Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 68,662   Posts: 1,481,642   Online: 836
      
Page 3 of 6 FirstFirst 123456 LastLast
Results 21 to 30 of 57
  1. #21

    Join Date
    Feb 2005
    Location
    Sydney
    Shooter
    Multi Format
    Posts
    1,325
    Images
    84
    Quote Originally Posted by munz6869 View Post
    I tried it last night with an old Wollensak shutter on a miniature Busch Pressman and it works very well - can I suggest that in your comparative speeds table, you include speeds for older shutters like 1/10th, 1/25th, 1/50th etc. as well as the modern ones? I am far more likely to be suspicious of older shutter speeds and want to test/keep a note of them...

    Marc!
    I agree on adding the older shutter speeds. If i get this app it will be to check old LF shutters.

  2. #22

    Join Date
    Mar 2010
    Location
    Germany
    Shooter
    Medium Format
    Posts
    17
    Thanks for testing, I'm glad it worked. Including the speeds for older shutters is a good idea, will be part of the next update !
    Unfortunately there will be no Android version, as I have no idea how to develop for that (it's very different from iOS).

    @Diapositivo: I don't quite see your point, what has flash synchronization to do with the app ?

  3. #23
    Diapositivo's Avatar
    Join Date
    Nov 2009
    Location
    Rome, Italy
    Shooter
    35mm
    Posts
    1,844
    Quote Originally Posted by Echolot View Post
    @Diapositivo: I don't quite see your point, what has flash synchronization to do with the app ?
    When you use a focal plane shutter, the flash synchro speed as indicated on the shutter speed dial is the fastest speed that leaves a moment when the first curtain ended its trip but the second curtain did not begin moving yet. That is the moment when the flash can flash and its light will hit the entire frame.

    With shutter speeds faster than the X-synchro, as you know, the second curtain begins its trip before the first curtain ended its one, there never is a moment when the entire frame is exposed to light, the film is lighted by a "slit" of light moving along its length.

    You seem to be aware of the problem but not of the fact that the last measurable speed with your app is the X-synchro speed.

    <<
    Please consider that satisfying results from most SLR‘s as well as from cameras with focal-plane shutter can only be obtained up to the 1/125sec. Thereafter, the time is regulated by the distance of the slit between the two curtains, wich doesn‘t affect the shutter release sound very much and therefore can‘t be recognized in the waveform !
    >>

    Could become, for the sake of clarity, and as a mere suggestion:

    Please consider that satisfying results from most SLR‘s as well as from cameras with focal-plane shutter can only be obtained up to the the X-synchro shutter speed and including it, that is often 1/60 or 1/125sec but can be as low as 1/30th or as high as 1/250. Thereafter, the exposure time is regulated by the distance of the slit between the two curtains, which doesn‘t affect the shutter release sound very much and therefore can‘t be recognized in the waveform! The X-synchro speed can normally be recognised easily as it is marked by a "lightning" symbol or is painted with a different colour on the shutter speed dial. Some cameras have an X-synchro speed which is different from the normal sequence, e.g. 1/90. Refer to the instruction manual..

    Central shutters (leaf shutters) can be used with flash on all speeds and can be used with your app on all speeds, I suppose.

    X-synchro refers to electronic flashes. Some bulb flashes have a slow-combustion emission which allows the photographer to use faster speeds without side effects because the flash lasts long enough to hit the film during the entire "slit" travel. IIRC there are now some electronic flashes who work the same way and allow the use of a shutter speed faster than the X-synchro albeit with a lesser flash power.
    Last edited by Diapositivo; 09-25-2012 at 04:13 AM. Click to view previous post history.
    Fabrizio Ruggeri fine art photography site: http://fabrizio-ruggeri.artistwebsites.com
    Stock images at Imagebroker: http://www.imagebroker.com/#/search/ib_fbr

  4. #24

    Join Date
    Oct 2010
    Location
    Bucharest
    Shooter
    Multi Format
    Posts
    53
    Quote Originally Posted by MattKing View Post
    I think it is a great idea - android please .
    +2

  5. #25

    Join Date
    Mar 2010
    Location
    Germany
    Shooter
    Medium Format
    Posts
    17
    Ah ok, now I understood what you mean, thanks for explaining.
    You're right, this is a simple and elegant method to judge, up to which maximum speed the app can provide accurate results for a given camera. Haven't thought about this yet, I will add this to the website soon.

  6. #26
    polyglot's Avatar
    Join Date
    Jun 2009
    Location
    South Australia
    Shooter
    Medium Format
    Posts
    2,953
    Images
    12
    I actually don't think the X-sync thing is a problem, depending on what impulses you're lining up the time measurements with. There are four events:
    1) first curtain travel starts
    2) second curtain travel starts
    3) first curtain travel completes
    4) second curtain travel completes

    Slower than X-sync, the ordering is 1, 3, 2, 4 and faster than X-sync, it's 1, 2, 3, 4. As long as you measure the timing offset between 1 and 2 or between 3 and 4, that's the shutter time. The travel time (1-3 and 2-4) is irrelevant to the exposure.

    The above assumes that it's possible to make out these four distinct events of course, and that may not be possible depending on the shutter design. And it assumes that the user knows enough to select the correct pair of events, the ordering of which depends on the relationship between shutter speed and x-sync.

  7. #27
    declark's Avatar
    Join Date
    Nov 2006
    Location
    So. Cal
    Shooter
    Medium Format
    Posts
    244
    Images
    79
    Great idea Lukas. Was about to download the app, but then remembered that my 3rd Gen iPod Touch doesn't have a microphone that I am aware of, so wonder if the compatible devices listed on iTunes might need to be updated?

  8. #28

    Join Date
    Mar 2010
    Location
    Germany
    Shooter
    Medium Format
    Posts
    17
    Actually you can use this app on your iPod, if you have earphones with a built-in mic ! Just plug them in and voila, you have a microphone on your iPod . Maybe I should mention this in the description.

  9. #29
    RalphLambrecht's Avatar
    Join Date
    Sep 2003
    Location
    the villages .centralflorida,USA and Germany
    Shooter
    Multi Format
    Posts
    6,136
    Images
    1
    yes!
    Attached Files
    Regards

    Ralph W. Lambrecht
    www.darkroomagic.comrorrlambrec@ymail.com[/URL]
    www.waybeyondmonochrome.com

  10. #30

    Join Date
    May 2006
    Location
    Aurora, IL
    Shooter
    35mm
    Posts
    1,837
    I will try the circuit Ralph but I would use the oscilloscope for the measurement rather the sound card. My set up currently works quite well for manual camera but I can't test a camera on automatic. I am thinking that I can make a variable standard light source out of a dichroic enlarger head to simulate the light level than measure the shutter time to test an aperture priority camera.

Page 3 of 6 FirstFirst 123456 LastLast


 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



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