Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 68,706   Posts: 1,482,842   Online: 990
      
Page 4 of 4 FirstFirst 1234
Results 31 to 37 of 37
  1. #31
    johnnyh's Avatar
    Join Date
    Aug 2009
    Location
    near Bristol, England
    Shooter
    Medium Format
    Posts
    12
    Quote Originally Posted by wombat2go View Post
    ... (SNIP)
    -I wanted a real simple robust camera, the body is such the back balances the lens and forms a robust base. It can be sat on the ground or in the grass etc with the lens and back clear of the ground.The lens has a permanent metal hood with UV filter, and no lens cap. It is carried either by its handle or in an old video bag and does not have to be babied.

    -This camera has no batteries (after my dslr batteries laid down in the Michigan winter) and can be used with gloves on which is not possible for example with a dslr.
    -Having the spirit level in the viewfinder is good feature, more accurate than the grid in the slr and dslr. However I need to work on a better VF than the present one.
    (ENDofSNIP) ...
    For me, these reasons are sufficient justification for the project , even if being additional to your satisfaction in the hardware design and implementation. And the technical discussions and contributions in the thread are interesting and useful. Having just come across the thread, I will follow it with interest .

  2. #32
    Steve Smith's Avatar
    Join Date
    May 2006
    Location
    Ryde, Isle of Wight
    Shooter
    Medium Format
    Posts
    8,435
    Images
    122
    Quote Originally Posted by Dan Fromm View Post
    Wombat, you're on the slippery slope. There;s a law of nature to the effect that there are no inexpensive wide angle lenses for formats larger than 35 mm still.
    But sometimes they can be acquired cheaply. I paid £20 for the 65mm Super Angulon on my 6x12 camera.

    http://stevesmithphoto.webs.com/pano612.html


    Steve.

  3. #33

    Join Date
    Jul 2013
    Location
    Michigan
    Shooter
    Medium Format
    Posts
    107
    Steve
    Excellent job!
    The helicoid solution is a smart one, I am thinking about a Crayford

  4. #34

    Join Date
    Mar 2005
    Shooter
    Multi Format
    Posts
    3,195
    Quote Originally Posted by Steve Smith View Post
    But sometimes they can be acquired cheaply. I paid £20 for the 65mm Super Angulon on my 6x12 camera.

    http://stevesmithphoto.webs.com/pano612.html


    Steve.
    Steve, you're right, miracles do happen. I've had my share and am happy to have had them.

    Relying on the right miracle to happen when needed, though, seems a little risky.

  5. #35

    Join Date
    Dec 2013
    Location
    Whidbey Island WA.
    Shooter
    35mm
    Posts
    1

    Great Work

    Greetings,
    I was looking for a shutter for a DIY medium format camera and found this forum and your posts. As a machinist I can really appreciate your excellent work. Looking at your posted pictures I saw a Computar lens. I may have this lens. I have an optics bench and fiddle around with optics. I bought two Computar lenses from Surplus Center so I could make a camera. You say that your lens needs to be used with a bellows. Though I want to make a camera with a bellows I would like to know why this lens needs to be used with one. Any advice you can give about where to start looking for info about a DIY camera is greatly appreciated. And once again, great work on your DIY camera.
    Eric

  6. #36

    Join Date
    Jul 2013
    Location
    Michigan
    Shooter
    Medium Format
    Posts
    107
    Hi etpm,
    The Computar 1:16/105~150 needs a bellows to be fully functional because it is a variable focal length lens, and its internal scroll adjusts that.
    So the focus has to be adjusted at each focal length, needing the bellows, or a helicoid behind the lens.

    It should also be possible to use the lens as an approximate fixed focal lens (eg 135 mm) and obtain focus ability by just using the internal scroll.
    So far I am using the lens on the 4x5 Speed with the rollfilm back and using the focal plane shutter. I leave it at 135mm to match the view finder and rangefinder.

    I think the lens is pretty good, although i have not used it much.
    Here is a photo with it on the Speed, with a 67mm UV filter and an aluminum hood.
    At 135mm, note that the lens image circle does not quite cover the RH/8 frame.
    Out of camera image (Fuji 400, home processed C41)
    https://app.box.com/s/mdtcfsz8tgo77qqrsniq

    Here is a heavy crop of the above which is still reasonably sharp even at 22 inch width on the monitor.
    https://app.box.com/s/aqvznhvq37b4pwuyfupv

    To help with your camera design, here is some data of the Computar from my day book (measured, not calculated):
    The register is the rear surface of the lens cylinder which is bolted directly onto a heavy aluminum lens board for the Speed.

    At FL= 105 mm the distance from register to film plane at infinity focus, is approx 135 mm at infinity
    The focus throw (front standard extension) to focus from infinity down to 5 metre ( 15 foot) is approx 1.6 mm (0.063 inch)

    At FL= 135 mm: focus throw :2.4 mm (0.093 inch)

    At FL= 150mm register: approx 150 mm at infinity
    The focus throw: 4.75 mm (0.187 inch)

    So it should be easy to machine a nice helicoid to mount the lens on.

    I had the bright idea to allow wider apertures than the fixed f/16. I made a prototype stop to attach to the front of the lens but even f/4 was useless by vignette.
    Changing the fixed aperture requires dis-assembly. Then I realized that even at f/16 the image on the ground glass is bright enough to focus fairly sharply.
    Anyway I just scale focus it.

    Good Luck with your camera!

  7. #37
    Mark Fisher's Avatar
    Join Date
    Dec 2003
    Location
    Chicago
    Shooter
    Medium Format
    Posts
    1,614
    Images
    151
    Nice....I have a secret desire to make something similar out of a LF lens and a 6x12 back. Nicely done.
    Your first 10,000 pictures are the worst - HCB

    www.markjamesfisher.com

Page 4 of 4 FirstFirst 1234


 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



Contact Us  |  Support Us!  |  Advertise  |  Site Terms  |  Archive  —   Search  |  Mobile Device Access  |  RSS  |  Facebook  |  Linkedin