It takes less than a couple of minutes to open the file add them to the specification matrix and close the file, which is then published. I agree that 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, but I do know that sometimes it is this kind of detail that tells a buyer that a particular manufacturer is in tune with their business and the cost of adding these dimensions is cents when considered in the light of advertising budgets.

    Quote Originally Posted by DennisS View Post
    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..
    I completely agree that one should go through a "calibration" to get the best set up and do this myself, but the reason for for wanting the numbers is to provide people with a starting point, a point of reference. Forgive me if I have got it wrong, but I see frequent request for help from new users, or those changing their gear, on this forum and giving them some numbers can help them by giving them a start, which in many cases is probably the right set up. Personally, I would ignore the numbers and recommend the kit is set visually in th first instance. However, there are circumstances when the giving someone the values for the rail settings is a useful way to proceed as I will elaborate on later.

    Quote Originally Posted by DennisS View Post
    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.
    Again, I agree that using a ring mount is the way to go provided that you can get the results required, but I use both an NN3 and an R1 because there are applications where using the R1 simply does not give me the flexibility I need. Unfortunately not everyone can afford the outlay for their ideal kit and may wish to use their existing camera and lens and purchase a Nodal Ninja to get started. If I could justify a "full frame" DSLR I would probably find that my NN3 would not get used, but I am afraid I have other priorities for my cash and I feel that helping people get started with panoramic photography whatever their preferences would be assisted by the camera manufactures including the dimension in their specifications.

    Quote Originally Posted by DennisS View Post
    If panoramic photography was more mainstream, manufacturers would include the numbers.
    Panoramic photography is palying an important part in a rapidly developing technology. HDS (High Definition Surveying) scanners measure a "cloud" of millions of 3D points to mm accuracy in minutes and the colours of the points are a result of the strength of the returned laser light. This "false colour" result does have its uses, but many users wish to have "true" colours on the points and this is achieved using panoramic photography. Leica Geosytems Cyclone software uses the Cube Images to colour the points in the point cloud. Those doing this are using panoramic photography as a tool and in some cases need training in photography itself. To add "true" colour to the point cloud it is essential that the NP occupies the same point in space as the centre of the scanner, which is achieved by using a forced centering system and having adaptors (marketed by Nodal Ninja and some Dealers) to give the correct height for an NN3 for different scanners. In supporting these applications I like to have all available options at my disposal and these dimensions can be extremely useful in some circumstances. The telephone rings and the Engineer at the other end has just received the NN3 and wants to go to the field now! or perhaps it is a Police Officer from a CIU (Collision Investigation Unit) who has arrived at an RTC (Road Traffic Collision) scene and is faced with carnage (CIU Officers in the UK a required to record the scene if there are any deaths of likelihood of such) and opens the camera case to find it disassemble because the camera has been used for normal photography. In such cases I have to guide them to set up the NN3 and camera over the telephone and it has to be right so that they get a working result because there is no second chance. Even if the tripod location is marked on the ground with the laser plummet it is inordinately difficult to get the NP into the same location in space once the tripod has been moved and in any case the scene is unlikely to be the same as when it was scanned, especially in the case of an RTC where the debris is removed as soon as the scene is recorded so the road can be opened. If I am told by the user that they have a particular body and lens and I can compare the dimensions with a different body for which I have the NN3 arm values for then I am confident that the user will get a panorama of the precision required to fit the point cloud. Earlier this year most English CIUs purchased HDS scanners for recording RTCs and a recent buzz word is BIM (Building Information Modeling) an important part of which is a detailed 3D model of the building and its components, which is achieved to mm accuracy using HDS. In these cases "true" colour for he point cloud is essential so panoramic photography becomes an integral part of this technology. Perhaps I have wandered off topic here, but I feel that panoramic photography has an ever more important role to play in todays world and that many of those using it as a tool, rather than to generate beautiful panoramas that you and others that frequent this forum do, that setting up the kit is more a science than an art and the fact is that Nick not only makes superbly engineered products, but precisely engineered products and lenses are manufactured to micron precision so for such users it has become a numbers game.

    Quote Originally Posted by DemonDuck View Post
    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.
    Surly it is much easier and more reliable if the camera manufactures can add these dimensions to the specifications of new cameras as and when they introduce them than try and maintain a 3rd party database?
    It takes but a few key strokes to bring up a comprehensive specification for a camera of interest on the Internet and I really do not see that a couple of minutes to include these "known" dimensions for a new camera model is too much to ask, especially as these dimension are not just useful to panoramic photographs but are useful in other applications such as photogrammetry.
  10. #10
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    Does there aways need to be a financial implication for doing something
    The real world dictates that corporations must turn a profit in order to stay in business. They have to answer to sharholders and the board of directors. I would like to see Sony change the firmware on the NEX-7 so I could bracket at least 5 shots, all 1 stop apart. That is just not going to happen. Getting manufacturers to provide the dimensions is just not going to happen. I went out and purchased a set of vernier calipers and learned to take the measurement myself. 360Precision uses a very expensive computerized measuring rig. You want the info? How much are you willing to pay?
  11. #11

    Hugh, you should send your thoughtful letter to all the camera manufacturers. I'm convinced but what good does that do?
  12. #12

    Quote Originally Posted by DemonDuck View Post
    Hugh, you should send your thoughtful letter to all the camera manufacturers. I'm convinced but what good does that do?
    Good question DemonDuck, as my Uni lecturers would say when they did not have the answer to hand.

    Over the last three or so years there have been quite a number of occasions where I have found these values useful if available and would have been useful, especially when manufacturers launched new bodies and I did not have access to one to measure, and I know from conversations on this forum and elsewhere that others do and would find them useful.
    John reminded me that a database existed but pointed out that it may not always be accurate or up-to-date, which is especially the case when new cameras are launched as it takes time for the database to be populated.
    The idea of the manufacturers including these values, which they have to hand and are "knowns", germinated from a conversation I had with a Nikon Support Engineer and Terrywoodenpic's post acted as a catalyst.
    If lobbying the camera manufacturers results in even one of them adding these values to their specifications than I will have achieved a result, but if I am completely ignored I will not have wasted very much time so I thought it worth a try.
    Last edited by Hugh; 05-17-2012 at 01:28 AM.
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