inFINNity Deck

Hi Seelive, glad you read the article. Indeed it deals with 30micron 'pixels', whereas nowadays we use anything between roughly 3 and 9 micron, so the answers in that article need to be corrected by a factor of roughly 3 (for 9 micron pixels) to 10 (for 3micron pixels). Even then, as you have noticed, the errors are not that significant unless you want to do 60m subs (and get overexposed images). In my region (Bortle 5) I cannot even do 60m luminance: my image goes 100% white well within 20 minutes... Only in NB I can manage 20m subs, something I only occasionally do to test my unguided system. Cheers Nicolàs

Hi Stuart, You will find the following article of interest: http://adsabs.harvard.edu/full/1989JBAA...99...19H Nicolàs

Here is the Bubble Nebula on Astrobin, imaged with a SkyWatcher Esprit 80ED and combination of a Canon and ZWO ASI1600MM Cool. Here is another one, imaged with same scope and ZWO ASI1600MM Cool only. So, clearly the scope can perform better at this pixel scale. Nicolàs

According to the original post (under "Background information:") the camera is a "ZWO ASI1600MM Pro binned 1x1 @ -20c." The SkyWatcher Esprit 80 is f/5 (400mm focal length, 80mm aperture). This means that it will produce an Airy-disc (at green light) with a radius of 0.66 x 5 = 3.3 micron, so a full Airy-disc of 6.6 micron diameter. This is just under 2 x 2 pixels of the image. The other way around it is recommended to image with a f-number of at least 3 times the pixel-size, so around f/10. The images shown here are therefore slightly undersampled, but that would not cause these fat round stars (contrary even). It would be great to see the original image at full resolution, but if I look at the noise in the first crop the stars seem to have a diameter of roughly 15 pixels, which seems to indicate a focus issue. Nicolàs

Hi Lostone, According to High Points Scientific the back-focus would be 233mm. On Astrograph.net it is more specifically stated as "233mm from back plate, 127mm from supplied focuser". Nicolàs

Hi Brendan, yes, indeed I get more used to the observatory and the equipment, I now can start up in 5 minutes and start imaging well within half an hour. The biggest challenge is to have several objects ready in the planning, both RGB and NB, so I can choose what to image based on the presence of the Moon. What also helped this year was C2020-F3-NEOWISE, which I imaged 12 times, most times through tiny holes in the clouds. In a similar way I took some 13 images of Saturn last year. Those images only required luminance as it was for two high school students who wanted to determine the orbital periods of Titan and Rhea. Those images could be taken within 10 minutes. Why am I sharing this? Simply to show how much fun one can have even under 80-90% cloud-cover, which makes imaging a fun challenge at times as well. Nicolàs

I count myself lucky to have an observatory, which is in Castricum, the Netherlands. I built it in first quarter of 2018 and started imaging in May that year with first results in June. Despite being not in the best of places I do manage, after a slow start in 2018, one imaging session per week on average as can be seen in below graph. The imaging sessions include planetary and deep-sky. In addition I did some 19 sessions on our own star in this period, but those are not included in the graph. Clearly January and February have not been very rewarding so far and the same accounts for the last two months of the year. Best seasons so far have been April-May and July-September. Yes, the long winter months can be frustrating at times, but it is a good season to do maintenance. The rest of the year the observatory keeps me quite busy... Nicolàs

Hi Olly, interesting, and you are absolutely right: if guiding fails by the same amount in both directions, you will get bloated round stars. I thought that would be as rare as donuts being created by seeing, but apparently not... Nicolàs

- Seeing: unlikely, the stars are very round, so that seems not to be the case. - Donut stars due to seeing: only in the very rare event that seeing and poor tracking will cause the star to make a circle during your exposure. So, no, not possible. - Better performance by electronic focuser: Yes, provided it is used in combination with proper auto-focus software (see below). - SharpCap's seeing monitor: never used it, have no idea how useful it is. - Guiding performance: no, poor guiding will not result in round stars. - Future options: get a decent imaging package like SGP or MaximDL. There are some free packages as well that do fairly well, perhaps others can comment on that. I used the focuser routine of SharpCap myself, but was not impressed, especially when compared to the one built into SGP that I normally use. - Other suggestions: wait for other SGL-members to respond. As far as I can tell your camera was not in focus. Please note that during the night your scope will cool down and as a result of it will loose focus. The imaging packages mentioned above will allow you to check focus every so many degrees, frames or minutes. Nicolàs

Hi Blue Silver (is that your actual name?), I use two ZWO lenses here: the one that came with the camera (ZWO ASI290MC) and the ZWO zoom-lens. The former I use to create time-lapses of the observatory while it is doing deep-sky, the latter I use for catching meteor-showers. I also used the zoom-lens once to catch C/2020 F3 Neowise, which I mainly imaged with the Esprit. You will notice that the quality of the zoom-lens is mediocre, but then, what can you expect for that kind of money? Nicolàs

I recently replaced these two filters for new-style versions from ZWO. They are in mint condition and come in the original packaging. Below two images have been taken with them. The difference between the old style and new style images is that the old ones create halos around bright objects. New price is 205 euro each, asking price is 50 euro each ex shipment or best offer. Nicolàs

Hi Vulisha, as far as I can tell from the tiny scale, this result indeed looks pretty good. I have mirrored your image along two axis: It seems pretty symmetrical in both directions, so well done! Does it also make a marked difference when observing? Nicolàs

Hi Coriorda (is that you real name?), Welcome at the forum! I do not think there is a typical starters focal length, started myself with a 1050mm f/7 apochromat. It is true that controlling a scope with a larger focal length is less forgiving than one with a shorter one, and generally needs deeper pockets as the scopes are more expensive and the mounts needs to be larger. What you will find out when imaging at larger focal lengths is that larger objects may not fit the image size and needs mosaicking (for me the Pleiades is one of those objects as I have a small chip-sized ZWO ASI1600MM Cool camera). On the other hand there are objects that are too small for the RedCat like Stephan's Quintet (even on the small side for my apo). What you can and cannot image in a single frame can easily be checked using free software like Stellarium. In it you can define your scope(s) and camera(s), select an object and then see what the framing will be. At some time in future you will therefore, just like me, find yourself considering getting a second camera and/or scope for objects that are otherwise difficult to image (for me this would be a SkyWatcher Esprit 80ED with a focal length of 400mm). Nicolàs

Thanks John, that explains why I have been unable to find a larger FOV eyepiece. Sadly enough the C11 does not accommodate larger barrels, will have to use a different scope then for wider views. Nicolàs

Dear forum members, The C11 EdgeHD in my observatory is used for planetary imaging and visual observing. For the latter I have a range of TeleVue Ethos eyepieces and one TeleVue Panoptic eyepiece of 41mm. The that last one I have a reasonable wide field of view, but would appreciate an eyepiece with an even wider FOV. I have seen several 55m eyepieces (like the 2" TeleVue 55mm Plössl-oculair), but those all have apparent FOVs that are so small that the resulting FOV is smaller than what I get from the 41mm PanOptic. Are there any options left, or is the 41mm PanOptic as wide as I can get on a C11? Nicolàs