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NGC4565 - Needle Galaxy

Tim

By Tim
in Imaging - Deep Sky

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Tim

Tim

Posted
Posted

Tricky target from my obsy, by the time it gets dark, it was only an hour until meridian flip, and after the flip it's only an hour and a half until it goes behind next doors giant Leylandii.

So although I have a fair amount of data (72 x 500 seconds for LUM) it was gathered over too many nights and conditions, and processing it has been the Devil's own work, the flats were a nightmare.

This might actually be the first time I have properly attempted and finished an LRGB image I think, even though I added a bit of data from my new OSC 460ex, although that was mainly to even out the background.

If anybody knows of an easy to follow guide to getting the right ratio of exposure times for the RGB filters I would be very pleased to see it, I struggle with maths heavy tutorials though :/ Unless it would work the same as somebody elses rig with the same filters and camera?? Baader filters and 460ex?

Skywatcher Esprit 150 and Atik 460ex cameras, total integration is around 18 hours.

Thanks for looking.

Tim

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nmoushon

nmoushon

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Yes, F7, the Skywatcher flattener doesn't reduce the scope as far as I am aware.

I wasnt sure if you could get just a reducer for the triplets or not. Thought I'd ask.

Its a great amount of detail for f/7. Nice job.

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Gina

Gina

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Excellent image Tim :) AS for balancing RGB - I just play with things until I'm happy with it :D I prefer to use art rather than science for this even though my best school subjects were Maths and Physics :D

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Tim

Tim

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Thanks all :)

Gina, that's what I've always run with, or if I alter the exposure times at all then I try to get the max ADU within a similar range for each filter, but I think it becomes important when matching stars sizes with each colour.

Peter Shah very nicely explained the G2V business once at a talk during a star party, and for me Peter has the best coloured stars in the game, just haven't got my head around it yet :p

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MartinB

MartinB

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That's top notch Tim, the Esprit has certainly delivered excellent resolution and contrast. It's right up with the best I've seen of this galaxy at this focal length.

As for colour, perhaps G2V is worth it but it's a bit of a faff and still isn't 100% reliable (varies with dec). some of the ugliest colour renditions I've seem have been accompanied with "colour G2V calibrated". I don't think Peter's beautiful images are down to G2V but the fact that he uses it indicates his colour work ethic! I think it makes sense. With my old astronomic filters I worked out the degree of stretching required for the different channels to give a colour that looked right to my eye and worked back from that to choose the ratios that I was happy with. Need to do it again now with my Baader filters. It's better than just doing 1:1:1

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ollypenrice

ollypenrice

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Stunning, Tim. Blisteringly sharp for the aperture. Well, blisteringly sharp, full stop. I think you have the colour right (unlike me in my effort which I'm still thinking about.)

Is your red channel perfectly aligned? I wonder if there isn't a slight offset up a bit? (I sometimes get this and Yves had the good idea of aligning red and blue onto green. Green lies in the mid spectrum so this seems reasonable and also seems to work well.)

I'm impressed by this Esprit.

Olly

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Tim

Tim

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I only know how to combine the colours in Registar Olly, and for some reason it threw a bit of a wobbly on this one, Most times the alignment is very good, but it is rarely perfect across the image for some reason.

One of these days I'll learn how to do it properly!

I have just had the Esprit os Saturn with a brand new Powermate 2x (my first decent barlow) and a Hyperion eyepiece, and I am still shaking from the view! I actually laughed out loud when I saw how sharp things can be with decent optics!!

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Naemeth

Naemeth

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It looks great Tim, the stars colours are great and the background colour is nice too.

Seems slightly less sharp in full res than in the preview image, but only seems a tiny bit off (to my inexperienced eye anyway).

HTH :)

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