Carbon Brush

Before rushing out to buy the bargain, I would have a think. In all probability the weak £ has limited sales into the UK. Coming at a time of little solar activity. If Lunt have a huge number of tilted tuned 60s on the shelf, does this mean users much prefer a pressure tuned version? Are you happy with amount of light passing through a 400 or 600 version of filter? I'm not saying avoid these models. But it would be worth asking around other users to obtain their views. For what its worth. I have a Lunt 60 with pressure tune and bf1200. The choice was in effect made for me because this package came up hardly used and very local. At the time, other scopes with different configuration were a long way to travel. So I spent on the scope rather than petrol. The combination I have works well. But not having tried other variants I am not in a position to give an informed opinion on any reduction in usability or performance from the other options. Hope this helps, David.

Hi Dan. Eyepeices are as much about what you are comfortable using, as they are about performance. I use Hyperion eyepieces. To me they are very useful. I like the long eye relief if using specs. If you want to change the eyepeice FL, you can add a tuning ring or remove the bottom section. The 68deg FOV is a good wide viewing experience. Though that is to some extent a personal choice. The downside is an F5 scope is at the bottom end of the tolerance for a Hyperion. A bit soft at the edges as Robin pointed out. They are also 'jam jar' size and weight, which can be an issue with certain small scope/mount combination. But on balance I think they are good. My Hyperions aren't going anywhere anytime soon. I like them. Hope this helps, David.

Take note of the 'specmanship' used by the seller, and read the small print. In other words he is misleading you about the battery power storage. You have a battery comprising 7 cells in series. Each cell is about 3.7V and 3.2Ah. To obtain 12V, he is most likely using the series connected cells into a switched mode power supply. Assuming 80% conversion efficiency, then you have something that looks like a 12V 9Ah battery pack. But how it will handle inrush on a tablet/laptop supply, or a mount slewing is a guess. If it was me buying, I would buy something from a reputable manufacturer. Tracer for example. Poorly designed or incorrectly assembled lithium power packs are a big fire risk. If the switched mode supply plays up, you may end up with expensive mount or laptop damage. Hope this helps, David.

Yes camera tripod thread. 1/4" UNC. A good source is ebay. Nice stainless bolts for Harley bikes etc. Available in small quantity and various lengths / head types. David.

A suggestion before spending on an extension tube. In daylight, point your scope to the horizon. Offer the DSLR camera + barlow up to the focus tube and move the camera by hand. Use live view or a separate screen. If you see that to obtain focus the camera is in mid air, you have demonstrated that you need an extension tube and you have an idea of the length. If you only need a millimetre or two. Is there enough space to pull the main mirror back a little? I have had the opposite problem (on different scopes) and had to lift the main mirror or swap to a low profile focusser. Hope this helps, David.

Thinking here about thermal conductivity of the various materials in most Maks. A metal tube, being a good thermal conductor, will transfer heat to the outside quickly. This means the air in the tube will cool quickly without the tube being left open. Thick glass will hold a lot of heat. It has lower specific heat than aluminium. But is an awful conductor and can be in thick slabs. Well thick compared to the metal tube. The front glass has one face to the outside to help cooling. But the mirror can only lose heat to the air in the tube. I have not done actual trials, but my gut feeling is that a plastic (poor heat conductor) front lens cap will slow cooling. If you can swap for a thin metal cap, that will help. Could this be why, for example, the ETX90 (a budget scope) had an aluminium front cap? In the numbers these were made, surely a mould plastic cap cost a lot less. Just a thought, or two. David.

Any society or group involves a long journey for me. They are all an hour or more driving each way. So any I attend are on the basis there is something special going on and I pay for the event. I was a member of a local society a long time ago. But they decided they didn't want me. Being a bit busy at membership renewal, I forgot about my subs. They did not send a reminder either. I was at the end of a long and unstable chain trying to sell my house. Looking for another to buy, and helping someone with theirs for sale. I thought that under the circumstances sending in my cheque 2 months late with an apology was not unreasonable. But no. They sent the cheque back. Limited seating the lecture room so they had put a cap on membership and it was full. I was told I was on the waiting list and they would contact me when there was a vacancy. That was in 2007 and I have yet to hear from them. Then again. Did I want to join a society that had elected a chairman who did not even own a telescope. They do a lot of public evenings with a significant admission charge. Apart from that, it appears to be a secretive group. Not exactly 'you can't join unless you are already a member' but not far off! The exact opposite was my experience with East Midlands Stargazers. A fantastic friendly crowd who get their scopes out at a dark site. Can't say enough good words about them. But at 70 miles round trip when I have reasonable skies at home.... So if you have a local society who are friendly and welcoming, do join in. David.

At home I have enjoyed pointing out the nebula (unaided) to visitors from areas with more polluted skies. Just going into that part of Orion with binos or a low power eyepiece gets you lost among the stars. I always look forward to Orion showing over trees as winter approaches.

I think for anyone thinking about meteor or comet impacts, this report about the Tunguska event is interesting. https://en.wikipedia.org/wiki/Tunguska_event Long distance 'instant' communication by telegraph was established - in a few places. Individual institutions and researchers in Europe and further afield noted changes to the sky, etc. But presumably did not receive reports from those local to the event. Those 'local' to the event. By that I mean Russian scientists, who did not investigate for years. OK they may have been sidetracked by WW1 and a revolution. Had the impact been over somewhere densely populated, like Europe, the casualty count would have been huge. Had this been over open water, there would have been extensive coastal flooding - and casualties. I'm sure the earth has suffered impacts that nowadays would flatten a city, or small country, many times in human history. But it is only recently, and some parts of the world that they are documented. In my lifetime, comets have been binocular or telescope objects. There have been daylight visible comets in the past few hundred years. So just because I have seen nothing more than dim fuzzy blobs, or the odd metoer streak, it does not mean there is nothing bigger out there. Am I right in thinking Barringer crater is only about 50K years old? An instant in evolutionary timescales. Now here is the really worrying part. What if Tunguska had happened at the height of the cold war? 1950s or 60s. Would this have triggered a man made mass extinction from those with fingers on the missile buttons?

For what it is worth, here are my thoughts. It costs a lot of money for solar panels, wind turbines, charge controllers and batteries. The real world implementation of these is not as well established as the salesmen with their glossy flyers would have you believe. Batteries have a limited life (particulalry lead acid) and high capital outlay (particularly lithium). A mains cable is well established technology, not expensive and can outlive the owner. The only sound arguments for a solar/wind/battery powered observatory are: 1/ A very low power requirement. In other words a simple goto mount. No dew heaters or anything else. 2/ The observatory is hundreds of metres away from a mains supply, making the cable run expensive. 3/ Being prepared for extensive mains power cuts that will remove light pollution at a stroke. Just my thoughts... David.

This does sound interesting. An alternative to laser might be to cut to particular depth using a hot blade. That would allow you make holes with variable depth. When I made an EP case, it took ages to do the cut outs working from paper templates. Looking forward to seeing your results, David.

ROR can restrict views near the horizon. In my build, I accepted the restriction. On the basis there are hedges and the like to contend with. Also low angle viewing tends to give a poor outcome. My pier top height is set so the scope, when horizontal, just clears the roof. This minimises the restriction caused by the wall height. The pier top is adjustable so if in future I change mount, or scope, I can still set the horizontal OTA to just be below the roof. HTH David.

Another personal opinion. I bought direct from OO many years ago and the post above reminds me of my experience. There were lots of arguments and the 'person who can make the decision' not being available when I phoned. The first scope was poorly packed and damaged in transit. They tried to blame me! Then on inspection, the focus tube didn't line up with the secondary mirror. A manufacturing defect! Eventually a second attempt by OO produced a scope that gave excellent results. But I still had to straighten out a bent part - more transit damage. I would though buy OO again subject to certain conditions. Buying new, only from a dealer. Pay a small deposit when ordering and check the product in the dealer's shop. If it isn't right, the dealer can argue for you. Or you can walk away with the usual methods of obtaining refund. Buying used. From a seller you have some confidence in, and a personal inspection. At the Kettering show this year, I spent some time having a look over the various OO products. Nobody approached me, despite there being staff on the stand doing very little. Maybe my experiences were unusual? David.

If you are absolutely defintely certain that you will never want to join your scope for the evening, and you will never ever fit a bigger mount or bigger scope, the a roll off shed is the way to go. However, if you have the space and money, or you want flexibility, build the biggest roll off roof structure you can. That way you are future proof. I have never regretted my decision to go for a roll off roof vs other options. Details in design, yes I made mistakes. But compared to a dome or roll off shed, no regrets. Why not make a warm room next to the scope? That way it is easy enough to go out and give the scope a kick, waggle a connector, etc. Just my thoughts. David.

An excellent example of why SGL is the best astronomy forum.

Hello and welcome to SGL. I would not recommend giving up on a dob just yet. At this stage, being able to set up and view easily is quite important. An 8" dob, like the SW200, will give you the 'wow' views of deep sky objects, and take the magnification for the planets. https://www.firstlightoptics.com/dobsonians/skywatcher-skyliner-200p-dobsonian.html This size is a good compromise between light gather and portability. It is within your budget. I would not bother with thrying to use an EQ3 mount for any phtography. Think in terms of a small scope on EQ5 or HEQ5 upwards for anything weighty. Bear in mind the scope/mount/eyepeice packages are made to meet a price point. It is fair to say the mount/tripod are usually the smallest the manufacturer can use. I think that your nearest shop is going to be Rother Valley Optics, near Sheffield. They are a reputable dealer who have been around for a long time. First Light Optics tends to get first go at my wallet for online new purchases - excellent service. Hope this helps and Keep asking on SGL and at a local astronomy club. David.

Cigar power connectors are OK for lighting cigars. A second to Peter's comments.

Is your internet connection usually happy about uploading this sort of file size?

I have gathered barlows over the years. Often part of a scope or eyepiece package. To be honest, they rarely come out of the boxes as a magnification device. Only sometimes to help bring a DSLR to focus. I have preferred to spend on eyepieces. I would be tempted to look for an eyepiece with wide AFOV to get the stunning views available from your light bucket. Hope this helps, David.

An ED80 would keep you happy for much longer than the ST80. They are a good scope and should you wish to part with it, it won't take long to sell. David.

Hi and welcome to SGL. Another one to throw into the information overload if I may? The ST80 is a shorter tube. This makes it easier to get a stable image for the same magnificatuion, and the same mount. It might also help you in transport and storage. The ST80 will give good enough views to keep you happy for some time. I used to own the bigger brother. The ST102. I thought that was good value for money. Of course, when I did a side by side against another scope costing 3x the price...... By buying used, you won't lose much money should you decide to sell on and buy something else. You said you were looking to buy from a supplier. I assume you mean an astronomy equipment retailer, not some other retailer. Enjoy the journey. David.

Don't give up! My experience of new scopes is that they sometimes have something not quite fastened correctly, or not quite aligned. Secondhand scopes may be better or worse. Then new scopes sometimes have poor accessories to meet a price point. With an 8" newtonian on dobson mount, you have a scope that is easy to sort out and easy to modify to suit your use. If the dob mount is a bit sticky, take it apart to find out why. A bit of silicon grease on bearings may be all it needs. Or a fraction of a turn backing off a retaining bolt. There may be a bit of muck or dust ona bearing surface. The scope. Yes look at the mirror fixings as suggested earlier. My experience of 8" and 10" newts is that they hold collimation quite well for everyday viewing. Unless of course you give them a really good knock on door frames on the way from the house to the garden. I used to regulalry travel with an 8" newt on the car back seat and don't remember any collimation issues.. On the rare nights that you can push the magnification to the scope limits, then accurate collimation becomes more important. On the finderscope - which is a vital part of the scope - what are you using? There is no 'one size fits all' solution. I hate the straight through optical finders often supplied with this scope type and have always swapped for a right angle finder, positioned near the scope eyepiece. For me, a 9x50 right angle finder is first fitting to a newtonian in this size range. Some love a Telrad finder. I never liked them. I use a Rigel Quickfinder for basic alignment. Some hate them. As for straight through red dot finders. They can be good. Some should be put with your papier mache teapot collection. I have seen examples with a spot so bright that it obscures Venus, Jupiter, etc. Others have had a tinted viewscreen that dims anything less bright than Venus to invisibility. Keep going and don't sell the scope just yet. Keep asking the questions. David.

A vote from me for Hyperions. Yes they are jam jar size and weight. But if the scope is up to holding them, they give good views.

I think the OP means 100 amp-hours. Which is more than enough to run a mount, laptop and enough dew heaters to keep a the scope warm for ages. I think most people who go for this sort of size are working on the basis that the battery does not deliver full capacity when cold. Further, it degrades and loses capacity on a daily basis in storage. Whether charged, kept warm, kept cold, etc. A battery that starts life at 100 amp hours can become half that in a couple of years though still run a scope and accessories for the night. On connectors. There is a lot to be said for the XLR series connectors. They are popular for stage use as they are robust enough to stand on and throw around. Available in various configurations from multiple manufacturers and many suppliers. Here is one example. https://www.neutrik.co.uk/products/audio/xlr Hope this helps, David.

An excellent cleaning job. Although modern mirror cotings do seem to be tough, how do you know before you start? Brillo pad the centre spot? Or the edges under the clips? Even if you cleaned a particular make or type of scope and found it was an 'armoured' mirror, can you be sure every scope was made the same way? Particularly as many mirrors are made in China these days. No harm in being cautious. David.