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M51 - sort of


rocketandroll
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Ok, so, having failed to even find it on my first attempt a couple of weeks back, then having got 40mins of out of focus data on Thursday night... Friday I finally got about 80 minutes of good data on M51 at Kelling.

This hasn't been played with much other than lightened and tweaked in curves to try and bring some feinter bits out.

It's not very impressive... but given it's the first thing I've imaged other than M42, and was done in howling 20mph+ wind which made all the other 'hardcore' imagers give up and go to bed :-) I am happy I've got something recognisable at least!

Open to help and advice on processing to try and get something out of it, can send the original tiff stack if someone wants a play.

This was imaged on the Meade 127mm on the HEQ5-pro with my 350D, no guiding, about 1hr 7mins total in this stack, done in 40sec subs at ISO 1600 with darks and flats applied.

Cheers!

Ben

post-23494-133877556179_thumb.jpg

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You should be very proud of this image Ben!

You have done very well, 40s subs are short to show much of the whispy stuff but you certainly have some! :)

My only sudgestion to processing is to have a play with the individual colours in 'curves' streaching each out and giving control over colour balance.

Good on you for sticking it out despite conditions as it has paid off! B)

Keep up the good work!

Michael

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That's a good capture,the galaxy shows quite a lot of fine detail when enlarged so here's my edit with enhanced colours and sharpened up a tad.

There are four vertical lines running top to bottom of the image,two on the left,one right through the centre of M51 and one on the right, don't know what they are but assumed they were not wanted.:)

post-13495-13387755643_thumb.jpg

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Cheers all for the kind words!

Cloudwatcher... I'd love to know how you got that out of my diabolicle image??!!!

I have now re-checked the subs (all 140+ of them!) and removed five that had satelite trails through them (the lines you noticed) and have stacked it again with some different settings and got a LOT more data out of it.

CW... can I either ask what you did or ask if I can send you the new stacked TIFF file and see if you can get something useable out of it... I have to admit I can't believe that image you've put above is really mine and isn't just one you've taken yourself :-)

Thanks for the help folks!

The enclosed is the new stack, cropped and with just a little tweaking, there's way more data in there than in the original.

Ben

post-23494-13387755651_thumb.jpg

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CW... I have to admit I can't believe that image you've put above is really mine and isn't just one you've taken yourself :-)

Ben

[ATTACH]55165[/ATTACH]

Hehe.....No chance,can't remember the last time I did any imaging....... prefer to let others do the hard work,I just play with their results. :rolleyes:

Talking of which,I had a go at your cropped version.... to be honest I think I like the widefield better....may've over saturated this one and sharpening needed? :icon_eek:

post-13495-13387755686_thumb.jpg

Edited by Cloudwatcher
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Wow, this processing malarky really is a dark art. Wish I could get colours looking that natural (I have to use a CLS filter).

And less of the 'sort of'... looks like M51 to me :icon_eek: Great image despite the adverse conditions

Matt

Edited by Vega
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Ben, that puts my effort to shame - (I'm too embarrassed to put up my attempt to image M51 taken from SGL6 )

Seems these Canon 350d's are real performers

Hey Malc...

It's not great :-) I'm quite shocked at what Cloudwatcher has managed to pull out of it :-)

There's quite a lot of data stacked there... in total I think I was imaging for a little over two hours, getting about 150 40sec subs at ISO 1600 in total, plus about 30 darks (not enough).

I didn't finish until 1:45am by which time I was knackered and freezing cold!!!!!

I'm just glad it was vaguely in focus, the night before I had tried doing a 2hr run on it but the haze moved in after I'd only captured about 35mins of data.... and the next morning I stacked it and found it was slightly out of focus!!!!! THAT was annoying!

I've had no complaints about the 350D so far, especially having got it pre-modded second hand at a great price.

The only issue is focusing the thing with no live-view. I have it down to about a 20min procedure now to get it in focus by just taking lots of short subs and tweaking it a little between each sub to home in on the focus point. M51 has a useful close double star near it which I was using to check the focus... once that was resolved as two stars, I started imaging.

Must get sorted with a laptop and some focusing software, I think it'd save time in the long run and I may as well use that for guiding too if I'm going that route... I've been talked out of the 'laptop-free' setup route I was trying to go down :-)

Aiming to have guiding set up and all this sorted for September when I'll be back at Kelling to try and capture a lot more :-)

Ben

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.

The only issue is focusing the thing with no live-view. I have it down to about a 20min procedure now to get it in focus by just taking lots of short subs and tweaking it a little between each sub to home in on the focus point. M51 has a useful close double star near it which I was using to check the focus... once that was resolved as two stars, I started imaging.

Ben

Thanks for the heads up on the lack of live view - I was hoping to get a camera with this, although I read that the downside is amp glow !

Also thanks for the focusing tip. The problem I had was that I would find the object and then remove the eyepiece and bolt on the camera which then needed focusing again, and given I need glasses... well you can guess the rest !

OK here's my effort - around six images stacked (iso 1250) and then curves pushed to the limits to bring out some structure - image then resized to fit screen !

Whirlpool.png

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Hey Malc... that's not bad at all, it's recognisable as M51, well framed and in focus... just needs more data, simple as that. It's better than the first one I did on Thursday night :-)

And yeah, the focus thing is a mare... doesn't seem to be any 'easy' answer to it... I got the go-to working fairly well so told it to go to M51 and looked with the 27mm ep in there and there it was, not dead centre, but in the fov. I tweaked it to get it central, then swapped for the camera, then got the focus as close as I could by eye, before going over to the laborious 'take a shot, see if it's in focus, tweak it, take another shot, etc etc' process mentioned before. The night before I'd really cocked it up, slewed it away from M51 to find a star to focus on, then couldn't get it back in frame again afterwards so had to swap for the EP and then start the whole focus thing again.

Phil... yeah, I'm pleased there's something there... I was quite proud of the fact I carried on battling on despite the wind when all the other imagers who were guiding had given up... everyone said "Don't get a scope bigger than 80mm unless you're guiding, it'll be a 'mare!"... it's not as easy, but I've done ok so far I think. I feel part of the fun is trying to do something that other people have told you shouldn't work ;-)

I will be guiding later this year though... just trying to work out what kit to use specifically at the moment before committing to any more money :-)

Is it sacreligious to use my 80ED DS Pro as a guide scope? :-)

Ben

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@Fay: thanks :-) I was expecting nothing at all, glad I was at least vaguely in focus this time :-) I kinda felt, seeing as i get so few chances to try imaging somewhere vaguely dark, I might as well stick with it and try.... I'd have been far more upset to have missed a chance to try, and learn, than spend a couple of hours imaging and find the wind had messed it up :-)

@Malc: ISO 1000 is faster, er-go more sensitive than ISO 400 so you will capture mor light in a given space of time at a higher ISO speed than at a lower one, but at a lower speed the data will be cleaner and it'll all be less grainy. The optimum is to get the longest possible exposures at the lowest ISO... but you're fighting tracking issues and the feintness of these objects. With galaxies, unless youre guiding, you want to stick with ISO 800 or higher... try and get the subs as long as you can manage before the stars start elongating. Mine were at 40 seconds, I could probably have managed 60 seconds but they were starting getting a little oval round the edges so I decided more shorter subs was a safer bet.

Theoretically at least an hour of data at ISO800 is an hour of data at ISO800 whether it's collected in 120 30sec subs or 12 X 5min subs. That said, I think there is a point where longer subs do reveal more subtle nebulosity. Some things are so feint they don't even excite the receptors on the CCD enough for it to register anything other than black without being exposed for a few minutes. No matter how many layers of black you add on top of each other, you'll still only get black at the end of it :-)

Ben

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Sorry, malc, to answer your specific question, when I say more data... I just mean more total exposure time added up to make the finished image. whatever you were doing was working... just lots more exposures the same as the six you got would start to reveal a lot more once stacked.

Ben

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Hi all

Ok, I've now uploaded the re-stacked data to flickr incase anyone wants to have a play with it... this has had to be reduced from 16bit to 8bit to fit in their upload limits... but hopefully not too much has been lost in that. The tiff file is here:

m51-megastack-directsave-2-8bit | Flickr - Photo Sharing!

It still has the spiral trail of the hot pixel on the left hand side of the image but all the frames with satelite trails in have been removed and some extra frames added from my previous imaging run, so this is about 20% more data than the last one. Hopefully someone can drag something useful out of this :-) Or at least tell me how to :-)

Ben

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Hi Ben,hopefully the quick edit of the flickr image will appear below.

Not one of my best efforts but does show quite good detail for a wide field. :icon_eek:

Cheers muchly Clouwatcher, it's looking really nice :-)

As you say... despite using a 5"+ Apo, it is fairly 'wide'... what sort of scope is generally recomended for a more detailed image of a subject this sort of size? An 8" Newt or similar?

I'm looking at scope options for later this year and it'd be nice to have something in my arsenal that can get smaller FOV, close-up shots of this sort of target?

Cheers again!

Ben

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I'm looking at scope options for later this year and it'd be nice to have something in my arsenal that can get smaller FOV, close-up shots of this sort of target?

Cheers again!

Ben

You could try a Skymax 127........ not too expensive,compact and about half the weight of your 127mm APO it will give you twice the magnification over half the FOV using the same eyepiece.

When imaging you will probably have to increase the ISO or exposure time above that you would use with the refractor and I would recommend a dew shield.

Attached are a couple of images which show the approx. FOV of both scopes.

HTH

post-13495-133877558335_thumb.jpg

post-13495-133877558341_thumb.jpg

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Ben, that puts my effort to shame - (I'm too embarrassed to put up my attempt to image M51 taken from SGL6 )

Seems these Canon 350d's are real performers

Just to put that into context, I borrowed a fellow members 350D last night and took this image of M51 from the middle of town (Stevenage).

6 x 300sec exposures + 3 x darks stacked in DSS, cropped and curves tweeked in PS

M51.png

Looks like I need to get myself a 350D... wonder if Steve would sell me his :D:rolleyes::hello2:

Edited by malc-c
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