Setting B&W and Slide ASA/ISO Question

Sorry if this has been covered before...

 

I mainly rate my 160ASA color negative film to 100ASA and 400ASA negative film

to 320ASA when using my Mamiya RB67 with 90mm and 180mm lenses. I really like

the results that this combination provides in my portrait work.

 

Now, since prices have come down, I have also been able to purchase a Hassy

500CM outfit with the older C versions of 250mm and 50mm lenses and a more

modern 80mm lens. Additionally, I have purchased a Mamiya 645Super outfit with

a 80mm N and 150mm N lenses. I add this only because I have heard that the

camera/lenses make a difference in how one rates their film--I don't know if

that is true or not.

 

My question is this: I would like to start doing fine art work in both B&W and

slide. I prefer 100 speed films or slower and am thinking that my slide film

choices might include Velvia, Astia, and the Kodak 100G (G/X) films. Not sure

on what my flavor would be for B&W films, but I want something that produces

deep blacks and nice and contrasty (recommendations appreciated). So, how do

you guys who use this film/equipment rate your ISOs? Do you use the ISO on the

box or vary it like negative shooters do? Thanks in advance for your help!

 

William Markey

Birmingham, AL

You need to exposure the film correctly, which involves a lot more than which ISO rating you presume. Start by reading "The Negative" by Ansel Adams. It is a companion to "The Camera" and "The Print" and "The Making of 40 Prints", which would also round out your perception of fine art photography.

 

Fine photography, artsy or otherwise, usually involves subtle tonality, presented in the form of prints. That is the realm where B&W reigns, and to a lesser extent, negative color. Subtlety and slide film are not often mentioned in the same breath, but you may find otherwise.

For B&W, I rate Tri-X (both 400 and 320 ISO) @ EI 200 and develop it in D-76 1:1 with benzotriazole. This combination gives me deep blacks and nice contrast.

I rate slide films at their box speeds unless I intend to push them. Your slide film choices

seem good. As for black and white, do you do your own developing? If not, then you might

want to ask your lab what films work best for them. You would probably like the t-grain films

like Fuji Acros, (my favorite), Delta 100 or Tmax 100. I usually rate these at their box speeds,

but I develop myself so I have figured out how I need to expose/develop to get the effect I

want. The only way to really figure it out is to shoot and test...do some tests and drop it off

at your lab, or process it in your standard chemistry.

STOP:

 

This question needs a factual answer, not an opinion. Here are the facts.

 

1. Rating 160 film at 100 means you are giving it 2/3rds of an f-stop over exposure.

2. Rating 400 film at 320 means you are giving it 1/3rd of a an f-sto over exposure.

 

You mention this with regard to using color negative film. Most color negative film has a

"latitude" of 1.5 stops to 1.625 stops--that is 5/3rds either over/under--a total range of

ten 1/3rd stops, and you can still make a good print. The same holds true for most B&W

film. Since you have at total of "5"

1/3rd adjustments to play with, and you are only adjusting by 1 in the case of 400 speed

film and 2 in the case of 100 speed film, this whole discussion is rather pointless for the

following reasons:

 

(a) Color negative and B&W films generally tolerate a wide range of over/under exposure--

up to the ten 1/3rd stop variables. Yes some may give you only six 1/3rd stops or

"latitude" or acceptable exposure range, but we're still talking about the number of Angels

dancing on the head of a pin.

 

(b) Your SHUTTER SPEED is likely to already have a variable of 1/3rd to 2/3rd f-Stop error

that you don't know about unless you have a "calibration chart." Because of film latitude,

you don't ordinarily NEED a calibration chart to tell you that when shooting at 1/250th

your shutter is actually firing at 1/325th or at 1/60th it's really 1/40th, again such

differences are masked by the film latitude.

 

© Color REVERSAL film--slide film--has a much narrower latitude, as little as 2/3rds of a

stop so adjusting your film speed based on tests and experience is often necessary if you

don't have a shutter calibration chart. (That's a whole other subject.)

 

THUS, all discussions about moving exposure 2/3rds of a stop for color negative or black

and white film based on your experience with your camera will APPLY ONLY to the

particular shutter speed that produced what you find are "desired exposure." If you have

your shutter calibrated at a shop with an electronic calibration system, it doesn't

necessarily mean they will "fix" the shutter to operated at "indicated" speeds. It usually

means they will just give you an accurate shutter speed report on paper and you will have

to expose according to how your shutter is actually responding, not what's engraved at the

setting point.

 

Therefore, other people's experience with other cameras--even of the same make and

model--are useless to YOU, even though they are using the same film. F-STOPS, on the

other hand ARE constant and are correct for the lens in which the diaphram is mounted. F-

Stops don't change unless something breaks. Shutter speeds vary with the temperature,

the amount of use, the spring tension, the camera age and all that stuff. Also, if a repair

shop adjusts your shutter to be precisely accurate at 1/250th second as marked, it doesn't

mean it will be precisely accurate at 1/500th and at 1/30th.

 

And, when you get into the lower speeds--1/10th to 1 second, especially with leaf

shutters--a whole different set of variables affect accuracy and therefore exposure and

most of the time the variations are within 2/3rds of o an f-stop. But, with negative film

and up to a ten thirds range of latitude, you never notice the difference.

 

As someone else said: Buy the book, THE NEGATIVE by Ansel Adams, read and understand

the whole concept of FILM and chemicals interacting with EXPOSURE to produce images on

black and white OR color negative film and you will understand that your question can

never be answered by anyone else except yourself, using your own camera, at ONE

particular shutter speed that produces EXACTLY the result you desire.

Hi William,

 

This may be a bit of a simple answer (cos that's the kind of guy I am!) - and I am sure that the other answers here are from more experienced people - but I was in the same situation as you - liking B&W especially for the rich darks and good contrast.

I have tried a number of different films - all at 100 ISO - and I really find that if you use a yellow or red filter to get those rich blacks then it kind of evens them all out.

I stick with the ISO on the box - the developing times on the box - use filters wisely - and just keep it as simple as that.

 

Good Luck!

 

Mike

I've got a short article on my site discussing exposure and developing of black and white negative film that explains a very "tried and true" method of control of contrast. Go to http://www.redisonellis.com and click 'Articles' at the bottom of the navigation window. These methods do not work the same way with color film, so keep that in mind.

Further reading on this topic that I suggest (sorry, but the Adams books tend to be a bit over rated in my opinion) that cover more details would be:

 

"Edge of Darkness" by Barry Thornton (ISBN: 0817438157 )

 

This book goes into more detail than I have about this technique as well as discussing what is actually happening when you follow these steps. In addition, it covers a number of other topics and is very well written.

 

"Creative Black-And-White Photography: Advanced Camera and Darkroom Techniques" by Bernhard J. Suess (ISBN: 1880559889 )

 

This book has a very nice chart showing the effects of over and under development and exposure, allowing you to see at a glance a comparison of these effects.

 

- Randy

Willaim

 

I haver to say I really would agree with CPeter Jorgenson and his comments above. Frankly, there are so many variables, particularly with old cameras and leaf shutters like these, that it is impossible to take note of what others recommend and then suppose that you can simply adopt their methods with success. For a start, precisely WHY do you presently downrate your negative films? Is there good science behind this, or is it just a seat of the pants thing?

 

John

Thanks everyone for taking the time to answer my question! I learned quite a bit in this thread...very detailed and educational answers.

 

John- I downrated my negative color film because all the older, more experienced photographers did so when I used to work in a portrait studio (not just that photographer, but many did so). It gave me great photos, so I just continued with the practice. Guess I just followed the myth that the did! lol

John, print film can handle overexposure much better than underexposure. So by overexposing a little (1/3 - 1 stop) you achieve better shadow detail without blocking the highlights.

 

I have mistakenly overexposed negative film by 3 stops and it was still usable.

 

But if you underexpose it, you will lose detail in the dark parts of the image, because the shadow areas will be blank on the film.

There are indeed many variables. CPeter's no. 1 treats film speed as not one of them. It is. Whether rating a 'nominal 160 ISO' film at 100 ISO may be closer to its true speed, and not necessarily represent an underexposure at all.<br><br>With so many variables, there is only one thing: try, and try some more. Certainly when dealing with B&W film.