Susaron

Masked stretch preserves colors better, but it creates donuts and artifacts around big stars. I have found it is best to mix with Pixel math (In Pixinsight) a 70% fro Histogram transformation and a 30% from Masked Strech.

After playing with masks you can increase the saturation on the nebula and dark the background.

Cheers.

A reprocess around M8 taken last summer, bad weather has one con, to read and test a lot around Pix.

Latest tunning. The scope cover was broken, so a friend made me one with his 3d printer. 

8 hours ago, Adam J said:

The carbon fiber is not for stiffness its for superior thermal expansion properties that means you hold focus better.

Many premium scopes use CF such as the ES Comet hunter.

Well should it be for both characteristics. The problem is that in order to get the same stiffness from CF than for a 1mm thick stell tube, you need around 5-8mm, what means several CF layers with the appropiate fiber orientation.

Thermal properties and gradients are of course important, but I have been with the SW130PDS around -10C starting from 15C and if you use camping mat around the tube you won´t have to refocus in a 5h session. So invest 300 pounds in CF for a SW130PDS tube I think IMHO is useless, maybe a stronger spider with be a best improving opportunity with better collimation knobs etc..

Just one more reprocessing that could hurt your eyes....sorry for that.

Well for the SW130PDS a premium focuser is available at FLO, that´s what I did when talking with Moonlite to design a specific adapter for this scope.

But what I don´t see is the carbon fiber as material for it. The carbon fiber offers better strength as the diameter increases (related as well to the Inertia Moment of a cylinder of course). Maybe only a composite made of a sandwich structure with a core thickness of 10mm would be a good candidate in terms of structural performance.

PS: for the record I do work as composite manufacturing engineer in an aerospace company.

A reprocessed file from NGC6819 Foxhead cluster, it was taken beside Barajas Airport (Madrid) Bortle 9 or 10 but pointing outskirts the city and with 30 secs exposures you can deal with LP (also the IDAS helps). 100x30sec subs calibrated with darks and bias.

A new one believer for the community. What a capable imager is the SW130PDS.

Another reprocess to M7 with sharpest detail, maybe in north Europe (and UK) you have better weather than in the South these days.

These cloudy days I am reprocessing some of the 2018 SW130PDS "Greatest Hits", as long as I am increasing the knowledge on the tricks of PixInsight.

Here I leave you some of the pics.

Cheers.

Mario.

Mount, point and shoot....?? Unfortunately It is never as easy.

No hurries at all, many thks

I will be very gratefull if you could post a picture or screenshot with the parameters you use in APT to control dithering.

3 hours ago, smr said:

I'm still yet to get around to buying my first refractor. 

As the ED72 has been out for a few months now, I have a couple of questions...

Firstly, will it hold the weight of my Canon 80D DSLR? It's an APS-C DSLR and weighs a bit more than a Canon 700D but not more than a 7D Mk2.

Secondly, how easy is it to achieve a good reliable performance. Ideally I would want a refractor which I can just plug things into and it works, because I come from a photography background where you just pop a lens on and away you go, so spacing, and measuring, and back focus distance is all alien to me. Would it be easy enough for me to achieve, if someone would be so kind as to tell me what I need and give clear instructions as to how to go about fitting everything together.

Or 3) Would it be too much hassle and would I be better off buying a refractor like say, a Z73 and just buying the flattener for that and everything works straight away?

That's where I am at, any help or advice would be greatly appreciated.

Let´s go little by little.

1st Weight: I own a QHY168C cooled its weight is 700 grams aprox. plus the weight of the flattener-reducer and spacers I guess the total weight for the imaging trains could be around 1kg. At least I haven´t seen tilt or slip on the focuser.

2º As the QHY168C sensor is an APS-C from Nikon, I would recommend you the TS x0.79 reducer flattener in order to achieve focus. For a usual DSLR the distance from the M42 thread from the flattener to the sensor use to be 55mm, but with the TS reducer and this scope of 420mm focal length you will need 65mm. So the math is the following

Focuser + TS reducer + Extensors +M42 to Canon Bayonet (like this https://www.teleskop-express.de/shop/product_info.php/info/p194_TS-Optics-T2-Adaptor-for-CANON-EOS-Cameras.html)

The problem is that in TS page they do not specify the thickness of the M42 to Canon adapter, something important you need in order to achieve a perfect field with any refractor.

A list of M42 (T2) extensors with different thicknesses are available.

https://www.firstlightoptics.com/adapters/baader-t2-extension-12-16mm.html

https://www.firstlightoptics.com/adapters/t2-extension-tube-set.html

You should ask FLO or TS or any other dealer to get the data

"If you see Ghosts"

Composition of the C4-NGC7023 Iris Nebula with vdB141 The Ghost Nebula in Cephei.
3hours of 300s subs from La Mancha fields in Spain (Bortle 4 skies) at Gain 10, Offset 30, Temp -10C.

Pacman Nebula from La Mancha (Spain)

36x180s subs + darks + bias + flats.
QHY168C (G=10;O =30, T=-10ºC). + Optolong L-Pro + SW130PDS+AZEQ5+Baader MPCC+APT.
Not very happy with the light traces coming from Alpha Cas. Also my main mirror seems to suffer from astigmatism.
Postprocessed with Pix following Keller´s book.
Cheers.

Unbelievable

Looking at your work @Uranium235 I am seriously thinking on purchasing next year the new QHY550M, with a 3.5 micron pixel and a 2/3 sensor it would be a wonderfull add to catch planetaries nebulae and individual galaxies.

Cheers. 

More test from yesterday night using an Optolong Halpha filter it also achived focus, so deal done with the TS reducer. 25x60s subs around Mirphak an Mel 20. Also the result from the aberration analysis at the squares from Pix. My polar alignment was non-existent so the guiding suffer (but not much as I was shotting at 332m).

Cheers.

Mario.

I have recently discovered that my SW130PDS showed "weird" stars at the corners, the stars looked like pinched X shape stars, so after asking some friends they told me It could be that the clips which hold the mirror very tight thus creating astigmatism and stress on the mirror. The trick here is to leave an space of a sheet of paper equivalent thickness between the mirror and the clips.

I say this because I have seen the same effect in some of the pictures in this thread.

Best Regards.

Mario.

I just did a short test around Mirphak, as from my balcony I cannot see the Polaris, the stars looked good in 3 of the 4 squares, maybe the error comes from flexure or poor polar alignment.

True, I need an extra 1kg at the nose, one of those from baader

This evening

Dear all, finally I could test the TS x0.79 reducer with the ED72, my calculations where almost perfect. The focus point for my QHY168C with a distance between the sensor and the reducer of 64.5mm is around 17mm outwards so I got enough margin.

From my point of view this reducer shall be recommended for the ED72 accessories if you own an APS-C like sensor (ASI071 or QHY168C).

I took only fast pictures of Mirfak so I will check the stars at the squares this afternoon.

Cheers.