From various Kodak publications of the period, recommended exposures in the 1920's on "normal" film would indicate a "modern" ASA rating of 25-50 with normal developement. The sensitivity of generally available films seems to have increased in the early 1930's and higher speed emulsions became also available.
Since there are readers here who may have never seen film: ASA 50 is considered on the very slow, insensitive side today. ASA 200 is typical, and ASA 400+ is fast.
My mom may have meant ASA rating instead of shutter speed. Actually, both, right? If you have slow ASA film, you'd need to keep the shutter open longer to expose it, right?
You have to juggle three parameters when taking photos: aperture (How much light does the lens let through?), shutter speed (How long will the lens be kept open?) and film speed (How sensitive is the film to light?).
Slow film speeds inevitably lead to larger apertures or slower shutter speeds or both. The brightness of lenses is limited which means that the shutter speed (which you can take up to years with pinhole cameras if you really want to) has to do all the heavy lifting and exposure times can quickly get out of hand.
A little example: Say you are shooting with ASA 25 film and your light-meter tells you that, given your aperture, you need a shutter speed of 15 seconds. (You would get values in this range at dusk or inside at night with a normal lightbulb illuminating the room.) To bring that down to a more manageable quarter second (you will still need a tripod but capturing smiles might be quite a bit easier) you would need crazy fast ASA 1600 film (only to give you a sense of perspective on that: you could buy the first ASA 1000 color film only in 1982).
This is actually one area where digital photography handily beats film. A fancy and expensive digital camera like the Nikon D3S will let you shoot photos up to ISO 102400 (for the purpose of this comment let ISO = ASA) which will bring your shutter speed down from a quarter second to 1/256 of a second. Well, those ISO 102400 photos will look like crap, but you will get usable results up to ISO 12800 [+] (that would be 1/32 of a second, you could even pull that one off handheld if you really tried). Unthinkable with film. That’s the reason why digital point and shoots can get away with fairly insensitive minuscule sensors.
Long story short: You mom is absolutely correct when she says that shutter speeds were slow. The reason for that were slow films which cause slow shutter speeds (given a fixed aperture).
I bet she was referring to the shutter speed. People then didn't have context to know the film was slow, just like we don't call all of our digital cameras "low-resolution" although they will be in 50 years.
Some specifics from photo.net:
http://photo.net/black-and-white-photo-film-processing-forum...
From various Kodak publications of the period, recommended exposures in the 1920's on "normal" film would indicate a "modern" ASA rating of 25-50 with normal developement. The sensitivity of generally available films seems to have increased in the early 1930's and higher speed emulsions became also available.
Since there are readers here who may have never seen film: ASA 50 is considered on the very slow, insensitive side today. ASA 200 is typical, and ASA 400+ is fast.