Astronomik IR Block 1.25″ filter
If you photograph the night sky with a digital camera or webcam and notice strange halos around bright stars, low contrast, or a generally soft image, the cause is most likely infrared (IR) light. The Astronomik IR Block 1.25″ filter solves this problem in a clean, reliable and uncompromising way. It is designed specifically for digital astrophotography and will become an essential tool for anyone who takes image quality seriously.
Why infrared light is a problem in astrophotography
Digital sensors - unlike the human eye - are very sensitive to infrared radiation. When IR light enters the optical system without control, it causes:
- Loss of sharpness and overall image softness
- Unwanted halos around bright stars and objects
- Reduced contrast across the entire image
The Astronomik IR Block filter eliminates these effects while leaving the visible part of the spectrum completely untouched - no color shifts, no loss of detail.
High performance compared to similar products
Compared to competing products, the Astronomik IR Block is remarkably comprehensive. If you compare its transmission curves with those of other manufacturers, you will find that many of them would actually call this filter a UV-IR Block. What Astronomik labels as "UV-IR Block" is then an even more powerful product, one step above. This comparison shows clearly how high Astronomik has set the quality bar even for its basic IR filter.
Technical specifications
| Parameter |
Value |
| Filter size |
1.25″ |
| Supported focal ratios |
f/0.5 to f/50 |
| Transmission in visible spectrum |
over 99% |
| Glass material |
Optical glass with precision multi-layer coatings |
| Parfocal with other Astronomik filters |
Yes |
Optical compatibility
The filter is optimized for a wide range of focal ratios from f/0.5 to f/50, covering virtually any optical system - from fast photographic lenses to refractors and catadioptric telescopes. Typical transmission in the visible spectrum exceeds 99%, which means the filter does not increase exposure time and does not affect color balance.
Which camera types is this filter designed for
The Astronomik IR Block filter is an ideal choice for owners of:
- CCD cameras
- Webcams and video systems (for example Meade DSI, LPI or various planetary cameras) that have low sensitivity in the ultraviolet range but high sensitivity in infrared
- DSLR cameras with so-called MC (multicoated) modification, used in combination with optics containing refractive elements - meaning lenses
For systems without refractive elements - for example pure Newtonian reflectors without correctors - the MC Clear filter is a better choice.
Additional uses
Besides its main function, the IR Block filter also serves as a practical protection for optics and the sensor against dust. It is suitable for closing the rear opening of Schmidt-Cassegrain, Schmidt-Newton or Maksutov telescopes, or as a protective filter in front of a DSLR camera during transport or storage.
How to choose the right Astronomik filter
Astronomik offers a complete range of filters for different situations:
- UV-IR Block - if your camera has high sensitivity at short wavelengths (UV range)
- MC Clear - for optical systems without refractive elements
- CLS CCD - if you photograph from locations with significant light pollution; this filter suppresses emission lines from sodium and mercury lamps
- IR Block - the filter described on this page, suitable for most digital cameras with refractive optics
About Astronomik
Astronomik is a German manufacturer of premium astronomical filters with a long tradition and a strong reputation among the most demanding astrophotographers in the world. Each filter goes through strict quality control. The glass is made from optical-grade material with precision multi-layer coatings that ensure maximum transmission in the required band and reliable blocking of unwanted radiation.
Parfocal design
The entire Astronomik filter range is parfocal, which means you do not need to refocus when switching between filters. This is a practical advantage that you will appreciate especially during sequential LRGB or narrowband imaging sessions.
Durability and packaging
Astronomik filters are supplied in robust cases that protect the optics during transport and storage. They are built to resist moisture, mechanical abrasion and aging effects after many years of intensive use.
