Processing longer exposures times

[MarcoS]

Good day Ivo,

I'm into AP since about 8 months, and with the my Meade LS6" (AltAz mount) I usually took 45-60 second frames, (lots of them DSS stacked) and I managed nice results with StarTool out of them.

Since last week, I finally managed to install a derotator on my AltAZ mount to take longer exposures times.
I have obtained so far exposures up to 480 seconds with very little startrails.

For example the image here below of the Heart Nebula is
5 x 240 Iso 400
5 x 480 Iso 400
Total integration 60 minutes. (+ dark, flats and bias)

Normally in post processing with 60 minutes integration I can get nice detail out, but with this image, and a previously taken one of NGC281 I am not able to get any details out.
Question is:
Does longer exposures images require a different approach in post processing from the one used for shorter exposures?
Or is this one of those target that need much more than 60 minutes to bring out details?
I have never imagined those objects before with shorter exposure, so I cannot compare the results

Heart-nebula.jpg (462.08 KiB) Viewed 7015 times

For testing purposes the DSS stacked Fts file is available here:

https://drive.google.com/file/d/0B6oGP3 ... sp=sharing

Can you please advise?

Have a nice Sunday

[Alvinillo]

This object has a surface brightness of 10, so it is a fairly difficult object wich needs good skies, long exposures and a fast telescope. I think yours is f10.

I think there is nothing wrong with your image, you just need a lot more exposure time. In fact you got the nebulosity, wich is more than I though you were going to get.

I suggest you to begin with brighter targets wich can be equally challenging. Messier catalog should be a good starting point. For example Pleiades is a good target because initially it is easy to get some nebula, but you'll need longer exposures to get all the faint nebula surrounding it, lihe this http://www.astrobin.com/203/

About processing, I think that there is no fundamental difference between short and long exposures. The only difference I think of is that with longer exposures you may need to do some shorter exposures and combine then into a HDR image.

Regards

EDIT: Excuse me, I thought that the image was ngc281. Anyway, heart nebula is another faint object.

[MarcoS]

Hi Alvinillo,
Thanks for your reply, Yes, The Meade LS6" is f10, but for imagining I use a Focal Reducer at 6.3.
I also thought the this was a faint object but was not sure, will get more imagining time on it, it is in this period in a nice place in the sky from my location to image
Nice pic of the Pleiades you link to. they are at the moment a bit too close to the moon, but they are on my list.

I have already imaged about 20 of the brighter Messier object I even managed a shot of the supernova in M82 at the beginning of the year

You can check here below some of them, they are all short exposures between 40 and 60 second.

https://www.facebook.com/marco.satta.96 ... 193&type=37

Thanks for the tip of combining long and short exposures in a HDR image.

Clear skies
Marco

[Alvinillo]

Hi MarcoS. You've got pretty impressive images for such a short exposures, well done!

Before you choose a target you can look for an specific target at astrobin to see the 'usual' quality and to get an idea of its difficulty.

Regards

[MarcoS]

Hi Alvinillo,

Thanks, that is a good idea, to check astrobin, I choose this one because it "looked pretty" in stellarium...

Clear skies
Marco