Exposure Index Quick Check

Meter any uniform target and expose 4 stops under. Process the film and place the film over exposure meter, looking for a 1/3 stop drop from film base.

Good idea, but for a modest extra investment, I'd do also a zone V and a zone VIII (or more of them). A Sekonic 308 (or similar) reading to 1/10 stop is the next best thing to a densitometer.

V and VIII provide no useful exposure information as they are too dependent on development.

Dale,
Am I correct in thinking that one could make several exposures starting at Zone V (based on box speed) and then make additional exposures dropping one stop each time for say, several stops, meter through the film as you say and use this to find their personal EI?

If so leaving a blank frame in between would make it a little simpler in terms of metering through the film.

Thanks!

Yes, it is a 'go; no-go' test for any EI. One could do a number of tests on a roll at different EIs.

That's a really good idea. Plus, you'd be killing two birds with one stone as it would also function as a test for uniformity of development.

Shawn Dougherty said:

Dale,
Am I correct in thinking that one could make several exposures starting at Zone V (based on box speed) and then make additional exposures dropping one stop each time for say, several stops, meter through the film as you say and use this to find their personal EI?

If so leaving a blank frame in between would make it a little simpler in terms of metering through the film.

Thanks!

Click to expand...

Yes, I believe that's the idea,based on the reasonableassumption that the Zone I density target is a 0.1 transmission densityand the fact that0.1 density reduces the transmission by 1/3 stop.Should work in theory if no densitometer is available.

Being picky zone 1 is printable density distinguished from zone 0 which is black no detail on the print.

Eg zone1 is dependent upon lens flare if you have uncoated, single coated and multi coated lenses and it is conta-jour scene...

So if you want you can say x density above base density and developer fog but...

To carry on with that thought, are not Zones a measure that is applied to prints; although so many have come to speck of negative densities in terms of zones.

Xmas said:

Being picky zone 1 is printable density distinguished from zone 0 which is black no detail on the print.

Eg zone1 is dependent upon lens flare if you have uncoated, single coated and multi coated lenses and it is conta-jour scene...

So if you want you can say x density above base density and developer fog but...

Click to expand...

What is a "zone?"

I've started, for the first time, to make proper contact prints, getting a standardised time such that the sprocket holes to just disappear. I read about this in a Carson Graves book, and its just so simple. For me, this has been very illuminating about the way I have exposed my shots. Seeing them all on a single piece of 8x10 paper is helpful in understanding the impact of metering, which is of equal importance to what ISO you stuff into the meter in the first place.

Another really awesome idea in the Carson Graves book, once you have worked out your EI, is to shoot a pair of Z2 and Z8 negatives on consecutive frames. You then place the negative strip in the enlarger with the two negatives both on the same frame, half Z2 and half Z8. You can establish whether the development is correct by making test strips. At the point that the Z2 just hits max black, the Z8 should start to have some detail in it. I thought this was a brilliant idea, although I have yet to try it out. It means that you dont need to muck about with contrast settings on the enlarger.

I've also recently picked up a copy of the Phil Davis book, Beyond the Zone System, and there are some great ideas in there for working out EI, and having had a few hours looking through that book, I'd recommend that too for such considerations. Another would be John Blakemore's book on printing.

ic-racer said:

V and VIII provide no useful exposure information as they are too dependent on development.

Click to expand...

I agree. Nice idea in the OP BTW.

[Edit: after posting what I did below, I then stumbled across the active topic titled "Zone System - Find EI and dev time without resorting to sensitometry http://www.apug.org/forums/showthre...nd dev time without resorting to sensitometry
Where I probably should have posted what I did below"]

...so along the lines of additional zones, If somebody did want to extract additional process information such as the contrast index to check their film development time , temperature and developer freshness, could they pick two zones to expose two frames at to get an average CI from? (E.g. II and VII ?). We could however spend many posts agreeing on the best CI to target as it depends on many factors such as diffusion vs condenser enlarger, amount of flare in your lenses etc.

I like your idea of placing the film over the exposure meter (either TTL in camera or handheld light meter) to substitute for a densitometer.

Peter

Also see (there was a url link here which no longer exists)

bernard_L said:

Good idea, but for a modest extra investment, I'd do also a zone V and a zone VIII (or more of them). A Sekonic 308 (or similar) reading to 1/10 stop is the next best thing to a densitometer.

Click to expand...

I agree. I have a Sekonic L308. I also use a Gossen Luna Pro SCB which lets me set the meter for any of the Zones as well as easily put in filter compensation.

I do this (Zone I, V, VIII), with my mini tablet and a light meter app. Works like a charm if you know how to take a logarithm. ;-)

Hi,
Could this technique also be used to determine how accurate my shutter is as I move through the shutter speeds? If I start with the 1/3 stop over film base plus fog as a starting point, and adjust the shutter to double the exposure times shouldn't I get a full stop more when metering the negative developed of that same solid background originally used? I guess it would have to be a very bright day and iso 50 film...An f16 @50th sec daytime light could be f22@400th sec to get close to film base plus fog (zone 1-ish)and that would mean that I should be able to meter about a stop worth's of difference between each negative as the shutter speed was doubled from f22@400th to f22@200th to f22@100 to f22@50...etc. If the difference when metering each successive negative was close to a stop, then I could assume that my shutter is ok and that my developing process is consistent.
Could this be reliable if I was careful with development, would you trust your developing to do this kind of assessment of shutter speeds? I might have another shutter that is more reliable - could try with that one first.

Thanks

Thanks

The test is for the whole system, meter, lens, aperture and shutter. It might be difficult to separate out just the shutter's performance.

firefli said:

Hi,
Could this technique also be used to determine how accurate my shutter is as I move through the shutter speeds?

Click to expand...

I think it could be used to verify relative shutter speeds very well. Assuming you kept everything else constant, including of course the incident light levels. The problem with this method to test shutter speeds is in order to obtain the absolute shutter times (which ultimately is what you want to do) you must measure at least one speed using some other method . This could be the slowest shutter (1sec ?), but then the relative errors would compound as you then added up each additional density, making the measurement of the fastest speed the least accurate by a LOT. E.g. For 10 shutter speeds from 1s to 1/500s you will measure 9 delta transitions from the 1s one. If your exposure meter is only accurate to 1/3 stop then your fastest shutter will have an error term of +/-9x1/3 stops =+/-3 stops. If it is accurate to 1/6 stops then the error will be +/-1.5 stops. That is worse case error. If summing the errors in an rms fashion the total error will be less.

ic-racer said:

Meter any uniform target and expose 4 stops under. Process the film and place the film over exposure meter, looking for a 1/3 stop drop from film base.

Click to expand...

or 3 1/3 stops under.

Hi PeterB,




IC-Racer also posted another way of testing shutter/aperture settings for zone 8 by developing a contact print (see Contrast Index Quick Check) with a coin on it. If the coin's edge is just visible against the rest of the contact print, then the contact print of the image is zone 8. If I can get 1/3 above film base plus fog for zone 1-ish using the EI steps in this thread, and just make out the coin at the other end using the contact paper coin trick for zone 8-ish, while using the same development time for both, I'd be happy with that.


I could also try going down three stops from the zone 8 contact print settings using the shutter speeds, or likewise go 4 zones up from the Zone 1 contact print and compare the two zone 5 contact prints. I'm assuming that I would use different aperture shutter speeds for the zone 5 contact prints if I could. If not and they were the same - then the system works! From that I would know that overall I could trust my settings and development which I don't at the moment. Not saying that I would be successfull doing this, but it seems worth trying...then I could go about and pretend I planned my shots


Actually he doesn't mention contact printing in the contrast index thread - but something similar could work

Thanks