Ricochet

I don’t think you’ve got anything to apologise for, this is all on Celestron. Assuming you bought it new, they should have examined and replaced the mount when you contacted them. Did they ever see a photo like you’ve shown us? I doubt they will do anything after this time but I would still be inclined to go back to them and say this is the fault that has existed since purchase, here are all the support emails from that time, what will you do about it?

Presumably, they don’t use anything because normally it doesn’t unscrew. If the nut is unscrewing when the mount is moved in alt then the friction between the mount and the nut must be higher than the friction between the threads of the nut and the threaded rod. What you need to do is to decrease the friction between the nut and mount and/or increase the friction between the nut and threaded rod. Starting with decreasing the friction between mount and nut, I would first look at the nut itself. Perhaps on the face that touches the mount the surface is not smooth and needs sanding down. Also, with nuts generally there is one side where the corners are slightly rounded and one where they are not. I would turn the nut so the side with the rounded corners is facing the mount. I would also see if there is the possibility to fit some washer(s) between the mount and nut. With regards to increasing the friction between nut and rod there are two options. The first is to put loctite (I’d go with blue) on the threaded rod and then do the nut up to the correct position. The second, as you have already thought of, is to use a nyloc nut either instead of the original nut, or as a locknut behind the original nut. Using a spring washer will not help as it will increase the friction between the mount and nut and so help the nut unscrew. There is not going to be any set torque that anyone can give you for this adjustment. A torque setting is for when you have a static joint, but yours must be able to move for the mount to work. What you will need to do is to judge when the nut is in the correct position on the threaded rod to hold the dovetail in the correct position but not so tight that the movement of the mount is impeded and the motors strained.

FLO list the OTA weight at 19kg. If that's accurate I don't think picking one up with one hand is advisable.

👍 I wrapped handlebar tape around mine

Actually, I think the 12 is probably the most useful for an F5 scope like yours as it gives an exit pupil of 2.4mm, which is perfect for DSOs. Above this you want a high power star cluster eyepiece at 12/1.4, so the 8mm, and a low power wide field/finder at 12x2 so the 25. An exit pupil of 0.8mm is acceptable for a high power planetary eyepiece and with a small scope you'll want to push the magnification a bit so a 2X barlowed 8mm (8/2=4) giving approximately 163X should work well. This will give you the range of focal lengths of 4, 6, 8, 12, 25 and you can hold off buying the 5 until you determine if you need something between 4 and 6. The only fly in the ointment with this plan is the performance of the 25mm at F5. Optimal performance of the Starguider eyepieces appears to be achieved when using a scope with a focal ratio in the order of eyepiece focal length/2, or higher. The 12 should still be ok but the 25 will be increasingly astigmatic towards the edges (stars look like seagulls). Getting a better corrected eyepiece at this focal length is more expensive. The cheapest well reviewed option that comes to mind is the 24mm Stellalyra UFF, but it is double the price and weight of a Starguider.

What is actually wrong with the telescope that you need someone else to service it? If it is just a case of disassembling, cleaning, reassembling and collimating do you not think you could manage this yourself or do you think that the mirror(s) probably needs recoating and you want an expert to look at it? With regards to saving the money and putting it towards a bigger scope I think you should consider why you have not observed during those periods when you have stopped getting the scope out. The bigger the scope, the more effort it requires to get out and the less likely you are to use it. If this has already been an issue with the 8” then it will probably be even more of an issue if you were to switch to an even bigger scope. However, now that you have two smaller scopes this effect should be lessened as any night you don’t feel up to getting out the 8/10/12” scope you might still observe with the smaller scope. Flocking makes a small difference but nowhere near jumping up a mirror size. The thing that made a much bigger difference to my scope was to mask the edge of the primary mirror, which made stars much tighter and reduced scatter across the field of view so the background sky is darker. FLO sell a Primary mirror mask for Skywatcher Newtonians. It states the 200PDS but I assume the mirror clip screw holes are standard across al Skywatcher scopes. Whatever upgrades you consider for the current 8” scope I would also recommend you apply to any new, larger scope.

I don't think so. I've got six of them andI think they're all like it, particularly in dewey conditions.

It's funny you say that, as I have your old 14XW and if anything it's my favourite XW. Different scopes though, as I use it for DSOs in my F6 Dob where it gives a 2.3mm exit pupil, which is ideal, where as you would have been using it in what, your DC, where the exit pupil would have fallen below 2mm and so the 20mm would have been much more suitable for DSOs. Of course the radius of curvature is much greater in my scope too, so it will contribute less to the overall curvature of the system, which is the main complaint in the 14-40 XWs.

$1200 is a lot to spend on a surprise gift so I would consider whether it would be best if your daughter was involved in the decision making process as she is more likely to know what she wants from a telescope. Assuming that your daughter only wants to make visual observations and not take photographs then I think there are two main contenders within your budget range. The first is the 8" F6 Dobsonian telescope. If you are looking for an all round telescope that can show everything well visually then this is the one to go for. It will show the planets well as well as deep space objects (DSOs) if your daughter discovers that she likes those too once she starts looking through a telescope. The downside of this telescope is that it is a relatively big and bulky telescope. It is not one for carrying long distances, up/down stairs or taking on public transport. In addition, a height-adjustable chair is a must as the eyepiece is too low to the ground to stand. I use a drum stool with mine but ironing chairs and dedicated astronomy chairs are also options. Technically, "Dobsonian" refers to the mount so you know if you buy a Dobsonian you are buying both the telescope and the mount that it sits on as a single package. A nice model of this type of telescope is the Celestron Starsense which has a special phone mount that uses your phone camera to guide you to objects, which isn't really necessary for Saturn, but will make finding DSOs and the faint planets (Uranus, Neptune) much easier. For a lighter option you could also consider the 6" F8 Dobsonian, which won't show DSOs as well as the 8", but will still be very good on planets. The second option I would consider is the 5" (127mm) Maksutov. This is a much smaller telescope physically, but the mounts available for it range from small and lightweight to big and bulky. This type of telescope is also sold as an OTA without a mount so you need to make sure that you buy one that is bundled with a mount or account for the additional cost of buying your preferred mount. This type of telescope is more geared towards planetary observation, although some DSO observation is also possible (it can't show as wide a field of view and it is difficult to get a large enough exit pupil in order to use nebula filters). I like the look of the manual mount bundled with this Explore Scientific Maksutov, which should give steady views at the expense of it being a relatively big and heavy mount. Alternatively, this Skywatcher Maksutov comes on a mount which is much more transportable, and uses a phone app for full Go-To functionality (finding and tracking objects). The downside is that the tripod is known to not be great, however, it uses the standard 3/8" photographic thread so could be replaced with something better in future whilst keeping the AZ Gti head.

Check that too when you contact Bresser. The Bresser Messier range have 10 year warranties but you might need to register with them.

The 10” Bresser has been out for a few years now and I don’t recall any previous reports with flex. I have the 8” version and the same 28mm eyepiece and have never noticed any flex. I also have a 21E and a binoviewer which must be just as heavy as the large eyepieces which again I’ve never noticed any issues with. It might be that the reduced diameter of my scope increases the stiffness or that as a cost/weight saving measure they have switched to using a thinner sheet metal at some point but my initial reaction is that if your tube is flexing then it is not up to spec. The first thing that I would do (that I suspect you have already done) is confirm that it definitely the tube wall that is flexing and not the connection of the focuser to the tube. You have the four obvious nuts and bolts that hold the adaptor plate to the tube but there are also four tiny grub screws in the side of the adaptor plate that hold the focuser. From memory they are something like 2mm at the top and bottom and 1.5mm on the sides. If you bought the scope new then it is still under warranty so before you make any modifications contact Bresser (.de) and find out whether they consider that amount of flex to be within tolerance. They have a good customer service department and it would not surprise me if they replaced the tube.

I only have experience of using my 50mm Lunt so I can't give any direct comparison feedback but these are my thoughts. Firstly, I notice that both the 60mm Lunt and 70mm Coronado have "proper" 2 speed focusers. The 60mm Coronado has a sliding drawtube for rough focus and a helical fine focus. It might be fine but I'm not massively keen on the idea. Secondly, the Solarmax 2 range use a sliding pin to tune the internal etalon. This looks like a much faster adjustment than twisting the pressure tuner knob on the Lunt scopes, so is it more difficult to fine tune? Additionally, Coronado have removed this in the upgrade to the Solarmax 3 range and now use external etalons mounted at the front of the tube. They say that this gives a better image than using an internal etalon. We can take it with a pinch of salt that the external Coronado is better than the internal Lunt as they are competitors, but it is safer to assume that it is true that the external Solarmax 3 design outperforms the internal Solarmax 2 design. Thirdly, I have double stacked my 50mm Lunt. Since I bought the double stack unit I have never even considered observing without it. I would look at either buying a double stacked unit initially or consider how easy it will be to upgrade to a double stacked setup in future. The Lunt scope is a recent model and I think it is fairly safe to assume that the filter will be available as a future purchase should you wish to upgrade. If Mark is right that the Solarmax 2 scopes are old stock then might there be a problem buying a double stack filter if you want to upgrade a year down the line? If you go for the Solarmax 3 can you even buy the double stack filter separately? I don't see anyone selling them as separate units at this time. However, the double stacked 70mm Solarmax 3 is listed as having double stacked 60mm filters so perhaps it is the same unit for both scopes and it will continue to be available in future.

Try buying a pair of grip gloves from somewhere like Screwfix so you can hold the lower part of the Clicklock more tightly, then you might be able to unlock it.

M54 female (i.e. the thread is on the inside of the draw tube)

I think it’s more than just the prism size. They’re sharper due with less ca, although maybe that’s due to using a gpc rather than a standard Barlow. The coatings are better and the baffling and edge blackening is better resulting in a reduction in reflections.

I suggest you buy the Baader Maxbright II instead as it is massively superior, both optically and mechanically. If you can’t afford/wait for the Maxbright, go for the OVL which is the same binoviewer as the WO with upgraded eyepiece clamps.

No. You won't see any difference. The curve on the mirror means that any part of the image comes from all parts of the mirror, not just one point like on your flat wall mirror.

I own an 8" dob and a 72ED. Eventually owning both scopes would be ideal but if for some reason I could only keep one scope I would keep the 8" dob. Without wanting to stir up any frac vs newt debates it's just better on all targets (that fit in the field of view). Both scopes are relatively quick to set up. The Bresser dob mount has holes that can be used as hand holds and so I can pick up both scope and mount as one, lift it out of the shed and put it down in the garden ready to observe. That's a two handed, power from the legs type of lift. The things that slow it down are going back to the shed to get the adjustable observing stool that is a necessity given the eyepiece height, and carrying the increasingly heavy eyepiece case that really needs splitting into two sets. For planetary observing there is some cool down time required but for lower power DSOs you can just get straight on with it. With a 28mm Nirvana I can get about 1.8° which is just large enough for targets like the Pleiades or double cluster, but a 9x50 RACI is needed for manual finding. If, however, I do not feel like lifting the weight of the dob then I can use the 72ED. This is a much more lightweight setup although not necessarily any quicker to set up. This lives in the house in its case which has room for three 1.25" eyepieces. I can carry the case in one hand and the mount in the other and take them outside together. Once assembled the scope and mount can be lifted with one hand. As the limited selection of eyepieces are in the scope case I don't need a second trip for the eyepiece case and the tripod allows me to either observe standing or adjust the height for a garden chair so there is no need to open the shed for the observing stool. If I want maximum field of view then using 2" accessories opens the field up to about 5° but typically I have found that the 3.8° given by a 24mm 68° eyepiece is sufficient and helps with balance. With such a wide field of view no separate optical finder is required. Cool down is pretty non-existent on a 3" doublet. Maybe a few minutes are needed by it's not really noticeable. The 80ED is a bit bigger and heavier but I expect it would be similar to use.

I'm not sure that you can take that from the results of this poll. The options are never use goto and often use goto. How often is often? Perhaps always, sometimes and never would have been better poll options. Often includes anyone who owns both goto and manual mounts and presumably does know the sky at least at some rudimentary level. Of course if you do have goto on all your mounts you won't learn the sky to the same degree because it is simply not necessary. Once the mount has put the scope on target you might have a cursory look through the RDF to see where an object is in the sky but it's not going to stick as well as if you're manually having to find the object each time.

The problem with galaxies is that light pollution (or lack of) is probably more important that telescope size. I know I've seen both of those with my 8" so your 10" should have no problem, on the right night from the right location. M65 in particular is very small so making sure that you absolutely on target and switching to a high transmission eyepiece that produces an optimal exit pupil, say around 12mm in an f5, will give you a better chance, but if the light pollution washes the galaxy out you just won't see it. From a light polluted site open and globular clusters will be much more rewarding targets.

Try to work out what is wrong with your current eyepieces / collection. If nothing is wrong then stick with what you have and be happy with them. If there is a problem then find the eyepiece(s) that solves that specific problem, otherwise you are just buying new eyepieces for the sake of it.

Do Jupiter and its moons appear as disks when viewed visually instead of when you're taking a photo? What about when you view though the 8 mm Starguider without the barlow? If the shapes are disks without the barlow then lose the barlow, it then are the same then the first thing I would do is to remove the mirror cell and check that the mirror clips are not too tight as I think there is a hint of triangles there. You want the mirror clips so you can just slide a single sheet of paper between the mirror surface and clip. Once you have done that you will need to collimate the telescope as you probably also have a problem there and it will need doing after you remove and replace the mirror cell anyway.

How old is your son? Is he capable of moving the telescope by himself to track an object? If not going for something with a much wider field than an ortho, like @Mr Spock’s suggestion of a nirvana would be a much better choice.

Correct me if l make any mistakes in the following. Consider this diagram from https://www.handprint.com/ASTRO/ae2.html Which gives us the equation for image height: h’ = tan(a) x fo Where a is the field angle and fo is the objective focal length. If the angular size of the Sun is 0.5° then a= 0.25° and the focal length of the 50mm Lunt is 350mm so h'= 1.5mm. This means that at the focal plane the Sun forms an image 3mm in diameter so on first impression it looks like both 4 and 6mm blocking filters are sufficient. However, in order to focus an eyepiece we must place the field stop of the eyepiece at the focal plane, not the blocking filter. As most eyepieces place the focal plane approximately at the shoulder, the blocking filter is moved towards the objective by the height of the eyepiece holder. As we move from the focal plane back towards the objective the light cone must approximately increase in size by Light cone diameter increase = 1 / f# x distance towards objective The telescope focal ratio is 1/f7 and if we assume that the height of the eyepiece holder is 28mm then at the point where the light cone exits the blocking filter it is 28/7 = 4mm larger than it is at the focal plane. This means that with the 4mm blocking filter only the central point is fully illuminated and if we wish to have an unvignetted view of the whole Sun we require a blocking filter of at least 3+4 = 7mm, which is larger than either filter available with the telescope. For those of us observing with a manual mount where the Sun may drift across the field of view an even larger filter would be preferable. However, the sweet spot may also be influenced by other components, namely the etalon so increasing the blocking filter size may not have any advantage. I guess that the only way to find out is to try it. Does anyone have a spare b1200 that I can borrow find to out?

I think so. There are single speed and double speed options. I've heard other people say that they get on fine with the single speed but I've found that l prefer a double speed on all my telescopes. With the Lunt I think l only use the fine focus knob. If you look down into the top of the diagonal there is a small red window. I assume that the size is the diameter of this window. Now look at the size of the field lens on the underside of any eyepiece that you right expect to use with the telescope. It is probably larger than either 4 or 6mm so the blocking filter must vignette the image. With a Lunt there is a definite sweet spot where much more detail is visible in the centre of the field of view. I assume that the drop in detail off axis is at least partly determined by the vignetting and effective loss of aperture resulting in less resolution. Therefore the wider the blocking filter, the wider the high resolution section of the image should be. This sweet spot is another reason to upgrade the focuser. With the feathertouch it will be in the centre, with the stock focuser it will be somewhere else. The double stack lowers the band pass so that the telescope is more finely tuned to h-alpha radiation from the sun and finer details become visible. If you've ever used a budget UHC or OIII filter and then upgraded to a premium version it’s a similar thing. You can get by with the budget option, but the premium is just better and once you've used it you won’t go back. The downside of the double stack is that the two filters create a blurry reflection of the sun. There is a tilt tuning adjustment that you use to move the reflection off axis and out of the field of view. This and the aforementioned sweet spot mean that you are best off using eyepieces with a relatively small field of view. I use 50° Vixen SLVs. Unfortunately, none of this advice is good for the wallet. It con be summarised as: Buy the scope with the largest, most expensive blocking filter you can definitely upgrade the focuser and go for the most expensive double speed option make the telescope even more expensive by buying the double stack You might want some new eyepieces You're not finished yet. It doesn't come with a finder so there's another £30 you need to spend on the TeleVue sol searcher which fits the holes on the clamshell.