ISO 10 vs ISO 25 - Clear Photography

In my continuing study of Zone System exposure and development and a clarifying of my own personal photographic style, I find I tend to shoot most films at a lower ISO speed than what is marked on the box. There are several reasons for this. One, by shooting at a full stop slower you are giving the film more light, and therefore will achieve greater shadow detail. Couple this with reduced development to control highlight density you should come out with a balanced negative. This is also referred to as pull process. When you shoot this way, you will find the negative is very soft with low contrast. The second reason I like to shoot black and white film this way is I am almost always assured of getting motion blur. This is where creative interpretation comes into play. Living in China as I did, one of the ways I liked to achieve a sense of constant movement and hustle is to have clear fixed objects in frame (bicycle, sign, tree, etc) along with ghosting blurs of people or vehicles.

For today’s blog I would like to speak to you about some test shooting I did with two different films. Using a Pentax 6×7 medium format camera I shot in the darkened alleys and streets of Ganding, Guangzhou using Efke 25 and LUCKY SHD 100. For the Efke, I metered and shot it at ISO 10 and for the Lucky at ISO 25. It should be noted that I believe Lucky 100 to be closer to ISO 50, and therefore made my experiments under the assumption that I was shooting both films at an even 1 stop slower. Both films were developed in Kodak D76 at 1:3 at development times relative to each film, to achieve Zone V.


As you can see, this is a soft, low-contrast negative. I metered the shadows near the bicycle for Zone V and therefore the light striking the ground is slightly higher than I would have wished, perhaps Zone VIII. However this is the raw negative scan, the starting point. I feel it is a good starting point as there are no, or very little, perfect blacks or blocked highlights. You can also notice the film grain is very tight and fine. Once completed, this negative could yield a very large print without showing very noticeable grain.



Now we see the Lucky SHD 100 shot. Again, this was shot at ISO 25 which I believed to be a truer 1 stop difference from the true speed. However, upon close examination of the negative some interesting features are noted. Though using the same developer, dilution and relative times for this shot as with the Efke shot..this negative is very different. It appears slightly under developed with less shadow detail. Also, the grain structure is much more pronounced. I probably would not print this negative as large as I would the Efke. So why such a difference? For one, because I am not sure of the true speed of the Lucky film it is quite possible that I shot at more than 1 stop difference and therefore my exposure and development times are off. Its also possible that Lucky SHD 100 does not have as much latitude as does the Efke 25. For this test, I feel that Efke 25 is the clear winner in both shadow detail, highlight density and grain structure. More testing should be done with Lucky films, but for now I will continue to shoot it at a more even ISO 50 which garners much better results.


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