Yet another M42

[robindurant]

Taken last night. Can anyone explain the blue circles around the stars

Robin

(click to enlarge)

[Kaptain Klevtsov]

Nice image Robin. The blue haloes are achroitis from the ST80. As its not an APO 'scope these things will always appear.

Kaptain Klevtsov

[CELESCOPE]

What Blue Halo.s Robin ????

(click to enlarge)

can take the halo.s out but has an effect on the main image i may have hit it a bit to hard , but this can be done slowly a bit at a time and hopefully keeping the image the same

Rog

[barkis]

I quite like the image Robin, it has a surreal look to it.

That's a good trick Rog. especially if the image can be left intact.

I thought those halos were indicative of a LPR filter or something else in the optical train. I am only guessing, so I will have to bow to superior knowledge.

Ron.

[steppenwolf]

Robin, a trick that you could try to stop the halos a bit is to 'stop down' the lens - this means to reduce the aperture and a quick way of doing this with your telescope is to remove the centre part of the front dust cover only - this will mean longer exposures but the finished result will be sharper and will display less in the way of chromatic aberrations and halos. A more time consuming way is to make your own aperture mask out of black cardboard to get an aperture half way between the full dust cap removal and the centre removal.