Iris nebula

[Grant93]

Hello everyone!

Did a quick one on the iris nebula (Did this before I read that Iris nebula is definitely not good for a quick-one! As you need hours upon hours to get them dark dust clouds!) Please ignore the non round stars near the edges, I am still waiting on my flattener but don't want to waste clear nights waiting! It is quite cropped anyhow as using a ZS61, so the iris it quite small through that.

However, its no good to let the data go to waste so I processed it anyway! I think I picked up a decent amount of nebulosity to say its only 33x60s worth of lights. I used 9 Dark frames, tried to use some dark frames from a different night with a similar temperature, couple of degrees difference but for some reason DSS would only register the 9 from the same night, even if I put the other 5 in a different group, Maybe someone could answer the question as to why? I also took 20 bias on the night, and added a further 20 from another night with a similar temperature (I added from the other night because in my original stack it was still quite noisey, this is why I experimented with a second stack with added extra caliberation frames, I think it helped).

Watched a nice simple but very informative guide on youtube whilst processing it with GIMP. First time I've used noise reduction and a star mask!

Shot with the usual equipment, being ZS61 EOS 800D and iOptron skyguider pro, in my bortle 5 back garden.

Couple of questions also!

1. Does DSS Reduce star trails? I noticed I had very slight trailing (Different to the ones round the edges caused by me not owning a flattener yet), once I stacked they were gone! (Need to perfect my polar alignment, I know)

2. I want to shoot something next more to suit my ZS61, rather than having to crop loads, I was thinking North American Nebula. Is this worth shooting in an unmodded DSLR?

Anyhow, heres my image.. Hammer me with plenty of constructive criticism!

Grant

[CloudMagnet]

The Iris nebula is a tough one, so I think that has turned out really well given the short integration time and also lack of real nightime we see right now.

DSS won’t reduce star trailing in your raw images, but when you stack them together the maths that goes on in the background will start to average out your stars and they can look a little more rounded than in a single image. In terms of why DSS has only stacked 9 out of the lot, this is likely down to DSS not finding enough stars to use as reference points in the image. Try turning down the star detection threshold to increase the number that it can find. I aim for at least 30-40 stars detected.

I think you will find that using the flattener will help with this as well. I doubt that DSS will find any stars near the edges of the image due to not being round, so a flat field will solve that problem in time.

[Grant93]

15 hours ago, CloudMagnet said:

In terms of why DSS has only stacked 9 out of the lot, this is likely down to DSS not finding enough stars to use as reference points in the image. Try turning down the star detection threshold to increase the number that it can find. I aim for at least 30-40 stars detected.

 

Thanks for the advice! And sorry but just to confirm - it was an extra 5 darks from a different night but a similar temperature that wouldn't stack, is this effected by the stars from the lights? (Very much a noob to this, sorry!)

[CloudMagnet]

As long as the darks are the same exposure and ISO as the lights, DSS shouldn't have any issue adding them into the stacking process-the amount of stars in the lights will have no impact on how the darks are stacked.

Before you stack there will be a confirmation box that will pop up, this will tell you exactly how many lights and darks will be stacked and will also tell you if there are any issues such as exposure times being different.