>The Great Orion nebula and the filters

  • Posted on: 11 November 2020
  • By: tihomiry

Some shots from Sofia. A very bright sky place. Zenith sky brightness info (2015): SQM 19.13 mag./arc sec2 Brightness 2.41 mcd/m2, Artif. bright. 2230 μcd/m2, Bortle class 6.

However I think that with the LED lights nowadays it is much worse as I can see only the 7 bright stars of Orion.
So I did another comparison of different filters to compare which one is best for my observations.

You can notice that the IR image gives the most stars, as most of the artificial LED lights do not emit IR. However IR is less then 20% of the QE of the sensor and we do not have much details here. The best details and colours we have with the UHC-S as it is narrow band for hydrogen and oxygen. The nebula is reach of those elements. The general light pollution filter (Omegon city lights filter) is also good but my one do not have AR coating and cast some glows. However it is my default choice when shooting at sky with any kind of pollution. It is more universal then UHC-S and I can use it for galaxies as well. Here is the place to check your sky : light pollution map

Orion nebula comparison

No fake :) My filters tested with my hand made spectrum analyser and looks good. The light pollution filter cuts all the yellow. UHC-s cuts IR but pass blue light.

Mars spectrum with filters

Nowadays we are so into the globalization and technologies, that I can submit observation plan to a remote, professional observatory at the other part of the word!

This is a comparison of my not modified Pentax k5 DSLR and the same, but modified one without IR-cut filter.

Astrotracer is a great way to take advantage of the Pentax DSLR camera in-body shake reduction mechanism. It is available since Pentax k5 and track celestial bodies by moving the sensor. Here is what is it ablout:

Staying at my home inspires me to make some documentation of my experience. I got a dedicated drive for my astrophotos and start reorganize them by objects. Here is an article of the most recent process I use on my photos. Enjoy: )

For a few months from now Betelgeuse (Alpha Orion) dim so much, that it looks as bright as the stars in the Orion belt. This is not so disturbing and does not mean that cataclysmic events are happening with it.

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