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WIP: The Flaming Star Nebula

Deneb

By Deneb
in Imaging - Deep Sky

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Deneb

Deneb

Posted
Posted

Hi

I really can't make up which out of these two images are better, maybe you can decide for me...:)

Taken last night using a Altair Astro 115EDT Triplet @ f/7 & Atik 314L+ camera @ -23.3c

13x 10mins Ha, 8x Darks & 44x Flats. Processed in DSS & Paintshop Pro.

IC405.jpg

Version 2

IC405v2.jpg

Cheers

Nadeem.

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Deneb

Deneb

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I really don't know, my closest explanation might be some reflections from the clips, but thats just a guess. I was thinking maybe the mist from last night might be causing the issue, with some sort of reflection...

Nadeem.

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steppenwolf

steppenwolf

Posted
Posted

The third one is the best IMHO as the contrast was too low in the first and second images. I too do have to ask about the star shapes though, my first thought was that these must be diffraction artefacts from the iris leaves of a camera lens but I note that this was taken with the Altair Refractor. It could be atmospheric in nature but I'm not convinced by that but do acknowledge that the NGC891 image doesn't show them.

Was one night colder than the other? I am thinking pinched optics with temperature change perhaps?

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Deneb

Deneb

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Thank you for your comments Steve, last nights temperature was much colder then the previous few nights, with lots of Mist & fogging over at times. Even though the scope has a long dew shield I did not use a dew strip behind the lens last night, even though conditions were dictating I should have used one.

However I am waiting a reply from Nick from the email I sent him this afternoon & see what his response would be.

Hind sight tells me I should have used a dew strip last night, then the image would have been perfect..

Nadeem.

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ollypenrice

ollypenrice

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They do look just like the diffraction effects created by camera diaphragms - and these can be avoided by using a front aperture mask. But since they are not there all the time it can't be to with the scope or lens cell clips (which is what I would instantly suspect) and must come from eleswhere. (Maybe just check that the lens cell clips haven't become displaced. Unlikely.)

Something creating an irregular border in the imagning train? Icing aroud the edge of the chip window? Maybe even fogging around the edge of the chip window but that would be softer in its effect, I'd have thought.

Or, could it be a glitch with the mechanical shutter? I have no experience with these. Suppose it hesitated in closing or opening, might it create an effect like this? I really don't know.

Olly

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philj

philj

Posted
Posted

The last one is the nicest, more contrast. I like this nebula, plenty going on in there.

As for the star shapes they are very reminiscent of the temperature related spikes I used to get with my Orion USA 102ED doublet. When cold I used to get unusual diffraction spikes.

The side alignment screws on the objective elements would put a little pinch onto the optics in certain conditions giving a similar spike effect. Could this be the case here I wonder?

I'll try and dig an image out with the effect for comparison.

Philj

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Deneb

Deneb

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Thanks for the input Olly, it was very nice of Nick from AA to phone me last night & speak to me personally about the issue. Visually the clips look to be in the same position they were when I bought the scope. Looks like a dewstrip is in order behind the lens.

Nadeem

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Coco

Coco

Posted
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Thanks for the input Olly, it was very nice of Nick from AA to phone me last night & speak to me personally about the issue. Visually the clips look to be in the same position they were when I bought the scope. Looks like a dewstrip is in order behind the lens.

Nadeem

You actually mean you never used a dew tape? :)

Cant believe you didn't use a dew strap on a cold night .. Thought you was an expert .. innit

Pull ya self together lad.. :):evil6::):evil6:

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RobH

RobH

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The lower one's the best Nadeem, much better contrast.

Whatever is causing the odd star shapes, it isn't dew. That will just decrease your brightness overall and make your S/N ratio worse. If the dew is only on the edge of the lens, it'll soften your image a bit.

Looks a bit like lens pinching to me.

Cheers

Rob

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Tim

Tim

Posted
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Hi Nadeem,

If you can, try for longer subs than 10 mins for Ha, 20 mins or even 30 if you can. The reason being, you get much greater detail and contrast in the darker areas of the nebulosity.

Also, if you get time, check out some layer masking tutorials to slightly sharpen just the brighter edges of the nebula.

At any rate, nice one :icon_confused:

Tim

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