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Picked up a Double 8mm Camera "Keystone 8mm K25 Capri" which came with a single lens Labeled Keystone Elgeet 1/2" f2.3.

On this lens it has a single control ring for f-stop. But it also has a sort of readout that reads: Type A Color at X feet where X is a number shown through a little window and can be 12, 10, 7, 5, or 4 depending on the selected f-stop.

The lens doesn't appear to be be focusable at all. My questions are:

What does the "Type A Color..." Message mean? What is "Type A Color"? What is the purpose of the foot number.

What is the distance I should be be from the subject for an in-focus image.

Type A Color At X Feet F Stop Markings Camera With Lens On Front

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  • \$\begingroup\$ Kodak invented many film types through the years. Type A film seems to be one of them. Take a look at this data sheet - there's an exposure table in it with distances listed, though after a cursory look, I can't immediately figure it out. \$\endgroup\$
    – osullic
    Sep 28, 2022 at 23:34
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    \$\begingroup\$ Oh ok so maybe the footage indicator is for distance from a standardized light source of some kind? \$\endgroup\$
    – WillD
    Sep 29, 2022 at 2:12

1 Answer 1

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The distance shown in the window is not a focus distance. It is a distance recommendation, measured in feet from the subject, for the placement of specified lighting when using the film at an indoor soundstage or studio.

For more, please see this technical data sheet for Kodachrome 40 'Type A' color reversal movie film.

Based on the data sheet produced in 2002, the distance recommendation indicator on your much older lens seems to be based on the equivalent of a 375 Watt halogen movie light with output centered on 3400K.

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  • \$\begingroup\$ Thank you for your research. This is helpful. Still looking for the other part of the question though: If this is a fixed focus lens. What is the nearest object that will be in focus? What is its minimum focusable distance? \$\endgroup\$
    – WillD
    Oct 3, 2022 at 17:45
  • \$\begingroup\$ @WillD What size is the frame produced by your camera? What size is the screen upon which you'll be projecting? How far will the viewers be from the screen? It's then a simple matter of plugging the numbers into a DoF calculator to find the hyperfocal distance for a specific frame size, aperture, intended display size, and viewing distance. \$\endgroup\$
    – Michael C
    Oct 4, 2022 at 7:35
  • \$\begingroup\$ Where do you plan to get 16mm film with twice the normal number of perforations in 2022? Where are you going to find a processor to split the processed 16mm film down the middle into two 8mm strips with perforations on only one side? \$\endgroup\$
    – Michael C
    Oct 4, 2022 at 7:56
  • \$\begingroup\$ Interesting thought about hyperfocal distance calculator. I don't have a 8mm projector at the moment so I was planning on getting it scanned to HD video. Also you can buy "Double 8" aka "Regular 8" film from FPP, here's a color negative but they also have a couple positive and black and white options: filmphotographystore.com/collections/movie-film/products/… same company will develop and slice the film down the middle. \$\endgroup\$
    – WillD
    Oct 4, 2022 at 13:34

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