Why ISO 160?

[RattyMouse]

Both Fujifilm and Kodak make (made in Fujifilm's case)color professional films at ISO160. Why is this? How did both companies end up making films at this somewhat odd ISO value?

I am guessing that there is an interesting back story.

 

[MattKing]

ASA 160 film replaced ASA 125 film when the emulsions were improved in ways that resulted in finer grain and better colour fidelity accompanied by a 1/3 stop increase in speed.

It was just a result of evolution of the products.

Kodachrome was once ASA 12 - then it got faster .

 

[Tom1956]

I suppose it is a holdover from the High Speed Ektachrome days of the early 70's. At that time it was the fastest Kodak color film there was. As I recall they used it in the XL movie cameras where they showed it being used by the light of a candle in their commercials. Then later, GAF came out with their 200 and 500 speed, just as a side note.

 

[thegman]

I just thought it was so you could shoot it at 100 and get a bit of over exposure, which tends to suit wedding photographers etc. The two films I can think of which are 160 ISO are both portrait/wedding films.

 

[cjbecker]

Don't know why but 125, 160 and 320 seem more appropriate then 100 200 and 400 to me.

 

[Mr Bill]

I don't know all the historic inner details, but I've worked with high-volume chains in the US for years. Prior to digital, all the main film manufacturers were interested in this sort of business. For a variety of reasons, Kodak was pretty much the way to go, in the nominal 100-speed line, from CPS (C-22 process) thru VPS II, VPS III, and then Portra.

If you were in sales for another brand, you didn't have much chance of displacing one of these films if you didn't have a same-speed, or nearly same, that could drop into an existing workflow. (The same situation existed with pro papers in the US, if your paper didn't give terrific results on a pro Kodak film, you didn't have a chance of getting the business.)

So this used to be an important reason to have matching products. Anyone who doesn't think this was an important factor just doesn't realize how much volume was there.

 

[MDR]

Just had a look at old Kodak films and interestingly enough those weird speeds were often given for use in tungsten light whereas the "normal" 100 ... etc for daylight. The 160 Films are nearly always portraits films so maybe there is a relation to the use of tungsten lighting for portraits and the choice to use 160 speed for that kind of film.

 

[AgX]

Both Fujifilm and Kodak make (made in Fujifilm's case)color professional films at ISO160. Why is this? How did both companies end up making films at this somewhat odd ISO value?

I am guessing that there is an interesting back story.

It is not odd at all.

It just depend from where one starts counting.

And as there are 20, 40, 80 ISO films, 160 and 320 ISO make sence again.
The same for 100 versus 125 ISO.

So you got the 10, 20, 40 row,
the 32, 64, 125 row
and the 12, 25, 50 row.

 

[Tom1956]

A better question to my curiosity is why did Kodak pick 68°F as the base temperature for their developing processes? Is it because 68° was just the easiest temp to maintain in the Kodak buildings? Because if so, those poor Kodak scientists had to go to work in a chilly place all day every day. Not cold, just uncomfortably chilly. I know I wouldn't have liked it.

 

[MattKing]

A better question to my curiosity is why did Kodak pick 68°F as the base temperature for their developing processes? Is it because 68° was just the easiest temp to maintain in the Kodak buildings? Because if so, those poor Kodak scientists had to go to work in a chilly place all day every day. Not cold, just uncomfortably chilly. I know I wouldn't have liked it.

It was because they knew that it was the same as 20C, and they were forward thinkers at that time.

 

[AgX]

Strange enough the colour film processes are designed for 100°F which corresponds to rather odd 37.8°C.
Seemingly those engineers were less forwardthinking...

Or they had clinical thermometers in mind.

 

[StoneNYC]

A better question to my curiosity is why did Kodak pick 68°F as the base temperature for their developing processes? Is it because 68° was just the easiest temp to maintain in the Kodak buildings? Because if so, those poor Kodak scientists had to go to work in a chilly place all day every day. Not cold, just uncomfortably chilly. I know I wouldn't have liked it.

Not surprising, you don't like ANYTHING haha

 

[StoneNYC]

I suppose it is a holdover from the High Speed Ektachrome days of the early 70's. At that time it was the fastest Kodak color film there was. As I recall they used it in the XL movie cameras where they showed it being used by the light of a candle in their commercials. Then later, GAF came out with their 200 and 500 speed, just as a side note.

Could this have been a shutter speed synch idea, for fast speed images, sunny 16 would sync up with 1/500 shutter with 500 ASA film?

Incidentally, my GAF aerial 200 film is some of the finest grain film I've ever seen (at least scanning wise) it's finer than TMY-2! wish they hadn't collapsed (or whatever happened to them).

 

[Xmas]

When you make a foot ball field of film and test it's speed it is the speed on the step wedge you declare as the ISO.

Forma's data sheets show the ISO & contrast variation with several dev and time and temp, saves time experimenting.

Ilford and Kodak quote different speed in daylight and tungsten light for cine film

my box of HP5+ says 400/200 respectively

always read the data sheets.