symmetal

You look to be familiar with the RASA and its design features, so much of what I said you probably knew. 😊 The UFC pieces you ordered are the same as I have, apart from also having an M54 camera adapter for the ASI6200MM. I also have the Celestron dew heater ring, though with the heat given off by the camera when cooled, it may not be necessary. The 3D printed tube insert I made does cover those threads on the clear filter mounting. The inside surfaces of the UFC sections are also not that dark, so I made the tube to slide inside it, which holds it nicely in position. Yes, the mirror support on the V2 is very stable. I was concerned that a meridian flip might cause it to flop a little but there is no change in focus after a flip. One corner has very slightly different star shapes after a flip but not enough to noticeably affect the image when stacked. One thing I recommend is not to let it fall when lifting it onto the mount like me. 😭 Luckily the only damage was the corrector plate and the guide scope, which took the initial hit. All fixed now. Alan

As long as it's secure when done up properly is the main thing. Hope it fits well with the UFC plate. I noticed on your video that the ring holding the clear filter in the front of the lens group is protruding beyond the front face. On mine it's slightly recessed when done up. I have the UFC system too. The vignetting is rather severe using the stock M48 adapter, particularly with a full frame camera and the UFC system is much better. The Baader adapter plate isn't conical like the M48 adapter so sits flat against the front face. The protruding ring may fit inside the opening on the Baader plate though as I had to make a conical insert as mentioned below I'm not sure.. There also looks like a flexible, possibly anti-reflective insert sitting inside this ring too which wasn't on my RASA. If using the UFC system with external filters you'll want to remove this clear filter anyway. I found quite noticeable relections and coloured spectral flares from bright stars outside the camera FOV when using the UFC system. The Cloudy Nights forum has many posts about this issue and seems to be reflections from the edges of the lenses in the lens assembly which are not visible using the M48 adapter as they are blocked by the vignetting. Removing the clear filter from its mounting ring and fitting the mounting ring back in place helped as it obscures the edges of the lenses to some degree, but to fix it properly I 3D printed a tube with a conical front end which sits snugly inside the UFC aperture from just before the UFC filter holder up to the front edge of the removed clear filter holder. I then sprayed the inside of this tube with one of the rather expensive 'super' black paints. The tube has 0.8mm thick walls so is rather fragile but when fitted in place shouldn't need handling very often. This fixed the issue for most images, though a bright star on the edge of the scopes 52mm imaging circle may still cause some issues. You will probably have some tilt issues unless you're very lucky, due to the extremely narrow depth of focus, and the UFC tilt adapter is worth getting, though it is rather expensive for what it is. Much easier to adjust compared to the camera front tilt plate though. Don't rotate the camera to frame the shot either or you will almost certainly introduce some new tilt. Align the sensor long edge parallel to the RA movement direction and leave it there. If the framing isn't what you want just do a mosaic of two panels. At f2.2 it doesn't take long to complete a panel even with narrowband. 🙂 Good luck. Alan

I thought you were using the SXT separate star layer to add back in but that's not the case. Maybe using curves to stretch the stars rather than the levels centre slider you can get more control on what stars are brightened and end up with more variation. Alan

Ah! I'm with you now. Yes that's certainly not right. Mine was fairly stiff to turn when new but freed up after a few tries. Is it a new RASA 11 or a previously used one? If new contact your seller who should sort it out. If used do the threads look well worn. A replacement locking ring may help. Hope you can get it sorted quickly. Alan

Congratulations on getting a RASA 11 🤗 Are you saying you can't screw it on any tighter than you have it. It should keep screwing on until the inside edge of the retaining ring meets the lens group front surface, so I'm not sure why you can't screw it on any tighter. Note that the inside edge of the retaining ring has a surface at 45 degrees or so to the lens assembly front surface. When you drop the M48 adapter inside the retaining ring its edge should be free to move up and down over the over the 45 degree surface until the retaining ring is screwed onto the front lens group, when the adapter edge will sit flush against the lens group with the retaining ring holding it firmly. The 45 degree surface allows the m48 adapter to move left,right,up and down while being tightened, and end up coaxial with the lens assembly rather than possibly having it sit slightly off centre when tightened which may be the case if there was no 45 degree angled surface to ride on. When new the edge of the M48 adapter may be too sharp, where instead of riding around over the 45 degree surface it digs in and jams causing it to end up tilted when screwed onto the lens assembly. It can then have some wobble in the adapter until it unjams and sits correctly. Mine initially did this and I just ran a piece of fine emery paper around the edge of the M48 adapter to remove the sharp edge and allow it to move freely which fixed it. Alan

That's quite spectacular Adam. 🤗 Loads of detail I haven't seen before. It has it's own 'Pillars of Creation ' too. 😃 It seems the one of the main stars illuminating the nebula and causing the 'pillars' is BD +66 1673 which I've highlighted here, and is one of the hottest stars within 1 kpc of the Sun and has a luminosity 100,000 times the Sun. It's also an eclipsing binary star. It looks innocuous but all the pillars are pointing at it. Where are you finding the clear skies to do these long exposures? 🙂 Alan

Thanks Olly. It's possible that SXT is not preserving all the individual stars when the density is very high and may be combining or omitting stars when creating the star layer. In the 'normal' stretch above the stars above Deneb are much denser than those in the dark patch below it but in your separately star stretched composite image the density is very similar. it would be interesting to see what it looks like if you gave the separated stars image the same stretch as the background and added it back in. Does it look like the image above? 🤔 Regarding the background stars all having a similar brightness, at short focal lengths several faint stars will fall on the same pixel and register as one brighter star Certain image scales may show this effect more than others. When rescaling to 80% the algorithm used will affect the star shape/size too along with jpeg compression of course. Alan

Excellent image with plenty of detail. I don't recall seeing the 'tentacles' hanging down in other images. Alan

Well done to all involved on such a large endeavour, but can I ask what happened to the Milky Way stars? On the large image the background stars are all pretty much the same size and brightness, and there's no change in star density throughout the whole image. 🤔 Alan

Lovely image. 🤗 Looking at images of Sh2-132 I couldn't match it at first until I realized yours is the central portion alone. Like the shafts of blue 'sunlight' too. 😃 Alan

A very good first image. Well done. A bit over processed as Stuart says though the jpg compression probably isn't helping. Stars on the left are showing coma/elongation type artifacts compared to the right side where they're pretty good. You don't say what scope you're using and whether you're using a coma corrector or field flattener, but that's for later images to address. Getting the basics right is the main thing and you seem to have done that well. 😊 Alan

Great image Adam. 🤗 You've captured very good detail, especially in the trunk's eye, or should it be trunk's nostril 😊 More than my narrowband effort does but then I only spent an hour per filter. You were lucky to have such an extended period of good weather too. Alan

Lots of good detail shown. Well done. 🙂 Alan

Some Zwo cameras are not airtight around the sensor with some models being worse than others. The internal cable assembly from the airtight sensor PCB to the rest of the electronics should be fully sealed with silicone rubber or similar, where it passes from the airtight chamber to the outside. If it isn't fully sealed then the desiccant tablets can get saturated fairly quickly as they absorb the damp external air leaking through the seal, and so stop working leading to ice forming on the sensor as you've seen when cooled below 0C. The ASI071 was notorious for this problem so in the end I just cooled it to 0C, when the issue doesn't occur. Changing the tablets or drying them out had little effect as even after a few days kept indoors the problem would reoccur. My ASI6200 will sometimes do this when the humidity is high outside and cooled to -10C so I also just cool this camera to 0C as well to avoid ice issues. The graphs produced by ZWO for dark current are a bit misleading at first glance, as the y axis is exponential and not linear, and the straight line graph makes you think the dark current reduces linearly with temperature which isn't true. If you replot the graph with a linear y axis you end up with this graph which shows that at temperatures below 0C the reduction in dark current is not so significant. The lower graph is just the top one expanded to show it better at lower temperatures. The dark current roughly halves for every 10C reduction in temperature. Admittedly the ASI294 has higher dark current overall compared to some other cameras, (for example the ASI6200 has only 0.003 e/s at 0C), compared to the ASI294 at 0.02 e/s, so a lower temperature will give a more significant improvement on the ASI294, compared to the ASI6200. If we compare that to ASI294 camera read noise which is 1.8 electrons at gain 117, when the HCG (high conversion gain) mode is enabled, how long can we expose an image where the dark current and read noise are about the same. It's about 200 seconds for -10C and 100 seconds for 0C I don't think you'll notice any difference, using 0C compared to say -10C in actual images when all the other noise contributing factors are taken into consideration. With CMOS cameras the noise from the sky background from will swamp any read noise, (or read noise and dark current for that matter) after a few minutes exposure. Or even less time in areas with more light pollution. This makes the sky background noise the dominant noise source, and the read noise and dark current actually become insignificant. As the ice crystals or dew are in focus they will be on the sensor itself. If they were on the sensor protect window thay would be well out of focus and just give a fuzzy haze over the image centre. Alan

Ah! I'm with you now. You're imaging circumpolar objects towards the North and as the object passes through the line at 90 degrees to the meridian, which passes through the celestial poles and East and West, its azimuth movement direction will reverse. I don't know if this line has a name but it indicates the maximum East or West deviation from the meridian the object will have. Alan

An object is moving parallel to the Alt axis when it performs a meridian transit but the azimuth position is always changing due to the Earth's rotation. I'm not sure if you're perhaps referring to field rotation, which is maximum at the meridian and zero due East or West, where the direction of field rotation reverses. Alan

Great image, one I haven't seen before either. Looks line Nessie is walking through some bioluminescent plankton. 😊 Alan

Both of your images show trailing in RA only, and it is on all the stars, it's just the brighter stars show it up more. You say balance is good, but you actually want the balance to be slightly off in RA so that gravity always keeps the RA drive gears in mesh and it doesn't 'float' between the gear teeth causing the effect you see. So called East heavy balancing. This should show in your guiding though where it's making corrections but the scope isn't moving as the teeth haven't yet meshed. It's only out around 5 to 10% of the total image duration so have you checked guiding for the whole duration. If guiding is good as you say for the whole duration then it has to be differential flexure between the two scopes. I had a similar effect and it was the guide cam locking ring wasn't fully tight. You can get a similar effect if you dither and the capture program starts the next image before the dither has completed. PHD2 does notify the capture software when it's settled after a dither but I tell the capture program (SGP) to also wait until there have been no guide corrections more than 0.2 pixels for 5 seconds before starting the next exposure. Alan

Thanks. Yes, to me, the usual red and blue renditions make me think they're two misregistered images on top of each other which is rather jarring. It seems like adding the SII layer gives a bigger range of colours, which helps blend them all together, although at first glance the SII didn't look much different to the Ha. A full frame camera lets you bin the data, so less exposure time's needed, and still end up with a large size image. I think the RASA 11 was a very good choice in the end. I was in two minds over the cost but it lets you complete a multi-filter mosaic in one session. With the weather here in the UK this is a huge bonus. Changing filters is quick and easy too compared to the RASA 8. Alan

I've reprocessed the data that was showing bad flares from a nearby star as the original was stretched too hard and also clipping some of the blue nebulosity. I've posted a half size version in the Summer Triangle Challenge, 😊 so I've posted full size versions of the three main parts here, along with a half size annotation. I've used a 50:50 SHO and Foraxx palette, as along with the yellows and blues in the nebula it gives star colours that don't look out of place. The flares were easily hidden using the 'Patch' tool in PS as well as they didn't show so much with the reduced stretch. Total of 1 hour of each filter. RASA 11v2 on EQ8, ASI6200MM with Astronomik FastFR filters. Processed in PI and PS. Original data was binned by 2 before processing to keep the image size down, and improve S/N, so it's shown here at 2.5" per pixel. The annotation was done before I treated the flares it seems, so they are present there though not as obtrusive as before. Eastern Veil Western Veil Pickering's Triangle Alan

Here's my two panel mosaic of the Cygnus Loop in narrowband. RASA 11v2 on an EQ8, ASI6200MM with Astronomik FastFR NB filters. One hour of each filter per panel so 6 hours in total. Processed in PI and finished in PS. Alan

Your downloads are the same as the images posted. 😉 The PI STF function will stretch the image until the brightest pixels are near white. If your image has a more noisy sensor like your atik then less stretching is applied by STF until the brightest pixels are near white. Your IMX571 sensor has lower noise so more stretching must be applied to achieve the same level of white pixels. This makes the IMX571 image look more noisy. To compare them the same stretch must be applied to each, so use the HistogramTransformation to stretch the Atik image until the noise is quite evident. Then apply the same HistogramTransformation stretch to the IMX571 image and you'll see it is much less noisy. 🙂 Alan

True. Not bad for an hour with each filter. In most images the background is black so the flares wouldn't show. The central 'spine' doesn't usually show up either. It's interesting that the dust 'revealed' by SXT follows the path of the flares so I'll need to 'patch' out the dust too. There's a bit of diagonal gradient too so I think I'll reprocess it again. Alan

I was going to put the stars back in but stopped when the flares showed. As it may be weeks before I can try again I'll try Photoshop. I find the patch tool (content aware lasso) is much easier at hiding flaws than the clone stamp tool for larger areas. As the flares are in different positions for each filter, when combined they do cancel out to some degree. Alan

So that's what cosmic strings look like. Here's the combined starless image. It shows more detail than is in many Cygnus Loop images making it less recognizable as such, and looks more like an H. R. Giger painting. As a painting the circular flares don't look out of place. Alan