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Thread: Focusing Rail Length?

  1. #1

    Join Date
    Mar 2018
    Posts
    46

    Focusing Rail Length?

    Greetings everyone!

    I haven't given up yet on building a ULF camera.

    I've been researching as many designs as possible but I have a question.

    After you move your standards around to get close to having the subject(s) in focus, how long would people recommend a fine focus mechanism should be?

    Edit* - I think the easiest to do design is one MAubrey is working on.
    It's a carbon fiber tube design.
    The only thing I'm thinking about adding is a fine tune focus mechanism.

    Does anyone know existing camera parts that could do the job.
    Something like this:


    https://i.ebayimg.com/images/g/N4EAA...2aq/s-l300.jpg




    Thanks for reading this!
    Have a great weekend!
    Cheers,
    Kevin H.

  2. #2

    Join Date
    Mar 2017
    Location
    Del City, OK
    Posts
    196

    Re: Focusing Rail Length?

    That would work, although it might be a bit cumbersome, depending on how it’s installed. It also looks a bit heavy. My Sinar has about 5-6” of fine adjustment, and that would probably be about right. It’s way more than I need on 4x5, but might be okay on a larger format. The thing to remember is, you’ll want about double the length you’ll actually need so you have the option to move it forward or backwards.

    You could make your own relatively easily. All you’d need is a thread bolt, a nut, and a handle to glue on the end. You’d probably want to glue some washers in place to hold the bolt in position, and build a housing around the nut that attaches to the standard. Or you could buy a gear and toothed rail and mount the fine adjustment sideways, like on the Sinar. There are some wooden rack and pinion sets on Etsy that might work. I guess it all depends on how much time and money you want to invest, and how nice you want it to look.

  3. #3

    Join Date
    Jul 2016
    Posts
    2,483

    Re: Focusing Rail Length?

    Lens ? Subject distance ?

    When you know what lens/lenses you will use and what minimum subject distance (landscape vs portraiture) you will have the answer.

    Here you have an 11x14 example: http://www.lg4mat.net/1114.html

    Standard bellows 34 inches
    Max. extension 865mm(34inches)
    Min. extension 130mm


    Of course the format size may determine what lens will you want.

    As a general rule you may take the bellows extension of any (field/studio) camera and make the bellows extension of the ULF proportionally longer to the format size proportionality. Then in theory both the LF and the ULF will be able to make the same framings with same close subject distances, if using regular lenses (not speaking about tele lenses that require less bellows).

    So you can use a 4x5 camera to know what bellows you like, and then multiply by the xTimes your ULF format is larger.

  4. #4

    Join Date
    Mar 2018
    Posts
    46

    Re: Focusing Rail Length?

    Hey jim10219, thank you for your input and suggestions!
    Is this something like you were suggesting? http://ritmindustry.com/upload/items/223/223717.jpg


    Hey Pere Casals, thank you also for your input!
    I'm a little confused to be honest lol
    I have the format, and bellows extensions sort of decided on, respectively, 20x20" and 2000mm. I keep changing my mind on what camera design is best. Maybe two cameras now, one for busk portraits and one for full body shots. I'm hoping to find a 30" lens for those busk shots and a 37" lens for full body shots.

    Would this one be too small in length adjustment?

    https://www.ebay.com/itm/Leofoto-MP-...e/142889655970


    Thanks guys for entertaining my thoughts and dreams. I have some time before I'm ready to build a camera.
    Hopefully taking a workshop soon on the process then it's full steam a head

    Cheers guys!
    Be well!

    Kevin H.

  5. #5

    Join Date
    Sep 1998
    Location
    GA
    Posts
    11,292

    Re: Focusing Rail Length?

    Linhof makes an insert geared section on the top of both there straight and their telescoping rails, these rails are normally 18 long. So the rear standard is geared for fine focus over the entire length of the rail. The geared section are about 6 long, have tapered edges and slide into a grove on the top of the rail. Multiple sections slide in till the rail is full. A stop block and screw anchors the tracks in place at each end and also act as blocks for the focus gear assembly on each standard. The rear standard is geared and the fron slides along the top of the monorail without using the gear track. Simple, elegant and delightful to work with!

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