Jump to content

SkySurveyBanner.jpg.21855908fce40597655603b6c9af720d.jpg

M51 Whirlpool Galaxy - now with added colour (Atik 490ex)


x6gas

Recommended Posts

PS I am grumpily coming to the conclusion that I may have to start taking flats. It's the obvious next step but I have managed to avoid them in the past just by keeping everything very clean (I believe that the bunnies on the 490 are inside the sensor chamber on the back of the window...) and eliminating the vignetting I get from 2" filters in AstroArt.

Link to comment
Share on other sites

  • Replies 43
  • Created
  • Last Reply

I used to hate taking flats, found them a real chore and avoided them at every opportunity. Now with all my cabling sorted it's easy to plug the light panel in and out, EQMOD moves the mount to a vertical position so that I can place my light panel on top of the dew shield, the Artemis readout is very simple to read and get the right exposure - Voila!!

Now part of my data capture, not a chore and easy peasy - Olly used to tell me off for not doing them - There really is no excuse and they make such a difference. Makes processing easier too :smiley:

Link to comment
Share on other sites

I sometimes find that the colours are pushed a bit hard on some galaxy images I see,

I'm with you on that one. A nice image .... the original one was clipped (blackpoint) a bit but a lovely image nonetheless. Use flats to get rid of the artefacts.

Good work

Link to comment
Share on other sites

I used to hate taking flats, found them a real chore and avoided them at every opportunity. Now with all my cabling sorted it's easy to plug the light panel in and out, EQMOD moves the mount to a vertical position so that I can place my light panel on top of the dew shield, the Artemis readout is very simple to read and get the right exposure - Voila!!

Now part of my data capture, not a chore and easy peasy - Olly used to tell me off for not doing them - There really is no excuse and they make such a difference. Makes processing easier too :smiley:

Yeah, I think I might be more inclined if I had an obsy rather than a mobile set-up; more complexity for images taken over multiple sessions and I very rarely get enough data in one night for a full luminance or narrowband channel... Still I can feel the weight of inevitability coming over me!

So what am I looking for in Artemis, Sara? Is it a particular reading of "White" in the display dialog box?

Link to comment
Share on other sites

I'm with you on that one. A nice image .... the original one was clipped (blackpoint) a bit but a lovely image nonetheless. Use flats to get rid of the artefacts.

Good work

Thanks Mick!

Link to comment
Share on other sites

PS I am grumpily coming to the conclusion that I may have to start taking flats. It's the obvious next step but I have managed to avoid them in the past just by keeping everything very clean (I believe that the bunnies on the 490 are inside the sensor chamber on the back of the window...) and eliminating the vignetting I get from 2" filters in AstroArt.

Yes, take flats!.....Not only do they deal with dust and vignetting, but they also (because of dealing with vignetting) allow the very faintest parts of the image to come through better.

From the size of the dust bunnies on your image, they aren't part of the camera itself...they're too big. They'll be on the filter(s). The closer to the sensor they are, the smaller they are, and those are quite large.

Cheers

Rob

Link to comment
Share on other sites

From the size of the dust bunnies on your image, they aren't part of the camera itself...they're too big. They'll be on the filter(s). The closer to the sensor they are, the smaller they are, and those are quite large.

Cheers

Rob

Strangely no Rob - definitely on the window of the camera. Not on the chip itself but on the window so 10mm or so from the sensor (the back focus of the camera is 13mm). They were present in the same place in the frame with all filters AND when I rotated the camera against the filter wheel by unscrewing it slightly. Actually, my set up with both the EdgeHD and my 'fracs is very forgiving of dust on the filters, though I do give them a regular blow and keep the camera/wheel/OAG/reducer in a ziplock bag when not in use...

Link to comment
Share on other sites

They're very big dust particles if they're that close!!

Can't be anywhere else though from what you describe.

Looking forward to seeing this with the extra data :smiley:

Cheers

Rob

Link to comment
Share on other sites

They're very big dust particles if they're that close!!

Can't be anywhere else though from what you describe.

Looking forward to seeing this with the extra data :smiley:

Cheers

Rob

It's a head-scratcher, right enough as I can't see anything on the window, cleaned the outside, and the camera is brand new. It's going back to Atik so that they can check it out...

Link to comment
Share on other sites

It's a head-scratcher, right enough as I can't see anything on the window, cleaned the outside, and the camera is brand new. It's going back to Atik so that they can check it out...

Very odd.

If the dust was actually on the chip, you'd get black dots.....I had this with my old H18 when the shutter was shedding its coating. Of course, you couldn't use flats to deal with it as the dust would move, and more would appear whenevr the shutter operated.

Link to comment
Share on other sites

I think it's dust on the sensor window in view of the size of the dust bunny. I have a spec of dust on my sensor window and it gives much the same size. I did a set of flats without any filter (empty hole in the wheel) so there's no glass between the secondary mirror and the camera.

This is one of my flats stretched in PS :-

post-13131-0-89485500-1367681496_thumb.p

Link to comment
Share on other sites

This sub actually shows two easily rectifyable faults. The dust bunnies (one fairly pronounced and one less so) and a shadow from the OAG prism holder. So I can improve things by moving the turret further out and using the rocket blower - then take another set of flats. It also looks as if my collimation is slightly off.

Link to comment
Share on other sites

Thanks Gina - good to have confirmation that those sized doughnuts are indeed an issue with the sensor glass...

And I wish I'd done this when I first got my OAG as all of the subs I took of the Horsehead Nebula suffered from huge vignetting from the the OAG pick off prism which I had far too close to the sensor!

Have a t-shirt stretched over the scope and I'm gonna see what I get!

Link to comment
Share on other sites

This sub actually shows two easily rectifyable faults. The dust bunnies (one fairly pronounced and one less so) and a shadow from the OAG prism holder. So I can improve things by moving the turret further out and using the rocket blower - then take another set of flats. It also looks as if my collimation is slightly off.

By the way, can you read anything in to the collimation from this? The dust may not be perfectly round after all?

Link to comment
Share on other sites

That M51 is superb,one of the best i,ve seen.

I cant get binning to work on my small frac because of bloated stars.

Mick.

Interesting. I found the RGB data for this to be pretty tight, but then the subs are pretty short...

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.