HollyHound

At the end of the day, it’s our own perceptions and experiences, and they can vary wildly, so not everyone will find coma an issue... or indeed audio quality! I haven’t yet tried an Ethos and am actually firmly resisting it for now, in case I find the experience irresistible. I’m very happy with the views I’m getting now, I consider it the sweet spot for me 😀 I will try with and without the Paracorr over the next few weeks (weather permitting) to confirm my initial findings, but it was quite overwhelmingly better for me last night.

I've found the same with audio gear... I spent many months years ago getting to a point where I was happy with my headphone/amp setup, but once I got to the point where it was as good as I felt it could then go, I have been using that same equipment for years now very enjoyably... there's always a sweet spot between performance/price and beyond that it's very much diminishing returns. It's good to acquire the gear you need/want, but then it must be used effectively and that's more important. Based on what I discovered last night, I have to say that I feel any reports of edge behaviour for eyepieces in a (faster) Newtonian without a coma corrector, are likely going to be limited by visible coma! Now it may be that some see it more easily than others, but to me, once the field curvature and astigmatism were solved with the eyepieces I now have, then coma was very much evident and (again to me) unacceptable. Again, this is my (relatively limited) experience and I'm sure others will other views on this, but I would classify the view I had last night as pretty much the same as I get from my 80mm ED f/10 refractor now... almost flawless from edge to edge 👍 Of course, this is with 70 degree FoV eyepieces. I do have a DeLite 13mm and 18.2mm (62 degree FoV) so will give them a try too and see if the coma is as evident without the Paracorr, before I let them go🤔

Still better than my version... by a long way 🤣

I've had the Bresser 10" f/5 Dobsonian for well over a month now, and despite the weather not always being kind, I have managed to get a good few hours with it. To go with it, I initially invested in some (hopefully) decent 70 degree eyepieces... Pentax XW30, 20, 14, 10 and 7. The views with such a large aperture (compared to my 5" SCT or Mak) have been awesome and I'm really enjoying the ability to quickly take the dob outside. Views of M31 and M42 are so much better than those I originally had last year in my smaller Mak, and I'm looking forward to hunting down some of the other targets with this scope. However, I'd found that the XW20 and XW14 suffered noticeably from field curvature, and so stars at the edge of the field of view were not sharp (more of a large out of focus blob), in both the dob and my 80mm f/10 refractor. It was possible to re-focus for the stars at the edge, but then the centre goes out focus... not ideal. I'd also noticed in the XW30 that stars near the edge, although reasonably sharp, where not always "well shaped". Initially I considered this was astigmatism, so have a Dioptrx 0.75 fitted to this eyepiece and it seemed to help, but still not perfect. In order to assess if the XW14 field curvature could be improved upon, I obtained a Delos 14 and this does indeed retain sharpness to the edge, but now it was clear that there was still a remaining aberration, as all stars from about half the field of view outwards appear to "ice cream cone shaped"... after investigation, I now know this is coma! I found this reference very useful to confirm what I was looking at... http://www.umich.edu/~lowbrows/reflections/2007/dscobel.27.html Perhaps I'm being too perfectionist, but I see any aberration that can be reduced/eliminated as worthwhile fixing, so yesterday I received the Tele Vue Paracorr Type 2 (thanks again @FLO). I'd read numerous threads about all the different types of coma corrector and consistently this came out as the easiest to use and of good quality. Last night, the dob was put out and the skies cleared for a good number of hours and so I was able to test for myself if this is the missing link for the (almost) perfect view 🤔 I've learnt that it takes a good 30mins to an hour for this size of scope to cool properly and whilst cooling it was obvious that the stars shapes were all over the place. Finally around 11pm, I popped the Delos 14 in the scope, without the Paracorr and used M42 and Rigel as my initial test targets. This eyepiece has excellent contrast and sharpness across the field and M42 was very impressive, but as stars moved outwards the coma was evident, particularly on bright stars (such as Rigel). I then inserted the Paracorr into the focuser, which involved removing the Clicklock extension adaptor I have been using (as the long nosepiece of the Paracorr wouldn't go fully in) and replacing it with the extension tube supplied with the scope. I replaced the 1.25" adaptor with my Clicklock adaptor and popped the Delos back in. TeleVue advise using the "A" setting for this eyepiece (when not using an "in travel" adaptor), so I set it to that. The tunable top has a lovely smooth and easily adjustable action and can be locked at anytime very easily. Focussed back on the targets and I saw no noticeable decrease in contrast, brightness or sharpness in the centre of field. Looking at stars towards the edge though, was unbelievable... they were sharp, had no coma or astigmatic shape and just looked as they did at the centre. I spent a good few minutes panning stars around in the view, but they just remained as sharp stars no matter where they are in the field of view, except for perhaps a (very) small change just before they disappear out of view. To say this was a revelation, would be a massive understatement... it was what I hoped and expected, but still remarkable to see 😃 I then locked the focuser, and followed the advise (I think it was @Don Pensack, thanks) on how to adjust the Paracorr for using other (non Tele Vue) eyepieces. Inserted the Pentax XW14 and just turned the tunable top until stars at the centre where totally sharp/focussed again. This indicated approx the "C" setting, so I locked the Paracorr here and had a look around again. Another revelation... again no coma, but also stars remained in focus over more of the field area. They still got a little blurry in the outer 20/30% of the field (to my eyes) but much better. I also tried the trick of focussing for half way across and it was very usable. I still much prefer the total sharpness of the Delos for this 14mm focal length and after extensive testing, I found (almost) no discernible difference in contrast, brightness or visibility for M42 between either eyepiece. The XW20 performed much better, this time the field curvature was very slight indeed and only noticeable in the last 10% of the view. I was able to focus a little to the middle and all looked sharp enough, not perfect but very usable. I guess if someone was a little younger, they would have no issue at all. I ended up focusing for the centre and just accepting a small amount blurriness at the very edge, unless concentrating intently on the target at centre. The XW30 worked perfectly, this time I had to reset the tunable top to the "G" setting and the view was very wide and sharp across the field. I'd read that this Paracorr increases the focal length slightly, and it did indeed, but not so much as to feel anything was missing. Given the increased quality across the field, I'm really not sure I would use the scope without it now. However, I will do further testing using my other focal lengths to make sure it's suitable for all eyepieces and targets. Given I really didn't know what to expect in terms of improvement (other than other reports/reviews), I was very impressed indeed with the Paracorr. I'm sure other coma correctors will perform as well, but the convenience of the tunable top makes this a pretty much permanent installation in my dob now. Just a shame it's so expensive, but I can confirm (for me at least) it really does make a big difference 👍 As a final footnote, whilst viewing M42 with both Delos 14 and XW14 (magnification approx 100x), I finally got a very clear view of the E and F stars in/around the Trapezium, the very first time I've been able to see anything other than the main four. There was very little difference between the eyepieces, although I did consider the Delos showed them (very) slightly more clearly. Perhaps it was the aperture, cold/clear sky or Bortle 4/5 conditions around here, but it was delightful to see them and they required no extra effort at all... a lovely way to round off a few hours with a clear sky at last 😃

Needs must... go John 👍

Correction... 1470 😬

Actually I could literally give that a go, there are 1500+ pheasants right behind us in the woods... although I strongly suspect they won't be all there come Feb 😬🙁 I think this one is for Parrots though 🤣

Another option if it doesn't have to be a 150p... @FLO have this 130p on a Starquest manual mount (Alt/AZ and Eq).... https://www.firstlightoptics.com/telescopes-in-stock/sky-watcher-starquest-130p-f5-parabolic-newtonian-reflector-telescope.html Which could be combined with this Star Discovery WiFi goto mount... https://www.firstlightoptics.com/telescopes-in-stock/sky-watcher-star-discovery-wifi-az-goto-mount-tripod.html This would give lots of options for goto and manual (both Alt/AZ and Eq), the Starquest can even have a motor drive added later. If she then wants to upgrade, both mounts would take other OTAs... not sure if there's really a great deal of difference between 130p and 150p for (presumably) beginner. More importantly, both items are in stock for delivery before Xmas... good luck 🤞

Well having got astigmatism sorted, field curvature (mostly) under control, I thought it's now time to tackle coma, so here's the very thing to slay this final aberration apparently... a Tele Vue Paracorr Type 2 😃 I'm hoping not to run into "in focus" issues with it, but have some options if I do 🤞 I do love my new Bresser 10" dob, but I now seem to spent more for add-ons for it than the telescope itself... wasn't it ever thus 🤣

Got this last Christmas, along with my little Mak... really good book both to get started and also plenty of targets to work through during the year 👍

Interestingly, also another batch of the StellaMira 80mm ED f/10 seem to have arrived too, these are the same price though... excellent scope, but then I’m biased 😀

Heads up...all models back in stock at @FLO 😀 However, big increase in price across the range... guess that’s not unexpected given current economic climate 😬

I hoped you'd tell me that they're awkward to use, as now I've only got weight and cost as arguments against 🤣

I had a lovely few hours just enjoying the sights late last night (clear skies 😃), rather than comparing eyepieces, so I'm happy to stay with these now. I sense you've been down this same slope yourself 🤔 So, I am done buying eyepieces... at least for this year 🤣

Interestingly, I've just run that through Astronomy Tools FoV and on my 10" dob that 21mm Ethos would give exactly the same FoV (1.65 degrees) as my Pentax XW30, but with almost the same magnification (x60) and exit pupil (4.2mm) as my XW20 (1.1 degrees). Discounting having to get used to moving your head around to see the whole view, effectively it makes both eyepieces redundant🤔 More than happy with these though for now, plus I can use the XW20 in my Mak/C5 too👍

Have to agree with this and they work superbly even when used with ES 2x Focal Extender👍

Still a work in progress, but yes in the 14mm slot, the Delos is now the favourite... purely based on field curvature with the XW14, which is a shame because in terms of centre of field view, contrast, comfort and ergonomics it's a tad better... these differences are so minor though that the better sharpness at edge of field makes a win for the Delos 👍 I still love that big view in the XW30 though, and the fact that the Dioptrx integrates into the eyecup too... now you see it, now you don't 😃

I'd forgotten I had this one, it sits in the ST80 as a finder when running dual scope on the iOptron AZ Mount Pro... really rather nice eyepiece 😃

I don't know what you mean 🤣 Actually, I would like to put the Delos 14mm in as my second favourite now, based on the last few nights with it 👍

Pentax XW30 with Dioptrx... just amazing, sharp, wide views in the 10" dob 😃

Sounds good, glad you’ve been able to get some time with the new scope and the Rigel... it’s a good finder 😊 I’ve been lucky here too, went shopping for an hour, came back and the sky had cleared, so just had 2 hours out with the Bresser, trying all the new eyepieces properly at last... interesting results, but need more testing before I write up a post comparing them 🤔

I noticed that too, lots of attachment points for encoders etc... future proofing no doubt, but would be great to see “push to” on this mount 🤞

Ah, and like you, once I have established which eyepiece works for my tastes, I will be ruthless with the rest 🤣 Just come in from 30mins looking at Saturn and Jupiter together and as luck would have it, 14mm is just right on the StellaMira to get both in the frame of view together 😃 It has confirmed that the XW14 suffers badly from field curvature (in this scope), the Morpheus a little (but tolerable) and the Delos was excellent (none at all). More testing will follow, but Delos currently number one on that at least 🤔

I’ve tried 82deg eyepieces and didn’t get on with the larger FoV, however that was before I got a dob, so may indeed look at those later, but for now I’m just going to enjoy these 👍

Likewise... I see three currently with the 80mm f/10 😃 Able to get Saturn and Jupiter in frame together (with bit to spare around edge), using 14mm Delos, XW or Morpheus 👍 Cloud on its way unfortunately 😬