Alnitak & Sigma Orionis

[josefk]

If anyone has any tips for sketching diffraction rings in a balanced way i'll gladly take them. Both of these sketches fail to capture the etched fabulousness of these two star systems last night with their associated super steady diffraction patterns really adding to the view. Seeing was fantastic and at an exit pupil of 0.5mm these two lovely systems were both exceptionally aesthetic.

Sigma Orionis (w/ STF 761). "C" was as "present" in the Sigma Ori group as i think i've seen it. No patience or peering required.

 

Alnitak. At the eyepiece this struck me like a black and white cross section of an eye with "B" like the cornea bulge on the wall of the eyeball. The separation at 2.1" was black and "wide". There were two steady diffraction rings, B was sitting on or just inside the first (with much more obvious contrast to it than i've shown here) and with the second ring much fainter than the first (and quite a bit fainter than this poor sketch). I think (but haven't checked yet) that this may be an Astro League double star (sketched) observation i didn't have before :-).

[John]

I think you are doing a great job of capturing the beauty of such stars 👍

My Vixen ED102SS F/6.5 shows more prominent diffraction rings (similar to your Tak FSQ 85) than my Tak FC100-DL F/9 does. I rather like seeing a neat diffraction ring especially surrounding or enclosing a close pair of evenly matched stars. My Tak does not show them around Alnitak, or at least they are so fine I can't see them. Gamma Leonis and Gamma Virginis look aesthetically slightly nicer with the Vixen than the Tak because of this, I feel. 

I also like the "diamond ring" effect of a dimmer secondary star apparently resting on the diffraction ring from the brighter component.

Maybe faster focal ratio scopes show slightly more prominent diffraction rings ?

Nice sketches 🙂

Edited February 25 by John

[SwiMatt]

Very nice sketches! Are the stars in pastel or ink?

I could only guess some ways to draw the diffraction rings, as I haven't tried myself, but you probably tried them already if you draw with pastels  first guess being a very sharp pastel pencil and a feather touch, hoping that the paper will catch the pigment. Which I imagine is what you did!

 

[josefk]

3 hours ago, John said:

I think you are doing a great job of capturing the beauty of such stars 👍

My Vixen ED102SS F/6.5 shows more prominent diffraction rings (similar to your Tak FSQ 85) than my Tak FC100-DL F/9 does. I rather like seeing a neat diffraction ring especially surrounding or enclosing a close pair of evenly matched stars. My Tak does not show them around Alnitak, or at least they are so fine I can't see them. Gamma Leonis and Gamma Virginis look aesthetically slightly nicer with the Vixen than the Tak because of this, I feel. 

I also like the "diamond ring" effect of a dimmer secondary star apparently resting on the diffraction ring from the brighter component.

Maybe faster focal ratio scopes show slightly more prominent diffraction rings ?

Nice sketches 🙂

Thanks John. I Seem to remember reading that faint diffraction rings are a signifier of throughput quality of the optical system because it means maximum light is going into the airy disk. I could be wrong or mis-remembering so now I’m going to look it up. When they’re steady I do like them myself too and as you say the diamond ring effect. 

[josefk]

2 hours ago, SwiMatt said:

Very nice sketches! Are the stars in pastel or ink?

I could only guess some ways to draw the diffraction rings, as I haven't tried myself, but you probably tried them already if you draw with pastels  first guess being a very sharp pastel pencil and a feather touch, hoping that the paper will catch the pigment. Which I imagine is what you did!

 

A mix of both @SwiMatt I go in any/every art shop I find looking for the perfect white equivalent of a 0.003 fine liner. I’m not sure what it is about white ink but it seems to only come in brush pens like the Pitt art brush series (nice) and roller nibs (not nice). 

[SwiMatt]

1 hour ago, josefk said:

A mix of both @SwiMatt I go in any/every art shop I find looking for the perfect white equivalent of a 0.003 fine liner. I’m not sure what it is about white ink but it seems to only come in brush pens like the Pitt art brush series (nice) and roller nibs (not nice). 

You could maybe think of a calligraphy pen and white ink? Nibs for calligraphy come in all shapes, but it might also be overkill...

[josefk]

...not that i get stuck on things and can't move on 🤣 but here's a digital version that captures the real view better...