What's the point with ISO 125?

Seems to me unstated is how a new film is created. Does one decide on the desired ISO value, and then find the conditions that will generate that value, or generate an emulsion, and then measure its value?

 

I suspect in the earlier days, the latter method was done, though in the earliest days there was no standard (or even non-standard) for measuring film sensitivity.

 

There is the additional complication that the ASA system changed sometime around 1960, which resulted in new ASA values for existing films.

 

That, and the standard rounding to 1/3 stop values.

 

Sometime around 1980, Kodak converted most films to multiple of 100. In the early E6 days, we had Ektachrome 64, as a replacement for the older Ektachrome-X, but not so much later, this was replaced by Ektachrome 100. (But Kodachrome 64 stayed around until the end of K14 films.)

 

Left unsaid, is how important a 1/3 stop difference is to film buyers. Given the choice between films from two different manufacturers, differing by 1/3 stop, and assuming the same price, will buyers go for the faster film? I suspect that brand reputation is worth more than 1/3 stop, but I don't know how much more.

Sorry about all the mention of color films in this forum. I presume that the process of generating emulsions with different ISO values isn't all that different between color and B&W, though the actual films that we are able to buy don't make that obvious.

Left unsaid, is how important a 1/3 stop difference is to film buyers. Given the choice between films from two different manufacturers, differing by 1/3 stop, and assuming the same price, will buyers go for the faster film? I suspect that brand reputation is worth more than 1/3 stop, but I don't know how much more.

 

Then you have nutty people like me who will pay an extra $20 for a box of 20 sheets of 4x5 from Japan to get a film rated at half the speed as what's available on the US market :)

Well, things are different now.

 

Now we have nice fast digital cameras when we really need pictures in low light, so film is more for fun.

 

I don't know that I would pay a lot extra for slow sheet film, but I do have some 100 foot rolls of Panatomic-X for when I feel like using it.

(Though maybe developed in Diafine at EI 100 or 200.)

 

But when we only had one camera, and didn't know what light conditions might appear in the future, faster films were useful.

That might include museums that don't allow flash, or places where the distance is too far for flash.

I agree with that.

 

Back when I first took an interest in photography, DSLRs were on the market but were out of reach of anyone but pros and rich amateurs. I don't know how many miles of Fuji Superia 400 I ran through my Canon A-1, or really any one of the other 400 ASA print films(Kodak 400UC became a favorite when I discovered it).

 

Much like you said, I considered ASA 400 color print film a general purpose film that would cover me for most situations, esp. with a 50mm 1.4. I'd even load up the occasional roll of Superia 800 or 1600(that was grainy stuff) if I though the situation would mandate it. I keep meaning to buy some Delta 3200-I shot a few rolls of TMAX P3200 back in the day also. Admittedly, these days if I need a fast B&W I'd rather shoot Tri-X and push it.

 

Grudgingly, I now use digital also in situations where I'm going to encounter varying light conditions. Admittedly, my cheap old DSLR starts to look pretty rough at 800.

 

The only 400 speed film I use with any regularity now is Tri-X.

 

As for spending extra for the slower sheet film-the reason I do it is because I prefer the color rendition of Velvia 50. The 100 version is actually(slightly) finer grained but then in 4x5 both are fine enough grained that it won't likely be an issue.

I don't miss Plus-x much. I use tri-x anywhere from 160 to 1600 with nice results. If I want more quality and finer grain I use Tmax 100. Both are developed in Tmax developer which is very versatile and under appreciated IMO.

Admittedly, these days if I need a fast B&W I'd rather shoot Tri-X and push it.

 

While a bit off-topic in a thread on IS125 film - between pushed Tri-X and Delta 3200, I'll take Delta 3200 personally. Though the grain look of Tri-X is nice, Delta 3200 to me keeps a nicer tonality, and hence is a bit less of a specific "look" (that is, nothing wrong with the pushed tri-x look, but it's in my view more of a one-trick pony).

While a bit off-topic in a thread on IS125 film - between pushed Tri-X and Delta 3200, I'll take Delta 3200 personally. Though the grain look of Tri-X is nice, Delta 3200 to me keeps a nicer tonality, and hence is a bit less of a specific "look" (that is, nothing wrong with the pushed tri-x look, but it's in my view more of a one-trick pony).

 

The actual subject is any film not in the 25 times a power of two series, 25, 50, 100, 200, 400, 800, 1600.

 

It seems that most newer films follow that series, and most old ones don't.

 

I do remember the change from Ektachrome 64 to 100, after 200 and 400 already existed.

 

In the E4 days, we had Ektachrome X (ASA 64), and High Speed Ektachrome at 160.

 

Panatomic X, at ASA 32, goes back pretty far in the early roll film days, way before Verichrome Pan.

It seems that most newer films follow that series, and most old ones don't.

 

Not necessarily-160 has been the "standard" speed for low contrast, fine grained color "portrait" film for a while now. Both Kodak and Fuji now make very popular emulsions in those speeds and have(under various names) for quite a while now.

Not necessarily-160 has been the "standard" speed for low contrast, fine grained color "portrait" film for a while now. Both Kodak and Fuji now make very popular emulsions in those speeds and have(under various names) for quite a while now.

 

Well, I did say most, but I suppose I don't consider the 160 portrait films as "new". I used Vericolor III as my favorite C41 film for many years. I always considered Portra 160 as a new name for (mostly) the same old film. But I don't know how much it changed.

 

It seems that Vericolor II is 125, I have a few cold stored rolls of that. Bought along with some other films on eBay.

 

But I suppose that the new series of 100, 200, 400, ..., is only for non-professional films. Tungsten films are different, where it seems that they come out a little slower than the matching daylight film.

Back in the 1960's Freestyle sold an unbranded ISO 160 B&W film in 120. I think it was made in Belgium. When the safety factor on black & white films was reduced in 1960 Plus-X went from 80 to 125, but many films were doubled. If Kodak had followed that with Plus-X it would have been an ISO 160 film as well. But as ISO ratings are really a starting recommendation one does not necessarily have to rate an ISO 125 film at box speed. Under flat lighting I used to shoot Plus-X at E.I. 200.