HP5+FP4+ shoot/develop....

I am sorry that I have to ask this again. Any comments on

o HP5+, shoot at ISO320 develop as 400?

o FP4+, shoot at 80 or 100 develop as 125?

Why? Or more accurately, what effect are you trying to achieve? Or even more accurately, what effect are you trying to achieve that rating the film at its nominal rated speed isn't giving you?

That's what I am trying to find out. Some people recommended, I am not an expert/pro at this so I am asking yours guys' comments. Thanks.

 

Here is the website.

http://www.dr5.com/fp4.html

 

I read about this on a book too.

Where you rate the film depends mostly on what developer you're using. The "speed" of a film is basically the EI (exposure index == personal ISO) at which you have sufficient shadow detail. Now, some developers will help more than others in terms of shadow detail.

 

For instance, Rodinal is generally thought to cost you some speed. Therefore, I shoot FP4 @ EI 80 in Rodinal 1+50. Conversely, Microphen is a speed-enhancing developer. I haven't tested that yet, but I'd think I could get at least 160 out of FP4 in Microphen, if not higher.

 

Furthermore, the methods through which companies calculate that, for instance, FP4 is an ISO of 125 are under very controlled circumstances, with very specific developers, etc. Not only will you find that your own EI's will be different, but I'd wager that the EI will be lower than the box speed in most developers. There are only a handful of developers that will give you more than box speed.

 

Therefore, a common suggestion is to rate film a bit lower than box speed. Remember that with negative film it's better to overexpose than to underexpose. In the absence of testing, starting off with FP4 @ 100 or 80 will give you more shadow detail than less.

 

allan

Blindly following recommendations for ISO speeds for a film isn't really any more useful than simply going with the manufacturer's suggested speed. In the end, there are way too many personal variables, as people have already suggested -- what developer(s) are you using? How do you process? How do you intend to print? Are your camera's shutter speeds and apertures accurate? Do you meter the same way, with a meter calibrated identically to the recommendation?

 

In the end, if you're going to change film speed, you should do your own testing with your own conditions to determine your personal speeds and circumstances.

Here is what I would do. Go and shoot a roll of 36 take one shot at EI 200 and another at EI400 of the same scene do the same for the whole the whole roll so you end up with 18 different scenes with 2 exposures of each scene develop the film normaly for the manufacters recomended time and see which EI 200 or 400 gives the best results not the most acurate way but it will get you started. If you find EI200 gives the most number of good negs then that is what you will use in the future.