Imaging with the 130pds

[Space Oddities]

Great captures nonetheless!  

[Pitch Black Skies]

Hi guys,

For anyone that has cut their focuser tube, I have come up with a little mod to stop the tube from coming off the rollers when racking all of the way out.

I attached a small washer on the tube's track with some metal compound.

We now have a low profile focuser ✊

It doesn't look great but don't worry as it's completely hidden.

 

Depending on where you have cut your tube and what type of coma corrector you use will determine where the washer needs to be placed.

You can check this easily with the focuser removed from the telescope.

[Richard Wesson]

On 02/04/2020 at 16:41, mAnKiNd said:

For anyone interested in fixing their star shapes (subject is Vega) from this to this:

I designed a 3D print on tinkercad (.sti file attached)Skywatcher 130PDS Newtonian Primary Mirror Aperture Mask.stl, found a local 3D print shop to make it for me and applied to the mirror clips as such:

Inner diameter is 125mm, which is sufficient to cover the mirror edge and mirror clips. The idea is that the mask blocks the stray light from the edges, which causes the flares you see on bright stars and the ghost flares from the mirror clips blocking the edge flare.

Hope this helps

Minos 

With the lighter nights now with us, I am looking at ways of making improvements to my 130PDS. One of the things I want to do is fit a primary mirror baffle like above.

It was suggested in a follow on post to ''Just send the .sti file of the 3d design I made to your local shop to get it printed'. I contacted one local to me (Bristol) but they replied that for a one off a minimum charge of £40.00 plus VAT applied i.e. £48.00! This seems very expensive for waht is in effect a plastic ring.. does anybody know of any cheaper alternatives or can anybody print one for me at a a more modest cost?

[alacant]

18 minutes ago, Richard Wesson said:

anybody know of any cheaper alternatives

Remove the clips and fix the mirror to the cell using neutral silicone sealant to coincide with the SkyWatcher cork pads. Leave the mirror to settle under gravity on a perfectly horizontal surface for 24 hours before refitting.

HTH

[Pitch Black Skies]

@Richard Wesson I have one if you'd like to buy it. I paid €36 for it from astroshop.eu.

PM me for further details.

 

[Richard Wesson]

3 hours ago, alacant said:

Remove the clips and fix the mirror to the cell using neutral silicone sealant to coincide with the SkyWatcher cork pads. Leave the mirror to settle under gravity on a perfectly horizontal surface for 24 hours before refitting.

HTH

Thank you for the reply. I did consider this, but I understand that the chamfering at the mirror edge can also cause artifacts, hence looking at the baffle route. 

[Richard Wesson]

2 hours ago, Pitch Black Skies said:

@Richard Wesson I have one if you'd like to buy it. I paid €36 for it from astroshop.eu.

PM me for further details.

 

PM sent

[alacant]

1 hour ago, Richard Wesson said:

the chamfering at the mirror edge can also cause artifacts

The bevel of the mirror prevents artefacts. The thickness of the plastic baffle and its irregularities are likely to cause more than the bevel alone.

Cheers

 

Edited May 29, 2022 by alacant

[Jamgood]

@Richard Wesson I had mine printed by a guy on facebook who prints Bahtinov masks. Just sent him the file and he charged me £11. 

[Jim Smith]

I have a spare 130 pds baffle ring if anybody wants it. I use the no-clips-with-sealant method now.

There is a split in it (see photo) but I suspect once it is in use it wouldn't make any difference.

Free of charge to a good home!

[Richard Wesson]

1 hour ago, Jim Smith said:

I have a spare 130 pds baffle ring if anybody wants it. I use the no-clips-with-sealant method now.

There is a split in it (see photo) but I suspect once it is in use it wouldn't make any difference.

Free of charge to a good home!

Have PM'd you. 

[Ratlet]

I'm considering the 130pds as a first scope to try both visual and astrophotography with an unmodified DSLR.

Is it always the case with it that you need to cut the focus tube to use this for imaging (assuming you use a coma correctors) and does cutting the tube affect it for visual?

What's the current opinions on the coma correctors?  I've heard the baader is good, but tricky to use and looking back through the thread the favourite seems to change with time.

[Richard Wesson]

1 hour ago, Ratlet said:

I'm considering the 130pds as a first scope to try both visual and astrophotography with an unmodified DSLR.

Is it always the case with it that you need to cut the focus tube to use this for imaging (assuming you use a coma correctors) and does cutting the tube affect it for visual?

What's the current opinions on the coma correctors?  I've heard the baader is good, but tricky to use and looking back through the thread the favourite seems to change with time.

It is not always necessary to cut it no. It depends on the indvidual - left uncut, there is the possibility of 'pacman' stars i.e. those with the appearance of parts being cut out. Being an inverterate tinkerer, I chopped the end of mine off, but you need to be aware that you will need to add a stop to prevent the tube coming out altogether... The other thing to bear in mind is that for visual, you may not be able to achieve focus as you have limited the extent the tube can move out. This could be solved with an extensin I guess though. 

 

With regard to coma correctors, I only have experience of the baader one. It seems okay so far, but maybe my observations skills are not as good as some more exacting members..

[barbulo]

2 hours ago, Ratlet said:

I'm considering the 130pds as a first scope to try both visual and astrophotography with an unmodified DSLR.

Is it always the case with it that you need to cut the focus tube to use this for imaging (assuming you use a coma correctors) and does cutting the tube affect it for visual?

What's the current opinions on the coma correctors?  I've heard the baader is good, but tricky to use and looking back through the thread the favourite seems to change with time.

I’ve never used the 130 for visual. For imaging, it will depend on the configuration used. If you can introduce the CC (no stop ring) then probably you won’t need to cut it. I did it though. 
Regarding the CC, I have the Baader MPCC MkIII and I’m far from being happy: never managed to get rounded stars in the corners. Perhaps I’m a bit picky. Or suffer from an incipient ODC. 
IIWY I’d spend some more money and go for the TS GPU. It seems it provides a full flat field (up to the corners!).

[Bibabutzemann]

2 hours ago, Ratlet said:

I'm considering the 130pds as a first scope to try both visual and astrophotography with an unmodified DSLR.

Is it always the case with it that you need to cut the focus tube to use this for imaging (assuming you use a coma correctors) and does cutting the tube affect it for visual?

What's the current opinions on the coma correctors?  I've heard the baader is good, but tricky to use and looking back through the thread the favourite seems to change with time.

I think the Baader MPCCIII is an absolute steal on used market for like 100€. But i read more good stuff about the GPU CC, which i rarely find used under 250€. Its less tilt sensitive and more future proof in case you want to add a f4 Newt to your collection. Oh another advantage of the GPU i think is, that the focus tube doesnt protrude as much. So i think both are worth what you pay for 🙂 I think i will switch at some point to the GPU

 

Processed an image from february: IC410

130PDS, EQ3Pro, EOS1200Da

6.3h with L-extreme Filter, 40min RGB for star colors

Processing with:

Starnet v2

SiriL 1.02 - They improved their Background Extraction signficantly, because they collaborated with the team from GraXpert (a standalone tool for Background extraction) . Just select the RPF as interpolation method and see the magic happen 😀

Photoshop - with a new plugin called NoiseXterminator, to reduce noise without losing too much details

I feel like this target needs another 6 hours, because i had to do lots of noise reduction.

Edited May 30, 2022 by Bibabutzemann

[Pitch Black Skies]

If you can at all, get the GPU. Excellent correction and hassle free.

It pushes the focus position out by 19mm so no need to chop the end of the tube.

It has another really neat advantage too in that it can be screwed into the focuser tube for extra stability and security.

[Space Oddities]

I hesitated between the TS GPU and the TS MaxField 0.95x, and finally went for the latter. I have yet to test it, but I heard it's as good as the TS GPU. It is also sold by Altair under their own name.

https://www.harrisontelescopes.co.uk/acatalog/altair-maxfield-corrector.html

Some real world pictures here: https://www.astrofotoblog.eu/?tag=maxfield-coma-corrector

Also more infos on coma correctors here. The TS GPU (same as Sky-Watcher Aplanatic ?) seems like a popular option and more mixed feelings about the Maxfield: 

 

Edited May 30, 2022 by Space Oddities

[Pitch Black Skies]

The Aplanatic is another excellent corrector. It looks the same as GPU but it is different. 

- The Aplanatic can't be threaded onto the focuser tube like the GPU can.

- The Aplanatic pushes the focus position out by 6mm. (You will still have a protruding tube in the light path).

- The GPU pushes the focus position out by 19mm.

 

Can't really comment on the Maxfield but @ONIKKINEN 's experience with it turned me off buying it. Maybe that was just a bad example?

Edited May 30, 2022 by Pitch Black Skies

[Pitch Black Skies]

P.S. there is a Skywatcher Aplanatic for sale in the classifieds section 🙂

[ONIKKINEN]

I found out more on my particular Maxfield 0.95x corrector, and that is that my unit is either not collimated properly or introduces tilt of its own somehow. Which of the 2 it is, or both, i dont know but in any case i figured out that if i want to have good collimation i need to collimate my scope through the coma corrector and in the exact orientation it will be used for imaging. A bit annoying but i just marked the body on its 0 and 90 degree orientations and used those to collimate before screwing the camera in.

I found issue in the outer edges of an APS-C camera even when in collimation but i suspect that if i had a micro 3/4ths size sensor like the 294 or 1600MM, or even smaller like the 533MC i would have not cared nearly as much about the star shape issues, if at all.

So your mileage may vary but i personally would not buy the Maxfield 0.95x again given its very close pricing to the GPU which most folks i read are very satisfied with.

[Ratlet]

4 hours ago, Bibabutzemann said:

I think the Baader MPCCIII is an absolute steal on used market for like 100€. But i read more good stuff about the GPU CC, which i rarely find used under 250€. Its less tilt sensitive and more future proof in case you want to add a f4 Newt to your collection. Oh another advantage of the GPU i think is, that the focus tube doesnt protrude as much. So i think both are worth what you pay for 🙂 I think i will switch at some point to the GPU

 

Processed an image from february: IC410

130PDS, EQ3Pro, EOS1200Da

6.3h with L-extreme Filter, 40min RGB for star colors

Processing with:

Starnet v2

SiriL 1.02 - They improved their Background Extraction signficantly, because they collaborated with the team from GraXpert (a standalone tool for Background extraction) . Just select the RPF as interpolation method and see the magic happen 😀

Photoshop - with a new plugin called NoiseXterminator, to reduce noise without losing too much details

I feel like this target needs another 6 hours, because i had to do lots of noise reduction.

Marvelous image.  I had a bit of a peep at the stars.  Thought I saw some coma.  Nope it's a double!  Ah there that's definitely coma... No wait it's another double 😂.

I absolutely love siril.  I've played with other people's data and struggled to get a nice image.  I call siril the "I win button".  It just makes the image feel so rich for so little work.

[alacant]

1 hour ago, Space Oddities said:

same as Sky-Watcher Aplanatic ?

The earlier European ones, yes. Proper GPUs come with a graph showing the relation between focal length and backfocus and have a chart showing recommended positions for various focal lengths. Beware modem mass produced copies.

This for example is a proper GPU which will give corner to corner over APS-c.

This, although it may still work up to a point, isn't but still way better than the 2 element correctors.

Cheers 

 

 

[Ratlet]

It seems the ts GPU is the best option from a 'just works' point of view. Plenty of time to think about things.  For the time being.

I don't mind fiddling with things but I remember a forklift at my work that kept breaking.  By the time the found the fault they had replaced almost everything except the forks and the seat! 

I'll need to have solid think about my next step but I appreciate the advice massively.

[Ratlet]

1 minute ago, alacant said:

The earlier European ones, yes. Proper GPUs come with a graph showing the relation between focal length and backfocus and have a chart showing recommended positions for various focal lengths. Beware modem mass produced copies.

This for example is a proper GPU which will give corner to corner over APS-c.

This, although it may still work up to a point, isn't but still way better than the 2 element correctors.

Cheers 

 

 

Ah, you replied just before I did previously!  I was going to send you a direct message to ask since I recall a thread where you posted some good advice!  There are lots of easy mistakes to make and you have helped me and others avoid many.

[kaelig]

My first true HOO with 130PDS, the Bubble Nebula (NGC7635)

Setup: 130PDS, CGEMii Mount, Asiair plus, ASI 183MM cooled @-10°C, guiding with 290MM mini & Vario finder (61/250), filter Astronomik 5nm

Ha: 20 x 300s

Oiii: 28 x 300s

with DOF, AstroPixelProcesor & Pixinsight processing