ASA ISO and DIN

[wintoid]

Yesterday, my stepmother gave me her ex-husband's camera, which is a Zeiss Ikon Contina IIa that has not been used since he died (late 1960s or early 1970s). It's in very good condition and looks like it has almost never been used. It's not a rangefinder, but uses scale focusing (although I believe it may be possible to buy a rangefinder attachment for it).

Atop the camera is a circular dial for setting the film speed, and the dial has 2 cutouts - one to reveal the ASA and one to reveal the DIN. I have started shooting a roll of Neopan 400 with this dial set to 320 ASA and am hoping that this should be about alright.

However.... I notice that the DIN number opposite 320 ASA on the dial is DIN 30, which doesn't make sense to me. So far as I can see, DIN 30 should be about ISO 800, but I thought 320 ASA = ISO 320. :bang:

Can anyone shed any light on this please ? No pun intended, honest 😀

 

[Sparrow]

3 DIN is one stop so
18=50
21=100
24=200
27=400
etc.

 

[rogue_designer]

ASA and ISO should be the same, and DIN 30 *should* be ASA/ISO 800. You are correct there.

I can't explain what you're seeing on the Contina.

 

[ZorkiKat]

ASA and ISO are exact equivalents. Perhaps the camera was from a time when
the equivalents were still not standardised. The ASA system itself underwent several changes in the 1960s. E.g., Plus X had been given ASA values of 80, 160 or even 200 until it settled at 125 when the 'safety factors' were removed.

What is more pertinent is the question whether the numbers set on the camera's dial bear any control on the exposure itself. If it's just an exposure reminder, best ignore it and just remember what sort of film you have loaded in the camera. And chances are, even if the film-speed setting does control the camera's exposure meter, that meter would likely be inaccurate now. Leave exposure measurement with another device - use a better, more reliable meter, or even your eye 😀

Jay

 

[Sparrow]

I seem to recall film speed had new standards applied just prior to my starting to take an interest so that would be in the early 60s I got my first proper camera in 1964 and the then CT18/50 stuck thereafter

 

[wintoid]

Thanks everyone.

I found this http://photography.about.com/library/glossary/bldef_asa.htm which implies that ASA speeds doubled in the 1960s. So I guess I'm working at ISO 640 or so, assuming the meter works with any degree of accuracy (which as mentioned above is doubtful).