Second Time Around

As you've repeated ad nauseam on Cloudy Nights! As others have pointed out there the 7-21mm certainly isn't parfocal for everyone, including me, but that may be down to lack of accommodation in my elderly eyes. I tested various eyepieces on the sun with my 72mm f/6 refractor and a Quark earlier this week. Included amongst them was the Svbony 7-21mm zoom and the Baader Mk IV 8-24mm. It was no contest - on prominences the Baader was far superior. Some of you will remember I'd previously tried various eyepieces with the same scope to find what the lowest magnification was to see Saturn was ringed. Here I was using just the low power end of the zooms. I reported there was little difference on axis between the Svbony and the Baader, but the Baader was better off-axis. The Baader is clearly better than the Svbony, but it ought to be at over 4x the price! However, at £40 to £45 the Svbony is excellent value for money, and as a result I've just bought another for a first scope for a friend's daughter. Moreover the 7-21mm Svbony (but not the 8-24mm or the 10-30) is really lightweight and slim. The slimness is especially useful in binoviewers. I'll be keeping both the Baader and the Svbony. One of the reasons is that a Dioptrx can be fitted to both the Baader and the Svbony 7-21 with an O ring/elastic band if you take the eyecup off. With the Baader it goes in the groove at the top just below the rim. The eyecup is tightly glued on the Svbony 7-21mm, but it does come off. The O ring then fits on the very top of the rim. However, on the Baader the top of the eyepiece revolves when zoomed. This makes changing magnification slower when using a Dioptrx on binoviewers, and could mean missing fleeting moments of good seeing. I can't see how to get a Dioptrx to fit the Hyperflex without sticking it on as the twist up eyecup design is similar to the Svbony 8-24 and 10-30. So I've given it to two of my grandkids. The main downside of zooms is the small apparent field of view at the low power end. But the actual real field of view of course also depends on the focal length. I've had only a quick look with the Hyperflex 9-27 mm, that has a stated field of view of 40-60 degrees. This was a daytime look at my shed. This showed the actual real field of view of the Hyperflex at 27 mm is more or less the same as the Baader at 24 mm. Of course with the shorter focal length the magnification is higher on the Baader. According to the specs, the actual real field of view with the Hyperflex should also be higher than the 10-30 mm Svbony.

Hopefully peer pressure over climate change will eventually improve matters. "Eventually" though maybe too late for us oldies.

As you said you'll try to get way from light pollution in town then a bigger aperture scope makes sense. This will mean a reflector is better value for money. However the Celestron 114AZ looks like it's a Bird-Jones design that's best avoided as it's difficult to collimate. It also advertises magnifications up to 750x! The reason I added an exclamation mark is that there's absolutely no way that this would give you a good image in a 115mm scope, and very rarely in the UK in any size scope. It's just manufacturers using magnification to suck beginners in. The Sky-Watcher Explorer 130 (EQ-2) is a much better bet, but as you pointed out is on an equatorial mount. This is a little more difficult to learn to use, and at about 13kgs it's also very much heavier. I'd choose a Dobsonian mount as others have also suggested. This will be lighter plus a lot more stable, but the table top ones do need something to put it on. All sorts of things can be used for this though, not just a table. I'd definitely choose the 130 over the 100 Heritage. The bigger aperture will give a lot more light gathering power, plus the focal ratio is f/5 rather than f/4 with the 100mm. F/4 scopes are more difficult to collimate, plus need higher quality and thus more expensive eyepieces to get the same quality image. This will negate the small saving in cost in the long run. You may have to wait a few weeks for the Heritage 130 to come back into stock, but the wait will be well worth it. However, they're extremely popular and the next batch may well be pre-sold before they arrive. I'd therefore get an order in as soon as you've decided.

You may have seen that I've just bought 2 different scopes for different youngsters (see the recent topic "Best budget scope for a 5 year old"). For the older one in the country it was a 130mm table top Dobsonian. For the 2 in London, including a 6 year old, who needed a lightweight scope it was a 70mm Starsense Explorer refractor. I was so impressed with the Starsense Explorer that I bought another of the 70mm refractors for my own use, and adapted the technology to my other bigger and better scopes. However, I kept the 70mm refractor as it's so lightweight, and being somewhat disabled there are nights when this is all I can manage. Like others who've tried it, I believe that Starsense Explorer is a game changer for beginners. It would be too for the more experienced if it had a larger database. The technology is available only as a package with a scope, not standalone. Unfortunately, the scopes themselves are all pretty basic, although some of them represent good value for money as the extra cost for the technology is modest. This doesn't however apply to be more expensive ones, where you pay a lot for Starsense Explorer. As far as I know there are 6 Starsense Explorer models that have been offered. 4 were released to begin with, then discontinued in the UK and replaced with 2 others. The first 4 were: 80mm f/11.25 refractor 102mm f/6.5 refractor 114mm f/9 Bird-Jones reflector 130mm f/5 reflector The 2 new UK models are: 70mm f/10 refractor 127mm f/7.87 Bird Jones reflector As others have advised, I'd avoid the Bird-Jones designs. This is because they're difficult to collimate, something that isn't mentioned in the blurb. Their only (possible) attraction is their compactness. You can spot a Bird-Jones as the tube length will be very much less than the focal length (the diameter of the main lens or mirror times the focal ratio). You'll may also find it harder to sell these on. The 70mm and 80mm appear to share the same mount, that I've found useable but rather wobbly. This would be especially so on the heavier and longer 80mm. It has slow motion on just 1 axis. The 102mm has a better focuser and mount as has already been pointed out, with slow motion on both axes. However, you pay a lot extra compared with a similar model without Starsense Explorer. The same applies to the 130mm reflector (that's not a Bird-Jones thank goodness). Once again, it's a lot extra compared with a similar model without Starsense Explorer. Whether or not it's worth paying extra for Starsense Explorer compared with spending the same amount on a bigger (but heavier) scope will vary from person to person. Starsense Explorer certainly makes locating objects very much easier. All too many beginners give up astronomy when they can't find more than the brightest objects without a lot of hassle. Many (especially youngsters) won't have the patience to learn how to "star hop" from star to star; others will love the thrill of the chase that comes with star hopping. However, in towns and cities light pollution will mean that they'll be many fewer stars visible, and this is where Starsense Explorer can make a huge difference in locating objects. Without it you'd probably need to also buy an extra finderscope that'll show you more stars, but this costs extra. Fine if you've already got one, but an added expense for most beginners. This is why for my grandkids in London I chose a scope with Starsense Explorer. The biggest problem though is finding any scopes in stock, let alone those with Starsense Explorer!

Bought.

I've just bought 2 different scopes for youngsters of different ages with different requirements. The first was a present this Xmas for the 13 year old daughter of a friend. In this case I chose an ex-display Bresser 130mm table top Dobsonian. They live in the country, so that aperture of scope is good for deep sky objects as well as the moon and planets. She's perfectly capable of learning how to collimate a reflector herself. The second was for two of my grandkids aged 6 and 13 who live in London. Here the choice was a 70mm Celestron Starsense Explorer refractor. With my disability there are some nights that is all I can manage. The 6 year old doesn't have the patience and attention span of his older sister, and experience with them looking through my own scopes made me realise that finding objects had to be fast for him. It would be bad enough in the country, but finding anything but the brightest objects in an urban area would mean that go-to or push-to would definitely speed things up, especially as his father has no experience in astronomy. Moreover, he has to carry the scope a quarter of a mile uphill to Blackheath as their garden is surrounded by tall trees. Go-to would need powering and would weigh more, quite apart from being more expensive. Celestron's new Starsense Explorer is a real breakthrough in push-to. The 70mm refractor version costs just £135. OK, I upgraded the eyepieces and added an extra diagonal, but these could always have been added later. The provided diagonal does have the advantage though of being able to be used for terrestrial viewing. I've tested out both these scopes at home, and that convinced me that I'd made the right choice in each case. In fact, I was so impressed with the Starsense Explorer technology that I've bought the same scope for myself! I've converted it so that I can use it on all my scopes, but kept the 70mm as it's so light and portable. So for a 5 year old I'd definitely recommend the 70mm Starsense Explorer. The only problem is finding one in stock. There are two schools of thought about binoculars. Personally I don't go along with the idea of buying beginners to astronomy binoculars before a telescope. This is especially so for young kids as few binoculars will fold close enough together. A telescope will mean many more wow moments, and will for instance be powerful enough to show the rings of Saturn - something that binoculars won't. These wow moments are far more likely to fan the flames and lead to a lasting interest. So for me binoculars are an adjunct to a telescope - something to buy later if you don't already have a pair.

Thanks, John. The OTA of my 10in f/4.8 OOUK is listed at 11kgs. I don't know whether or not this includes the 50mm finder. The corresponding weights of their 12in f/4 and f/6.3 are 14 and 16kgs respectively.

Does the Bresser have a steel or aluminium tube?

Louis, many thanks indeed for all the hard work. It really is a wonderful resource.

Thanks both!

Some of you may have seen that FLO kindly came to my rescue when I couldn't release my ScopeTech mount from my camera tripod. This was probably down to disability and getting the screw cross-threaded as I can't hold items steady enough. I want to avoid the possibility of this ever happening again in the future. What I think I need is some form of quick release mechanism, with a bolt rather than being spring-loaded. Even better, I had seen a video ad for a heavy duty click on/off design but can't find it now. There are a huge number of products out there, but does anyone have any suggestions please?

I agree with your idea of trying out a zoom. That and a Barlow plus a low power, wide field eyepiece is all you'll need to begin with, and possibly for a very long time. I've tried out 4 different zooms and kept 2. These are the Baader 8-24mm that's very good but costly, and the very inexpensive Svbony 7-21mm. This new Svbony is apparently identical to the Orion E-series but at an even lower price. The stated eye relief is 16.3 to 18mm. The Baader is a little better corrected off axis in my f/6 scopes and has a larger field of view than the Svbony. However the Svbony is much smaller and lighter, and exceptional value for money (about £40 to £45). I bought the Svbony because of the excellent reviews it had on Cloudy Nights, and am happy to recommend it myself. Svbony also sell 8-24 and 10-30mm models, but again I haven't seen these. Both are much bigger and heavier than the 7-21mm Svbony. Additionally the 10-30mm has a particularly small apparent field of view, plus only 5 elements and so is unlikely to be as good. The ones I didn't keep were firstly a Celestron (from a terrestrial scope rather than the usual astro model. This was because it didn't have a filter thread). Secondly a clone of the Hyperflex 9-27mm. There was nothing wrong with the Hyperflex, but both the Baader and the Svbony 7-21mm can be adapted to take a Televue Dioptrx adapter to correct the astigmatism in my eyes. I gather the astro model of the Celestron 8-24mm has a T thread that a Dioptrx will also fit. Turning to Barlows, I'd very much recommend a dual 1.5x/2x model on your f/7 as this gives much more flexibility. These dual models are sold as 2x Barlows, but some 2x models can also be used at 1.5x. These ones allow the lens cell to be unscrewed from the body of the Barlow and then screwed into the filter thread at the bottom of an eyepiece. Very often this won't be in the blurb, but on their website the US retailer Agena Astro states whether this can be done or not under the specifications. I'd also add that the 2x Orion Shorty Barlow that Agena doesn't sell can also be used at 1.5x. I use the 2x option when atmospheric seeing is good and in conjunction with a 7-21mm zoom will give you magnifications of 68-204x. However I find that there are many nights in the UK when a 1.5x Barlow gives the maximum that the seeing will allow (153x). Sure you could use the Barlow at 2x with the zoom set at 9.3mm to get this magnification, but this will give you a smaller field of view. This because the apparent field of view of nearly all zooms is lower at higher focal lengths. I've got an Altair 72mm f/6 EDF with a very similar spec to your new scope. I'm very pleased with mine and am tempted to add the 102mm to the arsenal. Good luck with yours!

I've tried out 4 different zooms and kept 2. These are the Baader 8-24mm that's more expensive than those mentioned so far, and the very inexpensive Svbony 7-21mm. The Svbony is apparently identical to the Orion E-series but at an even lower price. The Baader is a little better off axis at f/6 and has a larger field of view than the Svbony. However the Svbony is much smaller and lighter, and exceptional value for money (about £45). I bought the Svbony because of the excellent reviews it had on Cloudy Nights, and am happy to recommend it myself. Svbony also sell 8-24 and 10-30mm models, but again I haven't seen these. Both are much bigger and heavier than the 7-21mm Svbony. Additionally the 10-30mm has a particularly small apparent field of view, plus fewer elements and so is unlikely to be as good. The ones I didn't keep were firstly a Celestron (from a terrestial scope rather than the usual astro model. This was because it didn't have a filter thread). Secondly a clone of the Hyperflex 9-27mm. There was nothing wrong with the Hyperflex, but both the Baader and the Svbony 7-21mm can be adapted to take a Televue Dioptrx adapter to correct the astigmatism in my eyes. I gather the astro model of the Celestron 8-24mm has a T thread that a Dioptrx will also fit.

Some of you will know that I have problems with my fingers and hands. As a result I couldn't get my Scopetech Mount Zero off my tripod. I also had a Baader Diamond Steeltrack that was making a grunging noise. The only item I'd bought from FLO was the Mount Zero. Despite this FLO said to send everything to them and they'd sort it all out. Not only did they do so, they turned everything round by return. Plus there was no charge, including for carriage. Now, that's what I call superb customer service! So I've just given them another order. Thanks, guys!

Here are some more detailed instructions for my easy conversion of the Starsense Explorer I outlined in my previous post on this thread. 1) The dock mount comes attached to the telescope tube and is in 2 pieces that need to be separated. This can be done only by taking it off the tube. The lower part can then be reattached to the tube. 2) On the underside of the top part of the disassembled dock mount you'll see 3 screws as in the left hand picture below. The slotted dovetail is then screwed into the large lower hole. This is deeply countersunk so you'll need a long bolt. plus a nut and washer. 3) The mini ball head is then attached to the middle threaded hole on the dovetail. These have the same thread. 4) The second slotted dovetail is then attached to the mini ball head as seen in the middle lower part of the photo. I've read conflicting comments on whether the phone has to be level for the Starsense Explorer to work. If it doesn't the ball head may not be needed. However, it does make it easier to use in practice and so mine is staying.

Mark, on the long thread on Cloudy Nights there was a report on using the Starsense Explorer just after dark in light pollution. It worked very well. In fact, that's what decided my buying one for the grandkids in London.

There's a huge thread on the Starsense Explorer on Cloudy Nights. Early on there was a post from Daniel, who heads up the software and electronics development at Celestron. Here's his comment about adapting the Starsense Explorer for other scopes, plus whether Celestron will sell it as a stand alone product. "As an engineer, I think its pretty cool. We had expected that some people would do something just like what you're doing. I did not expect it to happen day 1 though 🙂 Selling a bracket separately and then targeting this product at new astronomers would lead to a lot of customers buying telescope x, y, or z and then the bracket, and then having difficulty properly mounting it, etc. It would take away from us trying to make this a product that makes astronomy easy. Maybe in the future, if the demand is there, we will figure out a solution that mitigates that concern. But for now, we will only be selling complete StarSense Explorer telescopes. Enjoy your endeavors with you custom StarSense Explorer dob. I look forward to hearing your results! "

The Starsense Explorers are in very short supply, especially the 70mm refractors - I had to really search around for my own. So here's a heads up to all who are looking for a Starsense Explorer to put on their own scopes. There's one of the horrible Bird-Jones LT 114AZ reflectors on eBay that might be worth getting for the Starsense Explorer. The eBay item number: 193715607646

Here are the promised photos. The first is the StarPal 100mm slotted dovetail. I used this to join the Starsense Explorer to the mini ball head. I could have used a 40mm slotted dovetail, but had only 1 of these and I used it to join the mini ball head to the standard Synta finder shoe that I have on all my scopes. The second pic shows the Starsense Explorer on the top of one of my Dob tubes. The third shows the Starsense Explorer at the side of my refractor, with the mini ball head at an angle so that my mobile phone is horizontal. I gather that having the phone horizontal is essential otherwise the Starsense Explorer doesn't work properly.

The 7-21mm Svbony zoom is very much lighter than their 8-24mm. At f/6 it's not that far behind my much more expensive 8-24mm Baader in sharpness. So at about £45 delivered it's really excellent value for money. I've just bought another for the Bresser equivalent of your scope for a friend's teenager. I find that AliExpress delivery times are much faster than advertised, probably to avoid poor feedback. If you need this zoom even faster the Orion E-series is the same eyepiece but costs £56.99. Orion also charge £7.95 carriage unless you spend £75 or over.

Two of my grandkids have just got hooked on astronomy so I've just bought them a telescope. They live under light pollution in London where there are few naked eye stars, so a Starsense Explorer was an ideal choice. Additionally, their father has got to carry the scope a fair way up the hill to Blackheath as their garden is almost surrounded by high trees. Light weight is therefore important, so the obvious choice was the 70mm refractor. The eyepieces and diagonal are very basic so I've upgraded these. I tried the scope out myself here in the country and was extremely impressed indeed with the technology. So much so in fact that I've bought myself the same scope just to get the Starsense Explorer. The idea was to adapt it to my own scopes - a refractor and two Dobs - and to be able to swap between them using finder shoes. The biggest problem I have is that my hands don't work properly, and so fabricating any parts is a non-starter. I therefore needed to construct something that needed no more than a screwdriver or an Allen key. The key is to connect the Starsense Explorer to a dovetail with a slot(s) rather than just holes. The slot means that a screw can be used almost anywhere rather than just at a fixed position(s). This is important as it seems as if Celestron is using an unnecessarily complex mount for the Starsense Explorer that I can only guess was done to make it as difficult as possible to use on other scopes! Luckily, I'd already sourced such slotted dovetails and used them for finders made out of camera lenses that needed different and varying gaps between the two finder rings. These slotted dovetails to fit standard Synta finder shoes were almost impossible to find. However, after much searching worldwide I finally located just one model on an AliExpress store. The store is called StarPal and the item goes by the long title of "StarPal mini small dovetail plate for guider scope finder bracket tail plate dovetail star pen standard plate"! These dovetails are available in several sizes (called colors!), and I'd already bought 3 in the 100mm size and 1 in the 40mm size. I was about to post this up when I saw John Inderby's excellent idea above of incorporating a mini ballhead so that the Starsense Explorer is always upright - thanks John! So I duly bought the same one from Amazon (Andoer Camera Monitor Holder Mini Ball Head with Cold Shoe Adapter for LED Video Light Monitor). It's tiny, and as John said this model is preferable as it locks tightly with the supplied Allen key. This ball head isn't needed though if your finder shoe is at the top of the tube, as it can be on my rotating tube Dobs. However one then loses the option of the tube rotation. Also neither finder shoes on my refractor are at the top of the tube, so the ball head is needed anyway for this scope. So I incorporated John's mini ball head into my design. John fabricated a part to fit the ball head to the Starsense Explorer. As I mentioned earlier though my hands won't allow me to do this. However, incorporating a second StarPal slotted dovetail solved that problem nicely. The complete arrangement is dead easy to make and seems to work very well on both my Dobs and my refractor. I just need a clear night to do a field test, but that seems a long way off! I was going to post this a few days ago, but delayed so that I could incorporate John's idea of a ball head. I'll try to add pictures later this evening, though it may have to wait until the morning when the light is better. Edit note: pictures 4 posts down.

I bought the 22mm/70 deg Omegon as a result of Louis recommending it on another topic. I too found it very close to the 22mm Nagler in sharpness at f/5, plus I'm another who finds the 82 deg FOV of the Nagler hard to take in. In fact, with the shape of my eye sockets some of us find it hard to see the edge of the FOV in most wide angle eyepieces with glasses on - even the long eye relief ones. The same applies with a Dioptrx astigmatism corrector. So personally, for such eyepieces I'm not worried about the performance at the extreme edge of the FOV as I can't see it! The Omegon is an absolute steal - I paid just £116 with postage. The 22mm Omegon Redline, the identical TS 22mm, and the 22mm Nagler all take a Dioptrx, as I believe the 24mm APM UFF does. Note though that Louis advised me that some of the other Redline clones such as the Celestron and Olivon have a twist up eyeguard and don't accept a Dioptrx, unless perhaps you glued one on. Having just got into night vision I don't currently do much conventional DSO viewing. If that continues I might sell off my 20 to 22mm eyepieces. The exception would be the 22mm LVW as it's the hard to replace, plus it's a 1 1/4 inch eyepiece that I can use with my new Maxbright II binoviewers.

Thanks, John. Any more?

Good point, Louis.

Which ones of these eyepieces accept a Dioptrx? Don? Anyone?