inFINNity Deck

I had exactly the same issue with my Esprit 150ED and solved it in two ways: first I replaced the 1:10 friction type planetary drive for a home-made 1:16 geared one. Once that was done I created a special tool to open the friction version, cleaned and re-greased it and tightened it until it had enough friction to work again. I now use the friction planetary drive for the rare times that I am visual observing with the scope and the geared one for imaging. The friction one now easily holds my 2" diagonal with the heaviest eyepieces I have, which are around 1.2kg. More info and pictures on my website. Nicolàs

ah, did not pay attention, you're down-under... 🤫 Nicolàs

Hi Neil, At the moment I find M13, M27 and M57 quite rewarding DSOs for visual observing and I am sure that others on this forum may have even better suggestions (I am not doing visual observation of DSOs that often). Also keep in mind that you need to look at them using peripheral vision as the centre of our gaze is not very light sensitive. Nicolàs

I image Mars using my C11 EdgeHD, 2x Barlow (so f/20) and ZWO ASI174MM. Getting Mars onto the chip is fairly easy when defocussing and imaging at a relatively long exposure like a quarter second or so. Initial aiming can be done by looking along the scope as Mars is currently the brightest object in the sky and therefore cannot be missed. I defocus the scope to a point that the resulting doughnut does not fit the imaging chip any more, the longer exposure time ensures that the faint doughnut still is visible. In this way the edge of the doughnut will be visible even when Mars is way off the chip. Once framed I adjust my finder scope so next move helps finding Mars even quicker. Nicolàs

The collimation of a RC8 was recently discussed in this forum: As you can read it is not overly complicated. Main importance is to only use two of the three collimation screws to avoid alteration of the mirror distance. Nicolàs

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

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

Next to my C11 I have a SkyWatcher 300PDS Newton (304mm f/4.9) on a Dobson mount, but even though the SCT is not my best friend, I have to say that I find the views trough the SCT more pleasant than with the larger aperture Newton. Nicolàs

Indeed he was asking about visual observing, I was confused by his line "...give me better lunar and planetary images". The larger the aperture the sooner seeing is going to play a negative role in the stability of the image, so less is more when it comes to aperture and seeing as Chris already stated. Nicolàs

That indeed is a key point: the Celestron SCTs do not hold collimation very well, and may not 'survive' a meridian flip due to excessive mirror-flop. I currently have two C11s here, a XLT and a XLT EdgeHD, and both show collimation goes astray when going through the meridian (see the link in my previous line, it is in Dutch but should translate properly when opened in Chrome). I had the EdgeHD serviced by Celestron in the US and apart from a big hole in my pocket it did not have any effect. Celestron did not want to specify the mirror-flop, so I could not check if it was damaged by the return shipment, and apparently this is not something Celestron has control over. Ever since I got it back I first slew to a nearby star, collimate the SCT, and then do the imaging. It then gives reasonable results. I also see nice planetary images being taken with Maksutovs, perhaps that is a good alternative. Nicolàs

Hi Tico, That the Moon gives better result simply is due to its massive size, all the planets are much smaller: the largest planet (Jupiter) is only about 2.5% the apparent diameter of the Sun and Moon (depending on its distance to Earth), the smaller planets only a fraction of that. The advantage of a reflector over a refractor are the additional aperture and focal length for the same price. More aperture means more detail, more focal length means more magnification. Downside of the refractor is that the aperture comes at a price... 😞 Below images or Saturn were shot on one night using a SkyWatcher Esprit 150ED refractor (150mm aperture f/7, but thanks to 2x PowerMate f/14) and a Celestron C11 EdgeHD reflector (280mm aperture f/10, no Barlow). Personally I find the refractor giving a better image with more details and less artefacts. But then I have to say that the C11 was undersampling at f/10, so I should have added a Barlow and then reduce the size after processing. Nicolàs

Hi Ken, like this: From from focuser down to the camera I use: - 2" TeleVue 2x PowerMate - ZWO EFW mini filter wheel with LRGB filters - a 1.25" clamp that allows me to rotate the ADC (although I could do the same by turning the filter wheel in the PowerMate or by turning the PowerMate in the focuser, but in this way I find it easier) - a 1.25" ZWO ADC - another 1.25" clamp that allows me to rotate the camera in respect to the ADC (although I could do that in the T2 to 2" adapter as well) - a T2 to 2" adapter that allows me to swap the ASI174MM for the ASI290MC without the need to refocus - the ASI290MC or ASI174MM camera The T2 to 2" adapter is very useful for adjusting the ADC when you want to image in mono as even within the bandwidth of the monochromatic filters dispersion will occur. So when I image in mono I first attach the ASI290MC, adjust the ADC using ASICAP (please note that the FireCapture ADC tool is not functioning properly), and then swap the ASI290MC for the ASI174MM. Using this adapter causes the two cameras to have the same focus position. Before I used a T2 to 1.25 adapter that screws into the camera, but when doing so both cameras have different focus points and that affects the setting of the ADC again. The combination of the 1.25" clamp and T2 to 2" adapter creates more distance between ADC and camera, which makes it easier to adjust the ADC due to the longer path. Prior to imaging I slew the C11 to a close by star and collimate it. Nicolàs

Hi Vladimir, thanks for your elaborate and interesting answer. I have to say that I image using FireCapture and it seems to handle histograms very well. As soon as I go over 100% the image clearly shows overexposed areas, so it seems to do its calculations in respect to the bit-depth of the image, but I could be wrong there. Mars I never tried at f-ratios higher than f/20, but I will try next time at f20 and f/40, see how that relates to each other and to the theory. Nicolàs