There is a faint arc of ionised hydrogen gas glowing in HII light around Orion. This is Barnard’s Loop. Its not really visible by eye or backyard telescope.
Tried to image this last night with mixed results.
As this is such a large object, I used a wide-angle Canon 50mm f1.4 lens with the Canon 60Da DSLR set at f2 and ISO 800.
I used FWHM focusing which seemed good but the final image (26 x 30 second sub-exposures) seemed to have a lot of poorly focused field stars. I guess I should take a few test images first in future – especially for low f-stop, wide angle images. (Ive also read since that the 50mm f1.4 is said to be best for astrophotography at f4).
Also the lower 20% of the image was overwhelmed with light pollution despite waiting until Orion was at its zenith (around 2330 GMT) and using a CLS filter.
Must try harder!
Sh2-276 emission nebula in Orion. Barnard’s Loop.