Figuring out my personal EI and Development Time

[Kevin Kehler]

I think I have figured out a method to determine my E.I. and development time. Tell me if I have made an error in my methodology (P.S. I don't have a densitometer).

To determine E.I.

1. Take pictures of blank white wall (south wall with a north facing window to give even illumination). Start with one blank frame, then using a spot meter to determine a Zone II reading (black, no texture) and then make a series of exposures bracketing by 1-3 stops (in 1/2 step increments). Develop as normal method.
2. Determine maximum black time by using the blank frame at Grade 2, exposing paper to various times until I determine minimum time necessary to get maximum black (ensure prints are dry when making this determination).
3. Print each negative from test at minimum time for maximum black. Negative which is just lighter than maximum black is my new E.I. time (Zone II - black no texture/details).

Development time

1. Take pictures of my ceiling, in the same room (it is a stippled white ceiling, thus some minor texture). Using new E.I., place ceiling on Zone VIII and expose whole role.
2. In the darkroom, cut role in 4-5 pieces and develop each piece separately at various times including suggested normal time, normal minus 10%, normal minus 20%, normal minus 30%, normal plus 10%.
3. Print each negative at time determined for maximum black Grade 2 and see which one has minimum required texture (one that is not pure white of the paper but some trace of texture).
4. Repeat until developing time is established.

I have been pondering this for a couple of days but am I missing anything? Thanks for any input.

On my Mamiya RZ, do I need to test each lens separately as the shutter is in the lens? Or is this lens independent?

 

[Mike Wilde]

Fred Picker would recommend doing the tests pieces for development time in with the balance of a roll of normally exposed film, so that you can make sure that not all of the developing agent is just working on 4-5 frames, but rather something in the 30-36 range, presuming we are talking about 35mm format here.

Otherwise you method appears sound. the late Barry Thornton's web site gives a reasonably understandable way of doing the same sort of test.

Good luck.

 

[ic-racer]

Since you have a spot meter, you can use that to get your EI also. You can do this in addition to your zone II method and see if they match.

Shoot a Zone I frame then use the spot meter and put the processed zone I frame over the spot meter. The frame that drops the reading by one-third of a stop (0.1) was shot at the correct EI.

 

[Kevin Kehler]

Thanks for the replies; the personal E.I. is Fred Picker/Ansel Adams, so it is fairly standard. The development time, I just have never heard of anyone using a ceiling before or the minimum maximum black time to determine correct development, so I wanted to run it past some smarter people than I.

ic-racer, I have a Minolta F I use and there are several posts scattered around the internets about .1 of a reading (since it reads on a 10-point scale for exposure, i.e. 5.6 7/10's at 1/125) being equal to .03 of a densitometer. Any thoughts on that? It seems....too easy if you know what I mean. In theory it should work but any actual experience.