> Isn't the EI (and therefore the film speed) the point where you get .1 over film base + fog for a zone I negative? I know I am testing lots of different films now and all are coming is slow, slow, slow.(posted 8425 days ago)That's the "traditional" speedpoint and perhaps the easiest to determine. There are other methods but the resulting EI should be pretty close to what you're using.
Now...why are you getting really slow speeds? While you should expect to find EIs perhaps a stop different than the film manufacturers' ratings, if you're getting several stops difference, you're using a "standard" developer and you're not developing to a very high or low CI then it's time to start looking for an error and checking calibration.
If we examine high-speed films in particular, we find that the manufacturers' ratings are actually push-development ratings; this is almost kept a secret, buried in spec sheets etc. For the films you mentioned, EI 800-1000 is the "real" speed of TMZ (and Delta 3200) and I believe EI 400 is the "real" speed of Fuji 1600. That may be the "error" that's causing what appears to be very low EIs with those films. If you go for push development, which is essentially underexposure and overdevelopment, you can expose those films at the speeds rated on the boxes and get usable negs; not necessarily good because shadow density will be low and contrast will be high, but usable.
When pushing, though, you can't go by the usual .10DU to obtain the EI because you're intentionally underexposing. You have to use another standard; I think it's personal and I've never seen any recommended standard to be used other than "does it print reasonably well?"
I start by plotting a curve for normal exposure and normal development, then for the pushed film look for the EI that causes its curve plot to cross the normal curve at Zone IV. If you want more shadow density use a lower crossing point or if you can tolerate less shadow density use a higher crossing point. That's just getting into the ballpark; what really counts of course is how the negs print.
Now..back to "normal" film and normal development. The first step imho is calibration of light meters. Calibrate to what? In a big debate in another forum between Ctein and George Wallace (Expo-Disc inventor) Ctein pretty thoroughly showed that there is no industry standard for the calibration of light meters, that manufacturers use their own standards, and that what passes for a standard, the Kodak 18% grey card, if used as intended actually provides 13% reflectance.
So you really ought to calibrate your meters to your own personal standard. It really doesn't matter what that standard is as long as it's consistent, but to make things easier it probably should be reasonably close to the default standard of 1/EI @f16 with a Kodak grey card in sunshine.
So, if you meter the grey card, meter an Expo-Disc or use an incident-light meter, in full sunshine that meter should indicate 1/EI @f16. If it doesn't, adjust the EI you set until it does; the amount of that adjustment becomes a correction factor to be applied to all EI settings applied to that meter, and only that meter. Another meter may be, and probably will be, different.
The next step is checking shutter speeds. Timing tolerances have to be accepted, but I think that in most cases an electronically-controlled shutter can be assumed to be fairly accurate while a mechanically-time shutter should be assumed to be rather inaccurate and non-linear. If you're using mechanical shutters you could have a local shop prepare a speed chart that'll show what the shutter's really doing or you could buy or borrow a shutter-speed tester (Calumet's is relatively inexpensive).
> cannot infulence the real film speed with the developer then that changes my search for a good film/developer combo...
You _can_ influence the real speed, but not by much. Compared to a standard MQ developer such as D-76 and film developed to the same CI, a developer that contains Phenidone such as Microphen, DD-X or Xtol will usually give a little more real speed but it's only on the order of 1/3 to 2/3 stop. Some developers give less speed; these include Rodinal and straight Microdol-X. Some developers also give more speed with dilution or to put it differently, give less speed loss; a couple of them are Microdol-X 1:3 vs straight and Xtol at a variety of dilutions vs straight.
Also, in my experience, high-speed films (EI 400 and faster) respond more to speed-increasing or speed-decreasing developers than slow films (EI 100 or slower).