A Horse is a horse of course of course...

[MGTechDVP (Mariusz)]

Hi All,

Haven't posted for a while since between weather, work and being determined to get my tracking/guiding/polar alignment sorted out I didn't get a chance to image anything worth sharing... until a week ago when I had a breakthrough with the guidiing and long exposure... in 2 words "cracked it".

Now I'm able to do (i think) indefinite time exposures.. on the test I did a 30 minute sub and the stars were perfectly round.
The Horsehead nebula consists of 15 minute subs through a baader 7nm HAlpha filter but the subs didn't drift at all in the 5 images captured, so I could have a sub of at least 75 minutes.

While waiting for the Horsehead to move into prime photographic position I tried to image M31 Andromeda Galaxy.. but the subs are short, only 3 minutes since I didn't guide those exposures... I had a guide star already framed up in the guider from previous nights Horsehead tests and didn't want to have to locate one again, so I didn't change the setup.

Can't wait to do more exposures on the horsehead, perhaps lower ISO 200-400.. but expose for about 30 minute subs to try to take down the amount of noise...

Horsehead
5 x 15minute ISO800 Canon 40D (Astromodded)

Andromeda
20 x 180s ISO800 (unguided)

Thanks for looking...

Mariusz

[brian nordstrom (As avatar)]

Very well done, I like black and white astronomy photos , and I see you snear,d the tiny 'Kiwi' dark nebula just left of the horse head , very nice
Brian.

[Saturn%5 (Graeme)]

Very nice well done

[blink138 (Pat)]

it must be a great feeling when it comes together like that mariusz, great pic and detail
i am guessing it was done at f/10 which is quite difficult anyhow
pat

[raymo]

Great job Mariusz; they can only get better from here.
raymo

[LightningNZ (Cam)]

Congratulations Mariusz. I've really got to get guiding sorted out.

[traveller (Bo)]

Well done, a great feeling when you cracked it!
Bo

[BruceG (Bruce)]

Awesome, bravo , 15 minute subs; wow that's guiding . Love the composition too. Congratulations!

[lazjen (Chris)]

Nicely done.

Do you think you'll have many issues with the longer exposures and summer around the corner?

[Rex]

Top shot, awesome detail in this.

[Flugel88 (Michael)]

Nice pixs!
great to hear you got your polar align/ guiding worked out.
I know how frustration that all is as im struggling with it my self.

[MGTechDVP (Mariusz)]

Hi all,

Thank you for the great feed back... It is a great feeling when things workout. Hanging to get back out there and do it again, and try to not only get a bit more detail but also get some color data. Perhaps there will be more surprise details like the "Kiwi nebula" spotted by Brian.

Bo and Bruce, getting guiding sorted and getting some descent shots for a change feels like being a kid and getting a new toy at Christmas.
Things can only get better from here, Raymo.

Chris I think my guiding will be ok for longer exposures, since during the whole time the subs didn't move a single pixel, so I don't see why I should have any trouble getting 30 minute or longer subs, judging by the last exposure even a couple of hours should be OK!!!

Pat, these pics were taken through a F6.3 focal reducer then cropped to get rid of the vignetting... I still can't get the flats working properly, every time I try, my pre-processed subs in Nebulosity 3 look washed out, so I decided just to crop the images and get rid of vignetting that way.

Cam and Michael, the way I got to the bottom of this dilemma that was haunting me for ages was experimentation and trying different things, but I'll tell you that as it turned out, I was polar aligning properly and quite accurately to the SCP for a while, but my drift errors were caused by MIRROR SHIFT!!! The 8SE mirror is mounted quite solidly, judging by when focusing back and forth, the star doesn't move in the view like I've seen in other SCTs, but non-the-less over time there is enough of a mirror movement during the exposure to ruin anything over 5 or so minutes. That explained also why I fluked a 20 minute exposure about 6 months ago and couldn't replicate for all this time... basically I was exposing close to north and there the mirror was getting pulled only down by gravity, so once it settled it obviously didn't move any more and the 1200 second exposed pic came out spot on.

Now all I need is a bit of luck for a few clear cloudless nights between last and first quarter moon dates...

Mariusz

[mariner10 (Steve)]

Hi Mariusz, like everybody else I have to agree, really nice shots.
I've never given much thought to doing black and white images but it's something I'll have to definitely think about.
Can you explain to me please (being sort of new to the technicalities of astro-photography) what you mean by "... 30 minute sub". Not sure I've heard of the term "sub" before.
Cheers.

[MGTechDVP (Mariusz)]

Thanks for the great feed back, Steve.. I'm itching to get back out there and do more imaging...
When I said 30 minutes subs, I meant the time I spent (or will spend) exposing a single frame before taking the whole lot, all of the "subs" and stacking them together to get a image with a better signal to noise ratio and hopefully more and clearer data...

The black and white images I had here are due to copying the red channel to green and blue channels, seeing that in HAlpha there was nothing in the Green and Blue channels anyway, except for thermal noise... that got rid of a lot of noise that was there only in the green and blue channels... I was surprised how much noise disappeared by just doing that.

I thought I was too aggressive in the curves adjustment in the Horsehead images which I posted so I had another go at the subs...

I think its a bit better now, a bit smoother, but a fair bit darker...

I posted the full res Horsehead Crop pic along with the 50% scale of the full frame after cropping out the vignetting...

[mariner10 (Steve)]

Well Mariusz, all your hard work paid off. The more I look at those photos the more I like them. Thanks for the info on "subs". Still trying to get my head around some of the terminology.