Page 1 of 2 12 LastLast
Results 1 to 10 of 16

Thread: View camera as extinction light meter

  1. #1
    Ironage's Avatar
    Join Date
    Apr 2012
    Location
    Wichita, KS
    Posts
    442

    View camera as extinction light meter

    While ready a 1950’s Kodak data guide I came across a method of using the ground glass as a extinction light meter by stopping down the lens. It gives a chart for Super-xx film. The old exposure index for this film was 100. In order to try this technique I need to know what the modern ISO would be.

    Tri-x is listed as 200, would that make Super-xx 200 ISO?
    ...Dilettante! Who you calling a Dilettante?

  2. #2
    Foamer
    Join Date
    Oct 2010
    Location
    South Dakota
    Posts
    2,430

    Re: View camera as extinction light meter

    If I remember right, the ASA rating was changed about 1960. I can't remember if the rating was doubled or halved though.


    Kent in SD
    In contento ed allegria
    Notte e di vogliam passar!

  3. #3
    Foamer
    Join Date
    Oct 2010
    Location
    South Dakota
    Posts
    2,430

    Re: View camera as extinction light meter

    Ah yes:

    "The ASA standard underwent a major revision in 1960 with ASA PH2.5-1960, when the method to determine film speed was refined and previously applied safety factors against under-exposure were abandoned, effectively doubling the nominal speed of many black-and-white negative films. For example, an Ilford HP3 that had been rated at 200 ASA before 1960 was labeled 400 ASA afterwards without any change to the emulsion."


    Kent in SD
    In contento ed allegria
    Notte e di vogliam passar!

  4. #4

    Join Date
    Jul 2008
    Posts
    3,901

    Re: View camera as extinction light meter

    Think that was part of DIN & ASA getting married then becoming ISO at some further point in their future.

    The higher film "speed" typically produced thinner negatives with a bias towards lower perceived grain in the print trading off shadow detail.
    IMO, this was a response to the market's want for less perceived grain in the print and higher film "speed" as the "Box speed" rating.


    Bernice


    Quote Originally Posted by Two23 View Post
    Ah yes:

    "The ASA standard underwent a major revision in 1960 with ASA PH2.5-1960, when the method to determine film speed was refined and previously applied safety factors against under-exposure were abandoned, effectively doubling the nominal speed of many black-and-white negative films. For example, an Ilford HP3 that had been rated at 200 ASA before 1960 was labeled 400 ASA afterwards without any change to the emulsion."


    Kent in SD

  5. #5
    Ironage's Avatar
    Join Date
    Apr 2012
    Location
    Wichita, KS
    Posts
    442

    Re: View camera as extinction light meter

    Thanks for confirming the doubling of the number. That will get me in the ballpark when I try this method. Here is a quote from photoguide:

    A Camera as an Exposure Meter.. A camera with ground-glass focusing can be used as an extinction exposure meter for black-and-white pictures taken in poor light. Under a focusing cloth, and with the camera lens wide open and the camera centered on the darkest important shadow, focus the subject on the ground glass. When your eyes have become fully adjusted to the light on the ground-glass image, close the lens diaphragm gradually until details in the share are barely distinguishable. Note the lens opening and expose as follows:”

    Then there is a chart for Super-XX at f/16 like this: f/8 32 seconds, f/16 8 seconds, f/22 2 seconds, and f/64 1/2 second.
    ...Dilettante! Who you calling a Dilettante?

  6. #6
    ic-racer's Avatar
    Join Date
    Feb 2007
    Posts
    6,736

    Re: View camera as extinction light meter

    Maybe I can calibrate my ground glass to my Leudi...
    Click image for larger version. 

Name:	Leudi.jpg 
Views:	17 
Size:	32.8 KB 
ID:	217246

  7. #7
    ic-racer's Avatar
    Join Date
    Feb 2007
    Posts
    6,736

    Exposure "Safety Factors"

    Click image for larger version. 

Name:	Exposure Safety Factors.jpg 
Views:	23 
Size:	34.1 KB 
ID:	217247

    Everyone knows this but in diagram form one can see how safety factors would be detrimental to, "push-processed" small format film, and how safety factors can improve large format photography.

  8. #8
    Drew Bedo's Avatar
    Join Date
    Oct 2006
    Location
    Houston Texas
    Posts
    3,225

    Re: View camera as extinction light meter

    UMmm . . .Why not take advantge of the technological advances of the past 70 years and use a digital lightmeter?
    Drew Bedo
    www.quietlightphoto.com
    http://www.artsyhome.com/author/drew-bedo




    There are only three types of mounting flanges; too big, too small and wrong thread!

  9. #9

    Join Date
    Sep 2010
    Posts
    831

    Re: View camera as extinction light meter

    Quote Originally Posted by Drew Bedo View Post
    UMmm . . .Why not take advantge of the technological advances of the past 70 years and use a digital lightmeter?
    I like the Minolta Flash IV s available at very reasonable prices. You a
    can have spot/reflective, flash, incident and enlarging all for a fraction of new instruments.

  10. #10
    Drew Bedo's Avatar
    Join Date
    Oct 2006
    Location
    Houston Texas
    Posts
    3,225

    Re: View camera as extinction light meter

    ^^^+++

    What he said. I use one of those.

    Plus there is a port to connect one of the focal plane probes.
    Drew Bedo
    www.quietlightphoto.com
    http://www.artsyhome.com/author/drew-bedo




    There are only three types of mounting flanges; too big, too small and wrong thread!

Similar Threads

  1. Can I use a 35mm camera as a light meter for macro photography?
    By Richard Raymond in forum Style & Technique
    Replies: 5
    Last Post: 1-Nov-2010, 15:26
  2. Digital Camera as a Light Meter
    By audioexcels in forum Gear
    Replies: 5
    Last Post: 2-Jun-2007, 08:38
  3. Replies: 4
    Last Post: 26-Dec-1999, 18:20

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •