When I made the switch three years ago to shooting landscapes exclusively with fine grain negative film, I avoided high speed film due to the fear of grain when printing large. My shots during hiking trips began to get thin. The availability of light and needing to stop, remove my pack, and set up a tripod for a spur of the moment shot was keeping me from putting together a well rounded travel essay. I love getting up early and staying up late hunting for that iconic shot, but I was missing out on the moments in-between. I decided to embrace the grain and step up to more sensitive emulsions. Though, I needed to find out if I could maximize my results. For some time now, I have been researching online discussion (dating back to 2003) on the validity of over exposing negative film in order to reduce grain. When shooting Portra 800, I have been rating it at an exposure index of 500. I decided to put together a side by side comparison to share my findings.
THE TEST
- Pentax 645NII
- Pentax FA 120mm F/4 Macro
- Portra 800 (of course)
- Matrix Metering
- Aperture Priority (F/5.6)
- Hand Held
- Scanned with Epson V600
- BetterScanning Variable Height MF Film Holder
- Light cropping and spot removal in Lightroom 5
All shots were shot on one roll of film to eliminate the chance of processing differences. Film has been developed normally (no push or pull processing).
Portra 800 Shot @ Exposure Index 800 (Box Speed)
The rose image turned out nice with very natural colors, and accurate to what I saw during the shoot. After detailed inspection, grain is apparent, but not very noticeable and in my opinion, has a very film like pleasing quality.
Portra 800 Shot @ Exposure Index 500 (+2/3 stop)
Now for the second rose shot, this time at exposure index 500. Two items are noticed right away, the difference in colors and the reduction in grain. The rose has now taken on a slightly darker hue becoming more saturated, which most people have reported when viewing over exposed film. This color change is not in any way bad, though is correctable in post process if one feels inclined to do so.
The second item is the grain. I find that the blurred out background is much more pleasing in this shot due to a creamier texture. I also find that the rose's sharpness is slightly better, despite the fact it was shot at a slowing shutter speed. Lets explore sharpness and grain more below.
100% Crop - Exposure Index 800
100% Crop - Exposure Index 500 (+2/3)
When reviewed at 100% magnification, it becomes clear that shooting at an exposure index of 500 (+2/3 stop) yields more pleasing results. Perceivable grain is much lower than the level witnessed at 800 ISO.
I have applied my empirical results by shooting Portra 800 at 500 ISO unless the lighting is too low to do so. Please keep in mind that this is typically done when shooting in 645, 6x7, and 6x9 formats. The level of grain seen in 35mm Portra 800 is much higher due to increased magnifications, so my next test will evaluate the level of improvement seen in 35mm.
BOTTOM LINE:
Shoot Portra 800 with your camera or meter set at ISO 500. This is an amazing film that gives superior results time and time again. You may be loosing 2/3 stop in speed, but I find 500 more than generous in low light situation with medium format film. At least you know that if you need more speed, you can reduce the exposure and still get good results with standard processing.