John

Filters won't really make much difference if you have lots of LP. I have only used the Astronomik O-III filters, not the ones that they are now making for Tele Vue but the latter are getting excellent feedback from experienced observers. Worth the price difference ? - your call I guess ! Here is a good piece on the deep sky type filters: https://astronomy.com/-/media/import/files/pdf/8/c/7/0805_nebula_filters.pdf

A Heritage 130 dobsonian a zoom eyepiece and a folding chair and small table could be pretty portable I guess: https://www.firstlightoptics.com/heritage/skywatcher-heritage-130p-flextube.html If you can get under truly dark skies you don't need a large aperture scope to get some wonderful views of the deep sky.

These filters only improve the views of nebula. For galaxies, find the darkest skies you can. With a 130mm I would go for the full UHC rather than the UHC-E. I use "full" O-III and UHC filters with 100mm apertures to good effect. Looks like @Stu agrees with me 😀

The Orion Ultrablock is a fine example of the crap shoot you mention. I've seen tests showing large variations in pass rate and width. Some are decent, some are pretty much useless. I had one years back which was OK. A more recent one I tried didn't seem to do much at all

I have mine at the same angle as the focuser. You just loosen the finder a little in it's mount, turn it so the eyepiece is at the angle you want and then re-set the finder in it's mount. You will probably need to re-align the finder with the main scope again after doing this. I do this with the RACI finders on my refractors as well.

Specs are often quoted inaccurately I'm afraid. Even the Baader 8-24 zoom has proved to differ in actuality from the Baader specs in terms of field of view offered.

Hello and welcome to the forum. Here is a link to the instruction manual for the scope that you have been given which might help: https://nimax-img.de/Produktdownloads/33297_1_Anleitung-EN.pdf You also have a number of additional accessories which we can help with once you have the basics of how the scope is set up.

In my case, I only use the barrel extensions to enable me to use 2 inch filters with the 13, 8 and 6mm Ethos. Otherwise the 2 inch barrels work fine with no extensions IMHO.

No deference needed - we can simply agree to disagree on this

Eyepieces between 30mm and 5mm in focal length will all be useful in your scope. The BST Starguiders are good although there is some variation in quality across their focal lengths - the 25mm is probably the weakest although still a decent eyepiece. Exit pupil is calculated as eyepiece focal length divided by the focal ratio of the scope. So all 8mm eyepieces will deliver the same exit pupil with your scope, as an example.

These distant and ancient clusters are fascinating. I tracked down NGC 2419 back in March this year:

I think the 7.2 - 21.5mm zooms do offer a bit more performance un-barlowed than the Seben / Celestron / Skywatcher / whatever 8-24 zooms, personally. I've also owned the Baader 8-24 (a couple of those) and the very expensive Leica ASPH zoom mentioned by @dweller25 above which is the best performing zoom that I have owned but it didn't really gel with me so I sold it on after a few months comparing it with Pentax XW's etc.

I was going to suggest the Castell O-III as a lower cost alternative that gives you a good dose of the "O-III experience". Mark has mentioned it above already !

Low cost eyepieces used with scopes of F7, F/6, F/5 etc often do show astigmatism in the outer parts of the view. It looks sort of like this:

And here !

I use the 2mm - 4mm Nagler zoom (no use in your 180 mak of course !) and a moderate cost 7.2mm - 21.5mm zoom which is sold under a number of brandings. I use the latter with a 2.25x Baader barlow lens for a 9.55mm - 3.2mm zoom which is really effective. I've been as surprised as anyone that the latter combo has worked so well but there it is. It was purchased as an outreach / travel setup but gets a lot more use than that. (not that travel and outreach has been on the agenda for quite a while now !)

My skies must be better than I think. I can get the E & W Veil with my 4 inch fracs quite easily even with a UHC filter. I have glimpsed the brightest section (eastern segment) with 11x70 binoculars (unfiltered) on one of the best nights I can remember here. With my 12 inch dob and the Lumicon O-III (one of the earlier good ones ) the detail in the segments of the Veil is outstanding. It is worth checking out the transmission charts of filters - there are a bunch of independant tests somewhere on line which tell all sorts of interesting stories. Of my two O-III's I reckon my Lumicon is a touch better than my Astronomik especially in my 12 inch dob but both are really effective tools

Ah - now that will make a very interesting comparison

I did the same re: the finder. Your current 4" scope - is that the FS102 ?

As above. That's normal for a dob. Congratulations on the new scope and welcome to the forum

Well I never ! Nice one David, very, very nice one in fact

Zooms are great for high power observing - I've become quite a fan of using them now. My short fixed focal length eyepieces are feeling a little neglected I think

Zooming makes so much sense when playing around to find what the conditions / target will bear. I've become quite a convert - my fixed focal length eyepieces are getting a bit neglected !

I like the $ sign incorporated into the scope mount graphic - very apt ! 3 boxes as usual - Tak know how to package properly Looks very like my DL boxes ????

I've owned a Pentax XF 8.5mm. It's quite a nice eyepiece but it does have some distortions - pin cushion I think it's called ? Interesting review here comparing the XF 8.5mm with a BST Starguider 8mm (the Paradigm is the branding they use in the USA for those) in a similar scope to yours: https://www.cloudynights.com/articles/cat/user-reviews/review-of-at-paradigm-8mm-and-pentax-xf-85-mm-r2737 Using a 3x barlow will introduce it's own issues I think. I doubt that sort of magnification will get much use in all honesty - it doesn't in my 12 in Orion Optics dob.