wimvb

I caught a gap in the clouds and am testing some more. Now I've set a fixed period of 120 s and tweaked a few parameters (such as single sided DEC guiding). After a few periods, the guiding rms is down to 0.63", half my imaging scale. I'm pleased.

How about the focuser extension tube? Is that set firmly in the draw tube? I had to fix it with a "shim" of aluminium tape, taped on one side. I wanted to tape three narrow strip evenly distributed around the extension, but one strip already fixed it in place. Clearly not much play to start with, but still too much to leave as it was. Is that with the TS concentre cap? What software do you use. Mind you, I only have a small sensor camera on my scope, so it would be difficult to measure flatness over the entire field.

You have figured out collimation by now, but there are a few old threads on this forum and iceinspace, about collimating the MN190 which could be of interest http://www.iceinspace.com.au/forum/showthread.php?t=140193

Single wavelength, multiple rays, you mean? 😉

I kept the settings at default for this session, just to get a baseline. Last season ended for me with almost erratic ra guiding, which turned out to be caused by too low belt tension. Honestly, I also expected this 120 s period to be guided out, and with ordinary guiding, it probably would. But ppec uses a combination of proactive error correction and reactive guiding. As such, I would think that the reactive part is less aggressive than usual. Next session I will concentrate on dialing in the settings. Presetting a 120 s period in ppec guiding should give better results. SW have also done a rather sloppy job with the belt drive in my mount. The ra timing pulley is visibly eccentric. It may only be the top flange that is off centre (in which case it shouldn’t affect tracking), but just in case, I have ordered new pulleys from beltingonline.

Thanks. The jury is still deliberating on this, so to speak. In PHD I always use the PPEC guide mode, so if it's just as good, and I can do the same in Ekos, that means one less piece of software to bother with. I also still need to dial in the settings, as the algorithm missed a 120 s period that was quite strong (I had preset 480 s). The multi star algorithm had no problem finding 6 or 7 stars to guide on. And that was away from the plane of the Milky Way, with a simple asi120 camera. It also picked some areas where there were no stars, and I see the need to create a dark library for the guide camera. I also wonder if my limited fov is enough to average out seeing, which is the purpose of multi star guiding. As long as it works at least as good as single star guiding, I'll keep using it. In short, it takes a little effort to dial in the settings for the new routines, but they are enough plug and play to use them as is. And let's face it, PHD is hardly "push here dummy" anymore either.

This target was chosen by chance, because after having set up my equipment, I wanted to test it, especially guiding. I used the new guiding routines in Ekos/Kstars: multi star guiding and predictive PEC guiding. During summer recess I took my mount apart and cleaned and regreased it. I also increased tension in the RA belt. This improved guiding, but I still have a 120 s periodic error that wasn't guided out yesterday. The timing pulley attached to the RA motor is not quite centered. I have ordered a new pulley from beltingonline, which hopefully will resolve this issue. Anyway, here is Arp 170, or ngc 7578 The main galaxy in this image, ngc 7578, is located approximately 550 Mly from earth, and even most of the other galaxies that you can see are at about this distance. I identified only one galaxy that is more than 1 bilion ly from us, it's hardly visible as a small red dot near the upper edge. 2 hours of RGB data (no Luminance), processed in PixInsight Equipment: SW MN190 on a SW AZ-EQ6 with oag ZWO ASI174-MM Cool camera with ZWO RGB filters Software: Ekos/Kstars for acquisition PixInsight for processing No flats yet, so there is vignetting left in the lower left corner. (click on the image to get to the larger version)

"You're da man", Olly.

Not if you're from down under. 😉 Personally, I don't care too much about image orientation in astro images, unless there is a definite asymmetry. The horse head nebula should never be mirrored, for example. The blue was weak to start with, and I didn't want to push the colour noise too much. This image should ideally be reworked from the original data. But that would be a major process. Maybe. I use background neutralisation and colour calibration in pixinsight. These processes work on the three colour channels simultaneously but in the same manner as linear fit does on mono images. Because I didn't know the pixel size that was used, I couldn't apply photometric colour calibration.

Quelle horreur

Thanks, Olly. It is a bit stellar indeed. I wanted to show the very faint structure near the core. Normally I would spend more time on the hdr process that I used, and probably blend the 20 s master image into the 120 s master. For this image, I only used the 120 s master.

Here's my version. As @ollypenrice already noted: before stitching panels together, they need to be flat and have the same background level. I could reduce the gradients somewhat, but they were eating into the galaxy. Anyway, as always: messed up in PixInsight

Using a process to reduce noise and sharpen details at the same time, seems counterintuitive. Noise reduction is done on the darker, low snr areas, while sharpening is done on the medium and bright areas. But it works. In your image, the smaller stars are blocky (undersampling? or a starmask that masked too little?) This can also be the result of deconvolution. For deconvolution to work, the image needs to be oversampled, rather than undersampled. To reduce noise further, try mmt on chrominance only, but quite aggressively on up to 8 layers. With a mask that protects the stars and nebula, this neutralises the background colour noise, but preserves all the fine detail. https://jonrista.com/the-astrophotographers-guide/pixinsights/effective-noise-reduction-part-2/

Putting a 150mm on an eq3 is pushing your luck. The scope itself is already near the load limit of the mount, but more important, the 150/750 is like a huge sail for that little mount. Imo, a small reflector, such as (up to) a Sky-Watcher 80ed, will be a lot easier for this mount to handle. if you go for a newtonian for astrophotography, get a P-DS scope (parabolic, dual speed). The regular P-versions may not come to focus with a camera attached. Also, keep the focal length short on the eq3. A long fl scope is more sensitive to vibrations and tracking errors.

Ok. I have no direct experience of any of those scopes, but I wouldn’t want to push the limit of the SA. So, not the SW 80ED. The SW 72ED and the WO 73 are very similar in fl and ”speed”. But is the WO ”, even though it’s an apo, worth more than double the price? You could have a look on astrobin and compare the images that both scopes produce. Not exactly a shoot out, but imo a decent indicator of what to expect from these scopes.

I think that a 12v leisure battery can do the job. But if you want something fancy, you could go for this https://www.firstlightoptics.com/batteries-powerpacks/skywatcher-powertank-17ah.html Although I have no idea what a siren is good for in astrophotography, or a big flashlight for that matter.

Aka low noise season, for those who don’t have a cooled camera. Batteries?

I agree. A bit of ringing around the stars, probably from deconvolution. But overall a great improvement. You’ll notice that processing becomes a lot easier if you gather more data.

Doesn’t mmt (multiscale median transform) in pixinsight do the same?

200 mm? Those collimation screws could be the cause of a nervous break down. The MN190 at least has phillips screws recessed in a "well". Progress!

If I had the funds and time for it, I would buy one and replace rhe secondary mirror with a smaller one. SW redesigned the scope at various occasions and among other things, replaced the original secondary with a larger one to cover larger sensors. But this affected contrast. A smaller mirror (combined with a small sensor) should bring this scope even closer to apo performance.

The MN190 isn’t any more difficult than an ordinary newtonian and it holds collimation well. Just, whatever you do, don’t mess with the secondary offset. I use a barlowed laser for collimation, and after I collimated my scope yesterday, it was spot on according to my cheshire. The primary only needed a tiny bit of tweeking. And that was after I accidentily bumped the rear part in a door post when carrying it from summer storage to my obsy. (A mild bump with no damage to either scope nor door post.) The tube is heavy for a Newtonian, but not compared to a refractor. Your eq6 should have no trouble carrying it. At f/5.3, the maknewt is no more critical to focus than any other scope of that ”speed”. The low profile focuser works well, once you fix the included extension. On my scope, there was some play in the extension, but it was easily fixed with a strip of aluminium tape between this extension and the draw tube. I have heard rumours that Skywatcher is discontinuing the MN190, so grab one while you can.

A high tech solution: use a drone with camera. Rotate the hovering drone after each sub. Then you can also try guiding on that drone. I wonder if phd is up to that job?

To get rid of spikes on a Newt: put the secondary in a glass plane in front. Then to also get rid of coma, curve that glass. The camera is in the right place so as not to cause additional diffraction. For an example of such a scope, see my signature.

Forget about Redcat, that solar panel looking contraption won’t even fit in my obsy. I wonder if they are going to use Pixinsight or APP to stack all the subframes.