Comparing Normal vs High-Speed Auto Iris in Epson Projectors |

If you are thinking about upgrading your projector with an auto iris, then I have some great news for you! Today we are going to talk about the differences between normal and high-speed auto iris in Epson projectors. An Auto Iris is a mechanism that automatically adjusts the light output of the projector based on the brightness of the projected image. The auto iris has three options these are Off, Normal, and High Speed. The Normal mode works fine but in High Speed it stumbles when switching from a black screen or dark scene to an image with much higher average brightness.


 Different Iris In Epson Projector 

This means that if there is a dark scene in your movie or presentation, it will dim down so you can see all details in black without sacrificing detail when everything else lights up again! The benefit of this feature is twofold: First, no more annoying jumps between scenes where sometimes things are too bright and sometimes they are too dark. Second, increased contrast which gives better colour saturation and deeper blacks.

Viewing Distance is Everything:

Think of it this way. If you are standing two feet from a 120″ image, you can clearly see the difference between native 4K and 4K-enhanced 1080p. The pixel structure is smaller on the native 4K image and it more effectively resolves fine detail that is, by comparison, muddled in the 4K-enhanced picture. Now if you back up and increase your viewing distance, you lose your ability to see the fine detail in the native 4K picture, and you also lose the ability to see the pixel structure in the 4K-enhanced image.


 What are Auto Iris Lens? 

Auto iris is an auto-adjusting feature for projector lenses that can dynamically change the lens in order to provide optimal images in ever changing light conditions.

It works by measuring the amount of light auto iris projector beam entering the lens. When there isn’t enough light, auto iris reduces or completely stops the flow of light through the lens which increases contrast ratio and preserves details in darker areas. This reduction allows less light to reach your projection surface, which makes it ideal for high ambient light environments where lighting conditions are constantly changing.

 What is High-Speed Auto Iris? 

The auto iris is a mechanism inside an auto-focus projector that automatically adjusts the light output of the projector to maintain a consistent picture brightness. A typical auto iris auto-focuses by contracting and expanding based on the average scene luminance. Auto irises work like this: they wait for a change in the scene, then expand or contract until it stops changing. Through this action, you can imagine that there is some time lag as the auto-iris tries to make up its mind whether to contract or expand (or at least more than one decision point).

An alternative method is high speed auto iris (HSI). In this case, high speed refers to thinking with higher frequency – instead of just evaluating the scene luminance once and then auto focusing, the projector auto focuses rapidly, perhaps as many as ten times each second. This way if there is a small high frequency variation in the brightness of different parts of the picture you will auto focus more often on these areas – contracting or expanding thousands of times per second to try to compensate for this high frequency fluctuation.

 Should I Use Auto Iris? 

The auto iris feature on projectors can be useful for certain applications, but not all. Put simply, auto-iris is an electronic circuit that automatically controls the light output of a projector depending on its inputs.

Some auto-iris systems are dc driven (downward only), based on the average brightness over time. Other auto-iris systems are ac-driven (adaptive) and follow the instantaneous light levels taking into account measurements available to it, such as brightness sensors directly around the lens.
Photosensors within the device or even 18×18 pixel sensors which gather data from specific locations across the projected picture, allowing accurate control across multiple zones – very useful when controlling cross fading/dissolves different images e.g. content creation where the content designer wants certain parts of the screen to fade first before other zones.

Auto-iris can also be used for preventing or restricting ‘light pollution’, by automatically dimming projector lamps during off hours. This significantly increases lamp life, without any need for action from an operator.

 How to Adjust Auto Iris? 

If you’ve ever wanted to get better images from your projector, auto-iris functionality may be able to help. Auto iris is a feature on many high end projectors that will automatically adjust the “aperture” (aperture is another name for the lens in front of the light source) to best match what is being projected at a given time. This means that if you have a very bright scene and a dark scene back-to-back in a single video, or if you have dark scenes followed by very bright scenes in a video, auto-iris can keep the image from being either too dim or washed out.

 How does the auto iris lens work? 

There are several technologies on auto-iris lenses. One of them is liquid crystal auto-iris (LACI).
The auto iris uses liquid crystals instead of the traditional blades found in auto iris technology. The liquid crystals respond to high frequency voltage changes across the two plates within the liquid, changing shape and allowing more or less light through its aperture. When there is no voltage applied, it blocks all incoming light. When a high enough voltage is applied across the liquid crystals, they open up and allow all light to pass through them. This allows for extremely fast auto-iris response times (<1 millisecond) compared with mechanical auto-iris that can take >30 milliseconds to fully open or close.
Auto iris lenses enable a projector to auto-adjust its aperture in order to increase or decrease the amount of light sent through it. Auto iris technology, when integrated into a projector, prevents images from being overexposed or underexposed by automatically adjusting the aperture diaphragm within the lens assembly.

 Epson Auto Iris Normal vs High Speed 

For auto-iris projectors, the auto-iris is a motorized lens assembly that automatically adjusts for light changes by physically opening and closing the lens iris to maintain the best picture possible. The auto-iris has two modes:

Normal mode – Best choice for most situations, Normal mode is designed to give you excellent image quality at normal light levels. This means your projector will be able to maintain peak performance even in well lit rooms or when watching movies with high levels of ambient light.

High Speed Mode – Ideal for low light environments where extra brightness is desired, High speed opens the auto iris wider than normal which lets more light into the system. However, it also increases fan noise and reduces image resolution to some degree.

 How does Pixel Shift work? 

Pixel Shift is a new technology being released with the Pentax K-1 35mm full-frame DSLR.
Pixel shift works by taking four pixel offset images, and combining them in a way that removes pixel noise and resolves more detail than a single exposure can do.

This results in very impressive image quality when pixel shift is activated. However, pixel shift only works on stationary objects; Pixel shift will not work for moving objects or if there is any movement between exposures (i.e handheld blur). Therefore pixel shift cannot be used at all times and you still must know how to use standard single pixel shooting for most occasions.


Going with the high-speed auto iris projector is a good choice for most people, but there are some cases where you might want to consider sticking with normal. If your school needs an interactive whiteboard that can be easily moved from classroom to classroom and doesn’t need as much power, then stick with a classic Epson projector. You also may not need an auto iris if you’re projecting from across the room or have no lighting control in your space at all. The high speed option does make it easier on those who don’t know how to set up their light levels before they start presenting though! It’s worth considering what fits best for your situation when deciding between these two options.

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