Saturday, October 20, 2018

Filters for Black and White Film

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The top picture was taken with no filter, the middle one with a light yellow and the bottom with a R25 red filter.

Notice the difference in the sky, the water and dark areas between pictures.

Shot with a 55mm lens on my C220. Ilford HP5 film developed in D76, 1:1, 12 minutes at 68 degrees.

These are straight scans from an Epson 4490 scanner with no adjustments in Photoshop.

©PeteParsons









Although the use of filters in black and white film photography seems like a good way to get better pictures through improved tones, most film photographers do not bother to use filters.

The two main reasons are that filters requires an increase in exposure from one to four f-stops depending on the selected filter making a tripod a necessity .

The second is that the tonal change is universal. A yellow filter may darken a blue sky but lighten foliage. A green filter may lighten foliage to the extent it may appear odd to the eye.

As we are primarily concerned with the use of the Mamiya twin-lens cameras and with films like Tri-X and Ilford HP-5 (our favorite film) it is to these combinations or to the interested film user to which this post is addressed.

Filter sizes for lenses manufactured by Mamiya TLR use a 46mm or 49mm filter:

   46mm filter for the  80, 105,& 135
   49mm filter for the 55, 65, 180 & 250

The use of a 46-49mm step-up ring is recommended to avoid having to buy both sizes.

Filter manufacturers use their own combination of letters and numbers to identify their own products but their color and the effect on panchromatic film are similar.

The filter factor is a number which these manufacturers use to tell photographers how much increase in exposure is required to get a good negative. A good idea is avoid filter factors altogether and mark on the filter's case the increase needed in f-stops. Most photographers would use a combination of increased shutter speed and aperture to get good results.

The following is a list using Hoya's website, for example, indicating the increase in aperture in f-stops for their filters:

Colour                  Exposure Increase   

Yellow                       1 f-stop              
Yellow-Green            2 f-stops            
Red                            3 f-stop            
Orange                       2 f-stops             
Green                         2 f-stops

As the yellow, red, orange and green filters are the most often used a brief description of each is in order:        

The yellow filter is often the first filter acquired. It is used to darken a blue sky on a sunny day, increasing the visual difference between clouds and darkened sky. Other colours such as reds, greens and yellow-orange are reproduced in slightly lighter tones. It will often give flesh tones a more natural look. Many landscape photographers leave permanently attached as it also improves penetration of fog and haze.

The red filter increases the effect of a yellow filter by making skies almost black. Photographs of buildings made of different materials are often improved with the red filters as tones may appear more interesting. A red filter is dark and will normally require an increase of three f-stops of exposure. A diligent photographer might consider the use of a tripod when using a red filter.
Infrared films such as Ilford's SFX 200 require the use of a red filter.

The orange filter is considered an all around filter like the yellow. It is stronger than yellow but not as dramatic as red. It too can be kept on the camera at all times spanning the effects of between the yellow-red range and lightening foliage tones. Haze and fog penetration are also improved as well as skin tones in portraits.

The green filter primary purpose is to lighten green tones as panchromatic film often will record foliage darker than they appear to the eye. Although limited in application the green filter can also be used in portraits by darkening lips and making skin tones more natural to the eye.

In all cases the use of filters should be considered experimental. Panchromatic film has nuances from manufacturer to manufacturer. Individual developers can give wildly different results. Scanning a negative is different from an enlarger print. Each photographer must decide if the use of filters is even worth the effort or cost.

It is my opinion however that the TLR user, always using the same film/developer technique, consistent scanning and printing will see better results by using filters.

Ilford Photo has a good introduction to filter use:
https://www.ilfordphoto.com/colour-filters/

Freestyle Photographic has a very detailed piece on filters for the more technically inclined:
https://www.freestylephoto.biz/black-and-white-filters-tutorial