M33 with Quattro and 1000D

[Carl M]

Well it's fair to say I've spent way too much time trying to process this...which is probably a sign it needs more data as well as calibration frames - no flats/darks/bias.

Still seem to be getting stars elongated at edges of images (worse in top left), which I cannot work out to be either coma or collimation, perhaps my Baader MPCC needs to be updated to a newer version (assuming it is coma)?

Anyhow.. finally managed to get some data I was happy with and where the guiding was content.

21 x 300s at ISO800

Full spectrum 1000D with Astronomik CLS-CCD clip filter

Quattro 8s on EQ6 guided with ST80 and QHY5II

Processed in Photoshop and Pixinsight for DBE

For just under 2 hours of data I'm quite happy with it!

Thanks for looking,

Carl

 

[Paul M]

I'd be happy too!

I think M33 can be a more interesting subject than M31. It's smaller size and relative sparsity help prevent visual overload!

[Carl M]

38 minutes ago, Paul M said:

I think M33 can be a more interesting subject than M31. It's smaller size and relative sparsity help prevent visual overload!

It's a lot easier to fit in the frame, I had no end of trouble trying to get the whole of M31 and it's companion in the entire FOV a while ago. Felt like I'd tried every degree of rotation around the focuser with the camera!

[ultranova]

That's come out very nice indeed

I like the way you have not over stretched anything

for a more pleasing natural look.

what's not to like about it.

well done

Paul

[laudropb]

Very nice image.

[Adam J]

The optimal spacing of the coma corrector is 55 mm at F5 however the spacing changes slightly at lower f ratios as far as I know. I do know that the mk3 works better at lower F ratios than the original.  It could also be that the collimation is slightly off. 

[Carl M]

18 minutes ago, Adam J said:

The optimal spacing of the coma corrector is 55 mm at F5 however the spacing changes slightly at lower f ratios as far as I know. I do know that the mk3 works better at lower F ratios than the original.  It could also be that the collimation is slightly off. 

Thanks for that, if it were to be collimation would rotating the camera around the focuser change the direction of the worse corner in the image? I imaged M42 on the same night and looking at the images from that it shows that the top left is still the worse corner? Got me thinking perhaps it's something to do with the t-ring/coma corrector not sitting square - maybe even the sensor itself since it was self modified.

[Adam J]

3 hours ago, Carl M said:

Thanks for that, if it were to be collimation would rotating the camera around the focuser change the direction of the worse corner in the image? I imaged M42 on the same night and looking at the images from that it shows that the top left is still the worse corner? Got me thinking perhaps it's something to do with the t-ring/coma corrector not sitting square - maybe even the sensor itself since it was self modified.

If its purely coma with perfect colimation and no tilt then you should get the same amount of coma in all four corners. As you say this is most likely caused by tilt combined with coma.

[MartinB]

Lovely job with some nice detail.  Don't worry about those marginally elongated stars, they aren't an issue really, except for geeks!  The issue for me is the overall redness, I'd love to see a bit of blue in there.

[Carl M]

4 hours ago, MartinB said:

Lovely job with some nice detail.  Don't worry about those marginally elongated stars, they aren't an issue really, except for geeks!  The issue for me is the overall redness, I'd love to see a bit of blue in there.

Thanks Martin, I agree the original is a bit too red - can see it especially in the stars. I added a star mask and de-saturated it a little to turn down the redness of the stars while boosting the blue and reducing the red a bit for the rest of the image. Hopefully this is a slight improvement.

[swag72]

I like that edit - The blue really makes it stand out - Nice

[MartinB]

Bingo!!

[gorann]

Yes, that last edit nailed it!

I did not notice the coma until I downloaded the full resolution and zoomed in, so it is probably more annoying to you than anyone else. However, you do seem to have the coma issue in all corners (although most apparent in the top left), so spacing could be the first thing to try. I assume you have checked that it is there is all subs, so it is not a guiding or focusing issue in a few of them.