Ricochet

This. The focuser is just for focusing, not for changing magnification. Magnification is set for each telescope/eyepiece combination and can be found by dividing the focal length of the telescope by the focal length of the eyepiece. For instance your telescope has a focal length of 1000mm and is supplied with 10 and 20mm eyepieces. This means that your 10mm will give a magnification of 100x and your 20mm will give 50x. For planetary observation 100x (10mm) will be the better choice of the two.

You could well be right. I was trying to remember whether it is the 10 or 14mm XW that shows them most clearly. 31 Nagler. 🤫

Definitely. The 9 or 12.5 are probably the best bets.

The focus points of the moon and all of the stars and planets are practically identical. If you focus on the moon and then move to a star it will also be in focus. If you focus on the moon and find that stars are not in focus at the same point then you have not focused on the moon. As a rule when focusing on astronomy you should always turn the focuser so that the image becomes smaller. Stars will always be point sources and planets will be small disks or crescents.

Yes, exactly the same. I returned mine for a refund. I think the fault was the self centring being inconsistent. I also thought the quality of the beam was pretty poor given the cost.

What telescope do you have and what is your budget?

Getting hold of distilled /deionised/reverse osmosis water might be an issue while we're under lock down. In that case I would simply put the telescope outside, uncapped and facing east of the sun. In the event that the stuff on your telescope is a fungus the UV rays will kill it and prevent it spreading. You can then safely leave cleaning the mirror until the ships are open again and you can source the correct water to rinse the mirror. When you do remove the mirror for cleaning I would create a mask for the mirror edge. The edge coating looks like its degrading a little which will be scattering light over the view and reducing contrast.

The cheapest option would be the 10 and 23mm "aspheric" eyepieces available on eBay direct from China. Alternatively, you can get a Meade branded set (I'm assuming you're in the US as you used $) more quickly. The 4mm, however, is reportedly not up the the optical standard of the other two. Plossls are the other cheap reasonable option. They should be better mechanically than the aspherics (which are plastic), but may not be so optically.

The silver knob in the centre is a lock screw. Make sure it isn't tightened.

I've just bought a Lunt 50. The first accessories I've bought for it are Widescreen Centre's Lunt 50 case and a TV SolSearcher. Annoyingly, the case can't hold the scope with the SolSearcher attached, but it is such a tight fit in the clamshell that I don't think it will cause any alignment issues. Eyepiece wise, my Pentax 14XW (2mm exit pupil) seems to be the perfect balance between brightness/detail and image scale so at this point I don't have any plans to buy any eyepieces specifically for the scope. I expect the best accessory is the double stack unit but such an expense should probably be left for a later date.

Download the manual from https://www.baader-planetarium.com/en/accessories/optical-accessories/bino-viewer/baader-maxbright-2-binoviewer-with-case.html Page 21 has a table that gives the required amount of back focus for different variations of diagonal and gpc when used with the binoviewer. Compare these to the amount of available back focus that your telescope has with any specific eyepiece that you might wish to use in the binoviewer.

1.25" is a standard size. If your telescope takes 1.25" eyepieces then any 1.25" eyepiece will work. What sort of budget do you have for buying new eyepieces? With a focal ratio of 8.8 your telescope will be quite forgiving and almost all eyepieces should work well. Plossl eyepieces will work well, or if you would like a slightly wider field of view the eyepieces sold in the UK as BST Starguiders are a good and popular choice. In terms of focal lengths I would start with something in the region of 2 - 2.5X the focal ratio, so about 18mm. Normally I would say to double this for your widest field but a 1.25" barrel will limit you to a 32mm Plossl. Eyepieces with a wider field of view will have to be even shorter, for example with the BSTs a 25mm is the maximum in the range. For higher powers, the 8 and 12mm Starguiders would work well, or equivalents in Plossls. However, with the classic eyepiece designs, eye relief starts getting very tight with short focal length eyepieces so you may wish to either use a longer eyepiece and a barlow, or a more modern design with consistent eye relief (i.e the BSTs, or the eyepieces sold as "Planetaries"). If you really want a "set" then the Baader BCO set would work nicely, but beware the short eye relief in the shorter focal lengths.

Not really. The 5, 8 and 12mm Starguiders are the ones I think are suitable for use with an f5 scope. With a 2x barlow that will cover all your high power needs, you could probably even get away with 8, 12 and 2x barlow.

I don't think so. You might see some vignetting with long focal length eyepieces but that only dims the edge of field. There is a lot of focuser travel in a Mak so you can probably focus natively, but doing so will move the primary a long way and increase spherical aberration. You will probably get better performance with a barlow and longer focal eyepieces than without and short eyepieces.

For a small balcony like that I think I would look at something like a Skywatcher Skymax 127 on either an AZ5 or AZ GTi mount. This would also work on distant terrestrial targets like boats on a lake and mountains. If you have a sturdy table on your balcony you could start really cheaply with a Skywatcher Heritage 130p for astronomy only and keep the spotting scope for terrestrial use.

What will you be observing terrestrially? How big is your balcony? When you talk about taking it on trips do you mean just putting it in the car and setting up next to it at the other end or are you envisioning carrying the scope on hiking trips?

The high number of adverts might also be a symptom of the way that ABS works. If an item is not sold quickly then the item might get bumped with a repeat advert so it is at the start of the (reverse date ordered) list. Each bump is a new advert and +1 to that user's advert count. I just looked at one advert, pretty much at random, and the user's profile shows 14 active adverts for that one unsold item. That number of adverts/item changes a 10 year old account with 500 adverts from selling one item every week to selling one every 3 or 4 months.

You will have to buy two different setups for observing and astrophotography. Neither of your choices are suitable for astrophotography, in which the most important item is the mount. A skywatcher HEQ5 plus either a 130pds (not 130p) or 80ED are the common starter choices.

Was this star the brightest thing in the sky early on in the evening? I would guess you might have been looking at Venus and that the compass on your phone needs calibrating so the star map is pointing in the wrong direction.

I think AC is a typo in one shop, it's AR elsewhere. From comments I've read on them, you're better off going for one of the 102 options as the 90 options have significant amounts of plastic parts (including the focuser).

Has your friend contacted the seller for a refund? When I was new to buying second hand astro gear I bought a few items that either were described as pristine but weren't, or that had flaws that in my opinion should have been clearly highlighted in the sale advert. Sometimes it takes a few weeks to find/confirm a fault and being new to second hand purchases with private sellers it feels a bit awkward going back to someone with an issue, so I didn't return some items that I should have. These days, having made that mistake before, if it isn't as described or is faulty, I'm going to demand my money back and I would advise everyone else to do the same. A faulty telescope should have been replaced under the original warranty, not sold on to the next unsuspecting user in the hope that they won't notice the fault or will to be too timid to query it.

As far as "rules of thumb" go I am of the opinion that selecting eyepieces by exit pupil size is the best starting point. Exit pupil = Eyepiece focal length / telescope focal ratio so for your f5 scope we can select eyepieces using Exit Pupil * 5. I am also going to assume that due to your location and light pollution the maximum exit pupil you want is 5mm. Technical limit for separation of double stars, aesthetically unpleasing: Exit pupil > 0.5mm => EP > 2.5mm Optimum Planetary Observation (no APO or binoviewers, ignoring atmospheric conditions): Exit pupil 0.8 - 1.0mm => EP 4 - 5mm Open and globular star clusters, aesthetically pleasing separation of double stars: Exit pupil 1 - 5mm => EP 5 - 25mm Unfiltered nebulae, galaxies: Exit pupil 2 - 5mm => EP 10 - 25mm Diffuse Nebulae, UHC filter: Exit pupil 2.5 - 5mm => EP 12.5 - 25mm Diffuse Nebulae, OIII filter: Exit pupil 3 - 5mm => EP 15 - 25mm The last two are probably the most contentious and I think it really does depend on the transmission of both the eyepiece and the filter as to how high you can push the magnification and how much the image is dimmed. At the price range you're talking about they might be a bit optimistic. Also notice that for all the DSOs there is a range up to your maximum exit pupil. This is because many cover quite a large expanse and you may need the extra true field of view that a longer focal length eyepiece will provide. For DSO eyepieces I like 1.4x steps in focal length as this results in a doubling or halving of image brightness, which is what your eye needs for there to be a noticeable difference. For example with my f6 scope I use 5, 7, 10, 14, 28. I could also fit a 20mm between the 14 and 28 but so far I've not felt the need to fill that gap. For planetary observations you will find the atmosphere at the time of observation plays a big part. You will either want a closely grouped selection of eyepieces or a zoom + barlow combination which will allow you to dial in the optimum setting. At the £50 price point I would suggest you look at the 5, 8 and 12mm BST Starguiders and the 10 and 18mm Baader BCOs. These TMB clones are supposed to be pretty good planetary eyepieces but I've not used any myself to confirm that. At the low end I would recommend you look out for a second hand 24mm Explore Scientific 68°/Maxvision/Meade SWA to maximise your field of view in a 1.25" format. There are also the following second hand eyepieces with active adverts you may be interested in: Opticstar zoom 10 + 18mm Baader BCOs 16mm Maxvision I have no affiliation or previous dealings with any of the sellers listed.

Are you aware that the focal length of the scope is fixed and a function of the primary mirror? If you reduce the secondary - focal plane distance by 65mm then you will have to increase the primary - secondary distance by 65mm. This means that you will have to move both the focuser and secondary spider supports up the tube. I don't think that the tube is long enough to support such a movement unless you also plan on extending/replacing the tube as well. I think the most cost effective solution for this scope is to get a replacement mirror that is sized for the current position of the secondary. Depending on the length of time you have had the scope and the warranty provided in your country, a direct replacement from the manufacturer might be available (if you bought it new).

Only if it is a Howie Glatter laser, and even then I would suggest that as an addition to a standard sight tube/cheshire. Any other laser can be used for the primary if you use the barlowed laser technique. I'm not sure that any of the barlows you mention are "higher quality" than any of the others. I don't know who is claiming the Omni is usually £60, the £25 is normal. With regards to eyepieces, how much you are looking to spend per eyepiece and/or in total and what you want to observe with the telescope (DSOs, planets, everything!) would be a good starting point for people to give suggestions. The 50x aperture rule for magnification is also too optimistic, not applicable to all types of object and basically a marketing tool to sell telescopes.

The prism size limits the TFoV that you can view. This will not affect short/medium length eyepieces but long focal length eyepieces may be vignetted by the prisms, depending on the AFov. I think these are the same as the "Starguider" ones I have. From memory I think the maximum unvignetted FoV they can give is given by 20mm 68° eyepieces. Given my previous statement, a 33mm will be vignetted if the AFoV is above approximately 40°. Sounds pretty keyhole like. Also, if those are the same binoviewers and the supplied barlows are the same, then those barlows are absolutely awful and should be disposed of as soon as a replacement solution has been found.