First picture in ages

[roundycat]

or to give it another title, NA Nebula in narrowband, Part 1. The S2 and O3 are to follow. Whether it will be this year or not is in the lap of the Gods.

This was two nights, 12 days apart, for a miserly total of 60m of Ha.

FSQ 106ED, STL 11,000M and Astronomik NB filters. Guided by Atik16IC on my TMB 152. A bit overkill for guiding but what the heck.

12 five minute subs, dark subtracted and flat fielded. MaxIm dithered the subs and pre-processed. Usual PS after treatment with the history palette shown for interest. A very quick and dirty process.

Dennis

[Space Cadet USA]

Awesome picture! Colour will be nice but it looks stunning in mono IMHO.

[roundycat]

many thanks. The original is actually a lot better, I just used a screen grab here.

Dennis

[RobH]

Looking good Dennis, especially for just a screen grab.

Good luck with the OIII and S2

Rob

[ollypenrice]

Looking seriously solid, Dennis...

Olly

[step_hen]

looks great, i love this area. thats some guiding rig! what causes the halo on the brightest star to the left of the frame -sorry i have no experience of Ha processing!

Stephen

[darkside]

stunning image.... i wonder if the fov will be about the same as my new 200mm canon lens ? want to image this area

[roundycat]

Stephen, the halo is down to reflections off something in the optical train. Popular theory has it that Astronomik filters are not that good in this respect although this is one of the latest production. I really need to try it in front of my other camera as some believe the chip cover glass in the STL is the culprit. It is eccentric because is off-centre. Proper processing in Photoshop will see them gone!

Darkside, the field of view is down to a 35mm chip and a 530mm scope. To get the same field from 200mm you will need a 15x10mm chip. Exactly the size of the ST10!!

Dennis

[Tim]

Very promising Dennis, you must be pleased to have had some camera time!

[Tim]

As it goes I have just bought a 6nm Ha from Astronomik, I will do a side by side with the Baader 7nm at some point. Are certain stars more prone to producing haloes do you think? Alnitak is a prime culprit, but a bit late for that.

[roundycat]

Hi Tim, for my money the worst stars for halos must be those that emit light in that passband. Problem is, that doesn't explain why a lot of the bright blue stars around Orion cause big halos regardless of the colour of the filter. Of course, if you stretch the dimmer stars they have halos as well.

Below is the NA nebula area but not as a screen grab, it looks a bit better.

Dennis

[Tom How]

That is a lovely dataset Dennis. I see lots Ha images, and most of the ones with halos around stars have the word Astronomik in them somewhere.

I've used Astrodon filters for years and never seen a halo.

You pays your money and takes your choice. Although the Astrodon filters are expensive, he seems the only filter supplier who will publish* the detailed specs about his filters required to make an informed buying decision - as such is the only supplier of filters I actually trust.

* To qualify this: I haven't actually researched this for a while, but last time I asked one of the other filter supplies about the level of Out of Band blocking on their filters I got a very rude response.