Easy-Bake Scheimpflug Recipe

[sharktooth]

Easy-Bake Scheimpflug Recipe

Do you want to use tilts and swings on your large format camera to change the plane of focus? Of course you do, but you’re not a professional “chef” who’s been doing this for years.
Pro chefs don’t need instructions, since they do it all by “feel”, but that doesn’t work for the all the jr apprentices out there. Here’s some basic instructions for all yous’ jr apprentices who want to graduate from “clumsy Luigi” status. Best of all, you can do this from your own home without fear of embarrassment or social ostracism.


Ingredients:

1) A view camera with tilt and swing angle scales on the front standard. The scales should be marked in 2 degree increments, or smaller (the smaller the better).
Substitutions: If your camera doesn’t have a scale to show the actual tilt or swing angle, you could use a protractor, but it makes thing much more difficult, and is probably not worth the trouble.

2) The view camera should have some sort of focus scale for the rear standard. Any sort of scale that shows focus change in mm should work well.
Substitutions: If your camera doesn’t have a focus scale, you could easily jury-rig one with a piece of masking tape marked in mm.

3) A ground glass with grid markings, preferably in 1cm squares.
Substitutions: Any sort of grid system should work, but it’s easier to do the calculations if the grid is metric, and in squares.

4) Any cheap scientific calculator or cell phone calculator app that has the arctan function. (Often shown as tan-1 on calculators)
Substitutions: You could tabulate potential results on a piece of paper, so you could carry that in your pocket instead of an electronic calculator.

5) Something to record notes with. A pad and pen works great (pencil works too). Anything that you like to keep a record of values to enter into the calculator.
Substitutions: If you have a very good memory, that could potentially work too (but I wouldn’t know).


Baking Instructions for Lens Tilt:

1) Compose your scene on the ground glass, and decide if you’d like to change the plane of focus by tilting the lensboard. If you decided that a lens tilt would be beneficial, then proceed to step two.

2) Choose two features in your scene that you would like to be in focus. One of these should be nearer to the camera, and the other further away. Focus one of these features on the ground glass using the rear standard focus knob. Record the reading of the rear standard focus position in your notepad.

3) Focus on the other feature, also using the rear standard focus knob. Record the reading of the rear standard focus position for that one in your notepad too.

4) You should now have two focus position readings in your notepad. The difference between these two readings will probably only be a few mm. It’s that difference between readings that we need to use.
It’s basically the amount of focus shift at the ground glass when you focused each feature. We’ll call that focus difference “FD”, since it represents the displacement of the film plane between the two focused positions.

5) Next, we need to measure the vertical distance between the two features on the ground glass. This can easily be done by counting grid squares on the ground glass. If one feature is 5 squares above the other one, then the vertical distance on the ground glass will be 50mm, if each grid square is 1cm (10mm). You can also estimate ½ squares and ¼ squares to get 5mm and 2.5mm. We’ll call that the ground glass vertical distance “GGVD”, since it represents the vertical height difference between the two features on the ground glass. Write the “GGVD” value in your notepad.

6) The front tilt angle can now be calculated using the “FD” and “GGVD” measurements. The front tilt angle = arctan(FD/GGVD). Plug that into your calculator. The result will be the front tilt angle in degrees.

7) Tilt the front standard to the result calculated in step 6. You need to have a tilt angle scale on the front standard in order to do this with any accuracy.

8) Once the front tilt angle is set and locked, go back to the ground glass and refocus on one of the features. If you check the other feature, they should now both be in focus (or very close).


Baking Instructions for Lens Swing:

1) Compose your scene on the ground glass, and decide if you’d like to change the plane of focus by swinging the lensboard. If you decided that a lens swing would be beneficial, then proceed to step two.

2) Steps 2 thru 4 are the same as for lens tilt, so see above.

5) Next, we need to measure the horizontal distance between the two features on the ground glass. This can easily be done by counting grid squares on the ground glass. If one feature is 5 squares to the right of other one, then the horizontal distance on the ground glass will be 50mm, if each grid square is 1cm (10mm). You can also estimate ½ squares and ¼ squares to get 5mm and 2.5mm. We’ll call that ground glass width distance “GGWD”, since it represents the horizontal width between the two features on the ground glass. Write the “GGWD” value in your notepad.

6) The front swing angle can now be calculated using the “FD” and “GGWD” measurements. The front swing angle = arctan(FD/GGWD). Plug that into your calculator. The result will be the front swing angle in degrees.

7) Swing the front standard to the result calculated in step 6. You need to have a swing angle scale on the front standard in order to do this with any accuracy.

8) Once the front swing angle is set and locked, go back to the ground glass and refocus on one of the features. If you check the other feature, they should now both be in focus (or very close).