Rosette nebula (well, bottom half)

[Carole]

Done the same night as my HH nebula so also a first light.

Only managed 8 x 600secs
Atik314L+ and H alpha filter
SW ED80 on NEQ^ and guided

[MarkS]

It looks a bit noisier than I would have expected.  What level of cooling did you set?

[Carole]

Hi Mark, I set -15 degrees but it only went down to something like -13.8.

I didn't do any darks as they say you don't really need them with this camera.  When I get time I will do some darks and compare.

Also I didn't subtract any bias as although I took some they produced horrible streaks accross the image.  There was talk at SGL7 about DSS not applying Bias properly by Steppenwolf who gave the imaging talk.  

Also on reflection, I think the skies were very murky and it was getting low, I guess I just wanted to get my first CCD image to make sure I had everything working correctly. 

Carole

[RobertM]

Hi Carole,

The Rosette is quite a bit higher in the sky than the HH so I'm also surprised by the noise.  See my HH comments about filter bandpass and haze.  It's about what I'd expect from a 12nm filter from where I am (which is ever so slightly less light polluted).

Robert

[Carole]

Hi Robert, I never started the Rosette though until HH had dropped too low to do, so it was also pretty low by the time I started.  

Guess I wasn't really aiming for great images on this occasion, just a test really to see if I had got everything working OK and to see how it would all come out.

will look at the HH comments.

Carole

[Carole]

Done a bit more processing to reduce the noise:

[MarkS]

Noise reduction tends to be very subjective.  For this image I prefer the original.  My brain prefers to see noise rather than the "blotchiness" left after noise reduction.

But it's all a questionof personal taste.

[JohnP]

Yep with Mark on this - much prefer original - better details & stars look marginally tighter to me.. Carole I think under conditions & given lateness in season for imaging this you did great - Just look forward to giving it a proper go later on this year....

[Rocket Pooch]

On the second one I think you have managed to remove some stars as well as some noise...

1st is better.

I'd be temped to process it again, with no dards, flats or anything Sigma stack it and see what its like, when I have one of those cameras it was super easy to process images.

Chris

[Carole]

Yes, I am sure you are all right.  I kust say I wasn't really sure about the latest version.

As you say not good conditions and my lack of experience.  I don't think I'll bother to do any more with this one, it was only taken as a try out anyway just to see how it all worked.

I'm really pretty ignorant of filters and what objects are suitable with what so it's going to be another big learning curve for me.

Found out today my 7nm ha filter is not going to be compatible with Sii and 0iii so that's another thing I didn't know.

Lots to learn, but will get there slowly.

Have got myself a 2nd hand filterwheel but need adapters before I can use it, and also want to get a focal reducer, but all takes time and money.

Thanks for your input.

Carole

[RobertM]

Found out today my 7nm ha filter is not going to be compatible with Sii and 0iii so that's another thing I didn't know.

What do you mean exactly by 'not going to be compatible' ?

[Carole]

I was told that Sii and Oiii filters are 12nm and that the Ha filter needs to be the same or the stars will be different sizes and look weird.

Carole

[RobertM]

I can't believe someone would sell you an Ha filter and not take into account that you'd probably want to buy the rest of the set.

What make of ha filter did you buy ? 

[Carole]

Baader Robert.

Carole

[MarkS]

I was told that Sii and Oiii filters are 12nm and that the Ha filter needs to be the same or the stars will be different sizes and look weird.

Interesting.  So a 7nm Ha filter together with 12nm Sii and Oiii will potentially lead to problems around stars?  A kind of chromatic "rings" problem I suppose.  Is it really that much of an issue (I'm asking out of ignorance)?  Are there any examples of this problem?  I'm interested to see one.

Mark

[RobertM]

If they are baader filters then there are OIII and SII (and Hb) to match.  They are not exactly the same band pass but are part of the same set and can be used together.  I have the Baader filters and don't have any problems.  They are part of this set : http://www.teleskop-express.de/shop/product_info.php/language/en/info/p502_Schmalband-Filterset-2----H-Alpha-7nm--H-Beta--O-III--S-II.html.

It doesn't look like someone sold you a lemon, rather that you were misinformed about filter compatibility.

Robert

[Carole]

Thanks Robert, those were 2" filters on the link, but I have found some Oiii and Sii Baader filters at 8.5 nm so hopefully they will be close enough.  Thanks, that has put my mind at rest.

Carole

[Fay]

i also have never heard of that problem