Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 69,905   Posts: 1,521,385   Online: 1083
      
Results 1 to 8 of 8
  1. #1

    Join Date
    Mar 2009
    Location
    Gibraltar, Europe
    Shooter
    Medium Format
    Posts
    209

    What is the "toe and shoulder"?

    Hi, could anyone explain, in simple, non-mathematical and non-scientifc way, i.e. so artists can understand (, what the "toe and shoulder" of films is (I think I know but would like to be sure) plus which modern colour negative films, maybe all of them? give us detail between these toe and shoulder limits.....perhaps then someone can talk to me about Portra 160NC in particular.....

    I understand it to be where the highlights block off to white and the shadows block off to black on a given tonality curve so to speak....hence the toe would be the bottom part of any curve and the shoulder the top part....im guessing they use the analogy of a shoulder because in an 's' curve, for example it sort of looks like a shoulder.....(and this is the part where Im hoping what I'm saying is not cracking you all up in fits of laughter!)

    In particular, with colour negative film its interesting to hear the detail in both the highlights and the shadows fall within the linear part of any given curve and not on either the shoulder or the toe and thus colour negative film yields a bigger range of possibilities (loosely translated from Photo Engineer's interview on Inside Analog Photo Radio interview)
    Last edited by sperera; 04-05-2010 at 08:05 AM. Click to view previous post history.

  2. #2
    AgX
    AgX is online now

    Join Date
    Apr 2007
    Location
    Germany
    Shooter
    Multi Format
    Posts
    8,330
    You stated : "with colour negative film....the detail in both the highlights and the shadows fall within the linear part of any given curve"

    Any colour negative film, as any film, has limited capacity to reproduce subject brightness differences. If the the brightness range of the subject exceeds that capacity of the film, shadows or highlights or both (depending on exposure) are lost.

    In general, films designed and processed to yield a negative have the greatest of such capacity.

  3. #3

    Join Date
    Mar 2009
    Location
    Gibraltar, Europe
    Shooter
    Medium Format
    Posts
    209
    so how does this come in the "toe and shoulder" definition I'm after.....basically the 'toe' and 'shoulder' are the limits so to speak????? like Zone 2 and Zone 8 in the zone system which are in effects the limits of detail coming through in highlights and negatives.....

    Quote Originally Posted by AgX View Post
    You stated : "with colour negative film....the detail in both the highlights and the shadows fall within the linear part of any given curve"

    Any colour negative film, as any film, has limited capacity to reproduce subject brightness differences. If the the brightness range of the subject exceeds that capacity of the film, shadows or highlights or both (depending on exposure) are lost.

    In general, films designed and processed to yield a negative have the greatest of such capacity.
    Last edited by sperera; 04-05-2010 at 08:38 AM. Click to view previous post history.

  4. #4
    Toffle's Avatar
    Join Date
    Mar 2007
    Location
    Point Pelee, ON, Canada
    Shooter
    Multi Format
    Posts
    1,793
    Images
    121
    I definitely qualify as non-scientific... (I'm the head of the arts dept. at a high school outside Windsor ON.) I will most likely be called out for gross inaccuracies or generalizations, but this is the way I view the concept.

    What you are asking is of most value with films that you test and develop yourself. (most often Black and white, but some of the concepts are applicable to colour) Generally speaking, your knowledge of toe and shoulder are mostly used in keeping important shadow or highlight details out of those areas. As your post suggests, any film responds best in the linear portion of the curve. Separation of tones in the toe and shoulder are greatly compressed, and much harder to control, leading to blocked shadows and blown highlights. Within the exposure latitude of your film, you want to place as much of the important detail within the straight line portion of the curve. For a wider range, you can expand or contract your development, N+1, N-1, but that is another discussion.

    I think I'll let Bruce tell you. He's much better at it than I am.

    Cheers,
    Last edited by Toffle; 04-05-2010 at 10:26 AM. Click to view previous post history. Reason: splling
    Tom, on Point Pelee, Canada

    Ansel Adams had the Zone System... I'm working on the points system. First I points it here, and then I points it there...

    http://tom-overton-images.weebly.com


  5. #5
    Thomas Bertilsson's Avatar
    Join Date
    Jan 2003
    Location
    Minnesota
    Shooter
    Multi Format
    Posts
    14,164
    Images
    289
    The relationship between negative density and exposure is mathematically linear.

    But there are practical limitations to this because the film emulsion has limits to how much density, (shoulder), or how little density, (toe), it can record. If you plot a graph with exposure along one axis and negative density along the other, and you plot the densities of each zone, and then connect the dots you will see a curve which represents how the film reacts to exposure and development.

    The curve is S-shaped, and in the middle it's reasonably straight. Different films have more or less of an ability to record a long straight line. A straight line means that you have a normal relationship between negative density and exposure+development. The shoulder is at the top of the curve and represents where the highlight densities start to block up, and are unable to record detail with much separation, i.e. the negative highlights become difficult to print and a lot of dodging and burning becomes necessary to record tone in your print in those areas.
    The toe is at the bottom of the curve, and generally means shadow details that are so vague that they either don't exist, or they are not clearly visible due to the density of the film base and any potential existing fog at the very low end of the toe, and right where the tone curve stops being a straight line, separation between shadow values are difficult to record in your print.

    So, in summary you want enough exposure (and also long enough development time) to get substantial shadow detail density that print easily, and you will want to develop your negative at an appropriate duration of time and adjust your agitation intervals to keep highlights where they too are printable, i.e. below the shoulder.

    Then of course there may be situations where you either can't help breaking the rules, or you might even want to break the rules and expose too little on purpose, or develop your film for much too long, to achieve a certain effect. There is no right or wrong, but it's important to understand these relationships, if you wish to be able to control how your prints will eventually look.

    I hope that helps more than confuses things.

    - Thomas
    Last edited by Thomas Bertilsson; 04-05-2010 at 10:51 AM. Click to view previous post history.
    "Often moments come looking for us". - Robert Frank

    "Make good art!" - Neil Gaiman

    "...the heart and mind are the true lens of the camera". - Yousuf Karsh

  6. #6
    hrst's Avatar
    Join Date
    May 2007
    Location
    Finland
    Shooter
    Multi Format
    Posts
    1,300
    Images
    1
    Toe is where shadows lose contrast and get flat, but not completely blocked.

    Shoulder is where highlights lose contrast and get flat, but not completely blown-out.
    Last edited by hrst; 04-05-2010 at 10:38 AM. Click to view previous post history.

  7. #7
    36cm2's Avatar
    Join Date
    Aug 2008
    Location
    Northeast U.S.
    Shooter
    Medium Format
    Posts
    575
    Posted wirelessly..

    Toffle, nice assist on the Bruce videoM I always found that clip imensely helpfulM
    "There is a time and place for all things, the difficulty is to use them only in their proper time and places." -- Robert Henri

  8. #8
    keithwms's Avatar
    Join Date
    Oct 2006
    Location
    Charlottesville, Virginia
    Shooter
    Multi Format
    Posts
    6,079
    Blog Entries
    20
    Images
    129
    Quote Originally Posted by sperera View Post
    im guessing they use the analogy of a shoulder because in an 's' curve, for example it sort of looks like a shoulder.....(and this is the part where Im hoping what I'm saying is not cracking you all up in fits of laughter!)
    I prefer to call the nonlinear portions the toe and knee; then the part in between can be called the shin... and if you look down at your leg, you see exactly what's going on

    Note that most discussions of how to control the toe and knee/shoulder are in the context of b&w film. You can manipulate those regions somewhat with the c41 process, but not to the extent that is commonly done with the b&w process. With b&w film, you can get very different exposure-density curves... from the same film. With all the 160 colour neg films, the curves generally look quite similar. If you really want to see a big difference, compare the curves of one of the colour neg films to a slide film.
    "Only dead fish follow the stream"

    [APUG Portfolio] [APUG Blog] [Website]



 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



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