Astronomik UHC-E Sony Alpha Clip Filter

The Astronomik UHC-E Clip-Filter for Sony Alpha DSLR cameras is used for nebula photography in stronger light polluted areas and can be inserted into the camera body within seconds.

Note: This filter does not block IR, so it should be used only with purely reflective optics or an additional IR blocking filter.

The Challenge:

Do you own a Sony digital camera for astro-imaging? Then you have surely encountered the following problems:

Large filters for large camera lens objectives are very expensive.

If you place a filter holder between your camera body and lens, you loose the ability to focus to infinity.

For very fast (low f/ number) telescopes like the Vixen R200SS or the Takahashi “Epsilon” astrograph, a filter drawer or a filter wheel cannot be used since the distance to the corrector lenses would be changed.

With long exposure times, your camera’s sensor chip is exposed to more dust.

With the Astronomik Clip-Filter System you can take care of all of these problems at once!

The patented Astronomik Clip-Filters are made of black anodized aluminum and laser-cut on state-of-the-art machines. They can be inserted within seconds directly into the camera body. There are no changes necessary and all lens functions (focus, screen, image stabilization) remain operational!

The Clip-Filter System also acts as an outstanding dust shield, which prevents the possibility of dust settling on the sensor during long time exposure.

Compatibility:

The Clip-Filter are sucessfully tested with the bodies Sony Alpha 7, 7r and 7s. (Astronomik will test other/future models and add them here.)

The manufacturer has made a short video which shows installation and removal of the clip-filter for Sony Alpha:



The filters are not suitable for Sony alpha 3000 to 6500 or Sony alpha NEX cameras.

Main use

The Astronomik UHC-E filter provides a FWHM of 45 nm and blocks the light of typical streetlights (e.g. sodium and mercury vapour) as well as airglow. Thus it increases contrast between your target and the night sky. The contrast enhancement is less than that of the Astronomik UHC filter, but at the same time the transmitted amount of starlight is greater. It´s therefore better suited for slower telescopes. As the UHC-E filter passes a spectral line of Carbon (due to the higher FWHM) it opens up the possibility of comet observation.

Suitability

DSLR photography (original): Good, colour balance is near perfect

DSLR photography (astro modified): Good, colour balance is near perfect

DSLR photography (MC modified): Good, when used with an additional IR-block-filter

Filter transmission curve:

The horizontal axis is the wavelength in nanometers (nm). 400 nm is deep blue, at 520 nm the human eye senses green and at 600 nm red. At 656 nm is the famous "H-Alpha" emission line of hydrogen.

The transmission in % is plotted on the vertical axis.

The blue line shows the transmission of the filter.

The most important emission lines from nebulas are shown in orange. The most important lines are from ionized hydrogen (H-alpha and H-beta), double ionized oyxgen ([O III]) and ionized sulfur ([S II]). The square brackets indicate that these lines are forbidden.