I have completed the Instant Pinhole Camera which I mentioned in a previous question. To open the pack of Instax Film, I used a pitch black room, blocked all the edges around the door, and opened it using a few red LED's.

When I use a rolling pin to develop the film, it is all red. I have read many posts saying red LED's are fine for use as a safelight. It is possible that I did not expose the photo long enough.

Were these posts false, or is this a different problem?

This is a photo of the front and back of my film:

enter image description here

  • \$\begingroup\$ Yes, it does look like that. \$\endgroup\$
    – user78935
    Commented Mar 26, 2019 at 21:42
  • \$\begingroup\$ That's your red led's overexposing your image. \$\endgroup\$
    – OnBreak.
    Commented Mar 26, 2019 at 22:09
  • \$\begingroup\$ If you absolutely have to have some light to work, then use a single LED placed high in the room and aimed at the ceiling. You should have enough light to make out objects but that's about it. Work as fast as you can. You'll still end up exposing the film, but hopefully you can keep that to a minimum. \$\endgroup\$
    – OnBreak.
    Commented Mar 26, 2019 at 22:11
  • \$\begingroup\$ OooooK. Fail. Looks like I will just go back to the 'digital pinhole camera'! \$\endgroup\$
    – user78935
    Commented Mar 26, 2019 at 22:13
  • 1
    \$\begingroup\$ Dim red light is fine for use as a safelight with monochromatic film not sensitive to red light. There's no such safe light for color film of any type. \$\endgroup\$
    – Michael C
    Commented Mar 27, 2019 at 4:44

1 Answer 1


Were these posts false

Yes. Yes they are.

The iconic darkroom safelight is usually red or reddish in color. The reason for this is that the black and white photo paper that one is using to print their negative is sensitive to only blue and green wavelengths of light. This means that you can hold one of those unexposed pieces of paper right in front of a red light and it will not be exposed.

However, your Instax film is sensitive to the entire spectrum. Check out the Spectral Sensitivity Curve here. This means that you need to operate in 100% complete and total darkness.

I found a spare cassette. Here's the instax just held out in the open. I've crushed the developer out with my fingers and you can see it bubble up a tad.

Images thumbnailified for viewing. Click to enlarge.

enter image description here

Here's a single pass with a piece of wood to roll it out:

enter image description here

And here's the image on the other side:

enter image description here

As you can see, the whole frame is completely overexposed and where the developer has had a chance to work, the film shows what we would expect (100% white).

So, if you are still seeing this bright red back, it's because you haven't spread the developer around successfully.

If you are getting the developer around, then you need to observe the other side. If it's perfect white, then you have massively overexposed your image and need to alter your process to get less exposure. If it's pitch black, give it more exposure.

Aaaand if it's a perfect red image - you massively overexposed your image with your red LED's :-D.

  • \$\begingroup\$ The developer has leaked out. From the back of the film. black liquid has visibly leaked out and is covering more than have of the film. Only the part which the liquid has touched is black. I will update my post with images. \$\endgroup\$
    – user78935
    Commented Mar 26, 2019 at 21:53

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