Sigma SVC Generation II -- big changes have a look!

Started Apr 8, 2006 | Discussions
docmaas
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Sigma SVC Generation II -- big changes have a look!
Apr 8, 2006

If you read my last report you'll know that a fellow over on the Fuji group has developed an xy stage for Cambo/Calumet cameras. I had always thought that attaching the camera directly to a rear standard would be a better way to do things but I did't have a lf camera so I went a different direction. Unfortunately the different direction while it did work, was susceptible to too much slipping and falling out of alignment so I went back to the drawing board.

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_svc_view_camera_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

docmaas
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Re: Sigma SVC Generation II -- big changes have a look!
In reply to docmaas, Apr 9, 2006

bump

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Kendall Helmstetter Gelner
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Impressive job
In reply to docmaas, Apr 10, 2006

docmaas wrote:

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.

That is some impressive engineering. Have you taken it out in the field yet? How many images does it take to cover what you consider a full frame?

 Kendall Helmstetter Gelner's gear list:Kendall Helmstetter Gelner's gear list
Sigma 70-200mm F2.8 EX DG OS HSM Sigma 8-16mm F4.5-5.6 DC HSM Sigma 24-70mm F2.8 EX DG HSM Sigma 50-500mm F4.5-6.3 DG OS HSM Sigma 85mm F1.4 EX DG HSM +4 more
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docmaas
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Re: Impressive job
In reply to Kendall Helmstetter Gelner, Apr 10, 2006

Kendall Helmstetter Gelner wrote:

docmaas wrote:

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.

That is some impressive engineering. Have you taken it out in the
field yet? How many images does it take to cover what you consider
a full frame?

Thanks Kendall,

The size of the image that can be taken varies with the distance away from the camera of the lens. Longer focal length lenses are further away and with a 150mm I can easily get up to 10cmx10cm. I tend to overlap a good deal then crop before assembly as it gives more opportunity to crop out unwanted effects like vignetting and flare so I might have up to 60 images for one shot. The disadvantage is that it takes along time to shoot 60 images and if the subject is moving forget it. The shortest fl lens I use is an 80mm and that takes around 40 images and the resultant pic is about 5cmx7cm.

Best,

Mike

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