Noon question, but: How do I safety check that there is no light in Darkroom / Darkbag?

  • 2
    \$\begingroup\$ "Noon question" - I am not trying to nitpick on the typo, but it's funny. Keeping no light in darkroom at noon is probably even harder. (sorry, I couldn't resist) \$\endgroup\$ Commented Aug 4, 2019 at 19:53
  • \$\begingroup\$ I was thinking to edit it, but in a way makes sense :) \$\endgroup\$
    – Andy Andy
    Commented Aug 5, 2019 at 18:21

2 Answers 2


If you are talking about locating a light leak in a changing bag for loading film into magazines and cameras without a darkroom available…

Periodically, to check the condition of your changing bag, put a bright light inside the bag through one of the sleeves. Close up the bag. Sit in the darkroom or a closet with no light for a few minutes to let your eyes acclimate. Turn the bag over. Manipulate it. Turn it every which way. Look at it from all angles and pretty soon, you'll see every pinhole if there is one.

It's easier to see a bright light in a dark room because your eyes will dilate within a few minutes to rival a sensitive emulsion.

Good Luck.

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    \$\begingroup\$ Changing bag hack: Make a frame to keep the bag open like a tent frame using a construction set made of dowels and blocks such as TinkerToy™ \$\endgroup\$
    – Stan
    Commented Aug 2, 2019 at 1:31

In the darkroom, place a piece of the material you will be developing, flat, face up, on the work space. Place a handful of coins on this material. Using a timer, remove a coin every 5 minutes. 12 coins will cover 1 hour. At the end of the time span, develop the film or photo paper. A perfect darkroom will leave no evidence. An unsafe darkroom, reveals circular images of the coins. This test will tell you how long it safe to have work out.

  • \$\begingroup\$ This is more useful with photo paper than film. \$\endgroup\$
    – Davidw
    Commented Aug 2, 2019 at 16:36
  • \$\begingroup\$ @Davidw Or sheet film, or (to a degree) medium format film. But not much useful for 35mm or small formats. \$\endgroup\$
    – gparyani
    Commented Aug 2, 2019 at 17:40
  • \$\begingroup\$ @Davidw -- Works for sheet film or 35mm or 16mm -- you just change the size to smaller objects. \$\endgroup\$ Commented Aug 2, 2019 at 18:02
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    \$\begingroup\$ @gparyani 35mm needs only to be pulled from the closed cassette by a fixed amount after each time interval, process, and then count the stripes after drying the roll. \$\endgroup\$
    – Stan
    Commented Aug 2, 2019 at 20:47
  • \$\begingroup\$ @AlanMarcus Does one sit in the darkroom for 13 hours or can I get in and out somehow (or is this another question, kind of?) : ^ ) \$\endgroup\$
    – Stan
    Commented Aug 4, 2019 at 12:58

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