Fixing a gobo by keystoning
Keystoning is not some new internet crazy such as vadering, it's a process to ensure your gobo's image is projected as intended even with the projector positioned vertically and/or horizontally off center of the intended projection target. Keystoning is the term for the process used to fix the "Keystone effect." This effect has been called the "tombstone effect" in some circles as well. It is a distortion of the image dimensions, making it look like a trapezoid. This trapezoid shape is similar to the shape of an architectural keystone, hence the name.
It's an image distortion caused when projecting an image onto a surface at an angle. Oftentimes gobos are projected from a location that is not centered perpendicularly with respect to the surface the image is being projected on. Examples of keystoning can be seen above. The bottom images are all skewed, while the top image has been keystoned to project as intended.
StageSpot has made it easy to get your gobos keystoned. If you know a few measurements, it's easy for you to get your image keystoned to the location intended. We will do all the hard work. The degree to which the image needs to be corrected will depend on how far the light source is from the projection surface and the obliqueness of the angle(s) at which the image will be projected. Provided we are given these two pieces of information we can calculate the shape of the image that will need to be reproduced on the gobo. As you might expect this can be a time consuming process, depending on the complexity of the image, but we are always happy to help you get the perfect look!
There is an easy form to fill out that can be added to your order. The following information will ensure you get a straight image from any angle:
The position of the projector with respect to the desired image:
Projected image on FLOOR, WALL, or Ceiling 

Projecting ABOVE or BELOW Projector 

The X and Y and Z dimensions if used (Ft/In or cm/mm) 

If using the Z dimension, to the LEFT or RIGHT of Projector 

The required size of the projected image (Ft/In or cm/mm), (only needed if you want smaller projected image sizes than your current lens can produce) 

The make, model, and degree lens of the projector to be used
An example of this information would be:
For Keystone on wall

X = 13' 6" to WALL
from projector
Y = 10' BELOW the projector

Z = NA

Size = Make full sized for gobo no reduction 

Fixture = ETC, Source Four, with a 26 degree lens.
As always if you have any questions, please do not hesitate to contact us, we are happy to skew you in the right direction.
