Imaging with the 130pds

[Stub Mandrel]

So near but so far last night...

I left my SD card at home which wasted half an hour fetching it. I also forgot my dewshield.

My shots of M81 and M82 were washed out by light pollution and moonlight, while my attempt at a faint nebula in Auriga lost to the moonlight and condensation

A final run on M42 as the moon was going down showed how close I was to decent data. This is just a screeen grab of a stack, crudely processed, you can see the promise ruined by the blur caused by condensation...

 

[Uranium235]

First of last nights efforts, not the best night to be out (moon and dodgy sky) - I guess thats alright for just over 1hr per panel (x2):

Taken with the QSI683 10x450 (L) x2

 

[Susaron]

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

 

[JohnSadlerAstro]

13 hours ago, Susaron said:

Maybe in north Europe (and UK) you have better weather than in the South these days.

I think not. 

Really nice starfield there though! The Milky Way is so crowded. ?

John

[gazza]

Tarantula

249x60 sec lights, Bias, Flats, no Darks

ASI071MC Pro

130PDS/Skywatcher .9x Coma Corrector

Bortle 9 Zone (Red Zone), 1/4 Moon

cheers

Gary

[Atreta]

11 hours ago, gazza said:

Bortle 9 Zone (Red Zone), 1/4 Moon

? impressive for a bortle 9 sky. What filters did you use? 

[gazza]

1 hour ago, Atreta said:

? impressive for a bortle 9 sky. What filters did you use? 

Only an IR blocker...used Astropixel Processor for stacking and PI for processing - used ABE in PI to remove gradients - did a great job, other wise it was only stretched. No sharpening at all - the wavelet stuff in PI smoothed background , but reduced detail so I didn't use it in the final image.

My skies suck - I'm 1.5km from the Central Business District of a city of 250K + people, I can only image in the East which looks directly over the central city. I have nights where I can barely see 6-8 stars ?

This was a test of whether I could image with OSC here, as well as a test of the 130PDS.....

Gary

[Atreta]

4 hours ago, gazza said:

This was a test of whether I could image with OSC here, as well as a test of the 130PDS.....

That test went really well then,  looks like pixinsight did its magic

Could you post or pm me a picture of how it looks like without processing? 

Thanks 

[gazza]

2 hours ago, Atreta said:

That test went really well then,  looks like pixinsight did its magic

Could you post or pm me a picture of how it looks like without processing? 

Thanks 

PM'd you a Dropbox link to a calibrated only fits file - let me know what you think

cheers

Gary

[Stub Mandrel]

9 hours ago, gazza said:

as well as a test of the 130PDS.....

Looks like it passed ?

[Susaron]

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

 

[Susaron]

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.

[Seanelly]

This is a remarkable image. Inspiring!

[gazza]

after looking at lots of the images in this thread, as well as my own test, I have to say who needs an FSQ106? ?

Gary

[Adam J]

58 minutes ago, gazza said:

after looking at lots of the images in this thread, as well as my own test, I have to say who needs an FSQ106? ?

Gary

People who cant colimate a newtonian and dont like diffraction spikes. Its got to be said thought that this is all without the use of even a premium 4 / 3 element coma corrector etc.  My personal thought on the matter is that a premium edition of the 130PDS with premium focuser and a carbon fiber tube would sell very well, I would buy one at any rate.

Edited November 22, 2018 by Adam J

[gazza]

26 minutes ago, Adam J said:

People who cant colimate a newtonian and dont like diffraction spikes. Its got to be said thought that this is all without the use of even a premium 4 / 3 element coma corrector etc.  My personal thought on the matter is that a premium edition of the 130PDS with premium focuser and a carbon fiber tube would sell very well, I would buy one at any rate.

As would I in a heartbeat!  I also wonder if it's worth an extra 4 and a half thousand quid to get rid of diffraction spikes  !!!

Gary

[Adam J]

21 minutes ago, gazza said:

As would I in a heartbeat!  I also wonder if it's worth an extra 4 and a half thousand quid to get rid of diffraction spikes  !!!

Gary

I think that the biggest factor is the larger flat field that can cover a full frame camera.

[Susaron]

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.

Edited November 22, 2018 by Susaron

[Susaron]

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

 

[Adam J]

3 hours ago, Susaron said:

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.

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.

Edited November 23, 2018 by Adam J

[Susaron]

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..

 

[Adam J]

1 hour ago, Susaron said:

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..

 

Ill disagree with you that you would not have to refocus a 130PDS between 15c and -10c insulation or not. In fact I would say that adding insulation to the tube will just prolong the cool down time of the scope something that is not desirable at all.  I see differences in focus over only 2-3 degrees of temperature drop. Hence why everyone purchases expensive auto focusers. 

I think that most of these CF tubes are around 5mm thick so there you go. 

Edited November 23, 2018 by Adam J

[Stub Mandrel]

46 minutes ago, Susaron said:

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..

 

If I have learnt anything from my dabbling in engineering, it is that if the best engineering solution is the one that maximises performance and reliability and minimises cost and complexity, it rarely satisfies the wants of upgraders.

The performance of the 130P-DS, like any newtonian, is down to the quality and design of its optics, the ability to collimate and focus it accurately and its stability (i.e. how well it keeps collimated and focused in use).

For me, the main improvements would be:

Making the collimation smoother by using a spring loaded arrangement.

A better focus lock screw (I plan to chop the end of the nylon button shorter as it seems to have bent slightly and can put focus out when tightened.

[RolandKol]

I am Not very sure about differences in focus within 5C and even 10C....

I used SGP for a while (been testing it), and always used Image History, which gave image quality statistics like FHM and etc.

I tried to collect data for my future DIY autofocuser, so I will be able to automate the re-focus routine in relation to temp change...

And I have not noticed any radical change in the image quality during all nights.... and temp drop was around 10c.

 

The main problem I have, - focus shift while locking it... I Hate it sooo much as it makes focusing a guesswork... (offsetting focus, locking, Fail, un-lock (focus runs away somewhere unpredictably), re-focus with offset again, locking, focus shifts to opposite side than expected.... .... ... It takes ages...).

If someone has focus shift due to the temp, it will happen with CF body also. Less, but I am sure it will, - and that focusing headache will remain...

My inner "Scrooge McDuck" simply does not allow me to go and buy a better focuser which will cost more than OTA itself! Insane!...

So started DIY autofocuser project... (burned few parts, waiting for new... hope to get them soon).

In this case, I totally agree with Neil.
I will make the collimation smoother (ordered bolts like BobKnobs for the secondary from China, coming in a week or so) not sure if I need springs, I simply tighten the primary bolts quite strongly and my setup is permanent most of the time.

Will deal with focuser's shift/locking problem using DIY autofocuser with a strong stepper motor, -  which is around 4 times cheaper than a Moonlite!

As I have lots of trees around in the garden....  unfortunately, I need to clean my Primary already (scope is 1 year old...)  I will use the cleaning day for Flocking.

Not sure if flocking the focuser's drawtube will cause any optical problems, but I will flock it also....

 

Edited November 23, 2018 by RolandKol

[Whistlin Bob]

I've not had too many problems with the focuser and mine seems to hold collimation pretty well- I check it most sessions and it's usually fine.

The thing I've always thought would be good was a shorter focal length f5 newt to go into the pds range, for a wider angle, so you can really go after some of those giant nebulas like the veil and the California. Wouldn't need to think so much about full frame then. I'd be more than happy to pay a similar price for that.

Sorry if this is getting off topic...