A spate of bad weather followed by the bright moon kept me from imaging the comet until this week. A little late to the game and a fading comet. Still, I did get an image.
The comet is currently high in the evening sky, an easy target. An now that the bright Moon has left the evening sky this week and next represent a last chance to see the comet before it truly begins to fade.
Comet ZTF has faded below 6th magnitude according to recent estimates, too faint for the unaided eye, but still spottable in binoculars and fairly easy to catch in a small telescope. The comet remain well placed to spot for some time to come but will slowly fade, dropping to about 8th magnitude by the end of the month.
Canon 6D with a TeleVue 76mm scope riding on an ZWO AM5 mount. 30 x 180s images processed in DSS. A version processed to remove stars does show a trace of the ion tail.
It has been a long time since I shot a full frame 35mm camera. Not since I shot film have I used a camera with a full 35mm image size. My older DSLR cameras have use APS-C sized sensors. The Canon 6D is a full frame camera with a 36x24mm sensor, something that has quite an impact on the camera’s capabilities.
A few months of shooting have given me a better appreciation of the camera. the camera is great to use. It is an enjoyable camera to shoot. The photos speak for themselves, the thousand words thing applies here. I have gotten shots where none of my other cameras would have, particularly in low light. The Canon 6D is one of the best cameras currently available for use in low light. It even edges out its more expensive siblings the Canon 5DmkII and III for making the best use of every available photon. Not just astronomy either, but star parties and lecture halls. The astronomy capability is excellent, attaching the camera to a telescope allows capture of more than just our small world.
There are other implications of full frame… The large format sensor behaves much differently than smaller sensors when it comes to focus. Depth of field changes the game. Very small sensors, particularly cell phone sensors, have enormous depth of field by nature of the optical design. Nearly everything is in focus, from near to far. Photographers love shallow depth of field, it allows the subject to be isolated from the background. Everything closer of further away becomes a soft blur, something photographers call bokeh.
The photograph was planned… Somewhat. I knew there were some picturesque trees on the lava field along Saddle road. The plan was to shoot one of these trees silhouetted against the Milky Way and Mauna Loa. That was the plan. At least until the plan met reality.
Shot as planned the results were less than stellar. Actually they were rather boring. The rising summer Milky Way was spectacular, nothing else worked. The enormous bulk of Mauna Loa became a bump on the horizon from the low angle with the 14mm lens. The trees did not look like much against the dark.
Serendipity intervened… First a passing car lit the trees with dramatic results. Car headlights caught the trees at just the right angle to light up the right bits, a lucky bit of geometry and road alignment. Looking at the image on my screen I was intrigued… I repositioned the camera and shot again when another vehicle passed… This was working!
As I waited for other passing cars the shots deteriorated, odd glows across the frame. Were the headlights catching the big dome of glass at the front of the lens? Blocking the light from the headlights on the camera did not help. I pull out a flashlight to check the camera… Ack! The lens was fogging up!
Retrieving the anti-dew kit and a battery from the vehicle I secured a dew strap around the camera lens. At this point I wanted the shot and was willing to work for it. I was lucky again… I had thrown the dew gear in the car as a last moment afterthought.
It took time for the lens to warm and clear. As I waited dawn crept into the sky. I took a last few shots as the light increased and the stars faded. The dawn light added a nice shade of blue to the sky with a hint of peach to one side, another serendipitous bit that added to the photo. A last wisp of fog on the lens was just enough to create halos around Mars and the brighter stars.
Not a bad result! With a little skill and more than a little luck. The shot has been entered in the Hawai’i Photo Expo. Hopefully the jurors think the shot is as good as I think it is.
After solving the little equipment issues, waiting out weeks of bad weather and waiting for the Moon to go away, I finally had a nice photographic night. Setting up at sunset I shot until the Moon rose. Most of the targets I have shot before, Orion, Rosette, Markarian’s Chain. I also shot Melotte 111, an object that has always intrigued me. The full frame camera and the TV-76 has a wide enough field to capture this very large and nearby star cluster.
I want to use this combination camera and telescope with a very wide field to work over the dark nebulae of the Summer Milky Way. With 384mm focal length the full frame camera gives me over 5.35° x 3.56° field of view. The beehive also lent itself to the wide field, another large object that was worth a stop to shoot.
Aside from one little equipment issue to start, more an operator education issue, the gear worked great. Note to self… Must turn off camera WiFi before the camera will link to the computer via USB. I am currently using APT to control the camera, a very impressive bit of software. The auto-guider worked perfectly, frame after frame nearly identical. I can slideshow through dozens of sub-frames and not see any difference, no drift!
A single sub-frame of the Rosette Nebula is shown to the right. The Rosette is an emission nebula with most of the light emitted at the wavelength of Hα 656.28 nm. My Canon 6D is stock, no astrophoto modifications. Despite an IR cutoff filter that blocks much of the Hα light the camera captures a fair amount of the nebula. Perhaps I should get a 48mm Hα filter for the camera to shoot from the driveway.
With everything working so well I really need to haul the rig up to Hale Pohaku for a night of imaging under darker skies than I get down at 1000ft. Next weekend is dark-of-the-Moon weekend. Need to plan an outing?
It will take a bit to process the results of the night. As usual, keep an eye here on Darker View for the finished photos.
The brightest nearby supernova in may years is currently visible in the bright galaxy M82. I did want to photograph the supernova before it fades much more. It apparently reached a maximum brightness of magnitude 10.5 a few days ago and is starting to dim. But has so far only slid a few tenths of a magnitude.
So I tried to photograph a supernova, and Murphy came to visit.
The last week has seen me dealing with a sinus infection, which combined with terrible weather has kept me from setting up in the driveway for photography. Taking advantage of a few clear hours last night I did make an attempt. Things continued to go wrong.
A high thin haze would not go away, lit up by the light of a bright quarter moon it created high background and gradients in the imagery that would not calibrate out. I forgot to install the LPS filter, meaning that the low pressure sodium lighting of the village compounded the moonlight in creating a poor signal to noise and bad gradients. The autoguider would not behave. This was eventually solved by adjusting the tuning parameters in PHD guide. Not before ruining most of my exposures, I ended up throwing out 24 of 32 exposures. When I did get everything figured out and corrected, and the Moon had fianlly set, the clouds rolled back in.
The final eight usable exposures did result in a somewhat acceptable final product. It could have been so much better…
I had set the alarm clock for 0230 to get up with plenty of time to setup and take comet photos. What greeted me was a sheet of cloud, an all to familiar sight lately. I did not reset the alarm and went back to sleep. A couple hours later I found myself lying awake again, realizing I would probably not fall back to sleep I got up to look outside. To my surprise Orion shown brightly over the street.
Is there enough time to setup and shoot before dawn?
I rushed the alignment, hoping to setup in less than half an hour. Things did not go smoothly… The EOS utility in the computer did not recognize the 6D, I need to update the drivers. A thin cloud stubbornly sat in front of Polaris, I think I got the polar alignment, the star was very dim on the polar ‘scope. Even when exposures seemed to be going smoothly I they were not. I find out later the auto-guider had moved itself to a hot pixel, probably when a bit of cloud passed through. In the rush I did not get a dark frame for the guider, most of the frames show small guide errors.
One not so bad bit of serendipity… The Hubble Space Telescope went right through one of the frames.
Despite all I did get an image of the comet. It should have been better, rushing astrophotography is not a good plan…