Page 1 of 4 123 ... LastLast
Results 1 to 10 of 36

Thread: Foot candle to aperture and ISO.

  1. #1

    Join Date
    Dec 2018
    Location
    Northern Indiana
    Posts
    26

    Foot candle to aperture and ISO.

    I looked up light meters on Amazon and was surprised to find that most read out in foot candles.

    I suppose photographic meters are a thing of the past in the age of digital.

    So the question is does anyone know how to convert foot candles to F stops and ISO values.

    Both are measuring the same light intensity.

  2. #2

    Join Date
    Sep 2014
    Location
    Montreal, Canada
    Posts
    979

    Re: Foot candle to aperture and ISO.

    -Foot candle is an illuminance quantity (think of it is as the amount of light falling onto something)
    -F stops have to do with lens aperture
    -ISO values are standard measures of emulsion speed

    There are relationships between these things in the context of photographic exposure (EV numbers for example) depending on whether you are using an incident or reflected meter etc.

    What are you trying to do specifically? For example, find a camera setting (f stop and shutter speed) for an exposure based on an incident meter reading in foot candles?

  3. #3

    Join Date
    Sep 2003
    Location
    South of Rochester, NY
    Posts
    282

    Re: Foot candle to aperture and ISO.

    I had saved an old web page that had tables for light and exposure conversions. I couldn't get the page into a pic to attach so I printed it to a PDF file. You can't see it here but you can download it to view it. It has direct conversions in a table for f-stop, shutter speed and foot candles. Maybe this will help?

    Alternately, I would just buy a decent used exposure meter that does the work for you...
    Attached Files Attached Files

  4. #4

    Join Date
    Nov 2017
    Posts
    190

    Re: Foot candle to aperture and ISO.

    there's a ton of photo light meters on amazon. just search for sekonic or other specific brands to WEED out the ones for indoor gardening, or try keh.

  5. #5
    Tin Can's Avatar
    Join Date
    Dec 2011
    Posts
    18,038

    Re: Foot candle to aperture and ISO.

    Trial and error by narrowing your plot to a good image

    No devices needed

    nor

  6. #6

    Join Date
    Sep 2014
    Location
    Montreal, Canada
    Posts
    979

    Re: Foot candle to aperture and ISO.

    There are simple formulas we can use to find EVs for luminance or illuminance values. Once you have an EV you can decide on your exposure settings (aperture, shutter speed). We just need to know a little more about what type of meter OP has in mind or make some assumptions to estimate. Need some clarity in the original question.

    But on balance I agree with the Maltese Falcon - just get a regular incident or reflected exposure meter which does this for you.

  7. #7

    Join Date
    Dec 2005
    Location
    Los Angeles, CA
    Posts
    5,262

    Re: Foot candle to aperture and ISO.

    or get a meter that does both, like a Weston Master III (reflective mode only).

  8. #8
    ic-racer's Avatar
    Join Date
    Feb 2007
    Posts
    6,098

    Re: Foot candle to aperture and ISO.

    Quote Originally Posted by Grandpa Ron View Post

    I suppose photographic meters are a thing of the past in the age of digital.

    .
    https://www.bhphotovideo.com/c/buy/L...0/N/4077634543

  9. #9

    Join Date
    Dec 2018
    Location
    Northern Indiana
    Posts
    26

    Re: Foot candle to aperture and ISO.

    I have an old Dejur selenium light meter which I am checking the against some of my old camera light meters. The problem is some of the the old film camera meters are through the lens meters of unknown field of view.

    For $20.00 or so I can get an inexpensive light meter that reads in Foot Candles, then match the reading to the conversion chart I down loaded. A gray card reading should do the trick.

  10. #10

    Join Date
    Jul 2020
    Location
    Canada
    Posts
    194

    Re: Foot candle to aperture and ISO.

    If you already have a gray card you can use that with your through the lens camera meter. Just fill the frame with the gray card, and it won't matter what the field of view of the meter is.

Similar Threads

  1. How many foot candles do I need?
    By Thom Bennett in forum Lighting Techniques - Studio, Artificial
    Replies: 7
    Last Post: 5-Sep-2019, 08:59
  2. Do You Use a Foot Switch?
    By Robert Kalman in forum Darkroom: Equipment
    Replies: 46
    Last Post: 24-Jul-2015, 10:55
  3. Big foot for big camera
    By luphot in forum Gear
    Replies: 5
    Last Post: 14-Apr-2011, 14:21
  4. Candle wax, furniture polish...camera maintenance.
    By David Kashuba in forum Cameras & Camera Accessories
    Replies: 4
    Last Post: 3-Jul-2004, 09:26

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
  •