As I have progressed with astrophotography it is easy to be seduced more and more with better equipment and of course this is all done to make the images you take easier / clearer / give access to more targets. In this race I have a setup where other than polar alignment still being hands on, it is pretty much automated, from the planning to the framing, focussing, tracking and of course taking the images. I love it, prior to this automation to get images of similar quality I would be sat outside in the cold for maybe 1 hour before I could start taking images, now this is down to about 15 minutes. I was reminded however on a recent trip to the South West of the UK, Cornwall that a truly back to basics approach gave me lots of enjoyment with some basic equipment.
The trip in question was late February 2023, my wife and I were travelling to see my daughter who is enjoying the student life in Falmouth. We had booked an apartment for the week, it happen to come with a balcony and was a stones throw (literally) from the beach. In the past I have thought about taking the full rig, Sky Watcher mount, laptop etc but limitation with power to feed all this equipment, the fact that all this stuff takes a large amount of space in the car and of course the famous changeable UK weather meaning there's no guarantees of imaging even if the other hurdles can be surmounted usually meant I decided it was not worth the effort. On this occasion however I decided to quickly stuff my iOption Skyguider Pro, lightweight tripod, DSLR and a single 80-200mm basic Canon lens into the boot of the car. With this kit it is possible I could have been totally disconnected, Canon batteries charged, spare charged, iOpton in built lithium charged. The only missing piece of equipment was my old intervelometer was missing (Amazon Prime to the rescue). Sorry, intervelometer, which is one of these words I love to say, is a slightly fancy shutter release cable, the fancy element being you can tell it take to X number of images with shutter open for X seconds and repeat, some cameras (I think the Nikon's being one example) have this feature built in, my Canon 600D does not, a £15 outlay solves the problem.
I am so glad I did, I had on night on the 22nd where the Moon was thoughtful enough to hand around early evening for a simple conjunction but no so long as to spoil the dark skys on the coast, my phone app was telling me my location was Bortle 4, I think it may have been 3, either way better than my 6 at home.
I knew from my old days with a simple set up like this that you have to be realistic in that targets you have a realistic chance of getting good images. Here are some of the limitations:-
No plate solving software, so you have to be able to see the object (or something that you know to be in the same frame as the target), sounds obvious, but there are many targets like for example the Rosette nebula that you would struggle to find
No Autoguiding so at best 90 seconds, maybe 2 minutes exposure before stars become too elongated
Keep the focal Length way down, to reduce the effect of the start tracking errors and make the framing of objects easier
With these points in mind I have already decided that if possible I would go for the conjunction that was happening that week, followed by some wide field views of Pleiades and Orion, especially with Orion for the lower half with the hop of capturing the major nebulae and possible the Witches Head, although I knew that would be a stretch (goal wise and well as literal image processing wise!).
When I arrived my intention was to possibly set up on the coast across on the beach or perhaps a short walk into a small park. Good intentions aside, the balcony actually gave great views to the South West, where most of targets were going to really shine, also, I don't mind saying that sitting in a park or on the beach in the middle of the night I did think of as a bit unsettling, maybe this is something that you become accustom to but given the balcony view I decided to stick to setting up there. The one problem that makes me regret this was that I did not have any view of the Pole, so there was no chance of accurate Polar alignment, it was a case of trusting the declination was something like the same as I had it set 300 miles to the North at home and Longitude wise I was left with my phone compass only. After a few 30 seconds shots it was obvious that I was a barn door away from polar alignment so all my exposures are dialled back to 10 second exposures. I used ISO 800 on the camera after I had found the framing I wanted.
I have to say though that simply using the memory card, intervalometer, unguided star tracker was really enjoyable, manually focusing, keeping the focal length at about 80mm really helped with the the image quality and at the end of the night I had had a really good time.
Here's the output of my efforts on that single night.
Jupiter, Venus and Crescent Moon
This image was taken around dusk - hence there was still a little blue in the low sky. I wasn't sure whether a stack would have been necessary, but I think in the end it did clear up the image. I took around 40 images at ISO 800, 1 second exposure, this is around 135mm focal length, I zoomed the lens to frame this almost exactly as seen, no big crop here.
In the end the registration of the 40 images only managed to hit on 20 for stacking. Very little post processing once the stacking was complete other than some levels adjustment.
The shadow side of the Moon is illuminated by Earth shine. Venus is dazzling at the bottom right with Jupiter at the top left. Zooming in you can just make out 3 of the Galilean Moons. Simple, pretty image or is it pretty simple image.
Pleiades
Once it had become properly dark Pleiades was to the South West, just passing its zenith but my main target for the night being Orion was not quite in view from the balcony so Pleiades was the obvious gap filler. An advantage of this imaging setup was it took no real effort to simply point, frame, focus and set the camera clicking away. Yes you could do this with my larger setup, but it would have taken a sequence to have been created, there would also have been the question of how I would piece together calibration frames (especially Flats) when these various targets were using different focus and focal lengths. I had already made the decision based on the lack of great polar alignment not to get hung up on grabbing lots of calibration frames (although I did at the end of the night grab 20 darks to be used on this image and the next Orion image).
The following image is the result of 122 images taken at about 135mm fl and ISO 800, 10s exposures.
Calibrated with 20 darks to build a master dark, these are 1220 seconds or 20m20s of exposure time. I played around with this image in Photoshop, mostly this was levels and curves and added a bit of vibrance to bring out the blues. I deliberately framed the object like this as I think the large blackness of space to one side really highlights the beauty of these blue sparkling gems. Oh - yes for the keen eyed I used a Photoshop script I purchased from ProDigitalSoftware.com (Noel Carboni) to add the diffraction spikes.
Close up inspection really highlights with this image and Orion how bad my polar alignment was, even at 10 seconds at this 135mm fl you can see elongation of the stars, but hey as a quick grab I think this is a really nice image, just don't go pixel peeping!
Orion
So after about 30 minutes on Pleiades I turned my attention back to the South and Orion. I had a deliberate shot in mind for this grand constellation.
You can see the platesolved map from astrometry.com, I actually cropped some of the top of the image in the final processing to bring more focus to the main objects, Orion Nebula, Running Man, Flame, Horsehead but I also wanted to try and grab the Witches Head starring at Rigel (star in the bottom right of this image).
I took 241 10s images at ISO 800 using the lens at 135mm fl I calibrated with 10 darks (same ones used with Pleiades) and stacked all but 2 of the light frames, so 2390s of exposure (about 40 minutes).
Feel free to zoom around the full image (just click on it) and you will see all but the Witches head nebula. It is there in the original stacked images but to see evidence of it in the final image would have required so much curves and levels stretch that the Witch would have destroyed the rest of the image. I am confident that more accurate Polar Alignment and perhaps triple the exposure time would have managed to grab her. I would also have taken a few 1 second shots of the same field of view to allow a Higher Dynamic Range image, so as not to blow out the central core of the Orion Nebula. However, when all said and done I had a great night imaging with a more relaxed attitude than my normal images allow, I was on holiday.
I'll leave this post with some of the objects that you can see in the wide field view taken over the last 3 months with my home set up. All the best and clear skies everyone!
Comentários