My attempt of 253 from a Melbourne orange zone on the weekend. 30mins intergration time using a combination of UVIR cut and NB filters. Stars are a bit eggy but I got some detail. Hard to tame the noise on a warmish night.
8inch f5 Newt with a modded 550d on an unguided HEQ5pro mount.
Nice Mick, really nice fo 30min. I've been having another go with my modded 550d. Trouble is I'm not getting much time with the clouds and the football !
Thanks Chris, yeah the weather's crap down here again. Just in time for the new moon this weekend. I swear the moon and clouds work together to spoil as many good opportunities for imaging and observing so we give up the hobby in frustration! Some kind of conspiracy is going on here. The last 5 or so new moons have passed without even an attempt to get the telescope outside.
Peter, perhaps we could make the next target NGC 2237, the Rosette nebula? It's coming into view following Orion and I'm sure we're going to get plenty of M42s over the coming months.
Since I haven't attempted a galaxy yet, this seemed like a good candidate, especially since I managed to find it by star hopping and have reasonably good polar alignment. Just cannot seem to get the Go-To accuracy everyone else seems to get using an HEQ5 Pro.
Anyway... Bresser Messier 127 f/5 on an HEQ5 Pro, unguided, Nikon D7200, ISO 640, 30 1 min subs, 20 ea. darks, flats and bias. stack in DSS, processed in PS.
Other than slightly out of focus, and really bad coma, does anyone see anything else I should be addressing?
Thnx in advance!
Last edited by sharptrack2; 18-11-2017 at 08:23 PM.
Reason: information added - ISO
Nice blue stars, and yes way out of focus :-)
I try and use all those focus assist tools like FWHM, and in can take me hours. It can get frustrating and sometimes you end up 'chasing the seeing'.
Take a few images and have a good look. Adjust and try again...
Since I haven't attempted a galaxy yet, this seemed like a good candidate, especially since I managed to find it by star hopping and have reasonably good polar alignment. Just cannot seem to get the Go-To accuracy everyone else seems to get using an HEQ5 Pro.
Anyway... Bresser Messier 127 f/5 on an HEQ5 Pro, unguided, Nikon D7200, ISO 640, 30 1 min subs, 20 ea. darks, flats and bias. stack in DSS, processed in PS.
Other than slightly out of focus, and really bad coma, does anyone see anything else I should be addressing?
Thnx in advance!
What are your PS skills like? Simple fix: grab the lasso tool, run it around the perimeter of NGC 253, feather the selection with about a 10 pixel feather, then select inverse. You now have a rough mask that will effect everything apart from the galaxy. Now go to selective colour, choose the blue colour and slide the cyan and magenta to the left and the yellow to the right (you could even side the black to the right as well). You should see the blue halos around the brighter stars disappear, or at the least, become more neutral. Hope this helps.
Unfortunately, fast achromatic refractors all suffer CA to some extent, I have tried filters to correct this but they ultimately change the overall colour balance too much.
Right now focus is by back of the camera, not hooked up to a computer. It is hit or miss until I get a Bahtinov mask for the scope. Saving to have Meru 3D print one for me. I may also invest in Backyard Nikon and EOS in the near future. Now to get my X2 barlow working with the setup, can't seem to reach focus.
PS skills are rudimentary at best. Have the hardest time with the selective brushing and adjustments. Practice makes perfect as they say... will give it a go on this and other images I've taken with that scope.
Sorry to hijack this thread, but Kevin, you don't have coma, refractors
rarely show any. If you magnify your screen you will see that the stars in the lower right corner are rectangular and elongated more than in the other
corners. Never seen rectangles before, but likely your camera is not
precisely perpendicular to the light path.
Re focusing; I assume your D7200 has Live View with 10x magnification; if so, choose a star that is not too bright, as it will have a sharper edge making it easier to discern when it is at its smallest size.
raymo
Probably wrong terminology being used... I think I have misrepresented the chromatic aberration with the term Coma. The elongation could be a little star trailing combined with a not so perpendicular camera orientation. I'll look into it, not sure how to verify but will read up.
I do use that method to focus but it is so easy to be off when seeing is not very steady. Will give it another go when I get back from New Zealand in 3 weeks.
