Hi there,
I'm holidaying on the south coast of NSW and would have liked to have brought my 8" Newtonian along with me but obviously the size and weight of this outfit would have taken up too much room in the car.
Looking forward to dark skies, I took away my Saxon 4" f5 achromat refractor which is extremely portable. However, this is really only suitable for visual observing and it's imaging capabilities are known to be below average. Consequently, my expectations of producing a quality image were far from high but I love the challenge and just being out there under the stars away from city lights was too tempting.
After eight days of cloudy night skies I eventually got a clear near perfect sunny day. A perfect day for the Department of Primary Industries or whichever government department they were decided to do some controlled burn offs in the local national park.
That night there was smoke haze hanging over where we were staying so I headed up into the foothills away from the coast and smoke haze to find an isolated sight to set up for some astrophotography.
The sky was clear of cloud but there was a slight smoke haze that reduced transparency.
The clearing I found to set up on was not flat and had a moderate slope with long grass so getting the mount level took some time. The gentle breeze started to blow the smoke away so despite this creating stability issues I had to be grateful it was doing some good.
So here's the result of the night's efforts. Plenty of coma and noise ( sensor too warm and not enough subs) but I managed five subs to stack.
5 x 30 second lights 1600 iso. Canon 550d full spectrum modified.
3 x 30 second darks.
Unguided Bresser EQ3 mount with RA motor.
I now know why no one uses these scopes for astrophotography!
The sacrifice I made to fit the family and all our luggage in the car. I'm still happy with the result and it's a nice memory of dark skies away from city lights.
It still gives a fairly pleasing result. Less than perfect but with a fast achromat and a light portable EQ mount, it could be better than you expected
Thanks for your comment Colin, yes, better than I expected. If you don't mind the CA. Maybe if I had reduced the saturation a bit in post processing it may not have looked as bad. It certainly is colourful!
Last night of our holiday the weather cleared. Stuck the scope out in the backyard of our apartment and shot Carina nebula again. M8 and M20 were low on the horizon but managed to capture some detail and just near Carina nebula is NGC 3532, so I had a go at that as well.
CA is evident being a fast achromat but I am relatively pleased with the results for a compact, take anywhere, easy to set up rig.
All shots were taken with the Canon Modded 550d at the prime focus of the Saxon 102 f5 achromatic refractor on an EQ3 mount with RA motor. Polar alignment wasn't great so I kept my subs short.
Each shot had 10 x 15 secs plus 3 darks @ 3200 iso
Hi Michael. I have to agree with you that fast achros are not the best for
imaging, but only because of the CA. Your scope could give you better results on Eta Car. Obviously your tracking was not spot on, and the first two images in particular, look a bit soft. How are you focusing? I see only a little of the coma that you mentioned; you wouldn't know
how much until your stars are round.
raymo
Last edited by raymo; 15-04-2016 at 12:31 AM.
Reason: more text
I find focusing difficult with this scope. Being an achro refractor and a modded DSLR, trying to find a focal point to choose when each wavelength focuses at different positions is a bit hit and miss. The full spectrum sensitive sensor tends to bloat bright stars anyway.
Much easier on my 200mm f5 newtonian with a Crayford focuser. Not a great fan of cheaper Rack and Pinion draw tubes, the image moves all over the place while trying to focus. I also did a soft blur in PS to reduce noise, as you would appreciate a warmish night at 3200 iso not a good combination for smooth results.
If you have trouble focusing using Live View at 10x mag, get a Bahtinov
mask for your achro, cheap, and spot on focus every time.
If after getting round stars you find the coma objectionable you can of
course crop off the worst of it.
raymo
