ISO 100 & up! How did we eliminate ASA 6 thru 64? Looking at a correlation chart I see ASA 100 equals ISO 100. Is there a technical reason why we don't have ISO 6, 12, 25, 40, 50, &...

Virgil Loc: The Hoosier State

Looking at a correlation chart I see ASA 100 equals ISO 100.
Is there a technical reason why we don't have ISO 6, 12, 25,
40, 50, & 64 that we had with ASA film values? I've shot Kodachrome ASA 64 for about 50 years and I can't seem to get that '64' out of my little brain. I get ready to shoot and there is this little guy back there saying "wait a minute - remember now, your'e at ISO 100 - double check!".

Danilo Loc: Las Vegas

Amazing, Virgil! I was just thinking exactly the same thing earlier today. Why did we lose everything below ISO100?
I'm thinking of all the people who need ND filters to get long exposures of waterfalls in daylight. They might not need the filter if they could set ISO25.
I'm glad you thought of this!

lighthouse Loc: No Fixed Abode

Many of us would love to be able to go lower.
You can push the Canons to 50 and I think some model specific Leicas and/or Sonys may go lower still.Nikons might only go to 100 with a push.
I think its a conspiracy by the Solid ND manufacturers!!

I'd also like to be able to go out to about 4 minutes without an intervalometer & bulb.

Nikonian72 Loc: Chico CA

Films rated by the American Standards Association (ASA) were more a product of chemical/light sensitivity, than convenience. Early wet plate formats were painfully long in full sunlight exposure, with calculated ASAs of less than one (1). As films were developed after daguerreotypes plates, etc., higher ASAs allowed shorter shutter durations.

I shot hundreds of rolls of ASA 25 Kodachrome, because of the tight grain pattern. I also shot ASA 64 Kodachrome, and ASA 64 Ektachrome, then on to ASA 100 Fujichrome, ASA 200 Ektachrome, etc. I only used ASA 400 film when working in low light conditions.

Now, I routinely shoot ISO 400 (International Standards Organization) digital sensitivity, which I find quite comparable to film of the same ASA rating, on a sensor of 12 Mp, or greater. Digital manipulation is so much easier than chemical re-formulation, to achieve higher ISOs to use in low light situations. I do not miss Kodachrome 25, at all. I can always use Neutral Density filters to lower the sensitivity of a digital sensor.

Rob O' Loc: Freakin' Hot Arizona

My Sony a77 does 50, 64, 80 then 100 and up. But you have to keep in mind that the native sensitivity of the sensor is, I believe, 200. That's where you'll get the best quality.

Festina Lente Loc: Florida & Missouri

Nikonian72 wrote:

Films rated by the American Standards Association ... (show quote)

Good response, and a pleasant trip down memory lane.
I don't miss Kodachrome 25 either, but I sure shot a ton of it and it performed beautifully (based on what I knew at the time).

Pablo8 Loc: Nottingham UK.

Thinking back also I can now smile at the Ektachrome 200 asa film being branded as 'High-Speed Ektachrome'. In comparison to Kodak 25asa, it was ...'High Speed'.

GHK Loc: The Vale of Eden

Virgil wrote:

Looking at a correlation chart I see ASA 100 equals ISO 100.
Is there a technical reason why we don't have ISO 6, 12, 25,
40, 50, & 64 that we had with ASA film values? I've shot Kodachrome ASA 64 for about 50 years and I can't seem to get that '64' out of my little brain. I get ready to shoot and there is this little guy back there saying "wait a minute - remember now, your'e at ISO 100 - double check!".

Will people never be satisfied? For years 125 ASA was the max speed without compromising quality. Now 100 ISO is so good that there's no need to go any lower.
Just be grateful.
GHK

photonphysicist Loc: Texas

Excellent point about using ND filters!

jerryc41 Loc: Catskill Mts of NY

Virgil wrote:

Looking at a correlation chart I see ASA 100 equals ISO 100.
Is there a technical reason why we don't have ISO 6, 12, 25,
40, 50, & 64 that we had with ASA film values? I've shot Kodachrome ASA 64 for about 50 years and I can't seem to get that '64' out of my little brain. I get ready to shoot and there is this little guy back there saying "wait a minute - remember now, your'e at ISO 100 - double check!".

I'd say it's just improved technology. They had to use ASA 25 to get good results, but now we can get good results from 100. Many new cameras have Low setting for ISO below 100. I've never gone below 100.

Max Kurz Loc: Newark, De

Virgil,Virgil, Virgil,,
It takes time to realize that the manufactors know more about what we want than we do !
Low end ISO went the way of viewfinders.
Trust the big guys, they only have your best interest in mind.

bull drink water Loc: pontiac mi.

in my mind it's like comparing lp's to cd's. the old low asa films had a depth and sense of essence that sensors are still striving for.

r.reeder Loc: Mesa, Arizona

Max Kurz wrote:

Virgil,Virgil, Virgil,,
It takes time to realize that the manufactors know more about what we want than we do !
Low end ISO went the way of viewfinders.
Trust the big guys, they only have your best interest in mind.

Speaking of viewfinders, I love shooting with older cameras. 1930's through 1970's. Mostly the ubiquitous Argus C3. With a top shutter speed of 1/300 sec, & an aperture range of f/3.5 to f/16, here in Arizona there is too much light outside for film speeds of 200 or more. I use ASA100 film because I can still easily & economically get it in both B/W & color. It would be nice to get it easy & cheap in ASA50 or even ASA25.

Nikonian72 Loc: Chico CA

r.reeder wrote:

. . . here in Arizona there is too much light outside for film speeds of 200 or more.

The latitude of Mesa, Arizona is: 33° 25' 20" N;
The latitude San Clemente, California is: 33° 25' 36" N.
We get the exact same sun here in San Clemente as you do in Mesa, and exactly the same as scores of other communities at the same latitude.

jimni2001 Loc: Sierra Vista, Arizona, USA

Nikonian72 wrote:

r.reeder wrote:

. . . here in Arizona there is too much light outside for film speeds of 200 or more.

The latitude of Mesa, Arizona is: 33° 25' 20" N;
The latitude San Clemente, California is: 33° 25' 36" N.
We get the exact same sun here in San Clemente as you do in Mesa, and exactly the same as scores of other communities at the same latitude.

The difference being that in San Clemente you have humidity that cuts the amount of light hitting the earth. In Mesa you frequently have a humidity of 3 to 6%. You may have the same sun but you do not have the same light.