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

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

1493653969_aperturemaskfix.thumb.jpeg.41f4a46a8416934e74ab60444098c1eb.jpeg

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:

IMG_20200328_132955.thumb.jpg.6a3de9f418d62106b8eed7103f3c6c5c.jpg36876823_IMG_20200328_133018-Copy.thumb.jpg.bf176068ff4548b63102771071c8a6f7.jpgIMG_20200328_133048.thumb.jpg.624dc12be354baca03f724e0b2d3ae45.jpg

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 

I did the same a few weeks back with mine, and can also confirm just what a difference this makes.
In regards to re-aligned the primary, I used the barlow'd laser method.

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Just a few of the goodies ive had from the 130pds over the past few months:            

All images have been made with a Canon450D (unmodded), on a HEQ5 PRO goto, 9x50 finder guider (QHY5). Me and my garden gnome: several M51 crops: M97 & 108: M81 & M82 (& NGC3077): M81

Not great pics from me, but this is what i got so far since beginning with AP in august this year. No guiding and maximum time of expousures 30 sek.

Posted Images

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

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

1493653969_aperturemaskfix.thumb.jpeg.41f4a46a8416934e74ab60444098c1eb.jpeg

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:

 

Minos 

That makes me wonder if the drawtube shortening is really curing anything. Very tempted to do this when my printer is back in action.

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17 minutes ago, Stub Mandrel said:

That makes me wonder if the drawtube shortening is really curing anything. Very tempted to do this when my printer is back in action.

I would still think that you'd get Pacman stars with the drawtube protruding into the light path, because just like the spider vanes render diffraction spikes, so would the drawtube in taking a chunk out of that side - but I might just test that to see. I'd need to reorganize my imaging train so that the coma corrector is not sunk further down.

Edited by mAnKiNd
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16 hours ago, mAnKiNd said:

I would still think that you'd get Pacman stars with the drawtube protruding into the light path, because just like the spider vanes render diffraction spikes, so would the drawtube in taking a chunk out of that side - but I might just test that to see. I'd need to reorganize my imaging train so that the coma corrector is not sunk further down.

Well I've already done the 'unkindest cut', but the clip ring does seem a good idea. Here's a comparison of a 150PL star (left) and 130P-DS star. I think teh slight assymetry of teh 150PL star is because it was near the side of the frame and using a 1.25" nosepiece does cause vignetting:

image.png.350d453916dac9863adaf35498b94fd9.pngimage.png.4997f76cfa712c688eee95709564313f.png

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

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

Hope this helps :)

Minos 

Just wondering if they've changed the design on recent models as the mirror clips on mine don't extend into the reflective part of the mirror, they just 'grab' onto a very narrow unpolished edge to the mirror (excuse the poor quality photo)

 

IMG_20200409_211713950~2.jpg

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That pretty much looks like the size of my mirror clips too. The problem isn't necessarily the size of the clips, it's the unpolished mirror's edge that's causing the flaring to spew in all directions when light hits it. As long as the clips are in the "flare path", they will cause that characteristic three-pronged ghost flare. Applying the aperture mask prevents light from hitting the mirror's edges, hence mitigating this "almost" completely.

Hope this makes sense ☺️

Minos

Edited by mAnKiNd
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Here's another sample demonstrating that the aperture mask works.

I went out last night and tested the ASI1600MM-P vs the ASI183MM-P for reflections/halos/microlens diffractions WITHOUT a filter on a star with an apparent magniture of -0.04, just to test the isolated performance of the sensor's AR coatings without light bouncing back and forth from filters, but that test result is beyond the scope of this particular discussion.

My point here, is that the photo below demonstrates that star shapes with the aperture mask look great, without the massive flaring from the upolished mirror edge, or ghost flares from the mirror clips that lie in the "flare path".

1418885159_Annotation2020-04-09172137.thumb.png.bba0ce486c83a813763fce9fa32d5299.png

Now the primary mirror mask I made is by no means a perfect mask, and there seems to be a little bit of flaring left, but that could be because of other optical elements, or due to imperfections in my "garage made" 3D print. Nevertheless, this is a huge improvement from a relatively cheap and easy mod.

Cheers,

Minos

Edited by mAnKiNd
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For anyone interested into why I delved into testing these cameras without a filter, it's because I got these halos/reflections/wavelength-dependent microlens diffractions with my ASI1600MM-P using Astronomik LRGB 2c filters.

image.thumb.png.9486f26dcc97b853eaaf0b9f5b67ebc2.png

The filters are fine, its the lack of AR coatings on the Panasonic sensor itself and its inability to mitigate bouncing light - this topic has been discussed to death on every forum, but I had to see it for myself and my setup. I suppose it still pertains here to the topic of "imaging with the 130PDS" because I imaged with it 🙃

I wanted to see if the effect was still present without filters on the ASI1600MM-P, and it wasn't anywhere near the effect observed with the filters. I then snapped my ASI183MM-P to compare, but run out of time before I could test these filters with that camera - maybe later..

Having said that, the good thing with these halos is that they helped me recognize my focuser wasn't square, or my collimation was a bit off, or both, because the halo is not concentric to the star that was frame centered and I suppose it should be, so I'm spending some time to fine tune that.

Edited by mAnKiNd
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Just seen some of the solar images here and as it's something I'd like to try myself with my 130PDS, could anyone advise as to the best ready made filter? I'm looking at the Astrozap Baader one here https://www.firstlightoptics.com/solar-filters/astrozap-baader-solar-filter.html

Would the 136-146mm be the most suitable?

Cheers all

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On 11/04/2020 at 12:03, CaptainShiznit said:

Just seen some of the solar images here and as it's something I'd like to try myself with my 130PDS, could anyone advise as to the best ready made filter? I'm looking at the Astrozap Baader one here https://www.firstlightoptics.com/solar-filters/astrozap-baader-solar-filter.html

Would the 136-146mm be the most suitable?

Cheers all

Hi,

I don't have one of these myself (I bought the film and made a cardboard filter), but I have purchased an Astrozap dew shield which was listed for the 127mm Mak. Unfortunately it was around 1-2 cm too short, so I would advise you go for the 155-165 mm size which is recommended for a 130mm Newt. I think its the ring which holds the cross vanes in place which makes the Newt's diameter a lot larger than its actual mirror size.

Hope this helps :)

John

image.png.30415b04f1ca360c9f06a9cb31d7c4ad.png

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6 hours ago, JohnSadlerAstro said:

Hi,

I don't have one of these myself (I bought the film and made a cardboard filter), but I have purchased an Astrozap dew shield which was listed for the 127mm Mak. Unfortunately it was around 1-2 cm too short, so I would advise you go for the 155-165 mm size which is recommended for a 130mm Newt. I think its the ring which holds the cross vanes in place which makes the Newt's diameter a lot larger than its actual mirror size.

Hope this helps :)

John

image.png.30415b04f1ca360c9f06a9cb31d7c4ad.png

Ah great advice thanks. I didn't even notice or maybe didn't look far enough down the list to see the newts in brackets.

Thanks again!

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6 hours ago, JohnSadlerAstro said:

Hi,

I don't have one of these myself (I bought the film and made a cardboard filter), but I have purchased an Astrozap dew shield which was listed for the 127mm Mak. Unfortunately it was around 1-2 cm too short, so I would advise you go for the 155-165 mm size which is recommended for a 130mm Newt. I think its the ring which holds the cross vanes in place which makes the Newt's diameter a lot larger than its actual mirror size.

Hope this helps :)

John

image.png.30415b04f1ca360c9f06a9cb31d7c4ad.png

Just as a side note, did you find a dew shield to fit the 130 PDS? I was after something to reduce internal reflections from a street light without flocking and asked FLO about the Astrozap ones who replied that none were suitable.

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11 minutes ago, CaptainShiznit said:

Just as a side note, did you find a dew shield to fit the 130 PDS? I was after something to reduce internal reflections from a street light without flocking and asked FLO about the Astrozap ones who replied that none were suitable.

I didn't sadly, while there was an dew shield for the 127 mac there was none to fit the 130pds. In the end I made one out of (you guessed it) cardboard and black paper. It has lasted for a couple of years already, and is showing no signs of falling apart. Just as good as the camping mats some owners use! :D 

John

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2 hours ago, CaptainShiznit said:

Just as a side note, did you find a dew shield to fit the 130 PDS? I was after something to reduce internal reflections from a street light without flocking and asked FLO about the Astrozap ones who replied that none were suitable.

I made one from an old camp mat, lined with flock. It's lasted years and been ace.

As for flocking the tube, a square opposite teh focus tube gives much of the benefit for little effort.

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14 hours ago, Stub Mandrel said:

I made one from an old camp mat, lined with flock. It's lasted years and been ace.

As for flocking the tube, a square opposite teh focus tube gives much of the benefit for little effort.

Really? Is that where the majority of the internal reflection problems lie then? Very useful info!

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20 hours ago, CaptainShiznit said:

Just as a side note, did you find a dew shield to fit the 130 PDS? I was after something to reduce internal reflections from a street light without flocking and asked FLO about the Astrozap ones who replied that none were suitable.

I've used a flocked camping mat for a couple of years, recently ordered one of these tho. I have agreed a delay in dispatch until things start returning to normal with the virus stuff. It doesn’t get properly dark here in the summer months anyway so I am in no big rush to get it.  

https://www.astromaniaoptics.com/astromania-flexible-dew-shield-for-telescope-front-outer-diameter-from-148-167mm-diameter-keep-dew-away-and-gives-you-clear-observing-for-entire-night-p0211.html

 

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7 hours ago, CaptainShiznit said:

Really? Is that where the majority of the internal reflection problems lie then? Very useful info!

I think the mirror rings could be the secret to eliminating 'star bloom'

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Markarian’s Chain, taken early March when a few clear nights presented themselves 

SW130pds, modded canon 550d with SW aplanatic CC, astronmik CLS filter, 2.5hrs worth of 5min subs, DSS stacked and PI processed with final touches in Lightroom.  I recently started to use dithering and now I know what “dither or die” means

32708737-A95B-4E5C-BA98-81096CD766FC.jpeg

Edited by lnlarxg
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21 hours ago, lnlarxg said:

Markarian’s Chain, taken early March when a few clear nights presented themselves 

SW130pds, modded canon 550d with SW aplanatic CC, astronmik CLS filter, 2.5hrs worth of 5min subs, DSS stacked and PI processed with final touches in Lightroom.  I recently started to use dithering and now I know what “dither or die” means

Hope you don't mind but I took a screen grab of your image, made a selection around the galaxies, inverted it and ran Gradient Exterminator on coarse/strong. There's a similar tool in pxinsight, if you run it on the full image the end result should be pretty impressive!

image.png.afc9ff3b26be0f970da3cb41a2b3c728.png

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On 15/04/2020 at 20:28, Stub Mandrel said:

Hope you don't mind but I took a screen grab of your image, made a selection around the galaxies, inverted it and ran Gradient Exterminator on coarse/strong. There's a similar tool in pxinsight, if you run it on the full image the end result should be pretty impressive!

image.png.afc9ff3b26be0f970da3cb41a2b3c728.png

Wow you got rid of the vignette sooooo good.  I need to learn more on how to get rid of gradient. I just got myself photoshop so need to experiment a lot more

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23 hours ago, Fieldsy said:

What to do if a spider takes up residence in your tube over night ?

Because I wasnt able to use the scope for several months, this happened rather badly to mine, there were lots of cobwebs so I ended up taking the back mirror cell off and pulling them all out. :D I'm not sure what the effects of spider droppings on the mirror could be though.... 😐 

John

Edited by JohnSadlerAstro
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