M51 LRGB

[cardconvict]

Here is a image that i did the other night of M51 using an GSO RC8 scope with a Trius 694 camera.

5 min subs of each channel LRGB with 12 subs in each channel.

This is the first time I have been playing with Pixinsight and loving the software but my results are still not brilliant, i think i need more data for this one and when the devils lightbulb is not in the sky

Any feedback and tips or help would be much appreciated

Ian

 

 

 

Updated with Ollys suggestion of SCNR

 

 

 

[laudropb]

Looks very nice to me Ian

[ollypenrice]

Yes, great to see this with a good image scale. The stars suggest that your optics need a tweak and I might try to pull down the cyans a little in the blues. It's probably coming from the green channel. SCNR Green, maybe? But very good and bound top get better with more data.

Olly

[cardconvict]

46 minutes ago, ollypenrice said:

Yes, great to see this with a good image scale. The stars suggest that your optics need a tweak and I might try to pull down the cyans a little in the blues. It's probably coming from the green channel. SCNR Green, maybe? But very good and bound top get better with more data.

Olly

Thanks Olly, when you say about tweaking the optics do you mean collimation ? I have included a single sub in the red channel and i was sure the collimation was bang on do you mind in having a quick look and seeing what you think.

M51_300sec_red 12.fit

[ollypenrice]

11 minutes ago, cardconvict said:

Thanks Olly, when you say about tweaking the optics do you mean collimation ? I have included a single sub in the red channel and i was sure the collimation was bang on do you mind in having a quick look and seeing what you think.

M51_300sec_red 12.fit

Sure. When I opened the image in AstroArt and gave it a screen stretch I found a stellar bright core, zoomed in to pixel scale, to be 12 pixels on the vertical axis but 15 on the horizontal. The star shape is slightly triangular like an arrow pointing to the right. I'm not a collimation expert but I don't think you're quite there yet.

Olly

[cardconvict]

7 minutes ago, ollypenrice said:

Sure. When I opened the image in AstroArt and gave it a screen stretch I found a stellar bright core, zoomed in to pixel scale, to be 12 pixels on the vertical axis but 15 on the horizontal. The star shape is slightly triangular like an arrow pointing to the right. I'm not a collimation expert but I don't think you're quite there yet.

Olly

Thanks Olly I have used a Howie Glatter laser for this but I did not do a final star test, I think I will a star test on the next clear night to finish it off.

[johnrt]

Nice work Ian,

I'm not so sure it's your collimation that is out, the Lum file you sent me and the Red above both look pretty good to me, Olly has measured stellar cores in them and found a little elongation which is something I haven't ever done, I don't think, with one of my images so I won't say he is wrong. But it looks to me that maybe the some of the data was shot under poor conditions? You do seem to have some bloat in the red. How was your guiding? Was there much wobbling around which could cause some elongated and poor shaped stars?

Here's what I saw when I stretched the 2 files, to the eye they look OK to me, but I won't argue with the facts!

 

 

PS What do your stacked master frames look like star wise? Sometimes only the process of stacking can bring out the subtlest poor collimation or focus.

 

[cardconvict]

2 minutes ago, johnrt said:

Nice work Ian,

I'm not so sure it's your collimation that is out, the Lum file you sent me and the Red above both look pretty good to me, Olly has measured stellar cores in them and found a little elongation which is something I haven't ever done, I don't think, with one of my images so I won't say he is wrong. But it looks to me that maybe the some of the data was shot under poor conditions? You do seem to have some bloat in the red. How was your guiding? Was there much wobbling around which could cause some elongated and poor shaped stars?

Here's what I saw when I stretched the 2 files, to the eye they look OK to me, but I won't argue with the facts!

 

 

 

 

The guiding that night was not too bad, but there was nearly a full moon but away from the target, if that affects anything. One thing I did not do was refocus after each filter change over the coarse of the night as the filters are the baader LRGB filter set. I have added a blue sub and green sub.

M51_300sec_2x2__frame2-2 B.fit

M51_300sec_2x2__frame4-2 G.fit

[johnrt]

10 minutes ago, cardconvict said:

The guiding that night was not too bad, but there was nearly a full moon but away from the target, if that affects anything. One thing I did not do was refocus after each filter change over the coarse of the night as the filters are the baader LRGB filter set. I have added a blue sub and green sub.

M51_300sec_2x2__frame2-2 B.fit

M51_300sec_2x2__frame4-2 G.fit

Were all these shot in the same night? The green sub does look off in collimation, but blue still looks fine!

[cardconvict]

Yes they was all shot over the same night over a 4 hour stint

[cardconvict]

Here is a 20 minute sub in HA on a different night

M51_1200sec_1x1_Ha_frame2.fit