establishing an EI???

[stradibarrius]

Generally, when I expose at "0"/Normal according to my meter I generally find it a it overexposed about 1/2 stop for my taste.
Then I read when people establish an "EI" for a film it is generally at a slower ASA which would seem to increase the exposure??? For example shooting ASA 100 at ASA 80. Where I would shoot at say ASA 200.

Am I confused. Shooting at a lower ASA will increase exposure correct????

I find that with all of my cameras and meters I like the look when I under expose a bit...

 

[ic-racer]

Look up "Zone I" test and try it.

If 'box speed' makes you think it is overexposed, the first thing that comes to mind is to ask how you are judging your negatives for exposure. If the shadow detail is too dense, there certainly are cases where you could get overexposure, like slow shutters etc.

 

[keithwms]

Rating at a lower speed will indeed increase exposure. And/but: how you meter can be every bit as important as how you rate your film. I find that people tend to meter in such a way as to protect the highlights. To see if you have that tendency, try metering off a grey card and see how that compares to where you have typically been placing a middle zone.

If you like to rate a bit slower than box speed while keeping development roughly the same, well, join the crowd, a lot of people do this with neg films. The manufacturer's ratings will tend to give the most equally weighted contrast from shadows through highlights, and that isn't necessarily what you want.

Bracketing can quickly reveal the effects of rating high or low relative to box speed.

 

[Willie Jan]

Generally, when I expose at "0"/Normal according to my meter I generally find it a it overexposed about 1/2 stop for my taste.
Then I read when people establish an "EI" for a film it is generally at a slower ASA which would seem to increase the exposure??? For example shooting ASA 100 at ASA 80. Where I would shoot at say ASA 200.

Am I confused. Shooting at a lower ASA will increase exposure correct????

I find that with all of my cameras and meters I like the look when I under expose a bit...

could be that your meter is showing the wrong value, or you measurement is not correct.
Maybe if you give more info about your development method we can see what you are doing.

 

[Mike Wilde]

consider Fred Picker's The Negative - Exposure and Development', which gave me the first advise to move away from manufacturers spec sheets. Then online look up the late Barry Thornton's site - personal film speed and personal development time.

 

[2Bugles]

Strad,
I second Mike's recommendation to look-up Barry Thornton and try his speed test and develop test. I just completed testing Ilford Delta 3200 and found my EI to be 800. Thornton is such a great writer, easily understood and fond of debunking myths. Since I'm up the road from you in Athens I could LOAN you his Edge of Darkness (you must promise to return it).
Paul

 

[Stephen Benskin]

A great deal of establishing an EI concerns personal working methods. If you find your exposures to be on the over side, then up the film's EI. No matter what the speed of the film actually is, if the negatives you produce are consistently one way or the other, then adjust for it. The reason most find lower EIs is because of the their testing method.

 

[Poisson Du Jour]

The reasons, methodology and testing of EI was recently given an overly exhaustive and far too scientific airing through a post on APUG recently with everything from chemists to engineers to mathematicians dishing it out, leaving the poor OP battling through a mountainous welter of waffle, and still no wiser for for the where and wherewithal!

In application, EI (Exposure Index or Indice) is a personal notation of re-rating the film at other than its marked box speed (to some, also, they apply it in the darkroom at such a level of complexity to conveniently bypass it here). Re-rating a film is based on experience and observing how the film responds exposed to various lighting scenarios. For example, Velvia 50 rated at EI 40 (which is very common) is +0.3 stop; at EI 32 it is +0.6; the reverse is true for negative values, in effect imparting slight to moderate over or under-exposure (more generally useful for transparency film destined for printing). Re-rating a film introduces risk of blowing highlights or blocking shadows so experience is very important. You do not have to strictly push or pull the film secondary to EI application, and this was where the original enormous discourse would make Proust blush in his bed.

 

[Stephen Benskin]

Strad,
I second Mike's recommendation to look-up Barry Thornton and try his speed test and develop test. I just completed testing Ilford Delta 3200 and found my EI to be 800. Thornton is such a great writer, easily understood and fond of debunking myths.

Ilford never suggests Delta 3200's speed is 3200. This is not the best example to support Thornton's statements, which I've just gone back and read. I've actually found his writings on his website to be full of mistakes with plenty of myths as well as logical fallacies and circular reasoning.

Almost anyone can get acceptable exposures listening to most of the popular photographic authors mostly because of the preponderance of average conditions encountered and range of acceptable variance within the photographic process, but most of the pop photo authors just recycle myth and hearsay and frequently only use arguments from authority to support their arguments. If anyone wants to truly understand the process, they will have to move up to the more scientifically oriented photographic sources.

 

[MattKing]

I've heard/read recommendations for Bruce Barlow's approach, as well as his "Circle of the Sun" website generally:

Dead Link Removed

 

[climbabout]

A great deal of establishing an EI concerns personal working methods. If you find your exposures to be on the over side, then up the film's EI. No matter what the speed of the film actually is, if the negatives you produce are consistently one way or the other, then adjust for it. The reason most find lower EIs is because of the their testing method.

To restate what the above poster said- your EI is a result of your combination of personal methods. Your meter, your shutters, your developer and development method. If it makes you feel any better, I rate my fp4+ at 160 asa, not the 125 noted on the box. I did zone 1 tests at 8 different ASA settings, and 160 gave me the proper tonality at my minimum proofing time. I develop in pyrocat hd with minimal agitation, which is at least partly responsible for a higher film speed. Other variables are my meter, my shutters, etc... Go with what pleases you and don't worry what most other people do.
Good Luck.
Tim

 

[2F/2F]

Pick a value to which you would like to calibrate. Do tests. Use the EI that lets you get what you want from, and in relation to, that value every time. No one sez it always has to be a zone I (and if they do, they are wrong). The whole point of using an EI that you figure out versus an EI that matches the ISO speed is that you can do different things than the ISO expects you to do, for the various reasons that you might want this. I have used the classic zone I density test (as I learned in school for using the Zone System), a zone II density test (which I figured out worked better for me in practice when using the Zone System, as I often placed zone IIs, but almost never zone Is, and I thought that even with a neg developed to the right CI for my paper, using zone I made my midtones more muddy than I liked with my Tri-X 320 and HC-110 combo), a middle grey normal print test (which I use almost all of the time, as I mostly an incident meter for exposure now), and zone VIII tests (for straight-processed transparencies) at various times with various materials and various situations.

So, pick a tone (any tone) to which you want to calibrate, and test until you get the EI that lets you perfectly place that tone every time. The way I work, the EI lets me place my one absolute tone at normal exposure and development, and exposure and development alterations allow me to control the other tones relative to my personal choice of absolute tone. As I mentioned, I first learned to make zone I negative density the absolute, moved on to zone II negative density via experience, and I now prefer using a zone V print value as my personal determinant of EI.

That is what is "cool" about EI. It lets you make fine personal adjustments. It is a very versatile photographic tool.

 

[Stephen Benskin]

The reasons, methodology and testing of EI was recently given an overly exhaustive and far too scientific airing through a post on APUG recently with everything from chemists to engineers to mathematicians dishing it out, leaving the poor OP battling through a mountainous welter of waffle, and still no wiser for for the where and wherewithal!

It's all about degrees and how much an individual wants out of it. Some are happy to understand gravity as all objects attract, but that won't get you to the moon. To each their own. If someone is in the first group and doesn't want to take it very far, then that's fine. But let's not berate those who want more. I personally find that most arguments are void of proof and generally consist of arguing about the number of angels that can dance on the head of a pin. The Bush administration is history. Knowledge is back in vogue. What's wrong with a little substance occasionally?

As for the referenced thread, the OPs question was answered within the first five posts. The rest of the thread was for the more advanced participants. Most of the time, there isn't much of a reason for them advanced to hang around.

 

[Chuck_P]

Generally, when I expose at "0"/Normal according to my meter I generally find it a it overexposed about 1/2 stop for my taste.
Then I read when people establish an "EI" for a film it is generally at a slower ASA which would seem to increase the exposure???

Pardon the zone talk, but I believe it will make sense to you.

Your're right, when the EI is found to be lower than the box speed that will impact the highlights, but it provides the needed amount of exposure for a Zone I density to print a dark gray and not full black.

It's a two part process when finding the EI, it does not end with the EI itself---once it is found based on whatever method is used i.e., ZS or BTZS, the next thing is to find the "normal" development time for that particular EI-----the normal development time sets the upper density limit that allows for printing the lightest print value that still retains adequate texture in the print. Traditional Zone System method defines that limit at a Zone VIII negative density of about 1.3 (in fact it works for me quite well with my paper), but actually considers Zone VII as the highlight zone that should render "full" texture in the print, thus making Zone VIII the lightest tone that should render a good sense of texture, not much if any at all in IX, and definitely not any in X while using the "normal" development time. In the ZS vernacular, it's referred to as calibrating your "normal" development time, but is not done until the EI has been determined.

So it does not matter what the actual EI ends up being, over or under the box speed, you must determine, even if it is not by such a refined method as the ZS or BTZS, etc...what development time will control the densities up around zone VIII and allow you to print it with predictability.

 

[Chan Tran]

Hi Barry! Good to see your post! I assume that you're talking about color negative and B&W negative films. It's strange that you like the results of slightly underexposure but if you like it by all mean do it. I don't think there is anything wrong with your equipment. I saw your images and I think you like your images on the softer side.
I myself would prefer somewhat overexposure about 2/3 to 1 stop. When I make prints or scan I always print dark enough so that some of the details (which is on the negative) bury in the dark part of the picture. In another word I want to be sure to have more shadow details than I would render on the print or on the monitor screen.

 

[johnnywalker]

Ralph Lambrecht summarized it nicely in another thread on EI:

"Understand that your camera, film/developer and meter is a system. Together they dictate your EI".

I pasted this quote up in my darkroom.

 

[36cm2]

Some are happy to understand gravity as all objects attract, but that won't get you to the moon.

I can attest to this. I have yet to figure out how to retrieve my Hasselblads from up there.

 

[Stephen Benskin]

I can attest to this. I have yet to figure out how to retrieve my Hasselblads from up there.

I knew the astronauts took Hasselblads to the moon. I just didn't know they took yours. Tough luck dude.

 

[markbarendt]

Barry, the only thing that really matters is what works for you.

 

[Willie Jan]

I knew the astronauts took Hasselblads to the moon. I just didn't know they took yours. Tough luck dude.

The left them on the moon because they where that bad....

 

[stradibarrius]

I have David Vestal's book on enlarging and on of the first sections is evaluating a good negative. He too suggest shooting a film at about 1/2 the box speed and the develop it slightly less time than the box speed. I am going to try it and see what my experience is...It seems opposite from my experience to this point but it is a good way to do some baseline testing.