Rho Ophiuchi Cloud Complex

Bill Richards

Well-Known Member
Galaxy season is just about over so it's time to focus on targets within our own Milky Way. This is a new & improved image of the Rho Ophiuchi (pronounced 'roh oh-fee-yoo-ki') cloud complex which I captured 3 years ago under windy conditions that resulted in "less than desireable" sharpness. So I decided to have another go at it this year.

This colorful nebula can be found in late spring/early summer in the southern sky, just to the west of the plane of the Milky Way. The extremely dense star field is indicative of its proximity to the center of the Milky Way. The bright yellow star at the bottom-center is Antares. To the right of that is the "Crab Globular Cluster" (M4), which is a spherical cluster of stars in our Milky Way galaxy, about 7200 light-years away.

This image is the result of integrating over 400 exposures, comprising over 4 hours of total "open shutter" time from the night of 5/31-6/1, 2024.

Rho Oph.jpg


Equipment and Software:
=======================
Mount: iOption CEM40 w/iPolar
Lens: Canon EF 135mm f/2L USM
Stopped down to f/2.8 with filter reducer ring
Imaging Camera: ASI2600MC-Pro
Guide Camera: ASI120MM-Mini w/ASI 30mm f/4 guide scope
Imaging Software: NINA
Guiding Software: PHD2
Image Processing Software: PixInsight

Exposure Details:
=================
Camera Temperature -15C
Bias: 50
Gain: 100
403 x 30s
Plus 32x Darks, Flats, and Dark Flats

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JimFox

Moderator
Staff member
This is awesome work Bill! You have captured such great color and detail on this.

Did you use any filters on this?

I have the Samyang 135mm, I haven't tried it yet. I really should because I like this field of view you got.
 

Bill Richards

Well-Known Member
This is awesome work Bill! You have captured such great color and detail on this.

Did you use any filters on this?

I have the Samyang 135mm, I haven't tried it yet. I really should because I like this field of view you got.
No filters, Jim. This cloud complex is a mix of emission, reflection, and dark nebulas so using a filter would omit a lot of the light and color.

I generally shy away from using camera lenses whenever possible because they simply cannot compare to the superior optics of a good telescope. However, Canon's "L glass" has excellent optical characteristics so it did a reasonably good job on this target. And the alternative was a 9-panel mosaic using my Esprit 100 with a focal reducer, and that simply wasn't going to happen given that this target can only be photographed about 4 hours per night.
 

JimFox

Moderator
Staff member
No filters, Jim. This cloud complex is a mix of emission, reflection, and dark nebulas so using a filter would omit a lot of the light and color.

I generally shy away from using camera lenses whenever possible because they simply cannot compare to the superior optics of a good telescope. However, Canon's "L glass" has excellent optical characteristics so it did a reasonably good job on this target. And the alternative was a 9-panel mosaic using my Esprit 100 with a focal reducer, and that simply wasn't going to happen given that this target can only be photographed about 4 hours per night.
That makes sense about the filter. I may have used a broadband filter on it when I captured it a while ago, but I would have to double check.

The L Glass from Canon does have a great reputation. Since I have moved to using an actual scope a few years ago, I don't have any real desire to go back to using a camera lens, though for a large object like this I am considering the option and will do it hopefully soon.
 

Bill Richards

Well-Known Member
That makes sense about the filter. I may have used a broadband filter on it when I captured it a while ago, but I would have to double check.

The L Glass from Canon does have a great reputation. Since I have moved to using an actual scope a few years ago, I don't have any real desire to go back to using a camera lens, though for a large object like this I am considering the option and will do it hopefully soon.
I'm using an Astromechanics adapter to mate the Canon lens with my ASI2600MC-Pro. Astromechanics is a Russian firm and their products were hit by the sanctions when Russia invaded Ukraine. So you may not be able to get those adapters now.
 

JimFox

Moderator
Staff member
I'm using an Astromechanics adapter to mate the Canon lens with my ASI2600MC-Pro. Astromechanics is a Russian firm and their products were hit by the sanctions when Russia invaded Ukraine. So you may not be able to get those adapters now.
I have a ZWO adapter to adapt my Nikon mount Samyang to my ASI2600mc Pro. The Scope was the last thing I updated so I was using my old Tamron 150-600mm on the 2600 when I first got the 2600 and upgraded from my DSLR. So I should be able to mount the Samyang 135mm okay.
 

Mike Lewis

Staff Member
Never get tired of this magnificent location in the sky, so many things going on creating so many colors all in one place. Lovely job on this one. I have not seen too many astro images with the Canon EF 135 f/2 L - as you say looks like it did a decent job, at least at this magnification.

ML
 
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