PEMS

Assuming that there is some technical ability, I would say a William Optics ZS81 and the Skywatcher Az GTi mount. The scope looks very good and very nice. May not be the largest aperture but will I expect be more what your father expects a scope to be. Also 80mm is likely one of the best all round sizes around, and the WO will, or at least should, produce excellent views. Many of the objects for large apertures have to catch that they remain small. Besides a large aperture you also need the potential of big magnifications and after a point even they work against you. A big magnification carries with it a reduced field of view and so not easy to use. A large aperture is stated as showing more, but more can be seeing something bigger, or more small objects. So be careful of the use of "more". A WO ZS81 will require a diagonal and a couple of eyepieces, you are in the US so perhaps look up the Astro Tech Paradigm range, maybe the ES 52 degree range. If you did then say 8mm, 12mm, 25mm in Paradigms and similar in the ES52's - I do not know the ES52 focal lengths off by heart. The mount is best if operated by an android tablet with Skysafari. You do a Level and North alignment and assuming successful you/father switches in or over tio Skysafari. On the Skysafari screen you touch the target then Goto, and hopefully off it slews to the target. Although may sound "technical" it is actually easy. May be an idea if you were there the first couple of times, if you are very unsure, and write down the series of steps. Then father could refer to them. Main problem may be sourcing the items. If you were concerned about balance of the scope then find the static balance point of the dovetail, with a diagonal and a representative eyepiece, and apply a small self adhesive dot. That then sits in the center of the mounting unit on the mount - easy simple solution and quick. Will say be a little careful, father may know more then you think, may know a lot more.

TS Optics in Germany sell GSO mirrors BUT I cannot see anything at 130mm. The smallest they appear to have is 150mm. Maybe a generalisation but the price of their f/5 mirrors seem to match the diameter in that a 150mm is 150€, a 200mm is 200€. So if a 130 appears it could cost at an estimate and guess around 130€. Then add in shipping and the UK import VAT and whatever administration charges are levied the final cost for a mirror alone could exceed the scope. Do not know where you are but at times clubs have "old" scopes they may want to lose. An alternative is a wanted request but unsure of the rules for posting a wanted here, simply never done it or looked into it. There is Astro Buy and Sell UK. But I suspect that owing to the diameter being what it is that your best chance is what is effectively an old or used scope for a mirror. As has been said a photo of the damage would be useful. If it is say edge damage then you might just make a sort of aperture mask to block off the edge and so carry on with a slightly lesser width mirror. Just had a thought - search astroboot. They often have small mirrors, but the last time I looked they were hesitant about sending to the UK with the various importing rules. But they I think will be the best option. Looked and they have no 130mm mirrors listed and are not shipping or taking orders from the UK. Email a few retailers like Harrison, 365 Astro, maybe Rother Valley and ask if they have anything. Might get lucky.

If you have the t-ring then attach it to the DSLR and if possible attach to the focuser, not sure how easy or simple that bit will be. Try try it out. The zs61 has a lot of focuser travel, so there is a chance that you may not required any extension. It is the easiest way to find out before you go buying extension tubes.

What depends on your budget and what features you want. For transport via rucksack or similar it would point towards a refractor and relatively small. Small refractor on a manual mount say £200 area, little more perhaps. Scope would be an achro. Around the 80mm aperture. Better then achro is ED and something along the lines of the William Optics 61mm but the scope is around the £400 mark I think. Only think, not sure. Costs rise rapidly. two or three eyepieces say another £120 more or less. Now a goto mount would be along the lines of the Skywatcher Az GTi, and they are at the £300 mark, and you would need a small lithium battery to power it. The lithium could likely be recharged from a car outlet, but check. The Az GTi is wifi operated so an Android phone is required. Or at least best. Could get the manual achro then add the goto mount later, spread the cost. A goto is useful and when setup and on a target it has the convenience of tracking the target. Which although overlooked is very useful. An achro, any refractor, would also allow the addition of a solar filter for warmer days and solar observing.

For either variety of mount then do the levelling as best you can in the time available. If you are on an EQ mount then yes the polar alignment should take care of it, but to set the latiutude and so get Polaris in a reasonable position the level status of the mout comes into play. If your level is out by 5 degrees then the latitude scale is out by 5 degrees and a very good chance that Polaris is not in view and you spend more time locating Polaris then just doing a good job of levelling the mount. Consider it as 2 minutes to level the mount or 5 minutes to find Polaris with a poorly levelled mount. So maybe you do not need to but it makes sense to do so. On an Alt-Az mount level is more relevant. People think it doesn't matter and that the software will take care of it all. The software might but the better everything is set uo the better the corrections applied by the software will be and the more accurate the Goto will almost certainly be. I found that Wilkinsons sold a very simple cross level, plastic, cheap. But it worked well. Put on the mount base and level that, put on the front of the OTA and level that. One thing I immediatly noticed was my idea of level was a lot different to reality. People are not generally that good at determining level. Easy a 5 degree difference and consider these days that if your car timing went 5 degrees out the EMU would almost certainly put a red warning up and stop the car. And I have seen it said by someone on here: Levelling everything well makes it look as if you know what you are doing. Even if you really do not.

Decent and least expensive I suggest means the EQ5, and get the Goto variant as adding motors afterwards will likely be around a similar cost. The goto's are steppers and the aftermarket is I understand simple DC motors, and so likely less accurate. Unfortunately Decent, Cheap and Astrophotography do not go together.

Couple of questions: Is the DSLR set to B, if not it will not follow the intervalometer, In general it seems a DSLR maximum exposure is 30 seconds. Next is the DSLR set to No Noise reduction. Otherwise when you take an exposure and then the DSLR attempts what is similar to a "dark" for the same period. That would really throw the Intervalometer setting out. You interval needs to be longer. The principle is that the DSLR has time to write to the memory, and RAW files are big. Also it should include some time for the sensor to cool a little and so reduce thermal noise. Mine handles an initial Delay fine, I tend to use 10 or 15 so I am less rushed to place it somewhere. For a one minute I would set a 30 second Interval, then in your case 30 shots. So Delay=10, Exposure=60, Interval=30, Cycle=30. I think you are trying to rush things and do it all as fast as possible. Suggest you slow down. If the DSLR is busy when the Intervalometer attempts the next instruction or command then everything is thrown out and very likely the DSLR just ignores the Intervalometer. There is the odd possibility that the DSLR has a temperature sensor and the imaging sensor is getting too hot, you are taking continuous 60 second exposures, so it will get hot. The DSLR software could in effect be shutting the camera down.

I might well be incorrect but wasn't the first Brit in space or on one of the early space stations a woman?

I would say that your big decision is the mount. In a way a number of scopes satisfy "portable" - WO Z61, WOZ73, Skywatcher 72ED and a few others that will be all along the same lines. Portable small mount I suggest the Skywatcher Az GTi or the iOptron SmartEQ. The astrophotography is where possible problems occur. Mount wise you want a good solid mount and that is opposed to "portable". The Az GTi can be loaded with appropriate software but is started as an Alt/Az mount and to an extent is a little limited. You need a wedge under it so you would end up buying Az GTi, Wedge and of course a power supply. The wedges are not inexpensive. The SmartEQ is small and is already an Eq mount, but add in carrying the counter weights and in both the general size of the tripods. Usually the scope is as said "easy", the mount is the area where the greater decision making is required.

I suggest that the question is unanswerable. It comes over as someone or some people are asking "What if ......" And there is no answer to that. A now long distant one I attended they perhaps simply wanted to know there was no chance of the filters coming in effect loose and falling off. I used a Herschel Wedge and had a continum filter, and I also added a UV/IR cut filter. As much for myself as others. If people are in effect saying or asking "But what if ..." in a cyclic manner then do not hold the event. With the number of solar observers within the astronomy hobby I have never heard or read of a single one getting eye damage.

Seems thjat you are polar aligning the scope and you should be polar aligning the mount not the scope. If you had or get an equitorial mount you can polar align the mount (which is what you want and need to do) without a scope on the mount. As the Az GTi is really an Alt/Az mount there seems that there is no accurate option incorporated for accurate polar alignment that I can see on one. It was never it seems intended for such.

A minus value for Longitude just means you are West of the Meridian. So -001 : 30 just becomes 001 : 30 W (or West, usually they just use W). Be careful of the leading zero's, double check what you enterand what the handset decides you have entered.

The Starguiders are a nice eyepiece for that scope, at the price they are. Seem they work OK at f/5 and people say f/4.5 and that I expect is the ratio of your scope. Likely a good idea to start at the 25mm simply for the wider views it will supply as that helps in finding things. An 8mm and perhaps a 12mm can follow later. One easy approach is, if it is possible, to buy one every month or something. The Starguiders look nice as a small set of say 4, (8mm, 12mm, 15mm, 25mm). Not sure the 5mm and 18mm would add a great deal. A little better may be ES68's and ES82's but as expected they cost more. So a decision is required. The one area Starguiders sort of fail in in not having a 6mm eyepiece. Sometimes it seems a 5mm is just a little too much magnification for scopes and at 5mm the eyepiece has to be fairly good as well as having to operate with a fast scope. Things just start stacking up against things going well. If in time you want more from the scope in terms of magnification maybe consider the ES52 at 6.5mm. Slightly lesser field than the Starguiders but as magnification reduces the field of view more it would make minimal impact. Jupiter and Saturn will not be around a great deal until the latter half of the year. Unless son wants to get up at something like 04:00AM. And I expect that is not an option.

Well yes a greater aperture is better resolution, but that is on paper and theoretical. Another consideration needs to be that there is likely no lens or mirror on earth that performs to the theory exactly. And the portions that are acting furthest from the theoretical ideal are the edge areas and the bigger the mirror or lens, the more "edge" there is and the worse they perform and so the worse the image. It is as ever a 3 way choice: Size, Cost, Quality. Pick the 2 that you want and the third is beyond your control. Scope design also has an impact.

Only item I can see is a Baader. Think Altair do it also but found the item on 365Astro so check the link. The A mount and the Minolta may be the same bayonet so you might locate a Minolta item as well. However check that they are the same. I assume that the WO flattener has a standard thread size where the T adaptor would fit. Seems a little odd that FLO do not have one, bought mine there, but many years ago now. Although a simple Sony A mount T-ring does not appear often in a search. Also think mine says Sony/Minolta on it. May be an idea ti check somewhere like TS but unsure these days of goods from the EU and the ease or otherwise of shipping.

I would think mirrors are SiO2 coated to prevent oxygen getting at them, aluminium is actually very reactive and forms an AlO2 layer very fast and it is a grey not a reflective surface. The layer is however stable and so prevents the remainder of an aluminium bar just oxidising (rusting) away. Did you never do the aluminium powder experiment at school? Take Al powder, add an oxidiser and set a flame on it. It burns fast and hot. That is Aluminium. Would not think that a lens can be so protected. The AR aspect calls for material properties of the various layers - mainly the refractive indicies and the material is chosen for the refractive index not the hardness. In effect a different requirement. The mirror is not AR coated just protected from the atmosphere. So they have different criteria at depositation.

I would think that as Methane could be either organically formed or from another inorganic mechanism then the finder of such methane has two options: Say that it is just Methane and forget it, or, say it could be from some form of microbial life. If it is found out to be from some form of life then they were amoungst the first to identify a form of proof of life and some kudos. Otherwise they are the person to have seen what could be proof of life then ignored it. So may as well push the "possibility of life" aspect. They have done the same for Venus and there the atmosphere is sulphuric acid, hot enough to melt lead and a pressur 90x that of the earth on its surface.

The focal ratio as mentioned comes from the photographic world. It does have some relevance to scopes and eyepieces however> To get a value you take the focal length and divide that by the aperture. So a 600mm focal length scope with an 80mm aperture is 600/80 = 7.5. The focal ratio therefore being f/7.5 It is possibly a strange depictation of the value, it always looks inverted to me. Ignoring that that is how to get the value. Yours is 127mm aperture and around 1500mm focal length so you have 1500/127 = 11.8 or f/11.8. Fast seems to be f/6 and numerically lesser so f/5 is "faster" then f/6 - like a lot it is backwards or inverted or something. Medium is around f/8 to f/6. Slow being in a general sense f/8 and what is often termed "upwards" as in f/10, f/12 etc. The relevance is that a "faster" scope is usually more difficult to make, either refractor or reflector. More difficult means greater cost owing to time. And for an eyepiece a fast scope is harder for them to reproduce a good image. As "fast" usually means the focal length is shorter then the curvature at the image plane is greater - images created are not flat. The greater the curvature the more difficult it is for an eyepiece to handle. Again a good eyepiece costs more. The inverse being that most eyepieces will operate well in a slow scope will, so you do not need to go searching out £300 eyepieces. In the old days of photography the almost standard mid setting for a camera was f/8, it managed to cover the majority of situations, good depth of field, good depth of focus and sensible shutter speeds. It is likely that in a scope f/8 is probably the still the mid ground where the scope will do the majority of situations reasonably well.

In your situation I would get a 2" diagonal but not the dielectric versions, just do not appear a great necessity to your equipment. RVO do a Bresser 2" diagonal and isn't overly costly. It is one I intend/need to purchase for myself. I have a 2" diagonal, but really do need a second one, and I identified this as my likely best option. Costs £65, and states 93% reflectivity, but to my thinking it should be a good idea.

I doubt there is the specific site that you would like. Unless you can link into the several clubs that are doing Zoom presentations in place of club meetings and most will be Zooming talks not scopes sweeping the sky. If you are any good at searching the internet there will be groups and organisions that look at the sky for probably survey purposes and output the survey on to the web. The problem is finding such organisations. There is the astronomy aspect termed EAA, Electronically Assisted Astronomy. That requires the purchase of equipment by you and then I expect some setting up. The core setup appears to be a goto scope, camera and video output to a laptop. Never done any so that is very much an estimate and is I expect over-simplified. In effect you focus on to a camera and display the output on a laptop. I expect the problem then is getting the scope to goto accurately the next target especially as I suppose the ideal is scope outside and you inside. I expect there are scopes outputting to the internet as said at the start. Maybe a search through ESA and NASA. Also try Swinburn in Australia. Does Oxford or Cambridge have anything. Even Leicester or Herford Uni or St Andrews, basically any that have an astronomy degree/MSc/PhD. With the internet you can search for and hopefully connect to anywhere worldwide.

Many go and purchase the Lithium Ion rechargeables at 12v. They work well. Talentcell seems to be the available one, eBay or Amazon have them. Check Amazon as one seller had the big Talentcell's at a good price. It may be more then you need but the price difference was significant. And the larger would give you a lot more time outside. I believe the Skywatchers use the almost standard 2.1mm connector so that should not be a problem. Keep it charged as if fully discharged they never work again, the nature of the battery means it has to always have a small charge present. As they have a small On/Off switch make sure that when you put it back in it's box that the switch is Off. Otherwise the LED drains the battery completely over time. Guess how I know. Using one does mean that it has to sit somewhere. I do not know the scope/mount you have so look for a good place to secure a small "box" about 12x8cms. As you rightly say Rechargeable AA's are not sufficent voltage. They supply just 1.2v per battery so 8 makes up 9.6v and the scope will want 12v. If the option exists in the scope reduce the Maximum Slew rate. Means there is a lower peak current draw and there is no real reason to go at maximum, 7 or 8 will be as good, and might mean you do not have to start the alignment all over again.

A dobsonian has the largest mirror for the £ but they are not the system for imaging, DSO or planetary. You might get the moon but the moon is a somewhat special instance. It is big and bright. For imaging the equipment for ease and decent results is a reasonable goto equitorial mount, they track correctly and at the correct rate. And what is often a relatively small scope. Think here of a smallish refractor or a small reflector. A Mak or SCT is generally more appropriate to planetary imaging, and at present there are few planets, and the one that is still available is now well past it's best position and distance. For cost in the scope side look at the Skywatcher 130PDS and 150PDS, in refractors consider an 80mm ED or a 72mm ED. Anything bigger will mean a probable mount increase in size and so in cost. In the mount aspect the Skywatcher EQ5 seems about the most suitable and fairly small for carrying around and transport. After the EQ5 they get big, maybe too big. One fairly common warning is that astrophotography starts at a level of cost. That minimum is likely around £1200 these days. May get it down to around £1000 but do not assume it. Plan on assorted accessories. If you can get an 80ED you would have a reasonable scope for both imaging and visual.

Cannot see any mention of polar alignment and unsure of polar alignment options of the tracker in use. The scale will be approximate but no more. First image almost looks like the mount is sticking a bit then jumping. And the amount of items on the tracker looks a fair amount. The ZS61 is 2.2Kg, add another 0.5 for the flattener and 1Kg for the DSLR and you are at 3.7Kg. Would expect the weights you have added need to be included so that is 2Kg. Now at 5.7Kg. If you add in say 0.3Kg for the finder and other bits you are at 6Kg. Odd question: If the weights are 2Kg what weight is the bar, bet it weighs something, but is ignored. I suggest the system is operating at over capacity and so beginning to fail. And will also suggest ignoring what people say they are able to achieve.

Curious why any Astronomy Course notes recommends binoculars. May be over simplified but I would have said that 99.8% of astronomy is performed with a telescope. Maybe more then 99.8%. Having used both I suggest a scope of some even basic variety. A 70mm or 80mm achromatic, preferably f/8 or maybe slower to minimise CA, would seem a better idea and more in keeping with Astronomy. Visit a University which does Astromnomy and you will find telescopes, what you do not find are binoculars. Binoculars are fine for looking around the sky but none will pick out and show you the Trapesium in M42. And I would have thought that that was the type of ability required. Where are you doing the course?

The Skywatcher is a very capable first imaging scope, many start with one, then they never move off of it. Good scope for the mount, well in weight considerations. Often a good idea is to get the polar alignment done manually first, simply learn what you have to do. That would allow you to start getting a collection of images to stack (DSS I expect). You can get Darks and Flats fairly easily. Darks are in effect very simple to obtain. If you get say 50 exposures for stacking then get 25 Darks and 25 Flats. You add them in to directories on your PC. Say this as PC's seems to be hiding the internal directories now. If you are not familiar with the Windows Explorer structure maybe ask someone. You will have to spend some time Polar Aligning, we have a very convenient Polaris, you don't. Maybe search Google for "astronomy clubs australia" should throw up something. Say this as a club is likely the best place to get information, pointers and help. If you are using a DSLR, cannot remember, then set everything to Manual and set all inputs yourself. Also if a DSLR you are likely to need a simple Intervalometer to get a series of images. They will cycle round a specified number of cycles getting an exposure and doing a wait time between.A DSLR needs the wait time between each exposure to write the data and allow the sensor to cool a little. It is no longer click, click, click. Also disable any noise reduction feature. Have fun.