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Thread: How to fix a lens with a larger flange on a Sinar board?

  1. #1

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    How to fix a lens with a larger flange on a Sinar board?

    Hi, does anybody amongst you have mounted a big Petzval or similar on a Sinar board? I thought about building an intermediate piece of wood or aluminium.... or PVC?
    Any ideas, any photos? It's not easy, since Sinar boards are not really big enough to hold these enormeous lenses...but I WANT to connect them!

    thank's for any idea
    cheers

    Torsten

  2. #2
    www.reallybigcameras.com
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    Re: How to fix a lens with a larger flange on a Sinar board?

    How big is the diameter of the rear threads on the lens? As long as it's not bigger than the Sinar board, you could simply send the board (and lens) to SK Grimes and have them thread the board to accept the lens directly without the flange. I've had them do this in the past for lenses that were missing the mounting flange. The cost of drilling + threading the lensboard was less than the combined cost of drilling the board + a new flange.

    Kerry

  3. #3

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    Re: How to fix a lens with a larger flange on a Sinar board?

    Big lenses are also heavy, so the material to mount it should be able to carry this weight. Threads in aluminium are not able to carry heavy lenses. So it should be at least brass, better mild steel. The adapter cone between lens board and adapter thread can be made of aluminium. But with PVC or wood one needs heavy bolts, so the weight increases and the adapter is heavier as one made from aluminium.

    Are you shure the Sinar is able to carry such heavy lenses? Possible it's cheaper to look for one of this heavy view cameras like the Kardan or the Kardan Color as to spend the money to repair the dislocated hinges of your Sinar. Also the lensboards of this cameras are as large to carry a Grundner shutter too.

    Peter K

  4. #4

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    Re: How to fix a lens with a larger flange on a Sinar board?

    For really big lenses you can use a lensboard sized to fit a 5x7/13x18 standard. Sinar used to sell them (at a price :-). There is also a Swiss maker of lensboards called mitiam who sells on eBay.de who sell them from time to time, and would I'm sure make one to order.

    If you are using 4x5 you can just turn a regular 5x7 bellows around so that it narrows towards the rear. If you are using 8x10 there was a special 8x10-5x7 bellows which turns up on eBay once or twice a year, or you can get Camera Bellows in the UK to make you one. There are no Sinar-made bellows for 5x7-5x7, but again, you could get one made up easily enough.

  5. #5

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    Re: How to fix a lens with a larger flange on a Sinar board?

    Thank's for all the comments, but I don't want to fix the lens on a Sinar, just on a Sinar board (which then will be fixed on another camera). So it's really about finding an intermediate piece fixing these big lenses on a standard Sinar board....

    Torsten

  6. #6

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    Re: How to fix a lens with a larger flange on a Sinar board?

    This is what I did on my Cambo which will work to the size of the largest circle you can cut within the light groove; say 4 1/2 inches.
    My machinist made an aluminum ring inside diameter is 4 1/2 inches
    Outside diameter the width of your petzval flange or the diameter of the threads for the flange.
    the depth or thickness of the ring depends on the needs of the lens to clear the hole and anything behind(like a packard shutter) and the depth of the bolts used. Say about 1 inch deep
    The ring is anodized black and bolted from the inside of the sinar board in the four corners within the light grooves. the ouside is threaded for the lens or the retaining ring is bolted on.
    I have mounted up to 18" lens for my Cambo. Very professional looking.
    If you want this done you can send the flange to me. I have a spare sinar board. Pay my machinist and I will send it back
    Regards
    Bill

  7. #7

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    Re: How to fix a lens with a larger flange on a Sinar board?

    One further think to keep in mind: you need to leave room at the edge of the lensboard for the lensboard clamps.

    Please don't ask me how I know :-)

    If things are really tight, you can cut away some material from the outside edge of the back of the ring and put the bolt holes that hold it on the lensboard on the diagonals.

  8. #8

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    Re: How to fix a lens with a larger flange on a Sinar board?

    Take the lens, camera, and the board to a local machine shop. A simple search found me one within a mile of where I work.

    Get a quote from them, and then go ahead and let them do the job. Many are craftsmen who do their own custom work after-hours.

    The fellow who mounted my 360mm Heliar on a Sinar board, makes custom parts for motorcycles, and was proud to help a fellow "artist".

    Just be sure to wrap everything in plastic bags, to protect them from dust.

  9. #9
    Whatever David A. Goldfarb's Avatar
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    Re: How to fix a lens with a larger flange on a Sinar board?

    These lenses may be large, but they often aren't very heavy.

    My Petzval is mounted on a Sinar board with a custom thin flange from SK Grimes. It's a focusing model, but missing the focusing gear, so I had them fix the focusing sleeve with screws, so the lens is focused at the farthest possible distance without obstructing the slot for the waterhouse stops. This way the lens protrudes partially through the lensboard and isn't cantilevered out too far in front of the camera.

    For the 14.5" Verito, I don't have it immediately at hand, but I may have had to square off one edge of the flange or something along those lines.

    The 36cm Heliar fit with no modifications. It's the heaviest of these three big lenses, but it is also the shortest in length, so it doesn't hang out too far in front of the camera.

    In general you want to orient the flange so the screws don't interfere with the light trap or other "working" parts of the lensboard.

  10. #10

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    Re: How to fix a lens with a larger flange on a Sinar board?

    If all else fails, there is always Armin's approach:

    http://portfolio.grossformatfotograf...?image_id=1266

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