I have been continuing to get data for NGC7822, although I’m yet to obtain quite a few narrowband subs as yet, so we’re not seeing quite the detail or colour I would like. I also think I will have to increase the length of my narrowband subs.
Anyway, here is another integration result, with still minimal post-processing as there isn’t much point working on the data too much until I have a full set and can start discarding the sub-optimal exposures.
I’ve been experimenting with the new set up, and what with the weather there are a lot of software changes to account for.
The following is an image of NGC7822, a random target that I’ve put on while I run through bugs and problems, mostly arising from lack of having been able to regularly use the equipment due to the current weather.
I’ve not bothered too much with post processing, just a quick, mostly automated workflow, and then quick levels adjustment with Gimp.
I continued to grab more data for M33, and have added the Hydrogen Alpha in a slightly different way to before, although I wasn’t able to get any more sub-exposures for Hydrogen Alpha due to software issues. Still think I need to continue to add more data.
Focusing is actually working well now, although the focuser appeared to want to refocus far too often. Guiding was also being suspended during focusing. I think we will now manually move the focuser to 83000 steps at the beginning and probably limit travel to 1500 steps in either direction or so, and work with much smaller initial steps (initial step 200, max step 300). This should allow me to refocus often and quickly and not have to suspend guiding during focusing, which appeared to be an issue. I am hoping some Kstars updates to Astroberry in the near future will sort some of the software issues I have experienced last night.
We don’t know, all I know is that it flattens the field to a image sensor, this is the SkyWatcher Field Flattener which is matched to the Esprit 120ED Pro, the main sensor is a CMOS ASI1600MM Pro in my case.
So we had a brief night of viewing, and as this is likely to be the last time using the StarTravel 120T I thought we would end where we started, with Andromeda. The results are not great, it is a Luminence only capture, with a mono camera, a mosaic of three panes, and you can clearly see the egg-stars caused by the chromatic aberration that the StarTravel exhibits. The StarTravel gets really good results with Narrowband imaging, but not when trying to get true colour. I intend this to be the first target with the Esprit soon, and hopefully we will see quite a difference to compare the two against each other – you need to be reminded that the Esprit costs probably around 8x more than the StarTravel, and everything I’ve posted here so far was achieved using the StarTravel. I have not bothered to perform much post-processing on this image, as I feel more compelled to focus efforts on new equipment, and hopefully better results.
We can compare that, with my first ever astrophotography photo, although I believe this was LRGB at the time, so avoided the worst of the chromatic aberration by re-focusing for each colour filter.
OK, Well the Esprit 120ED Pro has finally arrived. So a few unboxing photos, which I will follow up with a video comparing the upgrade from the Achromatic StarTravel 120T to this new Apochromatic scope, in particular testing out the Sesto Senso 2 on the Esprit, and comparing it with the DC Motor on the StarTravel.
I am told that there should not be any difference between the ED100 and the ED120 focusers, they are the same model, the only difference is the sticker, which I will either remove, or it might drop off with dew in time.
OK, so I took a delivery and this is the first look at the Primaluce Labs Sesto Senso v2, although I don’t yet have a compatible scope to attach it to. It feels sturdy, and without further ado, here is the review:
Just a note about the 12V power connector, my previous HitecAstroDC focuser accepted a 2.1 centre positive connector, and I hoped I would be able to use that. Unfortunately the Sesto Senso v2 power connector appears to be a 2.5mm centre positive connector, so you would need to buy another cable to get rid of the cigarette lighter cable that comes with the device.
This is a quick video about “The Box”, the system I use that connects my equipment (via INDI), to my desktop indoors, and allows me to control everything without having to go outside. Although it is sometimes enjoyable to go outside and watch some of the automation tasks, such as a meridian flip!
During the focus procedure on Friday night, I seem to have captured what I’m going to call “Musk Trails”. I expect this was part of a constellation of SpaceX Starlink satellites traversing my field of view while I was trying to focus. Here is a still from the video:
Thought I would rework the data of the Heart Nebula IC1805, I have managed to obtain some darks and bias frames. So I loaded everything into Astro Pixel Processor and started the registration and integration process. I’ve now discovered that there must have been some alignment issues during capture as there is a distinct rotation artefact in the top left frame. Still, this one has more contrast, and we can see more detail than before.
Now my ASI120MC-S is no longer my guide camera, I mounted it on a ordinary camera tripod and tried a few All Sky exposures. Because we’re not tracking or even aligned the result isn’t great quality, but you can make out an arm of the milky way.
So, at last the ASI290MM mini & Helical Focuser have arrived. This will hopefully be a significant improvement to guiding.
But first, some backstory.
Back when I went and got my main imaging camera, the ASI1600MM Pro, I bought the set of the 8-slot Filterwheel, all the filters (L,R,B,G,Ha,OIII,SII) and an Off-Axis-Guider (OAG). I was looking for a reasonable guide camera to attach to the OAG. The long list of equipment for the imaging train meant that my budget was somewhat limited. I chose the ASI120MC-S.
Really, the ASI120MC-S does guide quite well, but it is not entirely suited to the task. Firstly it is a colour planetary camera. Colour is not necessarily of any use when guiding, and might even hinder it for all I know, but at the time, completely new to astrophotography (and not really experienced now!). I thought, well, it will probably work for guiding, and I might be able to use it for other things too. In any case that’s what I got, and it has served me well for guiding.
Recently I’ve been looking to see whether I could get some improvement in this area, and eventually decided that the ASI290MM mini might suit pretty well.
Let’s look at some comparisons from the graphics at the ZWO website. First, the ASI120MC-S
Now, the ASI290MM mini:
OK, so the sensor on the ASI290MM is bigger, but so is the resolution, the pixel size on the 120 is 3.75 um, the specs don’t highlight that on the ASI290MM, but I believe the pixel size on that is 2.9 um. The read noise on the ASI290MM is a lot lower, also note that on the mini it is USB2.0 rather than USB3.0, which probably counts for why the frame rate on the AS120MC-S is higher. It is difficult to compare QE between the two, the MM mini slightly higher.
Clearly with the ASi120MC-S having a full well 13000, capable of higher frame rates, seem to lean that this is a camera meant for planetary imaging, which can do guiding, whereas the ASI290MM mini is a guide camerea, that you might be able to do some mono planetary imaging. So the mini is squarely aimed at guiders, and I hope it will excel at first light.
The areas where the ASI120MC-S excels at better than the ASI290MM mini are not significant for guiding, and the areas where the ASI290MM is better (lower read-noise, more pixels, lower pixel size) are all areas which should improve guiding, hopefully allowing me to reduce exposure times and cope with the small amount of light pollution I sometimes have.
Here are some pictures of the imaging train:
So I had my first outing with using the ASI290MM mini as a guide camera last night. I can confirm that the camera behaves as a distinct step up when compared against the ASI120MC-S. Firstly, with exposures set to 1s and binning set to 2×2 I was able to constantly guide without losing a star for quite a few hours, and the only times I lost guiding was when I attempted more aggressive settings. The frame acquisitions during guiding showed considerably less noise, and it should be noted that I was guiding without any dark or calibration frames. The helical focuser was great as well, I was able to quickly use ASICAP on my Tablet to ensure that the guide camera became parfocal with the main imaging camera. It literally just took a few seconds, and the position was easily locked into place with the thumbscrew. My experience of trying to use the adjustments on the OAG previously had led to a lot of frustration messing about with Alan keys in the dark trying to achieve some sort of focus. The clamp on the helical focuser also allows for rotating the guide camera to ensure that it is somewhat aligned properly with the mirror and/or the main camera. I’m of the opinion that with time, and the upcoming upgrades to OTA and focusing I will routinely be achieving sub-arcsecond guiding.
I’m gearing up for a new season, we have some pretty poor autumnal weather here at the moment, and very few clear skies forecast for quite a few days.
However, I have placed an order for the following new equipment:
A SkyWatcher Esprit 120ED Pro Triplet Apochromatic Refractor. This is to replace my achromatic SkyWatcher Startravel 120T. Unfortunately there is a long leadtime on these to arrive from China, so it might not be until November that we see first-light with it.
A Field Flattener purpose made for the above, to ensure better astrophotography results.
An Astro Essentials Filter Cell Adapter, which should allow me to fit a light pollution suppression filter between the field flattener and the focuser on the Esprit.
An IDAS P2 Light Pollution Suppression Filter to be used in the above (2″).
A Primaluce Lab Sesto Senso V2, this is a a stepper motor to replace the HitecAstro DC motor, it should be more accurate with less slippage, although going with an Apo should mean I have to spend less time refocusing during filter changes.
A Temperature sensor for the Above.
A 17ah Powertank – I will be trying to power all my kit from a battery this year, in preparation to see if travelling to a dark-skies site could be possible.
I suspect that this means that I will soon put the StarTravel 120T, with its focus motor and HitecAstro DC unit on the second hand market, it will come with a fabric carrying case as well, and I may be able to throw in a few extra accessories.
Of course, it all depends on when the above will arrive, which is forecast to be around 10-12 weeks at the moment.
I’ve also gone to place an order for the following now:
ZWO ASI 290MM mini USB2 mono camera for guiding
ZWO 1.25″ Helical Focuser for the above
On briefly attempting to guide with my ASI120MC-S at the weekend, I was reminded how noisy a camera it can be, and unfortunately, while I bought it for guiding I kind of let myself be lent to a possibility of doing planetary imaging, which it is probably more suited to. The ASI290MM should be a better dedicated guiding camera, and I hope the helical focuser will allow focusing off the off-axis-guider easier.
Still a work in progress, will probably work on some other channels to add.
I’ve not uploaded the video of processing the mosaic as it was necessary to use a downgraded version of the software due to bug in the current version, I had that version on my laptop, so I used that to stack the mosaic, but don’t have Video recording software I know how to use on the laptop.
Will re-do when there are more sub-exposures available, and the bug in the software is fixed.
This is one of my first long exposures (1hour 20minutes total) of M33. The light from this spiral galaxy has been travelling for 2.73 million years before the photons hit my camera to produce this picture.
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