inFINNity Deck

Hi Hughsie, this capture was six days before yours (19 June 2020 15:38UTC): My imaging and processing skills were still pretty poor, but having those prominences visible was a jaw-dropping experience at the time (and there was one whole sunspot at the upper-left!). What a difference a few years make (27 June 2024 08:23UTC) Such a shame that she will go back to this quiet featureless orange we saw some four years ago.... Nicolàs

Hi Andy, the focus point will move slightly further away, about 60% of the thickness of the two glass wedges (I believe they are approximately 4mm each, so 8mm together, and thus the focus point will move backwards (i.e. towards the camera) some 3mm. But I think you mean that the minimal camera distance will move further backwards as well due to its physical length. Depending on how you mount the ADC it takes at least 26mm extra space between focus-tube and camera (from which we can subtract those 3mm for the additional focus distance). Nicolàs

If you have an ADC at hand, try to incorporate that in your imaging train. Moving the handles to a non-zero position should remove Newton rings, see my website: https://www.dehilster.info/astronomy/removing_newton-rings.php Nicolàs

Hi Carole, that form should indeed do the trick, I filled it out some years ago and still use the free version of TV. If you still experience issues I can recommend AnyDesk. I had the commercial-use issue with a Canadian friend while trying to assist him setting up his observatory a few years ago. As action from TV was not instantaneously at the time we switched to AnyDesk and still connect that way in case he requests for assistance. Nicolàs

Hi David, for a first attempt your image is not too bad, and much better than I managed the first time! 🙂 Over time I have written three articles about solar imaging, the third one being the method I still use (the method in the second article was way too complicated). The third article shows how to produce inverted solar images and how to get the sun in your scope's sweet spot (but that is pretty okay in your case). https://www.dehilster.info/astronomy/solar_imaging_part_3.php Although I still use the method as explained in the article, I managed in the meanwhile to improve on sharpening, something I explain on my Solar Imaging page: https://www.dehilster.info/astronomy/sun.php Nicolàs

Ok, that is interesting. The tilt can be checked by placing a Cheshire eyepiece in the focuser and brightly illuminate it while the lens-cap is on. If the lens-cell is tilted you will not see concentric reflections of the Cheshire's reflector. Nicolàs

Hi Dan, indeed it is quite curious why these artefacts are not point symmetrical. Did you check the front of the lens-cell to see of the are any small uneven spots along its circumference? Do you also see the artefacts in each and every sub? Nicolàs

Hi PottyMonster (is that your real name?), the effect you see could be an uneven spot along the edge of the aperture, although I would expect it to be symmetrical, which it is not in your case. The same for pinched optics, these should be symmetrical as well. The Tak FSQ85 indeed has these dark spikes, which are always oriented perpendicular to the centre of the image. Most likely cause is an unfortunate lens spacing in combination with the type of coating of the lenses and that they are the result of physical amplification and extinction of the light. More information on imaging artefacts in a white paper on my web-site: https://www.dehilster.info/astronomy/imaging_artefacts.php Nicolàs

If this photo is the pin in your focuser, then that is not the original one. The pin should be smooth, only having a smooth thinner section where the large balls run against. The original pins are made of hardened steel, not sure if the dowels you found are made of it as well. If not, they will be too soft. cheers, Nicolàs

Hi Giles, that cage should indeed be properly filled as otherwise the pressure of the ring-nut does not get properly and evenly distributed. And replace all balls, so that they all have the same size. Then when tightening do it in steps and test whether it holds enough load. When overtightened the central pin may get dented at which stage the focuser gets beyond repair (unless you can source another pin). Nicolàs

Hi Giles, see fig.3 on my webpage about my SkyWatcher Esprit 150ED: https://www.dehilster.info/astronomy/skywatcher_esprit_150ed.php The tiny balls, 18 in my FeatherTouch focuser, should fill the whole bearing. The purpose of the large balls is to create friction between the central thin pin and the conic outer bearing cage. This friction is created by tightening the large brass ring-nut, which pulls the three balls down in the conic cage, and to avoid that this causes too much friction between the gear housing and that nut a bearing with small balls is placed between them. As I wanted zero slippage I replaced the whole friction planetary gear by teethed planetary gear from a electro-motor gearbox (see above page). Nicolàs

Hi Andro, I have written software (FITSalize) to do sub arc-second level deformation measurements using a stationary scope and plate-solving. During development, based on the algorithms in J. Meeus, Astronomical Algorithms, (Richmond (VA), 2005), I tested my software against Stellarium and soon found out that Stellarium corrects for precession and nutation, but not for aberration (the phenomenon where celestial objects exhibit an apparent motion about their true positions based on the velocity of the observer). Precession and nutation are accurately corrected for, I could not find significant differences with my software. In order to be still able to compare the results with Stellarium I made the aberration optional. Nicolàs

Hi Alan, I just saw this thread last evening, so a bit late to chime in. I built my own dome six years ago of corten steel (base ring), pine (rafters), plywood (first layer of cladding), and zinc (final cladding), the construction of which can be found on my website: https://www.dehilster.info/astronomy/building-an-observatory.php Regarding your questions: Wind: it is a very good wind breaker, I have been imaging and observing quite often in conditions that seemed to be unfavourable. If you are going to build your own dome you need to avoid any openings larger than 10 millimetres that cannot be closed as the wind will blow in rain, hail and snow. Size: my dome has an inner diameter of 2.8 metres, which is fine when I am alone or only with my wife, but not suitable for more than four adults. I'd recommend a diameter of at least 3 metres (yes, 0.2m already makes a difference), but preferably at least 3.5 metres, that will easily accommodate around 8 adults. Move house: why, if you have an observatory? More seriously: you are moving to a new home and already considering selling it? In other words: do not live on fears! My wife and I hope to move from our current home with our feet forward first. In case future decides otherwise we probably have bigger concerns than an observatory on the roof of our house. A motor for controlling the dome azimuth is a must, for controlling the shutters is nice to have, but so far I am doing without and I have not missed it yet (for my azimuth-motor solution, see https://www.dehilster.info/astronomy/dome_automation.php). Main advantage of a dome is that you can do maintenance and test-runs while the weather is poor, most ROR domes do not allow for the mount to turn when closed. Domes also do have a downside: whilst very comfortable under windy/cold conditions, the capacity of a dome to provide this also results in what is called dome-seeing. Especially when doing solar (but at times also planetary) imaging the dome seeing can have a significant effect of the quality of the collected data. One way to overcome this, is to have the option to open a door or large window opposite or below the slit to allow a steady airflow (in our case the observatory is 7 metres above ground level and we can have all doors open, creating a chimney effect that brings cool air). Looking forward to your progress on this! Nicolàs

I use an ADC to get rid of the Newton rings. It has the added advantage that you can move the solar disc into the sweet-spot with it. Nicolàs

Those four bolts (six in my pier) are also referred to as a "rat-cage" (or "rat-box" as you called it yourself) of which is said that it would ruin the stability of your set-up. My rat-cage is very low, but friends of mine have 'decent' rat-cages and no issues at all. As long as the bolts are thick enough and the set-up properly balanced, the rat-cages are fine (IMHO that is). Nicolàs