Film test results

[ic-racer]

How are you determining your ISO 160 frame or sheet is the correct "Zone I" exposure? I suspect you may have made an error in math when making or recording or reading your negative.

[macandal]

How are you determining your ISO 160 frame or sheet is the correct "Zone I" exposure? I suspect you may have made an error in math when making or recording or reading your negative.

ic, it's on my first post. I am using sheet film (4x5). I'm using the method described in The Negative by Ansel Adams where the net density reading (density - film base+fog) closest to 0.1 is Zone I.

[macandal]

I left the notebook where I took my notes at home. I'll post my results tonight, when I get home.

[macandal]

Hi Mario,

The speed you found is higher than I would expect when testing for Zone System speed. But at this point you haven't determined developing times. You might have developed longer than "N".

Yes, but what about the faster than normal rating my testing gave me? I was expecting this to be below the stated 100 ASA rating. I was expecting it to be 80 or 50 or somewhere in between. The 160 EI was a surprise even to a novice like me?

Thanks.

[Leigh]

ic, it's on my first post. I am using sheet film (4x5). I'm using the method described in The Negative by Ansel Adams where the net density reading (density - film base+fog) closest to 0.1 is Zone I.

I think you want to select a negative where the density exceeds the (base+fog) by 0.1 units.

- Leigh

[macandal]

I think you want to select a negative where the density exceeds the (base+fog) by 0.1 units.

- Leigh

Right. You are describing the net density.

[macandal]

Here are the results of my test:



Ilford Delta 100 + Ilfotec DD-X
68F
12 minutes, intermittent agitation
Source: The Negative by Ansel Adams

Zone V: f5.6 1/60

		ASA	f	Shutter	Density	No Density
1.	No exposure (blank)	--	--	--	0.17	--
2.	Zone I	100	22	1/60	0.37	0.20
3.	1/3 stop less than #2	125	22 1/3	1/60	0.31	0.14
4.	2/3 stop less than #2	160	22 2/3	1/60	0.26	0.09
5.	Zone 0	200	32	1/60	0.22	0.05
6.	1/3 stop more than #2	80	16 2/3	1/60	0.40	0.23
7.	2/3 stop more	64	16 1/3	1/60	0.48	0.31
8.	Zone II	50	16	1/60	0.57	0.40

[Leigh]

I sure don't understand that chart.

The negative density drives the zone correlation, not the other way around.

The chart should be in order by negative density, not bouncing around.

In this case, line 4 should be labeled Zone I, not line 2.

- Leigh

[Kevin J. Kolosky]

1. place a black card in shade
2. meter it
3. close down 4 stops (zone 1)
4. focus at infinity
5. make the exposure
6. develop normally
7. read the negative on the densitometer
8. note where the reading is in relation to film base plus fog
9. If not .10 above interpolate by 1/3 stops (remembering that .30 on densitometer equals 1 stop - exposure is recorded in terms logarithms and the log of 2 is .30)

[Bill Burk]

Hi Leigh,

The graph makes sense with Ansel Adam's book in hand. Negatives are exposed as if metered at rated speed, and that reading placed on Zone I. The remaining rows have test exposures relative to that Zone I at Box Speed shot. It's an arbitrary test sequence, not organized sequentially. Mario found a negative which meets the 0.10 over B+F criterion at an exposure 2/3 stop less than Zone I placement at Box Speed, which makes the test result indicate rated speed 160.


I think Mario's development is correct. But I would say the variables of the camera/lens/meter/shutter/flare which are also included in Mario's test (because of the nature of Ansel Adams' instructions) amounts to nearly +2/3 stop.

Mario, I'd be very cautious before choosing EI 160 for a 100-speed film.

Here are my test results with 100TMAX and D-76. I only achieve a 160 speed when I develop in stock D-76 undiluted for 24 minutes, and I barely hit 200 in 48 minutes.