John

I think they are niche instruments but it is a nice niche These longer refractors do need quite stable mounts though, to give their best performance. The tube length and moment arm force generated have become the challenge for the mount, rather than the tube weight, which is quite modest.

The best tip I can give is to make sure that the finder scope is as well lined up with the main scope view. Finding your targets when you can be confident that your scope is pointing just where the red dot or cross hairs of your finder are pointing is a lot easier !

There is a lovely double cluster below Cassiopeia (the W shape) which is well worth a look at low magnification. It is actually in the constellation of Perseus. Here is a chart: The clusters are known as NGC 869 and NGC 884 (NGC = New General Catalogue) and should both fit into the same view using the lowest magnification eyepiece. A nice pair of galaxies under a dark sky are Messier 81 and 82 in Ursa Major. Again use the lowest magnification eyepiece. Here they are: You can "star hop" to these like this:

My understanding is that the Meade SN's did indeed use spherical primary mirrors but what is harder to find out is the precise focal length of the primary and how it's figure relates to the meniscus lens and the secondary mirror. Overall I suspect that replacement is going to be both difficult and costly, unfortunately.

Thanks Mike - I'd love to see some of your earlier work It has been interesting comparing my 28 April 1984 sketch with Davids 7 December 2020 drawing here: https://stargazerslounge.com/topic/367811-mars-7th-december-2020/ When I did my sketch Mars was around 16 arc seconds diameter and for David it was about 14 arc seconds. The scan has lost a bit of the detail and contrast that I captured and the original was pretty close to Davids 2020 drawing. I must have had sharp eyes back then !

For the scope to work, the focuser tube needs to be moved back away from the secondary mirror to about where I have drawn the red line on the photo below and the focuser tube needs to be able to move smoothly back and forward along the green arrow that I have added in with the eyepiece on the outer end of the tube. There are probably a number of other adjustments needed but that is the main problem that I see at the moment. I have never seen a focuser mechanism of that design so it is obviously home made.

Adding another comment is the way to reply. That is the way that the thread on the subject develops. If you could post some photos of the whole scope as well as the details of how the mirrors are held and the eyepiece is held, then I'm sure you will get suggestions on what to do to make it a workable scope.

With a newtonian scope, the main and secondary mirrors are fixed in position and the focuser / focus tube moves the eyepiece in and out to achieve focus. At no time does the end of the focus tube come anywhere near the secondary mirror. Here is another design using a single vane to hold the secondary mirror:

The focus tube should be well away from the secondary mirror for the scope to work. The focus tube in the picture seems to be actually pressing against the secondary mirror pushing it out of alignment. The view down the telescope, towards the main mirror should look something like this with the focuser tube well away from the secondary mirror:

I don't think I could help ending up interested in space and astronomy. I was 9 when Apollo 11 made the 1st moon landing and had followed the preparatory and later missions with avid interest. My parents were not particularly interested in those subjects themselves but were very aware of the significance of what was unfolding so ensured that my brother and I had a good supply of newspaper and magazine articles, plastic model kits etc and were able to watch much of the TV coverage. Actually the "hit" rate from their efforts was just 50% because my brother is not all that interested these days I suppose there were a lot of folks who lived through the 1965-75 period relatively unaware of these momentus space-related events though I have always been interested in nature, wildlife, geology and the natural world though so I guess space and astronomy are an extension of that.

Pseonally I think the the best pure optical quality eyepieces that can be purchased for £100 or less would be Baader Classic Orthoscopics in the 18mm and 10mm focal lengths. These are actually £50 apiece. They don't have long eye relief (orthos don't) and their field of view is limited (like other orthos and plossls) to 45-50 degrees but in terms of pure optical performance I think you would need to spend a lot more than £100 to beat them. If you want a wider field of view and / or longer eye relief (eg: if you wear glasses when observing) then other options will be preferable such as the BST Starguider range or the Vixen SLV range. Are you looking to replace the focal lengths of the stock eyepieces that came with the scope or add new focal lengths ? Another option would be the Baader 8-24mm zoom. It's not perfect and you would probably want to invest in couple of other eyepieces to compliment it at low power (the zoom field of view is quite narrow at the 24mm end) and for high powers, say, a 6mm. The Baader zoom covers the middle ranges of observing magnifications pretty well and is a comfortable eyepiece to use with pretty good optical performance. Now prepare yourself for a host of other good suggestions as well

I think the pre-owned market will be awash with equipment in a couple of months time.

Such filters do benefit from dark skies and are more effective under them than they are under light polluted skies. For an observer trying to observe nebulae under bortle 8 skies, which is a pretty challenging proposition, the filter might be the difference between seeing some suggestions of the target and seeing nothing at all.

I think there are better eyepieces around for planetary viewing, but the differences are slight. The positioning of the planets over the past couple of years has made a really substantial difference to the quality of the views that we are getting in the UK. That is a much larger impact than changing eyepieces or even scopes as has been discussed on this forum many times. By all means try alternatives but don't be surprised if there are no "magic bullets" out there while the planets remain low

A nice cracker filler

I have an LXD 55 aluminum tripod. It seems to be broadly compatible with the EQ5 / HEQ5 tripod tops. The north peg might be a slightly different design though. It is in the same place but might be shorter or with a slightly different profile. If you got an EQ5/ HEQ5 steel tripod you could probably modify the north peg shape to get it to fit the LXD 55.

Hi, The 5mm X-Cel LX will be better than the stock eyepieces. It provides a relatively high magnification but at least it will be a useful one. Bear in mind that a lot of astro observing is done at low to medium magnifications. Targets such as the Andromeda Galaxy and Orion Nebula need low to medium magnifications (30x - 80x say) as do many star clusters. The 2.3mm X-Cel LX will just not be much use to you to be honest. It's well worth considering the BST Starguider eyepieces as an alterntative to the X-Cel LX eyepieces. Performance at least as good and somewhat better value for money. You don't need to use Celestron eyepieces just because the scope is branded that: https://www.firstlightoptics.com/bst-starguider-eyepieces.html I don't do any imaging so I can't help with that but long exposure imaging is a very different ball game to observing and much more demanding on the mount, scope etc. I would suggest that you start a separate thread on your scope and needs to avoid de-railing this one which is dealing with a slightly different issue.

Hi congratulations on your new scope. It is a nice one It will show you lots of nice views but Mars is now moving away from us and rapidly dwindling in size. A short focal length eyepiece will show a slightly larger disk but still small and discerning any details on it is now getting challenging even for powerful scopes. A small pink disk possibly with suggestions of vague dark markings is pretty much about as good as Mars is going to be for some time now. There are plenty of other good targets around though and dark nights now (when the clouds stay away) so you should have a good supply of non-planetary targets. Orion is a very fertile hunting ground for example and is well on display mid to late evening currently.

I had a couple of very nice astro related pressies from my lovely daughter and both complete surprises. The moon image was one of mine taken using my mobile phone at the eyepiece of my Tak 100 refractor. How she got hold of it I'll never know but it has made a lovely canvas type enlargement to go on my astro wall It's such a nice feeling when someone you love goes to that much trouble

Just a short session tonight with the 100mm refractor. Mars was hard work to be frank. Mediocre seeing, small disk plus a cold night with heating plumes abounding took their toll so it was only really possible to see vague dark markings on the small disk at 191x. The Moon was somewhat better and some lovely detail was on show along the terminator provided that I stuck to sub 200x magnification. Above that and the seeing held things back. Orion well up and very inviting as ever. Rather surprised (given the conditions) that I could pick out both the E & F stars in the Trapezium cluster. The optimum magnification for this seemed to be 113x (8mm eyepiece) more than that made the task a little harder and less didn't show them. Proved once again that there is a "goldilocks" magnification for teasing these fainter members of this famous group of young stars out of the nebulosity in which they are embedded. Alnitak (Zeta Orionis) was also rather well split at 191x given the conditions. 2.2 arc second gap but quite a brightness difference and a subtle tint variation between the stars in this pair with the fainter (mag 3.7) star seeming pale yellowish compared with the white of the brighter (mag 1.9) primary star. The third component, C, was also visible a little further off which is mag 9.6. Nice session, despite the seeing Seasons greetings to all

This was my first ever wide field eyepiece. A Speers-WALER 24.7mm. It sported a 68 degree apparent field and worked well in my TAL 100 and later my Celestron C5 both of which were F/10. As I moved to faster scopes though astrigmatism became rather obvious in the outer parts of the field and I was less happy with it. I later learned that they 24.7mm (that it it's true focal length apparently) was the least well regarded of the Series 1 Speers-WALER range. Another interesting early foray into wide field eyepieces was the Fullescopes Super Wide "plossl" which was really an erfle derivative. 80 degree plus AFoV's but, again, very nice at F/10 but the field edges went downhill fast as the scopes got faster. I also has the 20mm in this range quite recently but my current scopes were a bit on the fast side for it. Over the past few years, re-visiting eyepieces that I used to own has not proved too successful to be honest I had a set of these as well at one time which were a development of the same 80 degree design: These are the Japanese Widescan III's. An expensive eyepiece back in the late 1990's but with similar issues to those mentioned above. I had high hopes for the 30mm / 84 degree 2 incher in my Vixen ED102SS F/6.5 but the outer 25% of the FoV was really awful. The view looked a bit like water twirling down a plug hole ! Perhaps this lot are my greatest "misses" rather than hits ? My fault I guess for a) developing a liking for wide fields and also b) for moving gradually away from F/10 and slower scopes I suppose

Well done Doug ! I've just popped my 100mm frac out for a short spell following a nice family "virtual" meet up. Just saying "Hi" to a few winter favourites

Yep - I've just got out and it's not bad. Not the greatest seeing ever but good enough to have some fun Short session though - got to keep on the right side of the CEO

Quick set up and tear down are key to getting much astronomy done in the current UK conditions It is clear now so I've popped my 100m refractor out on an alt-az mount and can get on with observing practically straight off.

No more here I'm afraid Dave I've owned loads of them in the past though and enjoyed most of them. If we can post pics of eyepieces that we used to own then I might be able to help, eg: Some of the bottom row of this one are pre-2000 I think: I've owned sets of the old smooth sided TV plossls, TV Widefields and a number of Celestron Ultima's / Orion Ultrascopics. Older erfles and orthos too plus a couple of the Series 1 Speers-WALER's but I just don't have any photos of those, unfortunately.