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The following information is from The Digital Truth Website:  http://www.digitaltruth.com/devchart.php?doc=pushproc

PUSH PROCESSING (B/W)

These are general guidelines when no published development times are available. To use this chart multiply the published time at recommended ASA by the factor in parenthesis (ie. If Tri-X rated at 400ASA is normally developed for 6 mins in a standard soup, then when Tri-X is pushed three stops to 3200ASA development would be: 6 x 4.5 = 27 mins). Please use these recommendations as starting points only. In many cases these times will prove excessive, but when all else fails they can be a good guideline. Please note separate data for Tmax films.

Standard Developer

1 stop push = (x1.5)

2 stop push = (x2.25)

3 stop push = (x4.5)


Compensating Developer

1 stop push = (x1.4)

2 stop push = (x1.85)

3 stop push = (x2.5)


TMax Films

1 stop push = no change

2 stop push = (x1.33)

3 stop push = (x1.66)

*Compensating developers include Microphen, TMax, and any other developers which are specifically formulated for push processing

Southwestern College Websitehttp://www.swccd.edu
Printable HandoutPush_Times_files/122_Push_Film_2009.pdf

SWC Photo & Digital - Technical Information

Black & White Darkroom Tricks

Related Topics & Materials


PUSHING AND PULLING FILM GUIDELINES


Pushing Film:  allows you to shoot at a higher than normal film speed if you also increase film development.


Pulling Film:  allows you to shoot a lower than normal film speed if you also decrease film development.


When to Push Film:

1.If you can’t get a meter reading at your correct ISO in low or dimly lit situations. 

2.If you want to increase your chances of shooting stop motion in a low light situation.  This will give you a higher working film speed when taking pictures in dim light.

3.To increase contrast in a low contrast lighting situation.


When to Pull Film:

1.Seldom done if at all.  You could do this in order to use shallow depth of field in a brightly lit scene or to help lower contrast.  Essentially, you will end of following the rules of contraction which will lower the contrast of the negative. 


Procedure for Pushing Film or Pulling Film:

1.Change your ISO to the new desired film speed.  You are fooling the camera lightmeter when you do this.  In theory, you cannot push film more than 2 stops without major changes to the appearance of the images on the negative.  Sources say to not pull film more than 1 stop for the same reasons.

2.Shoot the entire roll of film at this “fake film speed”.

3.After rewinding the film, label this film with the film speed you actually used!

4.Consult the rules for development times for pushing/pulling your particular type of film, or consult the generic development rules listed below.

5.Remember to adjust your development times for this roll of film.


Example:

You are indoors and want to photograph a band playing on stage.  The lighting is dim, but you can meter the light.  Let’s pretend your widest open aperture is f-2.8.  You were smart enough to use 400 speed film for the interior setting.  You get the following meter reading:  f-2.8 @ 1/15 sec.  You would like to have less motion blur in your pictures.  So, you decided to push the entire roll of film.  You change the ISO to think the film speed is 1600.  You are fooling the camera.  Now you have added 2 stops more light sensitivity to the film.  You can move your shutter speed two stops to 1/60.  Thus your new exposure time for this scene is f-2.8 @ 1/60 sec.  Shoot the roll of film according the lightmeter readings.  Then in the photo lab, remember to adjust your film development times.  Let’s pretend that your normal film development time was suppose to be 10 minutes.  If you follow the Generic film development adjustment for pushing film 2 stops, then you have to double your normal development time.  Thus, now you have to develop your film for 20 minutes. 


Note:  Not all films are the same, it is best to check the push film adjustment listed on the film’s website first.


Generic Film Development Adjustments

You should look at the film manufacture’s statement for pushing or pulling film for accurate expansion and contraction.  But….in general this is what happens:


Push Film (increase ISO) one stop-increase development 25-50% (usually N+1 or 25%)

Push Film           two stops-increase development double normal exposure time

Pull Film   (decrease ISO) one stop-decrease development 25%  (not perfect, has problems)


This is similar to the zone system, but we are usually going beyond the film’s latitude.  Thus, this process isn’t totally accurate with the zone system.  Going beyond the film’s latitude cause film to record densities differently than normal exposure.  Pushing film generally cause higher contrast and more visible grain.