Landscapes with large format sheet film and increasing of depth of field.

April 05, 2016  •  Leave a Comment

After working two years with wet and dry collodion plates I take a short break and spent a few days before Eastern on Liptov, a North part of Slovakia, working with sheet films.

Nature is at this time of year still in a deep sleep. You can feel that Spring is around the corner, but everything is still grey with a mild light even in sunny days. 

As usually, there were some technicalities. Collodion plates sensitivity is at best 1 ISO. "Modern" sheet film is  50 or 100 times more sensitive, so wooden film holder which works with collodion perfectly can, loaded with a sheet film, ruin your day easily. On the other side, collodion transcription of colors into the gray scale is peculiar so it was a kind of relive to work with panchromatic films. 

I was working with a simple lens without a shooter, so I had to focus on early mornings and evenings. Cloudy and dull light days are the best for pictures like this creek photograph. 

Valley with this way is called "Žiarska dolina". Once one of the most beautiful entries into West Tatras sierra is today in a very bad shape because of a brutal harvesting of fallen trees. It is very sad to see what we are doing with nature treasures  we should take care of. 

Comparing to collodion plates it is much easier to travel with films. I was developing 18x24 cm sheet in trays in a provisory darkroom build in a bathroom. There is only one problem you should take special care in this situation. The bathroom must be totally dark, with a tray development even a small light leak can be dangerous. The only way how to be really sure is to sit in darkened room for a few minutes and wait until your eyes fully accommodated for dark. 

Gallery with works from Liptov

Depth of field on large format cameras can be a tricky topic. When you are using equivalent lenses and the same aperture, then depth of the field is with growing size of the film decreasing. A basic film for 35 mm film has a focal length 50 mm, the basic lens for 18x24 cm format has a focal length 300 mm. 

On the other side, with increasing film size you don't have to enlarge photographs so much. Actually, with 18x24 cm you don't have to enlarge at all and be very happy with contact prints.

The human eye can recognize from a normal view distance  in an 18x24 cm print 5 separate lines in every millimeter. So, the critical detail size is 0,2 mm. When you are making contact prints, 0,2 mm is the resolution you are looking for. But if you want to print 18x24 cm photo from 35 mm film, you have to enlarge it seven times. So, critical size of detail for 35 mm is seven times smaller, just 0,03 mm. (This critical size of detail is called Circle of confusion.  There is a great online DOF calculator.) 

Sadly, with growing of the film size is the impact of increasing of lenses focal length bigger then decreasing of needed size of detail. So, with 35mm film and 50 mm lens set at F22 you can have sharp everything from 2 meters to infinity. But if you are working with 18x24 cm film and 300 mm at a maximum aperture F64, you will be still able to have sharp everything only from 3,7 meters to infinity. Gladly, with a large format camera, you can compensate for shallower DOF when you tilt your camera back, the top part backward, the bottom forward. Very simple method when you are making a picture without dominant verticals.


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