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The Crescent nebula and a cry for a mono CCD


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Hello again fellow imagers.

I really struggle with this one. My OSC just won't catch enough Ha. At least that's my theory... always blame the equipment!tongue.png

I spent 5 hours on this, but it doesn't show. I hope my theory is right about the camera and I'm browsing around for a suitable mono candidate for the winter season.

This was taken with the 8"RC at a dreadful f8 on the iEQ45 last September. I hope to return to this thread with a mono comparison one day.

Thanks for looking,

/Jesper

gallery_16323_1516_374614.png

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Hello again fellow imagers.

I really struggle with this one. My OSC just won't catch enough Ha. At least that's my theory... always blame the equipment!tongue.png

I spent 5 hours on this, but it doesn't show. I hope my theory is right about the camera and I'm browsing around for a suitable mono candidate for the winter season.

This was taken with the 8"RC at a dreadful f8 on the iEQ45 last September. I hope to return to this thread with a mono comparison one day.

Thanks for looking,

/Jesper

gallery_16323_1516_374614.png

Hi Jesper,

I have done both, but I have to say that I am very new to all this, the colour one was done by an Atik 428 EX osc, with a very dirty glass or filter, the mono is a broadband Ha with an Atik 16IC , this is the best processing that I am capable of at the moment. Thanks again for cleaning up my M27 the other day BTW.

Regards,

A.G

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post-28808-0-01539400-1374175866_thumb.j

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I like it Jesper. As you say, at F8 the RC8 is too slow so you don't have enough data IMO. Why don't you use a CCDT67 to get it down to F5 or so? Much better - works great on my RC8. Yet to try it with the Atik yet but was fab with DSLR. :)

Steve

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Why don't you use a CCDT67 to get it down to F5 or so?

I do have one, but found that it was introducing some reflections. (I am 3' away from the white wall of an apartment block, so lots of light bouncing off the wall). I never got my RC spot on in collimation either, and the reducer made that even more obvious.

I have a brand new Howie Glatter laser sat in the cupboard. I thought I'd follow your videos on how to use one, but it turned out the holographic attachment was the on with a square pattern, so got stuck there. I haven't managed to source the one with circles. (FLO out of stock for instance).

But yeah, it sure did expose faster. A Moonlite focuser is attached too now. I hope for an RC comeback soon :smiley: . A galaxy hunter :p. Just need that Atik...

Good work there lensman57! Impressive - both verions.

/Jesper

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I do have one, but found that it was introducing some reflections. (I am 3' away from the white wall of an apartment block, so lots of light bouncing off the wall). I never got my RC spot on in collimation either, and the reducer made that even more obvious.

I have a brand new Howie Glatter laser sat in the cupboard. I thought I'd follow your videos on how to use one, but it turned out the holographic attachment was the on with a square pattern, so got stuck there. I haven't managed to source the one with circles. (FLO out of stock for instance).

But yeah, it sure did expose faster. A Moonlite focuser is attached too now. I hope for an RC comeback soon :smiley: . A galaxy hunter :p. Just need that Atik...

Good work there lensman57! Impressive - both verions.

/Jesper

You are very kind sir, I guess its beginners luck. I have had a lot of support and guidance from the good people of the forum, loads to learn yet.

Thanks and Regards,

A.G

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Hey Jesper, this just doesn't scan for me.

We all know you're good at this, so I can't make sense of this image. You say you've got 5 hours of data, but even at f8, you should get better than this.

My image below is 5 five min DSLR subs at F7 (at iso 1600). I know it's not brilliantly processed - I'm still learning loads now, and this was shot a while ago.

But I would hope a dedicated astro ccd, even osc, should beat this easily.

crescent5by5at1600-2.jpg

Jack

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Jesper, your theory is corect. You need a mono camera. (You can afford it :evil: :grin: )

This is a classic Ha OIII RGB object. Yes, you can shoot narrowband with a colour camera just as you can push a peanut with your nose to the top of Pike's Peak. http://www.justtrails.com/great-adventures/pikes-peak-peanut-pusher/#.UemWaY2eN8E

But do you want to?

This is a reasonable LRGB object and you have it. Nothing wrong with that. Add Ha and it is fantastic. Add OIII and... words fail. Incredible!! One of the most thrilling objects I've ever imaged.

Olly 'spend your money' Penrice...

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Thanks for you input all.

I don't want to put a Ha filter on the OSC because that would have to be a two inch, and I need to be easy on the wallet... Heck a set of NB filters for that lovely Hubble palette is 1500 euros! For the 1.25 inch ones! (Astrodon - I'm thinking that good quality 3nm is the way forward from here, and in the smaller version along with a 460/490 type CCD).

I guess I could mask off an area the shape of the Crescent as we know it and stretch it through the roof in red, and it should look like a lot of Ha in there... But given my location, I want to do 'honest' edits, keep some noise etc since it really is there - in the sky. I can't chase after the big boys here, but find my own style. And this has changed considerably, by learning stuff from SGL mainly.

Please just note, Lewis and Jack, that I'm not suggesting that is what you have done. You have good data there - really good and sure prove that looking at my equipment list it should be within reach. I just didn't manage this time. The data has been forgotten for close to a year, but now I was at a stage where I could at least do what I did in pulling out the elusive nebula. All previous edits were laughable to say the least.

But I must add that someone better at procesing could pull out more from my stack. I've had it demonstrated many times by members here who help me with various images. So there may well be more in there - but as Olly kindly put it, why do it the hard way? Money, yes, but I won't get those five hours back, and I don't want to waste valuable imaging time either...

Below is a PI STF autostretch of my 5 hour stack. Normally that function gives a very good hint of what is buried in the data. And I got the usual smog...

Thanks for looking and I'm impressed by what you guys demonstrated is possible! Big bow!

/Jesper

post-16323-0-79169300-1374275194_thumb.j

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Thanks for you input all.

I don't want to put a Ha filter on the OSC because that would have to be a two inch, and I need to be easy on the wallet... Heck a set of NB filters for that lovely Hubble palette is 1500 euros! For the 1.25 inch ones! (Astrodon - I'm thinking that good quality 3nm is the way forward from here, and in the smaller version along with a 460/490 type CCD).

I guess I could mask off an area the shape of the Crescent as we know it and stretch it through the roof in red, and it should look like a lot of Ha in there... But given my location, I want to do 'honest' edits, keep some noise etc since it really is there - in the sky. I can't chase after the big boys here, but find my own style. And this has changed considerably, by learning stuff from SGL mainly.

Please just note, Lewis and Jack, that I'm not suggesting that is what you have done. You have good data there - really good and sure prove that looking at my equipment list it should be within reach. I just didn't manage this time. The data has been forgotten for close to a year, but now I was at a stage where I could at least do what I did in pulling out the elusive nebula. All previous edits were laughable to say the least.

But I must add that someone better at procesing could pull out more from my stack. I've had it demonstrated many times by members here who help me with various images. So there may well be more in there - but as Olly kindly put it, why do it the hard way? Money, yes, but I won't get those five hours back, and I don't want to waste valuable imaging time either...

Below is a PI STF autostretch of my 5 hour stack. Normally that function gives a very good hint of what is buried in the data. And I got the usual smog...

Thanks for looking and I'm impressed by what you guys demonstrated is possible! Big bow!

/Jesper

post-16323-0-79169300-1374275194_thumb.j

Hi Jesper,

It looks like that you have talked yourself into purchasing an Atik Mono Camera, the 383 also appears to be great value for the money particularly as it can be cooled to about - 40c.

Regards,

A.G

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I don't agree that you have short data for the time. You have not stretched it above the noise limit but taken it to a point where it is still close to perfect. Very impressive is the split between the two central stars and their clear colour distinction. This is not seen in all Crescents by any means.

There is a demon trick for stretching the red without stretching it! In Ps go into Image-Adjustments-Selective Colour and it will open by default onto the reds. Take the top sider and move it to the left. You may get a pleasant surprize!

Olly

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That was a clever trick Olly! It sure lifted the reds across the board with no immediate ill effects. I won't repost here though, as I think the thread run its course.

Let's put it this way: A mono with a good 3nm Ha filter sure can't hurt to add to the original field :p .

It will be an Atik 460. I know I've been banging on about the 490 - and I still think it may be better in terms of sampling for short FL scopes, but the 460 has got a strong foothold, and I reason that it will therefor likely keep its value better. The 383 is a bargain, but the chip is an ageing one, and its only true merit these days is the chip size. So I gather there will be something new coming up to fill that segment in the market, eating into the value of a 383. (This is not to say that it can't deliver - I've been blown away many, many times by KAF8300 work of members here).

It may sound as if I'm picky and particular, but I'm just trying to be wise - for once. The idea is to use the reduced RC with the OSC for colour. The 460 can pick up the Ha. The FOV and sampling will be nearly identical - provided it's bolted to a Veloce200 :evil: . A most dynamic duo perhaps.

/Jesper

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  • 4 weeks later...

Hi again, not a bump as such - I have new data :smiley: .

I aimed the SW120 at this and captured 2 hours and 20 minutes of it. It seems to have gone a little bit deeper than the RC managed. This may well be down to seeing/visibility.

I think this one will serve as RGB backdrop one day for a Ha layer.

Thanks for looking

/Jesper

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Full resolution crop:

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Great images Jesper.

The Crescent has also been my target of choice lately. This was my effort with my 8" RC + CCDT67 + the much maligned QHY8 (52*5 minutes):

post-5202-0-92890500-1376677407_thumb.jp

I've also been putting together a mono rig. To keep costs down, I've been buying everything secondhand and got an SXV-H9, manual filter wheel, LRGB filters and a set of Baader NB filters at a reasonable cost. So far I've stuck the mono gear onto my 70mm refractor and here's my first and only Ha image. It was very rushed, only 4*5 minutes subs and the focussing was terrible but I am encouraged by the potential.

post-5202-0-63698500-1376677685_thumb.jp

Interested to hear what you said about reflections with the CCDT67 - I think I was getting them the other night when I started to image the Iris Nebula but I got clouded out almost immediately so couldn't investigate further.

I'm also tempted by the Glatter collimator and a MoonLite focuser so will be interested to know how you get on with them. They might have to wait until next year, I've spent enough already in 2013.

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Nice work Mike! Your RC looks dead straight.

The reducer is used by many, with superb results, but I have so much light coming from all sorts of angles here in the city, so that's why I struggle.

There's just one problem with the RC. I've been delighted by the golden SW refractor, and have actually developed refractoritis...

I have been toying with many scope ideas, but research and gentle hints from members here have made me realize I stare too much at the fact sheets. The reality can differ...

The Moonlite seems very solid and reliable - once straight it will probably not be a source of problems. Having said that I wish I got a Feathertouch instead...

/Jesper

PS, it's darker now - eyes sharper, so looking at my edit above I see how crude it is haha!

Edited by Jessun
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The Moonlite seems very solid and reliable - once straight it will probably not be a source of problems. Having said that I wish I got a Feathertouch instead...

Really? Why do you say that?

I do like the look of the Moonlite large format focusers because of the ability to have the whole image train screwed together via their 68mm threaded system. I find the compression connection on the standard GSO focuser to be a bit hit and miss in terms of getting things square and would love a focuser where I would be able to avoid that kind of connection completely. Also the Moonlite has the facility to accept the CCDT67 within the body of the focuser - it all sounds ideal, so would be interested to hear how the Feathertouch could be better.

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Just BMW over Mercedes, or vice versa really.

I had the opportunity to examine the complete product lineups from Moonlite and Feathertouch at NEAF this spring (after my purchase), and just thought the Feathertouch was one up in terms of build and operation.

Nothing to base your decision on tho.

/Jesper

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  • 2 months later...

Interested to hear what you said about reflections with the CCDT67 - I think I was getting them the other night when I started to image the Iris Nebula but I got clouded out almost immediately so couldn't investigate further.

A late addendum to this discussion.  With tonight being the first decent clear night in the last couple of weeks and it falling on the full moon, I decided to see if I could pin down the reflection issues that I had been seeing with my 8"RC + CCDT67.  And as suggested by Philming in his post a while back, the problem was due to the primary baffle tube not being long enough.

I took a few test shots, firstly with the scope as normal, then after that I placed a small piece of rolled up cardboard into the baffle to lengthen it a bit.  The results are below in a couple of rough raw screen grabs.  In the 'before' shot hopefully you can just make out a couple of reflections on the right hand side.  On the 'after' shot they have gone.  Just have to decide now on engineering a more permanent solution.

post-5202-0-77878900-1382046651_thumb.jp

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