Gobo Guide

GUIDE TO GOBOS


What is a Gobo?

Gobo Types

Projecting Dark Colours

Projecting at an Angle

Front and Rear Projection

Gobo Size

Supplying Artwork


 

What is a Gobo?

”Gobo” stands for Goes Before Optics. It is a compact stencilled disk used in lighting fixtures to produce a projected image on to any surface. The design could be anything, from a simple pattern, to a logo or message, a complex drawing or a photographic image.


Gobos can project


  • Logos, text or messages
  • Abstract patterns
  • Photographic images – both greyscale & colour


They cannot project


  • Video – This is called ‘data projection’
  • A ‘digital’ file that has been sent from a laptop or device.


Please remember that your gobo is only as good as the projector, projecting its image. Evica gobo projectors are the best on the market when it comes to optics, power and reliability. Check out our range HERE



Gobo Types


There are 4 types of Gobo and these can be bought as off the shelf design or a custom gobo made specifically to your artwork. Metal gobos are used for stencilled or patterned images. Glass gobos are used to create more complex and colourful designs as well as photographic designs.


The 4 types of gobo are


  • Stainless Steel Gobos
  • Black and white Glass Gobos (also known as blackline)
  • Spot Colour Glass Gobos
  • Full Colour Glass Gobos



Stainless Steel Gobos

Steel gobos are laser cut from stainless steel discs. They are cost effective but do have a small restriction on the amount of detail or resolution. They do not last quite as long as glass gobos due to the high temperature of gobo projectors.


As these gobos are effectively stencils, some designs will not be suitable. For instance a letter O would need a tab to hold the centre of the O. In which case other styles of gobo are more suitable. Many companies have a large catalogue of steel gobo designs, so if you need a generic design like a star pattern for xmas for example, these can be bought quickly.


Black and White Glass Gobos


The most popular gobos are black and white glass gobos. They are made using a high resolution process, so no restrictions like the tabbing needed to make metal gobos work. The detail can be fine too, even photographic when using a screen (similar to the printing process). The glass can withstand high temperatures making them suitable for all projector types including the higher powered outdoor types.



These are created using a precision laser that removes a layer of reflective material from one side of the glass gobo. This lets the light through creating your image. This type of image is sharper than metal gobos and avoids the slight glow around the edge of projected images


Spot Colour Gobos

These gobos allow you to project an open white design with one other spot colour (or more). These are great for logos as the extra colour/s is great for branding.


These are created similar to the black and white glass gobos by combining two or more layers. One for white and the others for each spot colour. Not all colours are available but you can choose from a specific range to find your nearest choice.


Full Colour Gobos

A full colour gobo is as suggested. It produces a spectacular and intricately detailed image or design. It can take advantage of the full colour spectrum, gradients and shades.


This is achieved by combining 4 layers of glass gobo printed in CMYK. These layers are carefully sandwiched together. They are the most expensive gobos and must be handled with care when inserting in to the projector but are stunning to view.


To seek advice on gobo Artwork or design before ordering please contact us here and we’ll call you straight back.


Projecting Dark Colours


White is the brightest and best colour you can project and there are some colours that don’t project well for example navy or dark purple.


If you do need such colours as they are an essential part of your design there are design tricks you can use to help. Lightening slightly or adding a white outline to hold the shapes.


We will always check your artwork and give you our expert advice and be aware that the colour of the surface you project onto can have an effect to due to the way surfaces absorb light.


Projecting at an Angle


Ideally your projector should project at angle of 90° for maximum clarity and zero distortion but this is not always possible.


Projected at an extreme angle the image can appear warped but also bear in mind the angle that the projection is viewed from makes a difference too.


In some cases corrective software when making your gobo can remedy this. If you are projecting at an extreme angle it is best you contact us to discuss to avoid any issues.


Front and Rear Projection


Glass gobos are non-reversible unlike metal gobos. If you plan to rear project onto a translucent surface you will need to make sure your design is reversed. Again please talk to us if you want more information on this.

Gobo Size


There are many gobo sizes available but the current range of Evica projectors only uses SIZE E which is 37.5mm


Supplying Artwork


Computers and graphic design programs are both highly sophisticated and incredibly easy to use. With clients using a diverse range of platforms and software, Rosco will try to accept almost any electronic file. Of course, many designer still work in paper and photographic medium and we will happily take these "hard copy" artwork formats as well. Below is a set of guidelines to assist you in preparing your design - in whatever - format for a successful transfer to a custom gobo. 


Electronic Designs


Postscript Formats

Adobe Illustrator (.ai)

For almost any style design except for photographic images, the preferred, ideal file format is a native Adobe Illustrator file. This kind of vector-based artwork creates the best gobo toolings.

 

EPS Files (.eps)

A close second to Illustrator files are files saved in eps format. This format can be created from many of the popular graphics programs available. EPS files maintain excellent image qualities and allow for moderate resizing without degrading the image quality.

 

PDF Documents (.pdf)

PDF files are usually created from good art files such as above but have been converted from the original file to pdf so that a dealer or customer can open it. If you have an art file you can't open due to format, always send us this file first. We are happy to then convert it for you to an easier format for you to see the art as well. This helps us to get the best art possible and to keep it from being down graded to lesser art quality.

 

Word Documents (.doc)

Word Documents generally are not great art files but can be used for text-only art. We ask that you please include the font name & or the actual fonts when sending over this type of file. A faxed copy of the actual artwork is also requested for Word Document text art.

 

Rasterized Formats

Adobe Photoshop (.psd, .eps)

Native Photoshop files provide tremendous versatility by allowing all the elements of a design to be edited by Rosco's graphic designers. This file format maintains text editing (v.5 and higher) and preserves layers. In addition, Photoshop is the ideal format for photographic designs or Hi-Definition Photogobos.

 

TIFF Files (.tif)

Digital cameras and many graphics programs provide means for saving images in TIFF format. These files are uncompressed and maintain a very high image quality. However, they are often extremely large, so much so that electronic transfers are difficult. Despite that, this file format produces excellent gobos. TIFF files work wonderfully if they are a Photoshop created, layered file and are unlocked. This is especially so for full photographic quality gobos.

 

JPG (.jpg), GIF (.gif)

These file types are commonly found in use on the World Wide Web. In general, they are less well suited as artwork for custom gobos. GIF files are 72dpi, and contain a limited color table. This means that altering the file in any way - resizing, adjusting contrast, color correcting - is virtually impossible to accomplish without significantly degrading the image. So unless the file provided needs no alteration at all (very uncommon), it is a poor format choice. JPG files are a compressed file type that helps to keep even very complex images relatively small. But this compression makes it difficult to alter the image without introducing artifacts which degrade the image quality. If you will be submitting jpg files, make sure to submit a file that is 2x the size of the finished gobo.

 

CAD Files (.dxf, .dwg)

CAD files should not be submitted at all. Despite claims by the software companies to the contrary, these file types almost never successfully convert into a usable file format.

 

Image Size and Resolution Guidelines

First, if you are working in Adobe Illustrator, this section is irrelevant to you. Resizing in Illustrator is accomplished with no loss of detail or quality.

Otherwise, you must decide at what the resolution and size to create your design. Your choice of gobo type will influence this decision. In general, you should create your design at full size, which is 100% of the size of the finished gobo, or larger.

Type
DPI
Notes
Custom Steel
150 dpi
Line art is not usually degraded by low resolution files. But small text may be difficult to render.
B/W line art, B/W Grey Scale or Photographic B/W
600 dpi
Smooth tonal values require high resolution images.
Multi color line art or Hi-Def color photo gobo
800 dpi
To achieve smooth color blends and fine details requires a very high resolution file.

To calculate the pixel size of your design, multiply gobo size (in inches) by the recommended resolution. The result is the recommended size of your artwork. For example, if you are creating artwork for multi-colored logo in B size gobo: 2.54 inches x 300 pixels/inch = 762 pixels. So the artwork you submit to Rosco should be no less than 762 x 762 pixels, though larger is perfectly fine.
Note that pixel size is independent of resolution and so is a preferred manner of describing file size.
Pixel Size = Size (inches) x Dots (pixels) Per Inch.


Help With Artwork


If you need help with your artwork, Evica Direct can help you with this. There is an hourly fee. Your artwork must be submitted in the right format and resolution.  Again our design service can help you here if you have issues.