Finding a Densitometer

Discussion in 'Film and Processing' started by jim_gardner|4, Mar 1, 2021.

  1. If there's a difference between that sRGB and Adobe, it must be subtle. I can't see it.
    jim_gardner|4 likes this.
  2. What you need is an M.C.M Wedge ;):

    LINK -- -- -- The M.C.M Wedge Manufactured by Ilford Limited

    Seriously, to assess the density of the various bands, I put the wedge on a light box and measured the light values of the sectors using my Sekonic View Spot Meter L438, with the spot set at 4 degrees. Perhaps the same technique could be used on a negative?

    The Miniature Camera Magazine Step Wedge: Wedgek.jpg
    jim_gardner|4 likes this.
  3. In places it's no more than a one bit difference, but it gets progressively lighter in the shadows, with a cumulative 'lightening' of the shadows.

    Of course, on a system with an Adobe RGB profile those density steps will look (nearly*) identical to the sRGB steps on an sRGB calibrated system.

    *Nearly, because an exact match would require fractional bit differences in brightness.
    To be picky, spotmeters are only accurate at infinity and long distances. They need to be fitted with an appropriate close-up 'dioptre' to be accurate at short distances.
    jim_gardner|4 likes this.
  4. I hadn't thought of a good way to say it, but I think that works.
    The small exception that some scenes might have a large shadow region, big enough to read through.

    But yes, normally there should be some dark areas, and some light areas.
    If all are dark or all are light, you are too far off.
    jim_gardner|4 likes this.
  5. The usual problem, with random pictorial negatives, is that usually there's no single area big enough to get a true density reading from. Densitometer heads generally take an integrated reading from anything between a 3 and 6 mm diameter circle of the negative.

    This tends to set one on the path of taking pictures of grey-cards, step-wedges and other pointless and boring stuff.

    Leave that to the boffins at your favourite film factory - they've been paid to do it.... and a darn sight more accurately than you realistically can!

    Everything you need to know about a film is available online. Just follow the frigging instructions that come with the film/developer/fixer, etc. and everything will be fine.

    Also severely ignore any 'how to' processing videos on YouTube. They all seem to have been posted by idiots with zero experience, knowledge or skills.
    peter_fowler and jim_gardner|4 like this.
  6. Vincent Peri

    Vincent Peri Metairie, LA

    Hmm... I thought "boffins"
    was an insult until I looked
    it up...
    rodeo_joe|1 and jim_gardner|4 like this.
  7. The one I have was designed for different sizes, but I got the smallest one. I think 3mm sounds right.

    The mirror isn't quite as good as it used to be, and doesn't get enough light though the smaller hole to
    reach the calibration point.

    I think if I replace the mirror, aim it carefully, then it might work.

    But it was only $10, so not a big loss if I don't get it to work.

    Macbeth TD-102 for those counting.
    jim_gardner|4 likes this.
  8. The truth is that nobody, outside of a professional colour processing lab, needs a densitometer.

    None of the pro darkrooms I've worked in or visited had one in evidence - although I never ransacked the cupboards to see if there was one hidden away and forgotten.

    I only own one - a Sakura PDA 081 - because it was handed to me as surplus to requirements. It was fun to build a base and light-source for it, and then play with it checking a few negatives....they were fine! End of story. It's had no serious use whatsoever in the last 10 years.

    P.S. A densitometer certainly won't protect you from those crazy incidents where a developer suddenly goes bad, or conversely you get over-dense negatives for no known reason!
    Last edited: Mar 5, 2021
    peter_fowler likes this.

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