Second Time Around

I think glasses v Dioptrx is very much a matter of personal choice. Depending on one's eyesight there are pros and cons of each, and what's best for one person may not be the best for another. Amongst the disadvantages are: 1) Not all eyepieces accept a Dioptrx 2) If the angle of the eyepiece changes when moving the scope (e.g. a reflector), you need to adjust the Dioptrx. The quick and easy solution is to put a small blob of glue on the rubber of the Dioptrx and always have this at say the top 3) No good when sharing eyepieces 4) You may need glasses anyway to look at the sky or charts etc However, I wonder how many have tried a Dioptrx? And of those, how many have actually done a head to head comparison? These are the reasons I prefer a Dioptrx plus some comments: 1) The coatings are better than on even the top of the range Rodenstock lenses on my glasses 2) The polish is almost certainly better than that of glasses - few people would pay for this on glasses so almost no demand, so no supply 3) My glasses have plastic lenses that scratch more easily than the glass lens in a Dioptrx 4) The angle of my astigmatism changes between my annual eye tests. With a Dioptrx I can adjust this at the telescope 5) I find that, like many, I need an extra 0.125 or 0.25 correction for astigmatism at night 6) I wear my glasses on a cord and have no problems taking them on and off for looking at the sky - it quickly becomes automatic 7) I have no presbyopia and so don't need glasses at all for looking at close range objects such as screens or maps 😎 I have a Dioptrx on my finder eyepiece, but even without this I don't find astigmatism critical on a finder as it's doing just that - finding 9) On the rare occasions I share my scope I do wear my glasses 10) And most of all, and this is the clincher, having done head to head tests I found that I can see more with a Dioptrx than with my glasses As has been mentioned already many Pentax and Baader eyepieces accept a Dioptrx. So do many from Explore Scientific. If the eyepiece has a M42 (t-thread) or M43 screw top it'll almost certainly accept a Dioptrx. The same goes for most others with a non-screw 42 to 43mm top. In some cases fitting an elastic band or an O ring to the top will give a secure hold whilst still allowing the Dioptrx to be turned. I don't find this necessary with an M42 thread, but do with an M43. For instance Baader Mk IV zooms have an M43 screw top and need an O ring. The O-ring has an inside diameter of 42mm and a thickness of 2 mm. Below is a pic of my holding a Baader Mk IV zoom by a Dioptrx without the eyepiece falling to the floor. The Dioptrx can still be turned.

Despite having high quality fixed focal length eyepieces, I use my zooms a lot more often. The zoom plus a Barlow lens and a low power, wide field eyepiece is often all I use the whole evening. Fixed focal length eyepieces may be slightly better corrected when compared with a zoom at the same magnification. But that's not always a fair comparison as that magnification may not be the optimum for a given object. This is because one of the many advantages of a zoom is to be able to dial in precisely the best focal length. For instance, this may be 13mm or even 13.1mm, which may actually show more detail than shorter or longer fixed focal length eyepieces - even the best quality ones. I especially like the ability to increase the magnification to make use of brief moments of good seeing (a steady atmosphere). It takes more time to swap out an eyepiece, and the opportunity may then be missed. You can't see anything if you haven't got an eyepiece in the focuser! Zooms also enable the field of view to be varied to frame an object to get the prettiest view. For this reason I particularly like them for clusters. They're also handy when you're using filters. You don't have to unscrew and then replace the filter when you change magnifications. Additionally, if you lose sight of an object at high power you can simply and quickly zoom out to find it again. Many of those who post here and advocate fixed focal lengths are experienced observers. It's so easy to forget what it was like as a beginner! A zoom eyepiece enables beginners to easily learn what difference a change of magnification makes on all the various classes of object. It also shows them what focal lengths would be most useful to their eyes, their telescope, and their observing conditions. They then have the option of buying/not buying the most appropriate fixed focal length eyepieces for them. For these reasons I'd always recommend that beginners buy a zoom as their first eyepiece.

Are you looking on Berlebach's own website? I ask because I had the same problem and ordered direct from them. Delivery was very fast.

Why I prefer a headtorch is that you can also hold it in your hand. So it's dual purpose.

I'd suggest looking at the Black Diamond Cosmo 350-R Headlamp. This is a new rechargeable version of what's been my favourite headtorch range for years. Most headtorches are way too bright for astronomy, but most Black Diamonds (including this one) can be dimmed right down low. What's more, they can be set to only come on at the lowest red light setting. So no more accidents! The only thing to watch is that the battery test lights up a series of blue LEDs, so I'd avoid using this at all. This is the reason I prefer the non-rechargeable version. However, I do use it with rechargeable AAA batteries.

Thanks all. Very helpful.

David, I'm probably being thick but could you explain how to determine where the point opposite the focuser is? Many thanks.

Apologies if you're already aware of rtings.com but the above is what I recently posted elsewhere.

A Berlebach Report may well be the answer. They have a modular system where you can choose both the head and the tripod. They can be also be supplied with 1/4 inch, 3/8 inch or 5/8 inch threads. Go to https://www.berlebach.de/en/?bereich=produkte&kategorie=105&ansicht=liste If you can't see what you want there they'll almost certainly be able to make something to order. I have a Report 112 Astro and can thoroughly recommend it.

There's pics of my mods and those of others on this long thread: https://stargazerslounge.com/topic/362327-starsense-explorer-stand-alone-conversion/ Happy reading!

Wow! Beautiful pics, beautifully told! I absolutely love the time lapse, and can't wait for more. Many congratulations indeed!

First Light Optics have a returned 10 inch Btesser DOB for a reduced price of £687. Go to https://www.firstlightoptics.com/bresser-telescopes/bresser-messier-10-dobsonian-telescope.html

I've just put the Teleview plus the 35-210mm zoom plus finder bracket up onto the For Sale/Swap forum.

According to Google it seems to be called "isolation effect". "The Isolation Effect, also known as the Von Restorff Effect, proposes that one item that differs from multiple similar objects that are present, the one item that differs will be more likely to be remembered. When the item in question stands out less, the likelihood of it being remembered similarly decreases."

Reluctantly, I've had to stop the project as I found it difficult to keep checking forecasts and making observations every night. It came to a head recently when we were on holiday and time was at a premium. Anyway, there are 17 months observations without missing a day to look back on. The main conclusions are firstly that there's no significant difference between the various forecasts, and secondly that they're totally wrong much less than I expected. You can confirm this by seeing how few red colours there are on the observations. I reckon that it's human nature to remember the wrong forecasts far more than the correct ones. I think there's a scientific term for this but can't recall it. Anyone know?

I bought a Baader Maxbright II binoviewer almost two years ago but it was faulty from the off and so had to go back to Baader. They were out of stock and couldn't send me a replacement until a few weeks ago. Unfortunately, as a few of you will remember, the courier threw this over a 5 foot gate onto our patio! I couldn't get the images to merge, but didn't know if there was a fault or if I'm one of those who can't use binoviewers. I'd just put another order into FLO and, as we were holidaying near Exeter, arranged to collect it. Even though I hadn't bought it from FLO (they were out of stock otherwise I would have done so) they very kindly checked the Maxbright for me and found it was out of collimation. Baader are now going to arrange collection from FLO and send me a replacement, although this may take some time as they're again out of stock. In the meantime I've bought a Stella Lyra linear binoviewer from FLO so that I can see if I can use binoviewers. Apparently some people who can't use conventional binoviewers can use linears. Once again this is superb customer service from FLO! No wonder they're my first port of call - if FLO have it in stock they get my business. Simples!

To make a telescope from a camera lens I use a Tamron Wide Field Tele-View. This is a 20mm/70 degree eyepiece connected to an Amici prism, so it gives a correct way up, non-reversed image that's much more comfortable to look through. It attaches to any of Tamron's Adaptall camera lenses, although I haven't tried it with any long focus lenses. Instead I've been using it to make RACI finders. The Tele-View is long discontinued now, but does come up fairly often on eBay, as do the Adaptall lenses. Below is a picture showing my 35-80mm f/2.8-3.8 lens attached to the built-in tripod adapter on the Tele-View. As you can see, I've fitted it with finder rings - a metal screw-in lens hood helps with this. With the lens set at 35mm it gives 1.75x magnification with an aperture of 12.5mm and a 40 degree field of view. At 80mm it becomes a 4x21 with a 17.5 deg FOV. Amongst the other lenses I use are a 35-210mm f/3.5-4.2. This again can be a RACI replacement for a Telrad, giving the same 1.75x magnification with a 40 deg FOV but with an aperture of 10mm. Set at 210mm it becomes a 10.5x50 with a 6.66 deg FOV. It is of course heavier though. I've fitted my Tele-Views with crosshairs (the eyepiece screws out with a bit of force). I've bought 3 Tele-Views, 2 of which have a 49mm internal thread and so with a 42mm step down ring may also take a T thread lens. When I find a suitable one I'll check if it'll reach infinity focus when set up like this. It does of course do so with Tamron's Adaptall lenses. There's a wide range of these zoom and fixed focal length Adaptall lenses available, including telephotos that would make higher powered scopes.

I'd recommend a dual 1.5x/2x Barlow. These dual 1.5x/2x Barlows allow the black lens cell to be unscrewed from the body of the Barlow and then screwed into the filter thread at the bottom of an eyepiece to give approx 1.5x. Thus you'd treble the number of magnifications you'd have. I've got this one https://www.firstlightoptics.com/barlows/astro-essentials-125-2x-barlow-with-t-thread.html Cost is only £25.

Good point, Dave! Whilst I haven't found a massive difference in what can be seen between 8 and 10 inch Dobs there's one big exception, and that's globular clusters. Here there's simply no comparison. Other DSOs are also better in the 10 inch, although not to the same extent as globulars. With planets I've found the sizes are closer still, possibly because in the UK it's atmospheric turbulence (the seeing) that's often what's the limiting factor rather than aperture. How far the scope needs to be carried and what obstacles like stairs there are in between would be relevant here. Talking of obstacles, will the scope need to be moved around the garden to see different parts of the sky? If travelling by car both sizes will fit most back seats. Plus of course a wheeled dolly would make it easy for either. I've got both 8 and 10 inch Dobs. On good days I can carry the 8 inch outside in one trip, with the mount in one hand and the tube in the other. The 10 inch takes me 2 trips. However, like yours, mine are expensive OOUK Dobs that are lighter and more compact than the ones mentioned so far. What helps most here though are the large altitude rings. The Bresser also has these, so would be easier to transport than the other makes. In fact, I compared OOUK, Bresser, Skygazer and GSO (what the StellaLyras are) in a showroom. Everyone's different, but with the OOUKs and Bressers I could manage 1 size bigger than the Skywatchers and GSOs. Starsense Explorer hadn't been invented by then, but Celestron Dobs looks similar to Skywatchers and are made by the same manufacturer. Other points to consider is that an 8 inch won't need as much time to cool down as a 10 inch and so will be ready to observe sooner. Additionally, many people won't feel the need to buy a coma corrector for an 8 inch that's usually f/6, but would eventually for a 10 inch that's normally F/4.7 to f/5. However, I agree with Dave. I think it best to always buy the biggest scope you can afford and transport. This is because you can (and almost certainly will) add accessories later. The 10 inch Starsense Explorer at £849 is over budget. However, you could buy one of the other makes now, then for £169 you could later buy a 70mm Starsense Explorer refractor and retrofit the technology via a finder shoe to almost any other scope. You'd then also have a useful lightweight refractor. Indeed, that's what I did myself. The 10 inch StellaLyra is probably the best value for money. Personally though, I'd choose the 10 inch Bresser for the better mounting amongst other things - in fact if I hadn't (eventually) found a second-hand 10 inch OOUK I'd have bought one myself!

Thanks, Rob.

+1 The Bresser has the better mount (and mounts would be expensive to upgrade) so would be my choice for the long run. On the other hand, the StellaLyra is better equipped and is excellent value for money. As Brett (Spile) also said I too would choose either of these over the Skywatcher. A further one to look at in this price bracket is the Celestron Starsense Explorer. I can't praise the Starsense Explorer technology enough, and it makes finding objects so easy. The database on this technology is now much improved with a huge number of objects included. In fact, it looks as though it has all the objects in Sky Safari Plus - not surprising given that the makers of Sky Safari helped in the development of Starsense Explorer.

I suspect that the breakages might be down to the shape/size of the seat with buyers leaning forward. Presumably there'd be greater leverage compared with a smaller, round seat. I have 2 what look like identical stools apart from the bigger seats and they've been absolutely perfect.

Cheers, Rob. Does it ever slip down like the Skywatcher/Starbound chairs? How easy is it to adjust the height (my hands don't work properly)?

These look interesting. I see that the adjustment range is 610-860mm (24-34ins), so too high for my Dob. Is there any way to modify one to go lower, Rob? It looks as though there may be stops on the bars in this video: https://www.youtube.com/watch?v=hSoLtYy2mio

Some of you may remember I did some tests on the minimum magnification needed to see that Saturn is ringed, even though it was just 15 degree high. See https://stargazerslounge.com/topic/362487-minimum-magnification-to-see-saturns-rings/#comment-3950610 You'll see from this that I was very impressed with my 60mm Opticron spotting scope that showed the ring at just 22x magnification. I've successfully used the Opticron terrestrially for several years and it was great to see how well it compared for astro with my 72ED. However, I'm going to have a major clear out next month and the Opticron will be amongst the many items I'll be selling, so look out for an ad. It'll come with a 22x wide angle, 40x, and 20-60x zoom eyepieces.