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Details: https://www.astrobin.com/2mxllu/?nc=user Thanks for looking

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. 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.

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". 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

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

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.

I knew nothing about 3D printing either, but I spent a day on tinkercad and sure enough, it was easy to do. Feel free to modify the ring to your liking: https://www.tinkercad.com/things/2AcLKhFYX4r

Yep, that's the idea! Depending on the quality of their 3D printer, it will make it to either exacting or loose tolerances. The height and outer rim are not important in terms of tolerance, but the inner rim should be as smooth as possible. Hope this helps Minos

Since we're on the subject of collimation, I'll share another neat little trick I use to ensure consistency when I attach my camera after performing a collimation routine. It involves female and male Canon EOS T-rings (Nikons would work too). First, I use the female ZWO short EOS ring on the drawtube: Second, I use a standard male EOS T-ring on the howie glatter parallizer, which allows me to snap it into the drawtube and use my collimation tools: Like so: Once I've performed my tripirtite collimation routine with the cheshire, laser and tublug, I unspap the parallizer from the drawtube, and snap in my camera, which also has a male T-ring (and the zwo t2 -> 1.25" filter adapter inside it): Like so: After this, I crack open a can of guinness and proceed with my imaging session wearing a big fat collimated smile on my face Hope this helps, Minos

That indeed occured to me when I was collimating, but I could still see the inner rim of the 3d print well enough to be able to center the secondary so that the inner rim uniformly appeared concentric. Hope this makes sense! I also collimate the secondary with a glatter laser after using my cheshire, and then use the howie tublug for the primary. I use the parallizer also to keep all tools...well...parallel!

Go for it, it makes a big return for a very small cost. Just send the .sti file of the 3d design I made to your local shop to get it printed, then attach it to the primary in a centered fashion to hide the edges and clips and then done, star shapes fixed! It also helps to sink your coma corrector further down the drawtube with spacers to avoid pacman stars. This way, when you maintain the correct distance of sensor to coma corrector, everything sinks further down and you have to focus outwards to reach the focal point. Clear skies, Minos

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

Hey buddy, it's this one: https://www.ebay.com/itm/Astromania-Flexible-Dew-Shield-for-Telescope-Front-Outer-Diameter-from-148-167mm/324104286055?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649 Cheers, Minos

Thanks for the suggestion, should work well

Fwiw, I've used different filter wheels over the years with different scopes for different strokes, and currently I'm decided that they're not worth the negatives (weight, downtime during changes, refocusing etc..). I screw a single filter right in front of the camera and thats my session for the night. Next session, I use another filter. I've found this is a much easier, efficient and ultimately more productive workflow for me. Ymmv

I've had the ZWO EAF on the 130PDS for about three months now and never needed to modify anything, I've been very happy with its consisten performance. I did own a Pegasus Focuscube before on a refractor, and I find that the EAF, even with half the stepper resolution of the Focuscube, still performs very well at a lower pricepoint.