Carbon Brush

@LDW1 Can I ask what sort of winter night time tempratures you usually see? Not the exceptional events. By looking at the general conditions, you can decide if battery life really is an issue. For example in my part of the UK we often go a little below freezing. -10C would be an exception. We had one winter a little over 10 years back when we went down to -18C. A once in many years event. Further north, it is a little cooler. On battery performance. I have been looking at a particular Samsung lithium 21700 size for a work project. This can be discharged from -20C up to 60C without harm. Capacity is defined at 23C. When hot, 60C, you still get 95% capacity. At 0C discharge, capacity is 80%, falling to 60% at -20C. These are very respectable figures and any equipment designer takes them into account. I'm not saying this is the cell that ZWO have used. However, performance from their selected cell is likely similar. HTH, David.

Thanks for your comment. ZWO are not alone in providing little by way of specification and explanation. A look at the vague statements made by many astro kit manufacturers shows ZWO are following a trend🤨 In terms of well understood and affordable rechargeable batteries, lithium is (in my view) the best choice for this application. Lead acid offers far reduced performance sub zero. Historically we have got around this by putting astro leisure batteries in insulated boxes. Also by rating the leisure battery to be sometimes 10x the energy required in a night. If you look at car batteries, there is a 'CCA' quoted. That is 'cold cranking amps' to help answer whether your car will start in winter. The manufacturers well understand how lead acid performance falls of when cold. Nickel cadmium (NiCd) and nickel metal hydride (NiMH) provide better performance than lead acid at low temperature. But they still provide significantly reduced performance when cold. Lithium rechargeable (in various varieties) do offer good performance with little performance degradation until they are so cold, they should not be used. Actual temperatures and performance reduction vary between chemistry & manufacturer. But they are always better than the mature technologies. A further big driver for choosing lithium is power per kilo of battery mass, and power per litre. Figures vary, but if you think in terms of 3x lead acid performance, you aren't far out. Would we be happy if the Seestar had an external power pack? I have not had a close look inside a Seestar. I hope ZWO have included a thermistor in the battery pack to allow temperature measurement. The signal from this device can prevent charging when too hot or too cold. Further during discharge it can signal switch off outside of allowed operation temperature. Typically lithium cells can be stored safely to 65C and hotter. But using them at elevated temperature does restrict life and can cause damage. Off topic possibly but the battery discussion may have prompted thoughts. Many of the lithium equipment fires we hear about result from incorrect charging regimes. Part of the safety testing for lithium cell type approval involves putting an almost short circuit on a cell, and there not being a fire or leakage. The ZWO manual indicates testing has been done, though I have not pursued the details. If you buy lithium cells and batteries from fleabay or the long river company, this expensive and arduous work may not have done 😮

The cost conscious markets (including amateur astronomy) use commercial grade electronics, which is sometime only specced to 0C. However, in practice it does continue to work at lower temperatures. Looking at the many discussions discussions on various mount operation in the cold, grease thickening is mentioned more than freezing electronics. The most temperature sensitive part of most amateur astro kit is the battery. ZWO say the device can be used to -10C, which is a reasonable limit for lithium discharge. Without knowing the exact spec of the cells, I cannot comment further. Note charging temperature for lithium is more restrictive. However, the charger control should look after this for you by disabling charge if too hot or too cold. ZWO say charging is allowed from 0C to 40C. HTH, David.

Sorry to say those platic leg brackets are well known for fracture. You say you got the scope in July. Was it new? If so try a warranty claim. It does look as if the screw has been tightened hard down. Alternatively look around for a used tripod and swap over the legs. But the quick fix is a Jubilee clip until you get a longer term solution. HTH, David.

I was in Florence for a short day some years ago. Galileo's tomb was on my limited 'must visit' list. The builders were in.🤬 The tomb was covered in polythene and protected by scaffolding. Yes Florence is a wonderful city. Your post has reminded me that I must return.

Sobering to think that only 30 years ago exoplanets were thought to exist, but nobody had actual evidence of their existnce. Now we know of thousands (anyone know the latest count?) and even obtain atmospheric information.

I have seen newt tubes suffer cosmetic damage from enthusiastically over tightened finder foot retaining screws. A great pity that oversize washers, star washers, nyloc nuts and the like have yet to become readily available components🤔 Then of course there are the filed out holes from 'not drilled in quite the right place' attempts. The damage doesn't affect views though. In scope balancing, heavy finders located a long way off axis need thinking about.

My goto for glass is Baader fluid. I have seen Specsavers lens coatings degrade and flake after repeated use of isopropanol.

You have to think about the effect of off axis light pollution reducing scope contrast. Take an average low cost newt reflector, look at the sky. Maybe a dark grey sky background? Now shine your dimmest red torch across the top of the scope, just catching a bit of the black tube inside. The sky will appear red. Now repeat the test with an up-market flocked newt. Or Mak Newt with baffles or a quality baffled refractor. The sky won't be as grey or red as in the low cost newt. At the Bortle 1-2 dark site is a 4" properly blackened reflector better than a cheap (dark grey painted) 8" reflector? I would say no. Because there is negligible off axis light. Here you are looking for the best optics, coupled with scope portability. Another factor is your eye dark adaptation. At your light polluted home, you do not fully dark adapt. You therefore need a big scope to produce a bright image at the eyepeice. Go to the dark site and adapt fully. Then a small scope will produce an image that is bright enough for you to use. No easy answers!

Before recommending, you need to tell us more..... You viewing environment. 3 flights of stairs to get outside? Overlooked by lots of lighting? Maybe drive out to a dark place to view? Kids ages & attention span. Will they use the cope unsupervised? Do they need an instant view to avoid boredom? As for 2nd hand purchases. From where? On general sale there is a lot of stuff that has been neglected, or has bits missing. Having someone experienced go with you to look would be a good idea. And last but not least. Welcome to SGL. We are all happy to help. Keep asking the questions.

Yes definitely. Some of the kit supplied 10mm EPs would be better repurposed as salt pots. I can't speak for the RVO offering. I have though used some of the BST Starguider EPs. For the ££ spent they are good. https://www.firstlightoptics.com/bst-starguider-eyepieces/bst-starguider-60-8mm-ed-eyepiece.html Is there someone local to you who might lend you an eyepiece? Don't forget you can get a good idea of views by using the scope on distant objects in the day.

Throwing something else into the pot. If you are building your own kit and basing it around 4 cells, you need to think about the voltage the equipment may be subjected to when in use. A LiPO charges at 4.2V/cell = 16.8V for a 4 cell stack. You also MUST MUST use a BMS with charge balance if you buy your own cells. Unless you really know what you are doing with lithium cells, buy a pre-assembled lithium pack with the protection already built in. IMPORTANT. Read the safety approvals and check the documents exist. There (almost weekly) reports in the UK news about lithium battery fires in houses, caused by cheapie dodgy imported product. In some cases there are deaths. In the wrong hands, or incorrectly used, lithium batteries are best thought of as potential fireworks and bombs. Sorry if this seems heavy handed. But lithium cells are often kept in our homes without thinking about safety. These people are not cheap. But their products meets safety standards and the documents to prove it are readily available. https://tracerpower.com/ Can you get similar traceable safety documents and test reports from an Amazon seller? HTH, David.

LED street lighting does have better radiated angle. When my village moved to LED, my back garden (50M+ from the road) became darker. On the main road though, you can read a book at night! Strange really. The principal justification for lighting in my village is the traffic on the main road. As vehicle lighting improves, we rely less on roadside lighting. Remember the little pool of yellow light cast (never far enough) forward from your Ford Prefect?😁 During the summer, the lamp posts have been renewed. The existing were rusting. Some posts have been resited. It did worry me. However, it is not a problem. The Hyper -Intelligent-Mega-Beings at Nottinghamshire County Council have thoughtfully placed quite a few of the fittings in tree canopies🤣 You couldn't make it up.

If you use NiCd/NiMH, then 5 cells are a must. A 5 cell stack will start at about 1.35V/cell and give 1.2V for most of the discharge, ensuring you get good results. That is 6.75V dropping to 6V. If you use lead acid, it will provide about 6.6V at the start, eventually dropping to about 5.7V. If you use a lithium based powerbank, as @Nik271 it will provide a constant 5V. If you use D size alkaline cells, as the original design, they sould last ages - unless slewing is your favourite activity😁 With ANY cells in holders, do not skimp on the holder quality. There are many holders that have significant contact resistance (about 0.1 Ohm at each end). This results in voltage drop when slewing and mount can forget what it is supposed to be doing. Either buy good quality holders. Or for NiCd/NiMH buy tagged cells and solder them. HTH, David.

Excuse my basic unproven physics here. I was taught physics in an earlier century so have forgotten a lot. All objects radiate infra red (heat) and receive it from the environment. For example after sunset a house outside wall can be much warmer than the air. Useful to lean against to stay warm😁. When you see infra red images showing hot people or objects you get a good visual representation. If you point a (posh expensive) infra red thermometer at objects you get more accurate readings. If you point the thermometer to the clear sky (remember these?) it may show 30C lower than your surroundings. Your scope glass, if the tube is insulated, can easily drop below surrounding air temperature, encouraging dew. The insulated tube does not echange with the surroundings and the open end looks at the cold sky. If my thinking is anything like correct, then a reflector that is open at the rear, will take longer to dew than one with a closed rear cell. This is because air will convect down through the tube if the mirror chills below ambient. But it is a slow process. If the fan is running, it blows ambient temperature air through the tube, so the mirror never chills (much) below ambient. If you blow warm air into the tube, obviously there is no dew. But you do get thermal currents disturbing the view. In extreme, uneven mirror heating means you can't get a good focus. I'm sure someone more knowledgeable will be along soon with a better explanation.

Maybe too much... I have two long LED fluorescent replacements for when I am doing serious dismantling/mending work. They were cheap and easy to fasten in place. A small strip fluorescent is enough to see for tidying up after observing.

The sory from NASA... NASA's Mars Climate Orbiter was designed to study Mars from orbit and to serve as a communications relay for the Mars Polar Lander and Deep Space probes. The mission was unsuccessful due to a navigation error caused by a failure to translate English units to metric. The story from me..... Do you enter orbit from 125 miles? 125KM? If NASA had joined the rest of the world and adopted metric measurements this would not have happened. Now go back a few years to the Hubble mirror fiasco. Inch/metric again! I can understand confusion in the ordingary workplace as the USA has been hanging on to inch measurement - separating from the rest of the world. However, space flight is an international undertaking. Whether dealing with subcontractors, overseas experts or buying products. They all need to use the same measurement systems. Contentious statement I realise. Reaches for hard hat😲 As for Beagle 2. It got a 'free' ride. There was no support or communication with the carrier craft - It ESA Mars Express. That is why Beagle was lost until visually sighted much later. I once attended a lecture given by someone from the project. A very telling comment from his presentation was 'a free ride is worth less than you pay for it.

I thought I would contribute my limited experience of a Celestron Starsense. Having heard about Celestron including a phone bracket on a cheap 70mm refractor with free software, I thought I would give it a go. The idea being to pass the scope on to a beginner and transfer the Starsense to another scope intended for loan/outreach. But I never got that far. As I was not at all certain about the product performance, and not had a look at it, I bought from Amazon. Yes I know about supporting astro retailers - and I do. But in this case I was unsure of the product and considered return a strong possibility. The Celestron 70 comes on a very basic tripod and mount. Low cost mostly plastic eyepieces - enough said on this part. On this scope (and many others) you are (in effect) paying to use the Starsense software. The hardware is your phone. The software is tied to your phone by a code provided in the box. I believe you can have 5 different device activations before having to negotiate with Celestron. The Starsense app is easily downloaded to your smartphone. In my case from the Google Play store. The phone sits on a bracket on the OTA. So far so good. The bracket comprises a diagonal mirror, phone grip and x/y adjustment mechanism. It looks well built. Then you locate a distant object (tree, aerial, etc.) and align the phone camera to the OTA - a bit like aligning a finder to OTA. It is a combination of turning the x/y mechanism and zooming the screen for accurate sighting. If you want to use your everyday phone, then you have to go through an alignment procedure every time you use the kit. Then what if you want to use your phone while observing? I opted to use a redundant smartphone and leave it attached, so making alignment a once only task. Alignment is best done in daylight, or on a distant street light. A caution. Your old phone may not have anything like original battery life, which means you should consider a power bank of some description to ensure the phone doesn’t pack up part way through a session. After installation, Starsense software does not need web access. It does not need GPS. It works by looking at the stars in the phone FOV and deciding where you are. In practice I found high clouds prevented this recognition. The software started trying to take photos at different exposures. Tried to get web access. The phone I used did not have GPS. How much of the problems were down to my phone, and how much were restrictions of Starsense, I cannot say with certainty. When there was partial cloud, but some stars clearly visible, Starsense did not recognise where it was looking. However, there were enough stars for me to work out where I was looking. As the phone (screen) is fixed to the OTA, the viewing angle may not suit. Think about this if you intend to fasten on to your own OTA. Had I got this far, it would have been sticky pads until I was happy with the location. A further consideration is phone brightness. You need to have good control over this to avoid your eyes reverting to daylight vision! In conclusion this appeared to be a good low cost package for beginners. I think you will get best results from a phone with a good camera. This means the apparently low-cost package actually ties up your (probably) expensive phone. After several attempts to obtain good results I gave up. The package did not offer me anything better than going out to look using the old established methods. Maybe the poor weather and August (light) skies did not help. Maybe I should have got a better phone? The clock ticked towards the returns window expiring, that made the decision for me. I could not justify hanging on to the package in the hope of clear dark skies in another month or two giving me good results. I am sure there are some who have used this kit and got on well, but not me. Please add to the review if you have your own story (good or bad) to tell.

I have used garden BBQ or seat covers. For indoor storage - in other words a dust cover. Outdoors I regard them as temporary in case the rains gods strike unexpectedly, or I am leaving the mount for a couple of hours.

Is your diagonal a mirror or prism? A prism can mean a smaller extension to the light path than a mirror diagonal. Depending on the diagonal construction. Take look at the link to get you started. If you are running out of travel, consider changing the adapter from the focus tube to 1.25" for something lower profile. HTH, David. https://www.google.com/search?client=firefox-b-d&q=prism+diagonal+light+path#vhid=gjh9-cm9TC17UM&vssid=l

If you have had a damaged screw in there, what about the state of the threads in the cell?

I followed this bit....We describe the 2023 release

On shipping scopes within the UK. A lot of product (for example Skywatcher) is drop shipped from the likes of OVL, the wholesaler direct to the end user. The retailers (FLO, RVO, etc) only handle the paper trail. OVL have considerable commercial clout with a carrier. If they drop too many scopes, they don't get their contract renewed. Further, the carrier knows that the truck load of boxes from OVL are fragile. If things do go wrong, you quickly get another scope or repair parts that you agree with the retailer. Big retailers who ship a lot also have some financial clout. Now if you as an individual ship something, you are expected to pay extra for delicates and breakables. Even then, some carriers refuse to insure glass - despite taking the money. Some carriers refuse to pay full value on secondhand goods - it is 3/4 down page 7 of the small print. You can shout and stamp your foot - but you are an individual. I have in the past for work had long arguments with carriers about loss and value. Basically some carriers are stupid, others are crooks. Though there are some decent ones around. When selling any scope related kit, I have always accepted the risk that if the box is lost or flattened I will be out of pocket. When buying from someone you don't have experience of, do they know how to pack for carrier survival? £50 spent on fuel collecting a scope is often better than the stress and headache.

Yes a proper stage/flight case would provide protection. But not fall within standard flight size/weight limits. Having had damage inflicted to my luggage on various flights, I know the baggage abusers are prevalent! In a flight situation, you have no idea if your box is going to be at the bottom of a hold luggage container - with a ton of cases on top. One of my (frequent business flyer) customers concluded it did not matter whether he paid £20 or £200 for a case. After a given number of flights, it was probably wrecked. Next time you watch a travel or wildlife, or nature documentary filmed in furthest wilderness, see if you get a chance to look at the travel plans. These people travel with lots of seriously strong flight cases. Definitely not worrying about a 20Kg luggage limit!

Oh dear. I would not trust a scope to baggage handlers unless it was in something like a pelicase. Even then, the shocks while dropping on/off conveyors are a big consideration for a scope. A refractor in a pelicase would be OK. Not a newt.