Davesellars

Well, I plan on something a touch higher power that the 4mm I currently have - this is mainly for lunar observation and some planetary later on once they've risen sufficiently. I currently have a 4mm TMB clone which works fine giving 179x. I think the 3.2 will give 224x so a reasonable step. So I like the price and particularly that it's 60 degree apparent FOV (for manual driven mounts). My 4mm gets a tonne of use actually in most of my scopes. The 3.2 may be restricted a bit more to seeing conditions but I think will get a reasonable amount of use for lunar observation particularly and double stars. Question is... what is the EP actually like? Is there light scatter? Reflections or other abberations? Would this be a good choice? I don't particularly have the budget to go up to buying a Delite at the moment (unfortunately), but perhaps next year...

That's good to know. I was thinking about possibly purchasing the BST Starguider 3.2mm which gives me that same power approximately or find a suitable 3mm which gives 238x.

Definitely!!! I had regretted rather selling my 120ED (was necessary at the time and its bulk meant it hardly got used back then as I need to walk with it to my dark site) - However, I think the performance of this scope really is not that far off the 120ED in what it was showing... I guess a few sessions on the planets later this year will give me a better comparison. However, I do have the big 'ol light bucket anyway for when the conditions really allow. Many times I don't have the time to get the 12" out beforehand & cool down. etc I think this 4" refractor may well become my main scope of choice for many nights.

The design of the Stellalyra base seems to be a lacking a vertical brace on each side (compare to the Skywatcher 12" version). I think this would help to stiffen up the entire base. There doesn't seem to be anything to stop movement in the horizontal axis without this brace on the outside?

It was a beautifullly clear and transparent evening of the 14th March. So far the 4" refractor had only seen a very brief (minutes) look at the Moon the previous Monday before clouds flanked in and shut off play on one one of the best night's seeing conditions in quite some time. I was unsure though the seeing was going to be that great... transparent sky normally means the seeing is not going to be brilliant. I let the scope cool down about 15 to 20 minutes while I got ready but it was freezing outside - the temperature differential meant realistically the scope needed 30 minutes and better yet 45 minutes to an hour to be completely stable. After some light viewing of the Moon (seeing was OK but far from great) I decided to test optics by splitting Alnitak which was easily achieved at 178x and just about possible with 142x. M42 was starting to get a little too far down into the murk and while the 4 main stars were nice and clear and probably just the E star, I could not discern the F star. Seeing conditions probably limited the testing but I did a star test. Inside focus showing perfectly diffracted rings and collimation was dead on as far as I could see using a 4mm eyepiece for 178x. Outside focus showed some difference and was slightly mushy but rings still apparent and looked to be not a bad result giving under-corrected optics. Probably to repeat if I can be bothered on a night of great seeing and have let the scope cool down more than 1 hour to be sure. It is understood that prism diagonals can be beneficial to under-corrected optics in refractors (English, N., 2011. Doublet Apos. Choosing and Using a Refracting Telescope, pp.123) by essentially nulling the under-corrected spherical abberation with the prism which is naturally over-corrected. Perhaps, when funds allow I may invest in one of these particularly when the gas giants again make their display once again where I think they will benefit the most from use of the prism diagonal. My 80ED actually displays the same under-correction (will come to this later...). But for now, the "proof of the pudding" is in the eating... and so, without further ado I pointed back to the lunar surface for rather more critical observation. The seeing initially allowed for 178x with my 4mm TMB clone however , the best view was at 142x with the Pentax XW 5mm The lunar surface was shimmering but not much at these level and there were sufficient periods of time of clarity to pick out detail. I only managed the most central craterlet in Plato. I have not managed to see any before with the 80ED and the seeing was far from optimal for this. The Mons Hadley region was quite spectularly three dimensional with great contrast and colour rendition with the white highlights on the mountain range. An outstanding region at the terminator from the Herodotus / Aristarchus craters and showed superb contast of pitch black in the gulley to the freshly illuminated walls from this upwards. This entire region resplendent in features hightlighted by the sun-rise across the face. Schikard was watched at various time during a 4 hour period. Initially with the 4" refractor the back wall of the has not yet illuminated however the raised basin central to the crater was slightly illuminated certainly giving the impression that this crater is far from flat. The nearby Nasmyth crater perceived depth of abysmal blackness inside the crater against the full illuminated walls was quite something at this stage of illumination. Moving upwards once again to Gassendi the central peaks here were very easily seperated as disinct peaks with the 4" refractor along with considerably detail of the surface of the crater with its many undulations, ridges and paths around it. At the current illumination it seemed quite optimal for picking up many of its features and not washed out. From Gassendi to Mersenius holds considerable interest. A "small" mountain range that almost connects the two craters and several rilles the easiest of these directly shoots off from Gasendi banking around Mare Humorum. However, more interesting to me was that of the rille that cuts across the mountain range between Gassendi and Mersenius. With the 4" refractor this rille was followed in its entirety as it seems to wend its way through a low mountain range through to Letronne. Later, with the 80ED I attempted the same however the rille was lost after the main deeper section. Mersenius itself showed at least 4 or 5 craterlets - again the current illumination and contrast probably helping with this. Sinus Iridium was viewed as point of comparison later with the 80ED. With the 4" refractor the detail at the edges of the bay seemed considerably more refined and with greater depth to the view. I had actually brought the 4" in around 10:30 and left the mount out as quite frankly it was two darned cold to grapple with it. I had something to eat and warmed up and later had the idea to get out with the 80ED... It seemed like a good idea at the time! The 80ED at least cools down very quickly... It was probably ready after 15 minutes pretty much stable or there abouts and was observing again by 11:45. I did similar observations as above. The time meant though that Schickard was now almost fully illuminated with the very top of the back wall of the crater just peeping though. The basin itself though was fully illuminated. Amazing how quickly actually light moves across the surface (something I had not really observed much before in the space of one session). Most of the finer / smaller details that I had observed were there in the 80ED although particularly noted was the loss of some low contrast areas of rilles and some of the smaller craterlets in Mersenius. However..... those small details that were existing in the 80ED were so much more difficult with the 4" showing them very obviously. OK, the the upshot is this... There is a substantial visual difference between the 4" and the 80ED - this goes in hand with the substantial increase in light gathering and most importantly resolution for lunar observation. On better seeing I feel that the scope can certainly handle more than my 4mm eyepiece as the image was far from dim nor lacking contrast at this stage. So, I'm happy with this scope! I will have to keep in mind that the scope requires a reasonable amount of cool-down time or be a little prepared for the 4" to reach its best optical ability for lunar and planetary observation in the future although this is more of an issue in winter.

Did you have such an issue with the primary collimation on your old Skywatcher 10"? I do have to collimate every time as the mirror does seem to shift quite easily from moving it in/out of the conservatory) however the primary mirror collimation knobs have always been quite responsive.... The secondary on the other hand I switched over immediately to Bob Knobs and did the "Milk Bottle Top" mod otherwise the collimation of the secondary was nigh-on impossible.

I use welding magnets on mine to balance properly like these at the base of the scope: Welding Magnets Although my RACI is quite heavy (an Altair 10x60) so when the scope is quite low down I lay an exercise weight (those things you wrap around your arm) across the top I agree about the positioning - there's a certainly angle where you can't sit on an ordinary chair nor really standing up which is mighty painful after a while for the back. I've seen people swear by the use of an adjustable ironing stool for as an economic option rather than go for one of the astro stools.

Thanks Stu. That's what I've been looking for! SkySafari doesn't render the terminator very well hiding most of the detail which is actually visible... I wasn't going to go out again but you lot are a bad influence... I broke and spent a little whle out again but with the 80ED Nice to have seen the progression of light and illumination of Schickard during the evening!

Well, now that I've had the opportunity to use the 4" Starfield on the Moon I'm pretty impressed by the quality of the optics on this scope. Absolutely zero CA anywhere to be seen. I could just about make out one craterlet on Plato but the seeing was definitely not steady enough for more. Alnitak was split (just) at 142x and with obvious seperation at 178x

Crikey it's cold... Seeing was OK with the 4" refractor best at 142x on the Moon.

Me too... That is a good idea... I should really invest in a solar wedge some day!!!

Nice if you've got the time!

Well... It's really clear here at the moment! Even ClearOutside says so... therefore it must be true. 😅 I shall get the 4" refractor out for some lunar observation and perhaps some double stars.

I'm pretty late to the game... Although I was very interested in astronomy when I was a young lad I only had some basic binoculars but really didn't appreciate what was actually up there however seeing the Milky Way very well back in the 80s in rural Lincolnshire was something else and unfortunately not something I've seen since... However, my first proper instrument I bought in 2014 which was a Celestron C8 on the EQ5 mount (I still have that same mount - what a work-horse it is!) which got me properly into observational astronomy and I quickly progressed through the Messier catalogue with this as I took to star-hopping like a duck to water.

I brought everything in in the end... wind really got up and looked likely to rain... If it does indeed clear I may get out with a refractor again (energy depending!)

Bah.. clouded here too. Hoping it clears... I was viewing M42 with the dob and realised the collimation was actually out so could have had an even sharper view of the Moon earlier... After I collimated I was easily able to get E & F in the trapezium and also split Alnitak. Was about to try for the same in the 4" refractor and it clouded over!

Really good! Have the 12" dob and the 4" APO setup... 375x with the dob no problem as the seeing is excellent.

Looking nice and clear right now and forecast good for tonight...

Looks great!!! These More Blue rings look to be a much more flexible solution that the Tak cradle... https://www.firstlightoptics.com/tube-rings/more-blue-80mm-tube-mounting-rings.html together with 4" ADM vixen rail you'd be set unless you need a finder....

I have my 60mm Altair Astro RACI (same kind of design....) in a boot bag something like this: https://www.amazon.co.uk/Puma-Unisexs-teamGOAL-Sports-Black/dp/B07XGBFYVG/ref=sr_1_29?crid=3EXWR7ZJY33JV&keywords=football+boot+bag&qid=1646227466&sprefix=football+boot+bag%2Caps%2C75&sr=8-29 Just about room to store my Rigel QuickFinder as well in it. If need be you could add some padding etc but I don't bother as I don't need to travel with it.

I'd recommend going through the entire Messier 110 list (or, at least what's possible from your latitude...) over the period of a year. The majority are bright and / or interesting and catalogue comprises a very good variety of objects and difficulty. Make a shortlist of those that are visible for the time you're going to be observing.

Thanks Dave! Fortunately, I like to write and reflect on what I've seen after the session.

Session Date: 6th - 7th Feb, 2022 Incredibly, a new scope had arrived just that day and by 7pm it was perfectly clear sky. Obviously, they had forgotten to pack the clouds... I wasn't about to complain! I setup the 102ED on the EQ5 and it's as steady as a rock. The scope had about 20 minutes cool-down time while I was setting up and getting other things ready before the first observation. Session 1 Time: 8:30pm - 10:30pm Scope: 102mm ED refractor Transparency: Excellent Approx NELM: 5 So, for the 4" frac's first light I decided to do a whistle-stop tour of Messier objects. As I've seen these many times with my 120ST and 80ED I would be able to make a decent comparison at the end. Betelgeuse - I used this to align the 60mm finder and noticed perfect colour rendition of the red giant. No flare from brightness and a perfectly round pin-point of light once focused which was a breeze. M42 - the Great Nebula seemed like a good start to test its ability on the depth of nebulosity and the trapezium. With the 17.3mm Delos (41x) the nebulosity was truly extensive with the wings spanning a wide area. Going straight to the 5mm Pentax XW (142x) the depth of the nebulosity was stunning with great contrast with the dark areas within the nebula. The main 4 stars of the trapezium were pin-point still - the seeing seemed to be very good as well as the transparency being excellent. Not something I bother about at all - but I looked for the E & F stars of the trapezium and could easily make a very fine pin-prick of light in their positions. These were actually cleared with a 4mm eyepiece (178x). F was more difficult for some reason although the magnitude is approximately same - but, as I said before this is not something I've really bothered about before. Overall, the nebulosity seen was at the very least equal to the amount seen with my 120ST but with such a large objective is difficult to judge accurately. M78 + NGC2071 (reflection nebulae in Orion) - So, on to a different type of nebula - M78 itself was very bright with the 17.3mm Delos particularly around the 2 main stars but also extending outwards a reasonable distance. NGC2071 was lighter but quite a bit clearer than I have previously seen it with the 120ST on a night of good transparency. M31 / M32 - Not ideally positioned at the moment as getting quite low, however M31 really showed a really bright extensive core with the Delos 17.3mm. M32 surprised by its brightness in the same FOV. With the Delos 10mm the amount of dust was quite apparent. M45 - What a view! Just about able to fit in the entire cluster within the FOV of the Delos 17.3. The colour rendition and accuracy of the various stars and brightness is quite spectacular with this glass, like in my 80ED. Double Cluster - Again, just about managed to fit in both clusters in the same FOV with the Delos 17.3. One of my favourites to view but the 4" really does do it more justice than the 80ED. The whole view just lit up with pin points of light in various colours back-dropped by the nebulosity of the milky-way. At this point I was able to see that the stars were perfectly still in focus right to the edge and with zero (that I could make out) optical abberations. M37 / M38 / M36 (Open clusters in Auriga) - With the 10mm Delos, these cluster shows very nicely indeed, particularly M37 with its profound amount of fine stars and M36 showing its starfish shape well. I was perceiving at the moment that this was actually outperforming the 120ST with regard to the star magnitude it was getting to. I could easily follow the milky-way region which showed some structure while faint it was quite obvious with particularly around dark region inbeteen Cassiopeia and Perseus. I spent a nice bit of time just looking up and taking it in. M97 (Planetary nebula in Ursa Major) - No filter and no problem... I wasn't sure that 4" was going to show this nebula as it can be difficult even with my 120ST but it is dependant on the transparency and darkness. However, the nebula showed a decent size ball that appeared slightly inconsistent contrast in the centre. I didn't have my filters out with me but I went to the Pentax XW 7mm which affirmed an area in the centre as being slightly darker than the outer region but no further detail. M108 (Spiral galaxy in Ursa Major) - With the 14mm Delos this was clearly visibly direct vision but without any detail. With the 7mm Pentax XW, I could discern a very subtle change of brightness along the line of the galaxy. There has bee some clouds hovering around in the background menaning to spoil the party but they seemed for stay clear for the moment and let me get on with it... I was having a great time! Mizar (double star) - I'm not a double star observer as such so - but I think this is Mizar A and Mizar B - This was easily seperated with my Delos 14mm (51x) and Alcor also in the same FOV. M101 (Spiral galaxy in Ursa Major) - With the 14mm Delos this was direct vision visble as a mere ball of light of reasonable size. I spent some time varying eyepieces from 7mm to also 10mm. 14mm seemed to produce the best overall view in terms of contrast. With the 10 and 7mm, while larger some averted vision was required. M81 / M82 / NGC3077 (Spiral galaxies in Ursa Major) - Both outstandingly bright with the 17.3 Delos however really showed their stuff with a 7mm Pentax with M82 showing its central bar (split) and M81 showing some extended dust surrounded the core region. Closeby NGC3077 showed as reasonably bright circular core surrounded with a touch of extension surrounding it. M65 / M66 (spiral galaxies in Leo) - Easily showed their bright cores only. Tried for the nearby NGC 3628 but something was up... Clouds had come in and covered most of sky. Although it looked perhaps temporary. It was 10:30pm and so I decided to pack away the scope, bring in the eyepieces etc and left the mount out for a possible session later on. after packing away the scope I noticed the clouds had indeed shifted off. I was hungry by this point anyway so had a good break until after 12:30 and looked outside again. It was stunningly dark and clear. All the stars just seemed to be a little bit brighter. All the neighbours had their lights off and all directions LP just seemed significantly less. I decided to pop the 120ST on the mount and get setup for the second session... Session 2 Time: 1am - 02:30am Scope: 120ST refractor Transparency: Excellent Approx NELM: 5.3 After spending 10 minutes just looking around and regaining dark adaption again I can could easily see M44 naked eye which appeared as a faint ball of dust against the darkness of the sky. M104 ("Sombrero" Spiral galaxy in Virgo) - It's been a long time since I've observed this and it was perfectly positioned. I spent a good amount of time with this at different magnifications down to using the 5mm Pentax (142x) which showed well the lighter dust from the galaxy. At the lower power, the contrast easily showed the darker region spitting the galaxy. M3 (Globular Cluster in Canes Venatici) - Some of the cluster resolved with the 5mm Pentax (142x). Very bright core. M64 ("Black Eye" Spiral galaxy in Coma Berenices) Very bright and with the 10mm Delos discerning a small dark area in the central region. M59 / M60 / M58 (spiral galaxies in Virgo) - It's been a long time since I last "delved" into the Virgo galaxy cluster... I shall be re-visiting soon enough with the 12" dob. These galaxies were nice and bright with the 14mm Delos but not showing any real detail. I could not discern the companion galaxy (NGC 4647) to M60. I have seen this before with an 8" SCT but this eluded me tonight. M89 and M90 were also obvious enough. M13 (Global cluster in Hercules). This was now sufficiently high enough to make a good observation. Indeed, with a bit of work and a touch of averted vision it was just about visible naked eye as a tiny ball of diffused light. M13 is spectacular - it's large and very bright and with high enough power (5mm Pentax) was able to start to resolve individual stars although not at the core. I have previously found that there is a massive difference to viewing this with good aperture (last time was with my 8" SCT) which easily resolves stars at the core. I'll be looking forward to seeing this again with the 12" dob. Nearby galaxy NGC6207 was directly visible but needing the 10mm Delos to bring it out properly as a faint small elongated smudge. M101 - This was now very high up and with the additional darkness was well worth re-visiting. It was now considerably bright with the 17.3 Delos very easy direct vision. Going to the 10mm Delos showed the disc of the galaxy. I stayed with it for quite some time and with averted vision helping to distinguish some areas of dark / light almost catching a swirl effect. M102 ("Spindle" Edge on spiral galaxy in Draco) - One of my favourites. Very bright core with a distinct dark lane running through it. I wasn't seeing the entire length but I'd imagine just a slight extension outside of the actual core. Impressive. NGC 5907 (Edge on spiral galaxy in Draco) - This one is considerably more difficult... It's very large and diffuse and no real bright core to speak of. Using the 10mm Delos and averted vision I was only able to see a very faint long area of brightening on the sky. I've seen this one considerably better with more aperture and it really needs much more light capture than 120mm. I was a little reluctant to pack up but I was tired and needed my energy for the following day so I called it a night at 2:30am and packed up. In all it was a really great session that food for the soul after February has been quite disastrous for observing (apart from a few shortish sessions observing the Moon). The 4" refractor really surprised me with its performance on DSOs - I would say that it pretty much matched the 120ST in what it was actually showing regarding nebulosity and picking out galaxies and detail. Obviously for star fields / clusters etc the 4" ED was by far the best and I certainly had a good feeling that the ED was actually going deeper than the 120ST regarding star magnitude. The performance of the 4" against the 80mm ED is a huge step imho comparing it with previous observations on DSOs with the 80mm ED. Can't wait to get in a session now observing the Moon with the new refractor (although would like a nice week of clear Moonless nights first to get the dob out for some good galaxy action around Virgo etc).

Here too, looking amazingly clear here with a deep blue sky should be fantastic transparency. I've been out all day but will try to get a good rest and hopefully it will be still like this around 10ish to get the dob out.

After a decent break had another couple of hours out from after midnight. After an abysmal February due to bad weather tonight has almost made up for it...