|Designation (lower left): Eta Carinae Nebula, Caldwell 92, NGC 3372.|
|Designation (upper right): Open cluster Caldwell 91, NGC 3532, Wishing Well Cluster.|
|Exposure: 104 x 29 sec = 50 minutes.|
|Field of View: 7.34° x 4.88°|
The last couple of nights outside with my telescope were used in an experimental attempt to capture a very wide field view of the Eta Carinae Nebula and surrounds.
The concept was to remove the guide-scope (see the page header image above) from its dovetail bar on the main scope and in its place mount a Tamron 70-200mm f/2.8 lens (normally used on my Canon EOS 60D DSLR camera).
The lens was then coupled with my main ZWO astronomical camera and used to live-stack wide-field images using SharpCap software.
The role of the main telescope was to be temporarily converted into a guide-scope by replacing the main camera with the guide camera. I was unsure how well this would function.
Night 1 did not go too well. I didn’t realise that the Canon lens f-stop was set to f/5.6 when I took it off the DSLR (and SharpCap cannot not control this feature).
I had not taken the lens cap off the main telescope (acting as a guide-scope). 🤨
Focusing was difficult. Moonlight was disastrous. The sky was light polluted suburban. Nebulosity was faint. Images were poor.
Night 2 went slightly better. Prior to starting I used the DSLR to reset the lens focal ratio to f/2.8, allowing more light exposure. Despite my concern, the main telescope functioned properly as a guide-scope.
Focusing the lens was still difficult (because the manual focus adjustment ring on a camera lens is very coarse) but at least the Moon was absent this time.
Capture of nebulosity was improved and the image became a bit more more presentable, although vignetting is obvious and the overall quality left a lot to be desired.
So I got my wide field image but the overall lack of quality that I achieved is unlikely to induce me to pursue this methodology very much in future, although it might have its uses.
Follow this link to see my image with Astrometry.net annotated overlay.
Also in the image are: NGC 3519, NGC 3572, NGC 3496, NGC 3503, NGC 3255, NGC 3324 and IC 2599.
I hope my readers are coping with the current pandemic threat, wherever you are. I hope you get to see a bit of the outside world and maybe even the night sky from time to time.
Here in Australia we are basically only allowed to leave home for essential shopping, medical care, work or one hour of exercise. No-one is allowed to undertake non-essential travel and the police make their own decisions about what is (and is not) essential travel during the current covid-19 restrictions.
So, if I left my home with my telescope gear in the back and drove to an observing site, any law enforcement officer who spotted me driving or observing would – not just could – would hand me an on-the-spot $1,000 fine notice. Astronomy is not a good enough excuse to test the police in Oz.
So it was with considerable surprise that I read one of my regular bloggers in the US this week, who wrote about travelling to Amboy Crater in the Mojave National Preserve to take some images of Comet C/2019 Y4 (ATLAS). Even more surprising was that he met an unspecified number of campers there.
I’m not criticising the blogger or the campers, just expressing my surprise that such activities appear to be allowed in the US during a pandemic, especially as it is affecting America much more than Australia at the moment.
By the way, the images this blogger took of the above-mentioned comet are superb! Well worth a look on his Orion Bear Astronomy WordPress site.
|SkyWatcher Esprit 120 mm apochromatic 3-element refractor |
|840 mm focal length @ f/7 with field flattener |
|SkyWatcher EQ6-R Pro mount.|
|Camera: ZWO ASI 071 MC Pro (CMOS 28.4mm 16 Mpx) |
(ON EOS DSLR LENS).
|Tamron 70-200mm f/2.8 DSLR EOS lens |
(ON ASI071 CAMERA).
|ZWO ASI120 guide camera, using PHD2 software |
(ON TEMP GUIDE SCOPE).