first light in so many ways - NGC3576

troypiggo (Troy) · #1 15-03-2011, 02:38 PM

Ok, first up, not the best image and I absolutely plan to get back to this target once some minor equipment issues are sorted. Will have to work on the framing a bit better next time too now I know what can fit in. Only recently learnt about this object and think it looks really cool.

I was so excited to set up last night, even though there were clouds everywhere and conditions weren't the best.

First serious attempt at actual imaging in almost a year, first light for the QSI583ws, first real light for my 10" newtonian that I've had for almost a year, I sorted out many computer/USB issues with my Mac, got Elbrus plate solving working with EQMod, tested the autofocus routine of Bahtinov Grabber and it works a treat, first time I've used a lightbox/flats seriously. All went pretty well.

But after all that equipment, software etc troubleshooting, along with clouds, only managed 2x5min Ha exposures here. Still. I'm stoked.

I also have some questions. See the stars in the corners are all eggy. Could that be due to the wrong spacing between the QSI583 and the MPCC? Don't recall that on test images with 40D and MPCC.

Also first time processing true mono Ha image from a CCD. I'm used to using curves in Photoshop with darks bottom left, but with this grayscale image the histogram seemed to be reversed! Can that be made the same way as RGB images, it just feels wrong and this image I gave up and just resorted to levels instead. Bit of a blunt tool for me.

And I've done heaps and heaps of reading on colourspaces etc for RGB, but now grayscale is a whole new world to me. sGray, Gamma 2.2 or what for working space?

Aaaaanywho - here tis. For what it's worth.

troypiggo (Troy) · #2 15-03-2011, 05:29 PM

Sorted the grayscale curves adjustment layer reversal thing out:
http://forums.adobe.com/message/3292359

peter_4059 (Peter) · #3 15-03-2011, 05:51 PM

Nice start Troy - looks like coma to me as the stars all point toward the middle - probably spacing if you didn't have this problem with the 40D/newt previously. Photoshop Astronomy has some info on the colourspace - I think it sugested Gamma 2.2 from memory.

Mighty_oz (Marcus) · #4 15-03-2011, 06:13 PM

If u are a Trekkie fan looks ok to me. Warp factor 9 i'd say

Aside from that u got to be stoked at that image with just 10 mins worth data hey

RobF (Rob) · #5 15-03-2011, 06:42 PM

Congrats on first light Troy (and on finding a hole in the clouds

). Centre of field looking great.

You probably need to read up on how far back the sensor is from the front mounting on the camera. Took me a while to get the QHY9 sorted with MPCC and filter wheel after being able to just whack the DSLR straight onto MPCC and into focuser.

ozstronomer (Geoff) · #6 15-03-2011, 07:12 PM

Troy well done on the image, well done on finding stars to image

That's an interesting nebula I hope you can add to it as it it certainly has potential.

alan meehan (Alan) · #7 15-03-2011, 08:21 PM

Nice subject and image Troy ,iam sure its your spacing of the mpcc which is giving you coma as pete has said,well done.
AL

DavidTrap (David) · #8 15-03-2011, 08:24 PM

Great start Troy! At least you saved yours.

DT

Octane (Humayun) · #9 15-03-2011, 08:48 PM

Haha, congratulations! I know just the excitement you've been through. : )

I reckon the coma in that image actually works, just from an artistic standpoint.

Looking forward to more. : )

H

troypiggo (Troy) · #10 15-03-2011, 08:51 PM

Thanks guys. Looking into that spacing issue. Well and truly bitten by the astro-bug again.

CoolhandJo (Paul) · #11 15-03-2011, 09:42 PM

Good detail amongst the coma!

RobF (Rob) · #12 16-03-2011, 12:06 AM

Probably a good time to be getting obsessed too - hopefully some decent imaging weather coming our way in the months to come as wet season slows down.....(pray, pray, pray...)

allan gould · #13 16-03-2011, 12:40 AM

A get that spacing right and you will really start to fall in love with that camera. It will give detail you won't believe. Great first effort, just keep at it Troy.

troypiggo (Troy) · #14 16-03-2011, 07:11 AM

As Pete suggested, photoshop astronomy recommends gray gamma 2.2 for windows and gamma 1.8 for Mac.

telecasterguru (Frank) · #15 16-03-2011, 07:15 AM

Fabulous first up effort.

Frank

[1ponders] (Paul) · #16 16-03-2011, 07:37 AM

Excellent Troy, way to go. Nice to see another Ha convert.

Paul Haese · #17 17-03-2011, 09:40 AM

Yes that field curvature needs to be reigned in a little. The metal back distance is pretty critical so I would suggest finding out the metal back distance and then work that to the sensor. Precision Parts in the US will be able to knock up an adapter which will be as tight a tolerance as you need.

As to the image I like the contrast and the smoothness of the image. I don't think you have indicated how many subs you used here. Looks to be a few though. What temp? Looking forward to more.

troypiggo (Troy) · #18 17-03-2011, 10:06 AM

Thanks Frank and Pauls

I've been doing some research on the distances. MPCC needs 55mm backfocus, the 583ws has 35.6mm from sensor to T thread, need to take off 1/3 of filter thickness because they change light path so for Astronomiks filters that's .33x1mm=.33mm, that's leaves 19.7mm. I've ordered a 20mm T thread extension tube from Edmund Optics and that'll be within the tolerances as I understand them.

Paul - Sorry, I thought I'd posted the subs info. It was only 2x5mins at -10deg. Very impressed with the low noise.

multiweb (Marc) · #19 18-03-2011, 05:55 PM

That's a beaut Troy. The field corrector is just the icing on the cake. Everything else is spot on. Nice one.

irwjager (Ivo) · #20 18-03-2011, 09:42 PM

Congrats on the first light! And what a first light too - gotta be happy with that.

I attached a (mostly) coma corrected version just for an idea.