help with best way to stack comet lovejoy

[red dwalf]

hi all,

I have 60 x 1 minute subs of comet lovejoy and i`ve never stacked a comet before, i guided locked onto the comet as i wanted to get the comet and tail as sharp as possible, so i`m thinking if i do a normal stack in DSS then i`ll have star trails or it may use the stars to align and i`ll have comet trail. 

i have tried stacking these images once using the comet box on the right hand side of the program screen but all i got after 20 minutes of stacking was a butterfly effect comet.

i have a few programs i could use to stack, one being DSS and the other is Nebulosity 3.

any help or suggestions would be great,

many thanks.

[Guest Eddy]

Not looked at DSS for a while but isn't there a comet option where you can align on the comet?

[Johnnyaardvark]

Interesting Rob. How did you guide locked onto the Comet? if you have done that rather than on the stars the method below in DSS may or may not help?!

 

As for DSS I have been playing with this to varying degrees of success. It has three modes one of which doubles the time it takes to process so my little pc sits there for about an hour saying not responding but is redoing the process in the background while it adds the stars stacked together, to the comet only. Comet and stars stacking : "star freeze effect"

 

You can also use: Standard stacking or Comet stacking : star trails
 

See: http://deepskystacker.free.fr/english/technical.htm#cometstacking

 

"Fun" and interesting but time consuming and so far I am not 100% happy with the results.

 

Mostly that my subs are coming out dark when I import NEF "raw" files into DSS. I have upped some settings in the way it process RAW files and this is helping (gone a bit too far currently as I am getting lighter images but too much noise) and also my final image is very grey lacking any colour.

 

Any extra thoughts/comments welcome to help me too!

 

Steve

[red dwalf]

i wasn`t sure if to guide on a star or the comet, two thoughts were going though my head , one, if i guide on the stars the comet might be trailed and losing detail in the tail, two, if i guided on the comet the comet and tail would look sharp but stars might looked a little trailed, as i wanted detail on the comet i thought i would use it to guide.

my guide scope is virtually 100% aligned to my scope, i know it`s not needed but you find yourself doing silly things when your bored and loads of cloud about, but it does help me a little to centre objects, for instance i can see the orion neb in the guide camera images even at 2 second subs and i know if i centre it on the screen it will be perfect on the image camera.

i`ve never taken 60 x 1 minute subs of a comet before so have never stacked a fast moving target before, i`ll try the method you have suggested above. 

i`m using cr2 raw files with my canon 1100d but if you need to change the file formats you can download DNG converter from adobe for free, this can be very useful for changing raw files like cr2 to fit files or other raw files that might work better in photoshop for example. 

 

a couple of things i do when saving the completed stacked images in DSS are to save as fit or tiff 16 bit file, where it says compression, select none, and in options i make sure the button that says - do not apply adjustments to the saved images.

[Johnnyaardvark]

Interesting. Tried the do not apply settings and then fid I can't open in DSS. Could be that they were then being saved as 32bit?!

 

Here's a few more recent stacks for interest...

 

Lovejoy with star trails by sja88, on Flickr

Lovejoy 92s exposures 18 mins 15s with star trails no processing. Unprocessed to show output from DSS

 

Lovejoy no stars unprocessed by sja88, on Flickr

Lovejoy no stars. Unprocessed to show DSS output

 

Lovejoy by sja88, on Flickr

Lovejoy 4x 1min 30s exposures. Thought i'd try best 4 consecutive shots and stack on stars only little trailing on comet (minor) but not really noticeable after stretching the image. Happier with tail detail but very noisy!!

 

Tried converting my files to TIFF before importing but DSS did not like the files when it came to stacking.

 

I have upped the RAW/FITS DDP Setting: Raw files Brightness to 3 for this last image, also used Auto white balance, Bilinear interpolation and set the black point to zero. Getting lighter stacks but quite noisy. Not sure what the best settings are to import NEF's from a D5000. I get the impression the optimum settings depend quite specifically on the camera/sensor but difficult to find out what they are for the D5000.

 

How are you getting on? Or given up?

 

Steve

[Orion]

Interesting Rob. How did you guide locked onto the Comet? if you have done that rather than on the stars the method below in DSS may or may not help?!

As for DSS I have been playing with this to varying degrees of success. It has three modes one of which doubles the time it takes to process so my little pc sits there for about an hour saying not responding but is redoing the process in the background while it adds the stars stacked together, to the comet only. Comet and stars stacking : "star freeze effect"

You can also use: Standard stacking or Comet stacking : star trails

See: http://deepskystacker.free.fr/english/technical.htm#cometstacking

"Fun" and interesting but time consuming and so far I am not 100% happy with the results.

Mostly that my subs are coming out dark when I import NEF "raw" files into DSS. I have upped some settings in the way it process RAW files and this is helping (gone a bit too far currently as I am getting lighter images but too much noise) and also my final image is very grey lacking any colour.

Any extra thoughts/comments welcome to help me too!

Steve[/quot

After the final stacking is completed, try increaseing the saturation to about 20% - and you should have some colour back.

[Orion]

hi all,

I have 60 x 1 minute subs of comet lovejoy and i`ve never stacked a comet before, i guided locked onto the comet as i wanted to get the comet and tail as sharp as possible, so i`m thinking if i do a normal stack in DSS then i`ll have star trails or it may use the stars to align and i`ll have comet trail.

i have tried stacking these images once using the comet box on the right hand side of the program screen but all i got after 20 minutes of stacking was a butterfly effect comet.

i have a few programs i could use to stack, one being DSS and the other is Nebulosity 3.

any help or suggestions would be great,

many thanks.

Rob

in each frame, when choosing stack on comet (star trails), I think you have to manually choose the comet centre. Since its moving faster, but guided, the comet in stack on comet should be sharp against star trails. I did that which made the comet as a single blob in a 55mm lens (untracked camera), and the stars become trailed. In fact the resolution at FL 55mm wouldn't allow me to precisely choose with the mouse, the identical anchor point on the comet (even in enlarged view). This resulted in the stars being more than trailed, but close multiple images except the comet.

Derek

[Johnnyaardvark]

Rob

in each frame, when choosing stack on comet (star trails), I think you have to manually choose the comet centre. Since its moving faster, but guided, the comet in stack on comet should be sharp against star trails. I did that which made the comet as a single blob in a 55mm lens (untracked camera), and the stars become trailed. In fact the resolution at FL 55mm wouldn't allow me to precisely choose with the mouse, the identical anchor point on the comet (even in enlarged view). This resulted in the stars being more than trailed, but close multiple images except the comet.

Derek

Hi Derek,

 

You can more precisely "Register the comet center" if you zoom in and then while trying to click on the comet use (shift and click) there can be issues if the comet is too bright OR doesn't have a well enough definened centre.

 

 

"If the comet center is too faint or too bright you can force DeepSkyStacker to accept any position by holding down the Shift key while positioning the comet center"

 

See: http://deepskystacke...m#cometstacking

 

You may have tried this already but if not give it a go.

 

 

As for colour and brightness... still fighting with DSS settings a little which regards to stacking Nikon Raw files but getting somewhere I think.

 

I do increase saturation after stacking and yes thus brings back a bit of colour. Out of interest do you tend to do this in DSS or in post processing? I assume that CS2 would do a better job than DSS. You can certainly more easily instantly check your changes. Also, any thoughts on the white balance settings in the FITTS/RAW processing tab in DSS?

 

I know others on the website have moved to other software to stack subs and get stacks with more contrast and colour from the off. Can't remember which off hand. DSS is great for free but I think there are some better ways to process.

 

Steve

[Orion]

Hi Derek,

 

You can more precisely "Register the comet center" if you zoom in and then while trying to click on the comet use (shift and click) there can be issues if the comet is too bright OR doesn't have a well enough definened centre.

 

 

"If the comet center is too faint or too bright you can force DeepSkyStacker to accept any position by holding down the Shift key while positioning the comet center"

 

See: http://deepskystacke...m#cometstacking

 

You may have tried this already but if not give it a go.

 

 

As for colour and brightness... still fighting with DSS settings a little which regards to stacking Nikon Raw files but getting somewhere I think.

 

I do increase saturation after stacking and yes thus brings back a bit of colour. Out of interest do you tend to do this in DSS or in post processing? I assume that CS2 would do a better job than DSS. You can certainly more easily instantly check your changes. Also, any thoughts on the white balance settings in the FITTS/RAW processing tab in DSS?

 

I know others on the website have moved to other software to stack subs and get stacks with more contrast and colour from the off. Can't remember which off hand. DSS is great for free but I think there are some better ways to process.

 

Steve

 

Steve

I think I did try the method you refer to. I only did it once, where I remember seeing an enlarged portion of the comet head. But I couldn't get a repeated register at the same place. But I need to go back and see if I had used the shift key or not.

I can't answer you Q re white balance. I'm just learning myself what is a steep learning curve.  I do increase the saturation in DSS. I don't have CS2, but have the image editor called Irfanview (free from Internet).  I have yet to explore CS2 or where to get it, and whether it is a paid for software or free version.

 

The process of seeing the effect of changing one parameter such as the RGB colours, or brightness etc, takes ages, with small square portions of the images changing. But I find I make a tweak, then the effect is too harsh and I undo it, then try again. I've read on some forums that some only use DSS to stack, then process in something else like Photoshop. 

Derek