Imaging with the 130pds

[Frank the Troll]

9 minutes ago, mAnKiNd said:

I went from a QHY miniguidescope on the findershoe to an evoguide 50 screwed onto the top dovetail of the mounting rings and saw a huge difference in guiding i.e. went from a total RMS (px) error >1.5" to ~ -0.5-0.7".

P.S. excuse the cable wrapping mess...also, you can see that I'm now using the qhy finder rings to run camera cables through..!

 

 

Looks good in this photo, the cables in the first pic would drive me nuts

[mAnKiNd]

44 minutes ago, Frank the Troll said:

Looks good in this photo, the cables in the first pic would drive me nuts

There's no cable mess when I'm setup for a session, just in that photo i wrapped them around the equipment... Cable mess drives me nuts too!

[Galen Gilmore]

Where could you buy a new set of OTA rings for the PDS? Mine have worn out threads, so I effectively only have one working ring.

[Stub Mandrel]

2 hours ago, Galen Gilmore said:

Where could you buy a new set of OTA rings for the PDS? Mine have worn out threads, so I effectively only have one working ring.

Do you mean the threads have stripped through over-tightening? They shouldn't wear out

You can ask a local garage to fit a helicoil insert for you which will restore the thread and make it stronger than before.

Or even buy a suitable set and do it yourself, cheaper than new rings.

<edit>I assume you mean the threads that fit the rings to the wedge?

Edited February 6, 2020 by Stub Mandrel

[Galen Gilmore]

1 hour ago, Stub Mandrel said:

Do you mean the threads have stripped through over-tightening? They shouldn't wear out

You can ask a local garage to fit a helicoil insert for you which will restore the thread and make it stronger than before.

Or even buy a suitable set and do it yourself, cheaper than new rings.

<edit>I assume you mean the threads that fit the rings to the wedge?

I am talking about the threads which clamp the two halfs of the ring together, not sure if what you said still applies.

You're probably right about them being stripped, and not worn out.

[Stub Mandrel]

9 minutes ago, Galen Gilmore said:

I am talking about the threads which clamp the two halfs of the ring together, not sure if what you said still applies.

You're probably right about them being stripped, and not worn out.

Those should be pretty durable! They don't need to be very tight.

It should be possible to replace/repair them, can you post a pic of the worn one some time?

[Uranium235]

Just rolling my 130 for just over an hour... got the MPCC spacing utterly wrong though...lol. So ive had to crop the ugly part out.

10x450 (Ha)

[spillage]

Slightly off topic but It would be used in the 130pds if I brought one  . Has anyone used one of these?

https://www.teleskop-express.de/shop/product_info.php/info/p5417_Lacerta-Thread-Adapter-for-using--Baader-MPCC-with-Skywatcher-Newtonians.html

[mAnKiNd]

3 hours ago, spillage said:

Slightly off topic but It would be used in the 130pds if I brought one  . Has anyone used one of these?

https://www.teleskop-express.de/shop/product_info.php/info/p5417_Lacerta-Thread-Adapter-for-using--Baader-MPCC-with-Skywatcher-Newtonians.html

Yes! I've been using one since i got my 130pds.

I also have this one:

https://www.teleskop-express.de/shop/product_info.php/info/p203_TS-Optics-T2-Fokaladapter-fuer-Skywatcher-Auszuege-mit-M54x1-Innengewinde.html

Edited February 7, 2020 by mAnKiNd

[Uranium235]

Im using the same kind of thing, but I built mine myself

The only issue with this arrangement is that the camera rotation is arbitrarily set by the travel of the threads - so you dont have much wiggle room to get it right (to the nearest 90 degrees).

[mAnKiNd]

5 minutes ago, Uranium235 said:

Im using the same kind of thing, but I built mine myself

The only issue with this arrangement is that the camera rotation is arbitrarily set by the travel of the threads - so you dont have much wiggle room to get it right (to the nearest 90 degrees).

Impressive that you built one. Yeah, no rotation is a bummer, but I suppose I've learnt to live with it.

I took off (and lost) the rotation ring on the FUFmpcc because it compromised stability, which was my whole purpose for using these adapters.

Edited February 7, 2020 by mAnKiNd

[Uranium235]

8 minutes ago, mAnKiNd said:

Impressive that you built one. Yeah, no rotation is a bummer, but I suppose I've learnt to live with it.

I took off (and lost) the rotation ring on the FUFmpcc because it compromised stability, which was my whole purpose for using these adapters.

I was pretty lucky in that mine rotated to portrait (with respect to the focuser) right at the point where the threads started to really tighten up. If it was to far before that I'd either have to come up with a different configuration - or take a chance and tighten it up as much as poss until the right camera rotation is achieved.... but the big danger with that is a cold-welded thread (never much fun to try and undo). Thats why I apply boot polish to my threads to reduce or prevent binding when doing things up fairly tight.

[Uranium235]

If i didnt know better, but whoever made that adaptor probably got the idea from here...lol..

I built my mod a good 4 or 5 years ago:

 

[mAnKiNd]

4 minutes ago, Uranium235 said:

If i didnt know better, but whoever made that adaptor probably got the idea from here...lol..

I built my mod a good 4 or 5 years ago:

 

I like it, especially for it's"built-in" tilter! Great job.

[KernowBeard]

Just seen someone's selling this little gem on gumtree for £85, ota only. I'd get it myself if I had a mount and such for it 😅

[Pankaj]

Hi Everyone. Posting some images taken by me through the 130 PDS. Taken from Brtle 3 skies of a small hamlet in the Himalayas called Kausani. All photos were shot without any guiding help hence with limited exposure time. The capture details are mentioned on the photos itself. I am not very hands on with post processing so I simple stack the subs in DSS and later do some post processing in Lightroom only before stamping the details in Picasa.

[Pankaj]

I fail to understand why do I get kind of ''drag'' lines in every image above. Any suggestion on the same ? 

[cuivenion]

10 minutes ago, Pankaj said:

I fail to understand why do I get kind of ''drag'' lines in every image above. Any suggestion on the same ? 

it's called walking noise. You need to dither to get rid of it. It happens when you have a slight drift in one direction and becomes apparent in the stacked image.

[Pankaj]

3 minutes ago, cuivenion said:

it's called walking noise. You need to dither to get rid of it. It happens when you have a slight drift in one direction and becomes apparent in the stacked image.

Can I do dithering manually, since I do not guide. That means, can I simply slew the mount using the synscan ''just little bit'' between each sub ?

[cuivenion]

I think you can do that but it won't be random. Backyard EOS software gives you the option to dither while not guiding with a DSLR, not sure about APT.

[Pankaj]

3 minutes ago, cuivenion said:

I think you can do that but it won't be random. Backyard EOS software gives you the option to dither while not guiding with a DSLR, not sure about APT.

Thanks a ton for the suggestion. I did use Backyard EOS couple of time earlier but never know dithering is an option there. But tell me, how would the mount move if imaging canon camera is connected to laptop and using backyard eos? I mean, its just the camera which is connected to backyard eos, not the mount. So how would dithering happen ? Excuse me if my question seems ridiculous...I am new to imaging...

[alacant]

8 minutes ago, Pankaj said:

canon camera is connected to laptop and using backyard eos

Hi

You could connect both mount and camera via INDI or ASCOM.

HTH and clear skies.

[wimvb]

1 hour ago, cuivenion said:

I think you can do that but it won't be random. Backyard EOS software gives you the option to dither while not guiding with a DSLR, not sure about APT.

It doesn't have to be random. Before I started using guiding, I dithered manually. Worked absolutely fine. 

@Pankaj: here's my recipe.

set the slewrate to 1x sidereal. After image 1, press the dec+ button for about as many seconds as your pixelscale (minimum of 1 second). This will give you a dither distance of 15 pixels. Let's call this one dither step. 

Take image 2. Then press ra+ for one dither step. 

Take image 3. After that press dec- for one dither step

Repeat the same after image 4 (dec-) 

Take image 5. Press ra- for one dither step.

Repeat efter image 6 (ra-) 

After images 7, 8, 9 each, dither in dec+

After images 10, 11, 12 each, dither ra+

After images 13, 14, 15, 16 each, dither one step in dec-

After 17, 28, 19, 20 each, one step in ra-

Etc. 

This will give you an outward spiraling dither pattern. Been there, done that, used a cheat sheet, and was never bothered by walking noise again. This will even work if you have a (moderate) backlash in dec. 

If you get tired of doing this manually, and you're not afraid of some diy, here's the automated version

 

Edited February 8, 2020 by wimvb

[Stub Mandrel]

8 hours ago, Pankaj said:

I fail to understand why do I get kind of ''drag'' lines in every image above. Any suggestion on the same ? 

Received wisdom is that it is caused by lack of dither.

Personally I can't see how fixed noise can become streaks when I'm guiding and the image drift over a session is far less than the length of a streak...

My pet theory is that it is associated with very thin cloud and it follows the wind direction.

[Pankaj]

8 hours ago, wimvb said:

It doesn't have to be random. Before I started using guiding, I dithered manually. Worked absolutely fine. 

@Pankaj: here's my recipe.

set the slewrate to 1x sidereal. After image 1, press the dec+ button for about as many seconds as your pixelscale (minimum of 1 second). This will give you a dither distance of 15 pixels. Let's call this one dither step. 

Take image 2. Then press ra+ for one dither step. 

Take image 3. After that press dec- for one dither step

Repeat the same after image 4 (dec-) 

Take image 5. Press ra- for one dither step.

Repeat efter image 6 (ra-) 

After images 7, 8, 9 each, dither in dec+

After images 10, 11, 12 each, dither ra+

After images 13, 14, 15, 16 each, dither one step in dec-

After 17, 28, 19, 20 each, one step in ra-

Etc. 

This will give you an outward spiraling dither pattern. Been there, done that, used a cheat sheet, and was never bothered by walking noise again. This will even work if you have a (moderate) backlash in dec. 

If you get tired of doing this manually, and you're not afraid of some diy, here's the automated version

 

That's an awesome solution indeed. I will try the manual version in the next imaging session surely. Are you doing any selling for this ditherbox you created ?