Spider in the Sky

Robert9 (Robert) · #1 09-11-2015, 10:09 PM

Hi,
Well at last I got a clear (well more or less) night without the moon. The clouds didn't clear till quite late so rather fewer exposures than I would have liked. Anyway my Tarantula, (NGC2070) 6 frames of 30sec at ISO 1600 plus dark frames. ED100 on guided HEQ5Pro. Nikon D90.
I hoped the following night was going to be totally clear, but Melbourne being what is, gave me cloud. Aaagghhh.

http://astrob.in/225395/0/
Robert

Cimitar (Evan) · #2 12-11-2015, 05:48 PM

Reminds me of my first image of the Tarantula

, mine also picked up a lot of blue. I hope to get another crack at it again soon but this time with my little Vixen piggybacked on top of the Meade. I'm also planning on using ISO 1600, with perhaps 3-5min subs, so it'll be interesting to see how it turns out!

When I use the 0.63 focal reducer on my LX200, my DSLR gets a little too close for comfort to the base plate on my mount, given that it's pointing very close to the SCP.

Cheers, Evan

Robert9 (Robert) · #3 12-11-2015, 07:03 PM

Hi Evan,

Interesting your comments. Funnily enough a previous attempt at this nebula gave me a horrible red image.

(see attached) Dunno why. - perhaps my processing got a little out of hand.

This time blue. Next time .....?

I did take some 1 minute exposures too but I have found that the longer exposures just brings up the level of the sky. But perhaps you are in an area of darker skies. I'm in the 'burbs. so much light pollution.

I'm a little surprised that you should have trouble with the camera hitting the mount. At 9:30pm the nebula is only about 35º above the horizon.

Cheers,
Robert

Cimitar (Evan) · #4 12-11-2015, 09:01 PM

Hi Robert,

Haha yeah, definitely some weird processing artefacts sneaking in there when it's that red

. Initially mine came up as a heavy green on the Canon at the telescope until I ran the Hasta LaVista green processing tool on it. I thought something was wrong at first - then I learnt that green is pretty common at the camera. Not many green DSO's in real life though apparently

RE: SCP - My latitude is about 31 degrees, and with the LX200 in equatorial mode, the telescope has to be rotated fully through the fork arms to point at the SCP (i.e. polar home position). Unfortunately when this occurs the eyepiece/camera etc. is pointing downward, directly at the wedge/mount. When I offset by a few degrees to point at the Tarantula, it's still gets reasonably close to the base. It's ok without the focal reducer though, and in alt-az mode imaging near the SCP is a breeze.

Mike Weasner has a sample image here of his LX200 in polar home position (approx 2/3 of the way down the page). His image can probably explain it way better than I can. As they say - a picture is worth a thousand words!

Cheers, Evan

jenchris (Jennifer) · #5 12-11-2015, 10:14 PM

I took a look at the big spider too... mine was green.
I ended up with vignetting and noise in abundance plus the effects of a field flattener on a flat field acf meade! Arced stars at the corners.
Its got plenty stars in it though and good guiding.
I'll have a look at it later with the 100ed when I get it set up. Hopefully it'll be a better ap scope.

Robert9 (Robert) · #6 13-11-2015, 09:42 AM

Quote:

Originally Posted by Cimitar

Mike Weasner has a sample image here of his LX200 in polar home position (approx 2/3 of the way down the page). His image can probably explain it way better than I can. As they say - a picture is worth a thousand words!

Cheers, Evan

Hi Evan,
You're absolutely right - that would be very difficult to describe but the picture tells it all. Those fork arms do make it difficult for you. Ever thought of putting the OTA on an "ordinary" equatorial mount (HEQ5 or 6)?

I do envy you your country location. You must have much darker skies than I do down here. My advantage is I'm 7º further south.

I checked back through my records and found that the red image of NGC2070 was taken with my GStar camera and LRGB filters. I took 40 frames each of RGB but only 20 of L. Might explain (???) colouring.

Clear skies (ha ha ha - I wish)
Robert

Robert9 (Robert) · #7 13-11-2015, 09:50 AM

Hi Jennifer,
Welcome to the spider chat. Interesting your image came up green. Evan reported a similar occurrence. See his earlier post in this thread.
I've got vignetting problems too which I cropped out

.
The SW ED100 is a great scope. What will you mount it on?
Cheers,
Robert

jenchris (Jennifer) · #8 13-11-2015, 04:34 PM

Here's the pic from my 8"meade.
I shall be mounting the ED on my neq6 and putting the 8" back on the forks.
I have a wge for it and took my previous Tarantulae with that but I wasn't overawed.
It's only 6 x 180 seconds so pretty dirty thing.... shrunk to fit.