Starwiz

59 minutes ago, alan potts said:

That's come out very nice, feel I may invest in one of the duel filters for OSC to help improve my NB content on my captures. Be a few day before I can use the scope after I have just had an operation, still getting better every day.

Alan

Thanks Alan, and best wishes for your recovery.

John

The Bubble Nebula.  Imaged in narrowband from Mellieha, Malta.

This is the first time I've used a processing technique to correct poor star shapes caused by coma.

John

 

2 hours ago, ollypenrice said:

No brainer. Go for a mono camera and narrowband imaging. Either buy second hand or wait till the CMOS camera does fall within budget.

Olly

I'll second Olly's suggestion.  You're in a Bortle 8, so Narrowband would make a massive difference, but you'd need to get to like nebulae more than galaxies.

Otherwise, a good light pollution filter and modified DSLR will take you a step further.

John

6 hours ago, carastro said:

You would not get a dedicated camera except for maybe a cheap 2nd hand planetary camera for under 130$ anyway.

+1 for the webcam or planetary camera.  I've seen the ASI120mc advertised at $149 which is close to your budget.  This would get you started with planetary imaging which is a lot more affordable than deep sky stuff.

John

2 hours ago, dph1nm said:

The Skywatcher Aplanatic corrector is very good in my f4 Quattro (for which they are designed). Not sure how well they work at f5?

NigelM

Thanks Nigel.

John

2 hours ago, tooth_dr said:

That’s very nice. Good job. 

Thanks.

1 hour ago, alacant said:

Hi

How about correcting the coma in software? Anything which allows you to make masks will do and most astro processing software will have their own one-click version. That way, you avoid having to pass the light through glass, which always seems to introduce more aberrations.

Cheers and HTH

 

Thanks.  I'll research that too.

John

49 minutes ago, carastro said:

Yes there is virtually nothing in Oiii in this target. 

 

I took some OIII, which I processed and although it looked fairly blank, I stretched it and added it as a layer anyway, which I think helped offset some of the stronger Ha/SII data.

John

42 minutes ago, carastro said:

Yes there is virtually nothing in Oiii in this target.  I stacked HSS when i did it.

You have some nice shades and colour variations.

Carole 

 

Thanks Carole. 

I played around with the data for hours before it started to look anything decent.  I found I had a problem with the Darks I was using, which I think was due to stray light getting in somewhere.  After I re-did these it started to look a lot better.

It's also the first time I've used Straton for removing the stars and creating an RGB stars layer.  It worked very well and saved me hours of work.

John

51 minutes ago, apophisOAS said:

love the colours and hues , well done,

Roger

Thanks Roger.

John

18 hours ago, Ships and Stars said:

I wanted the Paracorr, but due to price and inability to find one second-hand, I ended up going with a second-hand Explore Scientific HR coma corrector in as-new condition for around £175 I think.  It is adjustable or 'tuneable' like the Paracorr, so no need to buy additional spacers etc like some of the others require. I've only used it a few times, but on a 100deg Ethos eyepiece at f3.95 in a big dob it does the trick nicely. It adds 1.15x mag I believe. I've also used it as a spacer to obtain the right focus with other EPs I have that are either too far out with the normal 2" spacer and too close without. I think the Baader line is a fair bit cheaper but seem to recall they require additional spacers. I'm not any more familiar with the Baader line than that, am sure others who do AP (I'm visual only) will chime in here soon.

15 hours ago, alan potts said:

I bought mine about 3 years ago and I don't believe I have ever seen a secondhand one. I personally believe TeleVue are as good as any on the market for all their product and in many cases better. This better though is only very subtle in the case of many eyepieces I have tested and written about on here., I feel the same will be true of the Paracorr.  EXSc is very good gear too and even some SW stuff is not far behind for much less, I am sure given a bit of time many others will chip in with what they have for much less than the price on the TV.

Alan

Thanks both.  Some useful info to consider there.  Time for me to start doing some research for when my wife asks what I want for Xmas.  😉

John

Greetings from rainy Malta.

John

12 minutes ago, alan potts said:

It certainly looks exactly like the coma I can get with my 18 inch F4.3 Dob, I got a Paracorr by TeleVue which has a slight magnification factor, x.15 if I recall correct. There is no doubt it is an excellent piece of equipment but with a sizeable price tag. There are others available I am sure but as to how good they are that another matter. I went with the TeleVue because all my eyepieces are, they say it works perfectly for AP, which I am sure it does.

Alan

Thanks Alan.  That looks a great bit of kit, but I may have to do some saving.

John

In the never-ending quest to improve the quality of my images (which is strongly correlated to the reduction of money in my bank account), I want to improve the star shapes that I get at the edges of my frames.  I think this is coma.

The image shows a zoomed-in portion at the top left-hand corner of my latest image.  I get similar in all four corners with the stars trailing towards the corners.

So, do I need a coma-corrector, or is there another way?

I'm using a SW200p (F5) and ASI1600mm-Pro with filter wheel.

Thanks

John

4 hours ago, kirkster501 said:

Nice result!

Thanks.

3 hours ago, alan potts said:

Very nice image, I tried this last year and like you only got part of it, well i think I did, comes out rather more red with DSLR.

Alan

Thanks.  I was a little undecided on whether to go with the red look as I got nothing in OIII.  In the end I had another play with the data and settled on Hubble Pallet, using the OIII stack that I had, which actually contained nothing. 😀

John

Imaged in Narrow Band from Mellieha over the weekend.

John

On 29/09/2019 at 15:41, happy-kat said:

I look at the peak score then how the scores spread in the stack and ditch the lights that are obviously below the bulk range. For me the ones that score low on inspection are cloud or star trail effected to a point I consider detrimental. I'd have to load a stack to see what the score was but it's likely around 600 and lower, though I use the FWHM as well.

Thanks.  Sounds a bit more scientific than what I'm doing which is probably gut feel at the moment.

On 28/09/2019 at 10:22, alan potts said:

with the Canon it would have been easy to see after the first image

If you are using APT, you can use the Histograms tool to auto-stretch the image.  With it enabled, all the images will auto-stretch.  It does nothing to the data, just the view.

For example, here's a 'before' and 'after' auto-stretch of the California nebula Ha (single frame).

John

I've been using a score of 300 as the minimum quality for including an image in the stack.  There's no scientific basis other than it just 'feels right' for me.

I'd be interested to hear what other people use and reasons (if any) for choosing a minimum score.

Thanks

John

3 hours ago, tooth_dr said:

Thanks John

This is the first time I removed the stars from the images Ha Sii and Oiii. I then combined them as usual and finally added in the stars at the end again.  Otherwise I get magenta stars too. I bought Straton this time instead of doing it manually and it made all the different. I tried Starnet++ but I couldn’t get it to open up. At £14odd it’s not expensive.

Hope that helps

Adam. 

I've just bought Straton. 

A fantastic piece of software that'll pay for itself on the first image I process.

John

3 hours ago, tooth_dr said:

Thanks John

This is the first time I removed the stars from the images Ha Sii and Oiii. I then combined them as usual and finally added in the stars at the end again.  Otherwise I get magenta stars too. I bought Straton this time instead of doing it manually and it made all the different. I tried Starnet++ but I couldn’t get it to open up. At £14odd it’s not expensive.

Hope that helps

Adam. 

Thanks Adam,

I'll look up Straton.  It takes me hours to remove stars manually and I'm not usually happy with the results.

John

Lovely images!

What do you do to control the stars when processing?  Mine turn out a horrible magenta for the Hubble Palette unless I spend a lot of time trying to remove them.

John

1 hour ago, red dwalf said:

wow i wish i could get that amount of detail in 2 hours, excellent

Thank you.

A quick image from a couple of nights ago.

Two hours of LRGB data with the ASI1600mm-Pro.

L = 120 x 15s Bin 1x1 Gain 139

RGB = 60 x 30s Bin 2x2 Gain 139 (each filter).

John