wimvb

The optics in a SW is good enough. It's the mechanical part that's their weak side. Focusers are most often the first to go. The standard crayford can be replaced by something more sturdy. Maybe a Baader diamond steel track? TS even sell a carbon tube as a replacement for the 150pds steel tube. All the holes are pre-drilled or pre-cut. If you consider a Newton telescope as an optical platform, rather than one single instrument, then swapping parts makes sense. The TS Photon scopes are fairly new, but probably a good alternative to sw. As I wrote before, the Photons are one part in a TS offering, from budget (ts photon) to high end (ts n-ag). And while the parts may come from the same factory, it's the difference in quality that sets them apart.

You really need to ask yourself what you want to do with the new scope, and how accurately you want to do that. For astrophotography, requirements are different than for visual use. Do you just want a larger aperture, or do you require a stable mechanical system? AfaIk, the most stable ap reflector you can get has a carbon fibre tube with a quartz or pyrex mirror and a fan to speed up cooling. The focuser needs to be stable as well, which often translates to: needs to be upgraded. Within your budget, that may mean that you should be willing to a) buy used, or b) settle for a smaller aperture. An 8" f/4 or f/5 ts photon with carbon fibre tube can be had for 949 €. The metal tube equivalent is at least 500 € cheaper. Regardless, you need to add a coma corrector. One which gets very good reviews is the SW/GPU coma corrector, for 235 € (Baader mpcc is about 170 €, I believe). Personally, I would (and am) save up for quality. "Buy once. Cry once."

Btw, Lacerta offers a photo newton with quartz mirror. It costs 300 € more than the non-quartz version, and is marketed as "zero expansion". With a carbon tube, it's supposed to be veeery stable. That may very well be true.

Depends on who you ask. I have a thread going just about that. The concensus is that optically it doesn't matter which type you have, since glass only carries the reflecting surface. But thermal properties are important. (Quartz has the lowest thermal expansion.) And thermal properties affect optical performance.

Have been looking at those. The carbon fibre versions are almost twice as expensive as the steel tubes. But more stable, and less weight. 900 "quid", that's a bit over 1000 €: https://www.teleskop-express.de/shop/product_info.php/language/en/info/p5032_TS-Optics-UNC-200-mm-f-5-Newton-Teleskop-mit-Carbon-Tubus.html TS market all kind of variations of these scopes; from TS Photon to UNC to ONTC to N-AG (Astrographs). Differences between these scopes may be in the thickness of the carbon tube, mirror quality and material (quartz, pyrex or BK glass) and the quality of the focuser.

In its cradle. That ladder reminds me of pictures I've seen of those gigantic 19th century scopes with brick wall mount.

Increased sharpness is mainly determined in the deconvolution step. HDRMT only increases local contrast. Deconvolution 25 iterations, deringing 0.11 I believe, regularisation on two layers. HDRMT 4 layers to lightness with the lightness mask option checked. Blend 50% with the non-hdr treated image.

Tried a variation of LRGB combination on this image: L*a*b* combination. Basically like this: created a synthetic luminance (image integration of R, G, and B masters) and a standard RGB image. Crop, DBE, BN, CC followed by masked stretch for the RGB image. Then decomposed into L, a, and b Processed the synthetic luminance for maximum detail, using HDRMT, some star reduction, etc Then combined the synthetic luminance and the a, and b images in L*a*b* combination. Finished off with chroma noise reduction.

It's easier to use the combined r, g and b images as a synthetic luminance. The artefacts are only on the L image. The synthetic L is much cleaner and easier to process. And since the colour images weren't binned, they have the same level of detail. Btw, I love those tight stars in your image. Yes, PixInsight is a power tool, and you need to learn how to tame it. As I've said before: it's the driver and not the car that gets you to your designation.

Since your L master has a few nasty dust bunnies, I created a synthetic luminance in PI: ImageIntegration of the R, G, and B masters. Average combination, no pixel rejection. After applying a few passes of DBE (division as correction, because the only visible gradient has a circular pattern = vignetting), the background is flat and can take a lot of beating. I'm now doing deconvolution to reveal detail in the galaxy. Seems to work quite well.

Just to show what the "traditional" PI workflow will achieve: RGB combination of your colour masters, no linear fit DBE subtraction, checking the "normalize" box in corrections Background neutralization Colour Calibration using the galaxy as white reference Masked stretch, default values but target background reduced to 0.1 Saved as jpeg

An "embossed" circular artefact is most likely a dust bunny that moved between taking lights and taking flats. As it only shows on the L master, it's located on the L filter, and probably moves a little when changing filters.

Atm, my mount is parked in the same position.

So true. If there was such a thing as a best post challenge, this would be the winner.

I use indi on a rock64 single board computer. Ekos/kstars on winows as a client. This works for me with an ASI174MM. AfaIk, all zwo cameras use the same type of drivers, ascom (windows) and indi (linux) compatible. My solution for focusing is an arduino based SW motorfocuser that uses the moonlite protocol. Also controlled from indi & Ekos. Uses short exposures for focusing.

Like many of us, I had few clear nights. Last summer I got a new camera, mono cooled cmos replaced dslr. This one with a Pentax K20D on a SW EQ3 PRO, 135 mm fl, f/5.6 (I think). The following are all with the mono camera. SW Explorer 150PDS on SW AZ-EQ6, ZWO ASI174MM-Cool with ZWO LRGB First light, M27 Iris neb, ngc 7023 M110 (ngc 205) ngc 6946 (Click on an image to view a larger version)

Nice image of the Horsehead. The gradient is due to light pollution. A filter will make it less, but probably not remove all of it. Gimp doesn't have tools for AP as PS does, but you could try the following crude method. Make sure your image is not clipped. You need to replicate the gradient in some way (that's what DBE in PI, and Gradient Exterminator in PS do), and Gimp has a gradient fill tool. You could try using that. Sample two colours with the eyedropper tool. One becomes the foreground colour, the other the background colour. Create a new empty layer. Use the gradient fill tool to replicate the gradient in your image. Then subtract the two layers. Make sure this doesn't clip the image. You may need to do this in several small iterations, rather than one big swoop. It most likely won't remove the gradient completely, but it may make it less intrusive. I think there should be enough cloudy nights even where you are, to give you time for this kind of experimentation. Good luck. (Btw, I haven't tried this myself. There's always a risk that it won't work at all. )

Same here. I have more opportunities to take pictures OF my setup than WITH my setup, so here's a picture while taking flats after one such rare occasion.

Nice first images @StaceStar. Now just repeat a few dozen times, stack, and you're good. Welcome to the dark side.

Fwiw, here's my linear workflow. Maybe you find something you can use. 1. Crop edges - dynamic crop 2. DBE, using few but large samples. Place samples manually. Sample size 15 pixels or larger, the largest size that fits between stars. Correction method depends on cause of gradient. I always do a test without correction applied to examine the bg model. Depending on how it looks, I adjust the number, placement and size of samples. I always go for a background model that is smooth with no structure, and few colour variations. Adjust tolerance until all samples have a weight in all channels > minimum sample weight (0.75). Check normalise, discard bg model, replace image. Apply correction. 3. Define the largest possible preview in a bg area. Use this for background neutralisation. If there's very little background, I create several small previews and combine them using preview aggregator script. 4. Use the same preview for colour calibration as bg reference. Depending on target, use either with or without structure detection for white reference. If using an aggregated preview, this needs to be made fresh. 4 alt. Use photometric colour calibration with preview for bg neutralisation reference. This procedure gives good colour variation in star fields. ... For stretching, I use Mark Shelley's arcsinh stretch. This is superior to any other stretch I've used regarding star colour. Don't overstretch. A weaker stretch followed by curves transformation usually gives better results than one aggressive stretch. I hope that some of this may be of use.

Lovely image. I'm a bit confused about your process flow, though. 1. Do you separate colour channels of your dslr image? 2. Colour calibration after scnr:green may very well put green back in again. Personally, I always do colour calibration immediately after background neutralisation. Otherwise the neutral background that cc needs, may not be neutral anymore.

I ran mine off a 12 V leisure battery until I got a mains adapter. The synscan manual specifies 7.5 - 12 V. With short the fl and low load, the mount performs very well. As is consistently demonstrated here. The weak points of this mount are the aluminium tripod and the flimsy altitude adjustment bolts.

Nice catch. The star trails you have in the Orion image are actually a good way to see "real" star colour. In your case, they also show that you had excellent sensor alignment.

With just camera and lens (135 mm) I've used mine with no, or only the small counterweight. Unguided up to 7 minutes, with relatively few discarded subs. Runs fine on batteries. But if you have an outdoors mains outlet, I would consider using that. Be prepared to tinker with it, removing backlash and adjusting the gears. With the aluminium tripod, I would consider this a portable setup.

That's "low noise" season in all its splendor (assuming you're into imaging, Les). My main concern isn't so much ice on the scope, as it is cables getting stiff and brittle when it's really cold.