Imaging with the 130pds

[alacant]

 

Hi

13 hours ago, Whistlin Bob said:

they're sexy and people who don't like them are just wrong

Correct😀

3 hours ago, Space Oddities said:

not sure whether I like spikes

We believe that they ought to be made compulsory but, if you really must, you don't have to have them:

https://garyseronik.com/how-to-build-a-curved-vane-secondary-mirror-holder/

Cheers

[Rob F]

I like the spikes and love my 130pds. I’ve 
been having issues lately where the stars are round and sharp on one side and fuzzy out of focus on the other side. I have sie my time with collimation and focusing with a bahtinov mask. Not sure if this is due to using my CLS filter and or the mirror baffle. Waiting for a clear night to remove the filter and see if it makes a difference. Will also remove the primary for cleaning and check the baffle. 

[Whistlin Bob]

7 minutes ago, Rob F said:

the stars are round and sharp on one side and fuzzy out of focus on the other side.

That sounds like sensor tilt

[Rob F]

Yeah I was thinking that too, or not seated in the focuser centered. I use a PlayerOne camera and it has three screws to adjust tilt, might have to try that.

[Space Oddities]

1 hour ago, Rob F said:

Yeah I was thinking that too, or not seated in the focuser centered. I use a PlayerOne camera and it has three screws to adjust tilt, might have to try that.

Many people use CCD Inspector for this, perhaps you can give it a try? I haven't used yet it but it seems very handy to resolve tilt issues

https://ccdware.com/ccdinspector_overview/

[braybarr]

Curious how many people have issues with their primary mirrors dewing over? I’m going to try using a shower cap around the back end of the scope tonight, but I’m dreading the fact I might still get dewed over. 

Seems you have to take a DIY approach if you want to heat the mirror, and that’s intimidating to me. 

[Ratlet]

30 minutes ago, braybarr said:

Curious how many people have issues with their primary mirrors dewing over? I’m going to try using a shower cap around the back end of the scope tonight, but I’m dreading the fact I might still get dewed over. 

Seems you have to take a DIY approach if you want to heat the mirror, and that’s intimidating to me. 

I've had my secondary dew over but never the primary.  I've managed okay with a dew shield at preventing secondary from dewing over.

[braybarr]

9 minutes ago, Ratlet said:

I've had my secondary dew over but never the primary.  I've managed okay with a dew shield at preventing secondary from dewing over.

Interesting. I use a dew shield, and recently the primary dewed over and the secondary was okay. Do you cover the back end of the tube with a shower cap or similar? I think that’s what I’m missing. 

[Stefan73]

On 16/10/2022 at 09:15, Rob F said:

Yeah I was thinking that too, or not seated in the focuser centered. I use a PlayerOne camera and it has three screws to adjust tilt, might have to try that.

Both astap and siril have basic tilt measuring functionality, are free and multiplatform.  Siril has the tilt command and astap has it as part of its image inspection functionality.

[alacant]

On 16/10/2022 at 10:15, Rob F said:

not seated in the focuser

Hi

Almost certainly this. Simply removing and reseating the camera on an unmodified sw-ds focuser will cause tilt to change. Before suspecting sensor tilt in the camera (rare), as a minimum, remove the focuser rubber washers and set push-pull adjusters correctly.. Then try tapping a third m4 hole at 120º, then... etc etc.

HTH

Edited October 17, 2022 by alacant

[RolandKol]

Hi guys, anyone tried to attach GPU CC directly to the focuser (screw it in)?

 

[Space Oddities]

2 hours ago, RolandKol said:

Hi guys, anyone tried to attach GPU CC directly to the focuser (screw it in)?

 

Hi Roland,

I've been using this adapter from TS Optics: https://www.teleskop-express.de/shop/product_info.php/info/p5417_TS-Optics-Screw-Adapter-for-Baader-MPCC-and-TS-GPU-Coma-Corrector-to-Skywatcher.html

I had the Baader MPCC, but they say that the GPU will fit too.

Since then I've been using this other adapter, which I find more convenient to rotate the camera: https://www.teleskop-express.de/shop/product_info.php/info/p4018_TS-Optics-2--Adapter-with-Compression-Ring-for-Skywatcher-Newtonians.html

[edarter]

2 hours ago, Space Oddities said:

Hi Roland,

I've been using this adapter from TS Optics: https://www.teleskop-express.de/shop/product_info.php/info/p5417_TS-Optics-Screw-Adapter-for-Baader-MPCC-and-TS-GPU-Coma-Corrector-to-Skywatcher.html

I had the Baader MPCC, but they say that the GPU will fit too.

Since then I've been using this other adapter, which I find more convenient to rotate the camera: https://www.teleskop-express.de/shop/product_info.php/info/p4018_TS-Optics-2--Adapter-with-Compression-Ring-for-Skywatcher-Newtonians.html

How do you rotate the camera with the first of those two adaptors?

Thanks
Ed

[RolandKol]

24 minutes ago, edarter said:

How do you rotate the camera with the first of those two adaptors?

Thanks
Ed

The second link leads to the simple compressing ring type clamp, so you will be able to rotate cam just like the using the default focuser thumbscrews.
The first link leads to direct connector (CC will get screwed into the focuser) - no camera rotation option here, but much sturdier link.

 

P.S. just for comparison, the standard SW eyepiece holder here https://www.teleskop-express.de/shop/product_info.php/info/p4147_Skywatcher-kurzbauender-2--Adapter-fuer-Crayford-Auszuege.html

Simple compression ring variant will be a bit better, but weaker than the direct link.

Edited October 17, 2022 by RolandKol

[Rob F]

21 hours ago, Stefan73 said:

Both astap and siril have basic tilt measuring functionality, are free and multiplatform.  Siril has the tilt command and astap has it as part of its image inspection functionality.

I’ll have to check that out in Siril. I’m assuming it works when doing love stacking! I use Siril for color calibration and background extraction.

[Rob F]

21 hours ago, alacant said:

Hi

Almost certainly this. Simply removing and reseating the camera on an unmodified sw-ds focuser will cause tilt to change. Before suspecting sensor tilt in the camera (rare), as a minimum, remove the focuser rubber washers and set push-pull adjusters correctly.. Then try tapping a third m4 hole at 120º, then... etc etc.

HTH

I use the TS two screw compression ring adapter and think maybe I unevenly over tightened the two thumb screws. 
stars were good before using the filter and mirror baffle so  that was my first thought. With the nights getting cooler I think the plastic baffle will be spandex/contract etc.

[Rob F]

On 16/10/2022 at 19:48, braybarr said:

Curious how many people have issues with their primary mirrors dewing over? I’m going to try using a shower cap around the back end of the scope tonight, but I’m dreading the fact I might still get dewed over. 

Seems you have to take a DIY approach if you want to heat the mirror, and that’s intimidating to me. 

The swimming/shower cap I use now has helped with stray light and I think also with dew. I use heater straps at the rear of the ota and no issues with seeing on the secondary. I also have a dew shield which helps against dew and stray light, and my ota is flocked.

heater strap and diy dew shield for the guide scope helped greatly against dew and fogging of the the guide scope.

[8472]

Anyone have any recommendations as to what to cover the shiny silver drawtube with, as to potentially reduce internal reflections?

I haven't flocked any if my OTA, nor have I shortened the draw tube in any way.

Thanks.

[RolandKol]

13 minutes ago, 8472 said:

Anyone have any recommendations as to what to cover the shiny silver drawtube with, as to potentially reduce internal reflections?

I haven't flocked any if my OTA, nor have I shortened the draw tube in any way.

Thanks.

As a drawtube is mechanical part which is placed on the small wheels/rollers of the focuser, - the only way to go, - paint...
I used the permanent marker, got lucky it was not a shiny one (son had in his "toolbox")

Spray paint will do the job also, if no leaks will be left.

Edited October 18, 2022 by RolandKol

[braybarr]

6 hours ago, Rob F said:

The swimming/shower cap I use now has helped with stray light and I think also with dew. I use heater straps at the rear of the ota and no issues with seeing on the secondary. I also have a dew shield which helps against dew and stray light, and my ota is flocked.

heater strap and diy dew shield for the guide scope helped greatly against dew and fogging of the the guide scope.

Sorry for all the questions but I’m dying to get this sorted out. Do you just use a generic wrap-around heater? I’ve heard that causes turbulence inside the tube while not actually heating the primary mirror. But if it works for you then I might as well give it a go. 

[Rob F]

On 18/10/2022 at 14:26, braybarr said:

Sorry for all the questions but I’m dying to get this sorted out. Do you just use a generic wrap-around heater? I’ve heard that causes turbulence inside the tube while not actually heating the primary mirror. But if it works for you then I might as well give it a go. 

I haven’t noticed any. I keep the heater strap as far back as I can and on the middle setting so it warms the tube and doesn’t get too hot. It’s an inexpensive heater strap but does the job.

[RolandKol]

Yesterday been testing CC spacing as seeing was terrible with lots of high clouds and dew came even at 22:00 o'clock...

however test image came surprisingly nice

Sadly, slight coma is still present... Not sure if I can do better... 

Most likely will try to add 1mm distance.

(NGC 869 - NGC 884 below is without any crop at all)

Edited October 21, 2022 by RolandKol

[JimFR]

2 hours ago, RolandKol said:

Yesterday been testing CC spacing as seeing was terrible with lots of high clouds and dew came even at 22:00 o'clock...

however test image came surprisingly nice

Sadly, slight coma is still present... Not sure I can do better... 

Most likely will try to add 1mm distance.

(NGC 869 - NGC 884 below is without any crop at all)

That’s really nice!

[braybarr]

8 hours ago, Rob F said:

I haven’t noticed any. I keep the heater strap as far back as I can and on the middle setting so it warms the tube and doesn’t get too hot. It’s an inexpensive heater strap but does the job.

Sweet, I’ll start looking for one. Thank you very much. 

[Whistlin Bob]

On 21/10/2022 at 10:41, RolandKol said:

test image came surprisingly nice

The coma looks really slight to me- and absolutely loving the star colour. I've been working with refractor data quite a bit over the last year- both my own off a 72ed and other peoples- and even when you refocus between colours they don't seem to give the naturally rich colour that reflectors have straight out of the box.  Also a reminder that when conditions are a bit dodgy, clusters still yield lovely images.