Orion experiments

[Roy Easto]

Very clear skies at home late last night. I decided to recreate a photo I saw in Sky & Telescope magazine many years ago. The constellation of Orion is repeatedly exposed whilst slowly defocussing the lens to highlight the different colours/temperatures of the stars. Most stars are either Blue or Red supergiants. Betelgeuse being the obvious red supergiant in this picture.

Details: 10 exposures, 50mm lens f1.4, 1600 ISO, raw frames with flat field. 2 second exposure. Images were stacked with python program to add an offset between each image.

[drja...@aol.com]

 Hi Roy

That is a very striking image.  Great colours in reality and not just by the likes of something rather contrived,  like Spectrophotometric Colour Calibration in Pixinsight.   It appeals to me paticularly being colour blind.  Even I can see the red!

It'a real skill to adjust dslr lenses to perfect focus for astro imaging , let alone make tiny adjustments to the focus in small roughly equal increments,  and not get stymied by vibrations.

The Coat Hanger asterism might be another suitable target. 

Thanks for sharing.  

Good job

James

Sent from my iPad

On 20 Dec 2025, at 21:35, 'Roy Easto' via croydonastro <croydo...@googlegroups.com> wrote:



Very clear skies at home late last night. I decided to recreate a photo I saw in Sky & Telescope magazine many years ago. The constellation of Orion is repeatedly exposed whilst slowly defocussing the lens to highlight the different colours/temperatures of the stars. Most stars are either Blue or Red supergiants. Betelgeuse being the obvious red supergiant in this picture.

Details: 10 exposures, 50mm lens f1.4, 1600 ISO, raw frames with flat field. 2 second exposure. Images were stacked with python program to add an offset between each image.

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<OrionTrail.jpg>

<OrionRound.jpg>

[tcos...@gmail.com]

Hi Roy

I agree with James – that’s an interesting take on a well-known asterism rendering the star colours in a striking way. Not an easy technical feat!

Tim C

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