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  1. #1

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    Oct 2005
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    Fort Bragg, California
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    My Sigma View Camera SVC generation ii

    Hi,

    I know this isn't technically a home built camera but it is what I've been working on lately. This is the second generation of my efforts, the first can be found here:
    http://www.pbase.com/masimo/svc_sigm...mera_front_end

    The new one discussed below can be found here:
    http://www.pbase.com/masimo/sigma_sv..._generation_ii

    There are a number of us now working on ways to do flat or orthographic stitching. The idea is focus the lens on a large format camera then move a digital slr around the image circle taking multiple shots and then stitching them together into a large image.

    The major limitation is that the sensor on the slr is located at the back of the mirror tunnel and consequently the size of the image one can capture is limited by the vignetting caused by the mirror box. In addition the light fall off on the edges of the image is accentuated by pixel level vignetting and also by microlens vignetting.

    Finally, one must search for LF lenses with extremely good and wide resolution. The Nikkor-SW 90mm f8 is an example of such a lens.

    In any case here is my latest effort. Most of what I did is entered on each of the pics. The pics are very poor resolution unfortunately as my only other digital camera is a cheap 1 or 2 mp camera.


    The fundamental limitation of attaching an SLR to a rear standard is that the viewfinder hump and right side of the camera hit the standard forcing one to mount the camera further back from the standard and thereby increasing the distance between the sensor and the lens. This in turn limits the fl of the lens one can use. The rule is that the lens must be fl distance away from the sensor to be able to focus to infinity for lenses other than those designed to be retrofocal as are the lenses used on our Sigmas. So if I want to use an 80mm lens I have to be no more than 80mm away from the sensor to focus to infinity. The distance from the sensor to the lens flange is already 44mm to that leaves only 36mm to fit all the layers of bellows and flanges etc that go between the camera and the lens. If one had to account for the viewfinder hump and right side handle the distance increases from 44mm to around 54-57mm.

    What I did was to buy an old B&J 4x5 camera with a large front standard and carved out a hole large enough to mount the entire camera in it. I then attached a qr bracket on the side of the standard into which the camera slide in portrait mode. Both the viewfinder hump and the right side of the camera project out beyond the standard eliminating any impact from the standard on the focal length of the lenses that can be used.

    Most of the pictures here have captions that explain the various parts and how they work. I'm really please with the new stability and the looks of this version. If there is to be a next step, it will be to mount a ground glass via the qr bracket aligned with the sensor plane in the camera. That way I could remove the camera, place the ground glass on and focus the whole image I will take allowing better use of movements for dof. However, to do this I will also have to change the bellows significantly so it is a project for a later time.

    Not being particularly dextrous I tend to find parts I can modify rather than fashion new parts. I did most of the cutting with a sawzall, a file and a rotary rasp/file on my drill. The B&J standard was designed to hold a lens not a camera and I had to cut away a good deal of metal from it so I reinforced it. The L bracket comes from some nikon L brackets I picked up on ebay some time ago for about a buck apiece. The rotator is the base from a panhead cut off and leveled, the rail is a bogen 3419 upside down with the rear standard mounted fixed to one end of the rail and the front standard on the moveable plate. When I take the SVC off the rail I place the camera on the sliding end for normal use and can therefore adjust for entrance pupil or for centering when using a heavy lens.

    I went through a phase a while ago of mounting a portrait/landscape rotator using custom brackets flash brackets. I acquired quite a few brackets and attachments during this time and that is why I am using Custom Brackets parts in so many places. Arca Swiss might be a better choice if starting without anything.

    I always keep an eye on ebay for collections of brackets and parts that I think I might be able to use in the future. The only really new and expensive part in this project now though is the Bogen 3419 that replaces the pentax bellows rails I had been using. The bogen has 1mm/turn microfocusing on the 3419 which is very nice. However it is a little rough so you do have to be careful with it. In particular locking it too tight causes it to shift slightly resulting in changed focus.

    So here are the pics. Comments are encouraged and welcome.

    The pics are also at:
    http://www.pbase.com/masimo/sigma_sv..._generation_ii

    Apologies for the poor quality. My only other digital camera is a
    creative PC-350 2mp and that is what I used for the pics.

    Mike

    http://www.pbase.com/masimo/image/58355118/original.jpg
    http://www.pbase.com/masimo/image/58355119/original.jpg
    http://www.pbase.com/masimo/image/58355120/original.jpg
    http://www.pbase.com/masimo/image/58355121/original.jpg
    http://www.pbase.com/masimo/image/58355122/original.jpg
    http://www.pbase.com/masimo/image/58355123/original.jpg
    http://www.pbase.com/masimo/image/58355124/original.jpg
    http://www.pbase.com/masimo/image/58355125/original.jpg
    http://www.pbase.com/masimo/image/58355126/original.jpg
    http://www.pbase.com/masimo/image/58355127/original.jpg
    http://www.pbase.com/masimo/image/58355128/original.jpg
    http://www.pbase.com/masimo/image/58355129/original.jpg
    http://www.pbase.com/masimo/image/58355131/original.jpg
    http://www.pbase.com/masimo/image/58355132/original.jpg
    http://www.pbase.com/masimo/image/58355133/original.jpg
    http://www.pbase.com/masimo/image/58355134/original.jpg
    http://www.pbase.com/masimo/image/58355135/original.jpg
    http://www.pbase.com/masimo/image/58355136/original.jpg
    http://www.pbase.com/masimo/image/58355137/original.jpg
    http://www.pbase.com/masimo/image/58355138/original.jpg
    http://www.pbase.com/masimo/image/58355139/original.jpg
    http://www.pbase.com/masimo/image/58355140/original.jpg
    http://www.pbase.com/masimo/image/58355141/original.jpg
    http://www.pbase.com/masimo/image/58355142/original.jpg
    http://www.pbase.com/masimo/image/58355143/original.jpg
    Attached Thumbnails Attached Thumbnails 0028.jpg   0033.jpg   0044.jpg   0046.jpg   0049.jpg  


  2. #2
    Dave Parker's Avatar
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    As this looks to be a digital camera grafted onto a modified LF camera, this probably not the proper system for posting this one as this system is dedicated to film photography and showing a digital camera on the back of this LF camera will not get you to much good feedback..

  3. #3

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    Hmmm, when I joined the forum some time ago I'm quite sure "digital negative" was one of the options one could select as their primary interest in lf. This is a digital negative.

    thanks for you feedback though.

    Mike

  4. #4
    Dave Parker's Avatar
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    Mike,

    Actually "digital negative" is in reference to a negative that has been enlarged digitally and then printing in a traditional manner, at the least this would belong in the alternative area, I would suggest you contact the owner of the site and he can let you now..



 

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