rl

It's fairly common for Newtonian scopes to arrive with the collimation slightly out. They just don't travel well....part of life with a Newt is learning how to twiddle the knobs and screws to get the best out of it. It's not that difficult after you've done it once...look upon it as the astro equivalent of learning to ride a bicycle! Before touching any of the screws find out what stars look like on a well-collimated scope and see how yours compare. A bit of reading up front will pay dividends..don't dive in first before you're sure of what you're looking for. And then make the adjustments in small steps. The main mirror actually needs to be very slightly loose or the locking screws will bend the shape. The secondary supports are often a bit flimsy in order to obstruct the minimum amount of light, and to minimize the faint "cross" effect caused by diffraction. There are articles on this site of how to do it. Collimation is one reason why a lot of people prefer refractors...they are pretty much adjustment-free. But Newts show a lot more per pound of investment once you've learned to get the best out of them . You may well find Jupiter and Saturn look even better with the scope collimated..

That looks to me like it's out of focus, and out of collimation. At focus a star should be like a bright point of light too small to see the middle, no black dot. At low/ medium magnification it really is just a point. As the magnification goes above 100 you might start to see a bright central dot with a few very faint rings due to the wave nature of light (called a diffraction pattern). Out of focus the black dot should be in the centre; it's due to the secondary mirror blocking light. It's worthwhile reading up on collimation.

Buck converters and flyback converters are cheap (reasonably), very efficient, widely available..lots of plusses. They still suffer slightly from output noise at the chopping frequency which might get in to the kit and cause banding issues on images....might be worth looking at some filters just to make sure what goes in to the camera is really clean. It's the one area where a linear regulator might still have a place. I always use the metal box versions which helps contain noise issues. Mounts and dew heaters don't care about any reasonable amount of noise.

I know, I know....I just couldn't resist it. I'm hardly free of refraction affliction myself!

Very nice collection...add them all up and you've got about the light grasp of a 12" Newt....

Louis, Azrabella That's the puppy. The eye relief is not enough to use with glasses, but without glasses I find it rather comfortable. I can see the whole field easily without my eyelashes going anywhere the glass. The eye relief will be whatever Celestron say it is....

There is not a lot that's any good at 82 degrees for under a ton new. Having just bought a secondhand 14mm Delos to replace a 15mm Celestron 82 degree, you would be welcome to try the 15mm on a sale or return basis if that helps. I use f/4 or f/4.5 scopes and it's not the best but it should work a lot better at f/8. Beware weight and balance issues; your f/8 dob might be more suceptible due to its extra length. RL

I bought a CT8 new and a CT12 secondhand. They are f/4.5, f/4 and have been excellent imaging scopes without modification. That's using a skywatcher aplanatic 4 element coma corrector and a cooled OSC camera APS-C format, with an OAG and filters. There have been no issues on either with tubes bending and the newer focusers are great..a big improvement on the OO design of 10 years ago. If you really want to get heavy with the accessories then the AG range are specifically designed for AP and built like tanks, and the tubes can be reinforced with extra tube rings.

If you have any serious pretensions to doing astrophotography, just about the worst mistake you can make is to under-mount the scope. For a 10" OTA plus accessories you really need something in the EQ6 class. It's not just the weight...that sort of an OTA can be a bit of a sail and a small mount only makes shaking in the breeze worse. It's bending moments as well...the bigger diameter the OTA, the further the weight is from the axis, so you need more counterweights at the same distance, or a longer counterweight bar. My carbon fibre 8" f/4.5 OTA weighs 7kg. Add a coma corrector, camera, decent 80mm finder, tube rings...filter wheel..it soon all adds up to about 13kg. I'm running an AZ-EQ6 which copes perfectly even in a moderate breeze but I need a third counterweight to avoid using the extension bar. The tripod is really good.

DesignSpark is a fairly common freebie https://designspark.zendesk.com/hc/en-us/categories/201145765 Never used it myself so can't comment. As an electronic engineer myself I've never yet found a package I'm truly comfortable with. I've tried Pulsonix, Altium Pcad, Orcad, Easy-PC and several others. They are all a lot of work to learn there is generally a lot of setting up to do....how hard it can be depends on the quality of the parts libraries supplied. If you have only one simple design to make, have you considered giving it to a design house to get prototypes made? I use Morgatronics for the stuff I do professionally. : http://www.morgatronic.co.uk/ It may seem expensive, that depends on how you value your own time. Alternatively, can you frame your design to use DIP chips and leaded parts that can be mounted on veroboard. This is hard nowadays because of the prevalence of surface mount parts, but sometimes it is still possible. RL

+1 for the Maxvision 24mm. These were released a few years ago badge engineered after a major manufacturer cancelled an order, at knockdown prices. Every time I take it out I'm impressed, regardless of the scope,even at f/4.. It works a lot better than its original purchase price would suggest.

What is your light pollution like? Do you need a really narrowband filter to cut out streetlights or are you out in the country where a less aggressive approach might be more apt? As you're probably aware, the narrowband filters do a great job on revealing line emission nebulae at the cost of dimming stars (faint ones to extinction), and all the remaining stars look the same colour. The deep sky filters are often enough if you are at a moderate to good site in the first place, they give a useful increase in contrast on emission nebulae without ruining everything else in the field. I've had the Lumicon deep sky filter for 35 years and it's still my overall favourite, both for visual and AP. But the Astronomik CLS is also excellent. Sorry if I'm teaching granny to suck eggs here. Personally I regard the filter as the least critical link in the chain after the scope and the eyepiece. In my experience most O3 filters give much the same results, as do most deep sky filters. Personally I like filters that have a hydrogen alpha passband....I reckon I can see dark chocolate browns in the brighter emission nebulae which are supposed to be out of the passband for the rod cells. David Knisley did a good comparison: https://www.prairieastronomyclub.org/filter-performance-comparisons-for-some-common-nebulae/ You are obviously fairly close to me...if you want to try a couple for a week or so when the moon is not an issue you're welcome.

Having owned examples of 3 of the 4 types you mention and used them om a variety of scopes from F/4 to F/10: Most people rate ES100 as good as the Ethos. Personally I'm in the minority that would take issue with that..I sold all my Ethos collection when times were hard and got some secondhand ES100 series. They were good, but I found the edge correction and contrast not quite up to Ethos standards. Which is a bit strange...somewhere on this site is an X-ray of an ES14/ 100 and an Ethos 13; the optical configuration is almost identical. Having owned TV, you get used to excellence which raises your consciousness of minor faults in other products which might have otherwise have passed un-noticed ! It's close but I found there was a difference especially in my 12" f/4. Having said that I'm quite short-sighted and for some reason that seems to make a difference. I normally view without contact lenses...the TV eyepieces work just the same with corrected or uncorrected vision. The same isn't quite true with ES; with uncorrected vision I ran into issues with edge correction. The longer the focal length, the bigger the difference. I found the ES25mm virtually unuseable, the 20mm was good, and the 14 and 9mm started to approach the corresponding Ethoses. Mechanically they were probably better than TV, but at a cost in terms of weight. Over time, as finances permitted, they got slowly replaced again by the TV equivalents. But I paid the same secondhand as what I'd paid new for the original set. TV mania and brexit inflation have undoubtedly made them very much a luxury item. But as a rule you can knock 50 quid off the price if the box is missing.. The ES92 is a very good eyepiece indeed. I have the 17mm and it is superb. This is one range where ES really step up to the plate with something different that ticks all the boxes..pity there are only two of them! The 92 degrees is slightly wasted if you use glasses to observe; the field extends above and below my specs....and there is so much eye relief you need to use the fold-up rubber screen to keep out stray light. But viewing is really comfortable. It's my heaviest eyepiece and very much an inappropriate choice for a ZS61 on a star adverturer... It's the ES eyepiece I've kept over the years which says something. I've also got a Myriad 3.5mm for which I paid #150 secondhand. It's edge correction is very good, comparable with the 3.5 Ethos, even in an F/4 scope, but the contrast falls short. But for the price they're worth a look, No experience with the APM. Perhaps John will chime in?

+ another 1 for polemaster. I bought mine in a fit of pique and frustration at 1am after a particularly difficult imaging session where I'd messed up the polar alignment again, after forgetting the procedure. The following morning I had massive buyers' remorse. 300 quid for a webcam and a fancy lead? Come on!....But after it turned up and I tried it I have never looked back. It's convenient to use and setup can be finished in 2 mins. I've never had to refocus it since I bought it. It gives all the accuracy I can use, and PHD2 turns in sub arcsecond results any night when the sky is even halfway decent. My main source of tracking error is now me walking on the slightly uneven flagstones on which the mount tripod sits. The software does one job only and it "just works" which is rare in my experience. The only time it goes wrong is if I'm running 3 cameras on the same USB port..which is my mistake because it can be disconnected once PA is set up. And as has already been pointed out, it can be left running as a constant check, and is easily transferred to other mounts. If I had a fixed mount in an observatory it would be less useful, but if you have to set up from scratch every time then the consistency of results makes it money well spent IMHO, even if I could have bought a Delos for the same cash.

In my experience the short focus refractors can suffer from excessive spherical aberration as well, which is often not noticed over the CA. I've had 2 examples of the ST120 which differed markedly in this respect. They are wonderful for their intended job; widefield views on deep sky. Having said that, the field curvature can be a bit of an issue. It's obvious in some of the bigger TV eyepieces that have a guaranteed flat image plane. The Newtonian might be the better all-rounder if it's got really good mirrors if you have the enthusiasm to fettle it. Which would I choose? I've got both a ST120 and a 6" f/6 Newtonian with very good mirrors (which is a bit longer than your question asks). The Newt is the better overall scope by some margin because it will make a decent fist of everything,, but it's the ST120 that generally gets chucked in the back of the car simply because I know I won't have to faff about with the collimation on site.

Broke out the altair 60mm triplet for a change; had to wait a while for the instrument to settle thermally. It seems to take an age for the pale green CA to fade away on the limb. Worth the wait though.. Cracking view of Theophilus and Cyrillus at *105. Managed to make out 3 of the 4 peaks in Theophilus. Is the 4th peak in the middle or towards the rim a bit? Cyrillus A looked like a tiny white polo mint floating inside the main crater. ; the illumination seemed to catch the rim all the way round. Magic stuff, an hour well spent.

Nice view...the core is nice and granular.

Shokran Siddiq!!

Dangerous thread this one....I'm on memory lane now. I bought this puppy in 1989 knowing I was going to Saudi Arabia for two years. I had it shipped out along with my Meade 8" SCT. The whole lot was impounded by the customs at Dhahran airport, and, despite the valiant efforts of my Saudi employers, nothing could be done to get it released. However, during one of the many negotiating trips to the airport, I managed to trouser my Naglers. I walked out without being stopped with the inevitable question.."Excuse me sir, Is that a Nagler in your pocket or are you just pleased to see me?" or however that translates in Arabic. As far as I know the scope is still there. ....it wasn't that much of a loss since it was one of the Halley examples. During that frantic period anything with glass in the front was fit to go out of the door. Later, one of the internal lenses cracked during a long winter night, probably because of thermal contraction by its retaining ring. It went back to Televue (outside of the guarantee period) and was fixed FOC. I still use it a lot.

The three front eyepieces are Ramsdens bought from Fullerscopes in 1974. I had just built my first "proper" telescope at the tender age of 16; an 8" f/8 long focus Newtonian funded by a 50 pound legacy from an old aunt. The eyepieces were a subsequent birthday present. They are RAS thread, 1", 1/2" and 1/4 ", all without coatings (dust doesn't count!). Not so long ago I compared then to my ethos collection on Jupiter and I was amazed that they gave up very little in the amount of detail seen. The presentation in the ethoses was of course a zillion light years better with the vast field and sharp field stop, and lack of reflections, but in terms of what you could actually draw on paper there wasn't that much in it. I think they were 4 pounds each which I thought was expensive at the time! The 4.8mm Nagler has already featured in this thread. Mine was purchased for the 1988 Mars opposition, for use with a 5" f/10 refractor. At the time it was a big disappointment because Mars was low and the eyepiece was a bit too much power for the conditions. It languished rather unloved for some years until I got into medium/ large fast reflectors, for which it proved to be a match made in heaven as a high power planetary eyepiece. In a 12" f/4 or an 8" f4/5 the views are actually very good conditions permitting. I still use it very regularly in spite of the fact I have a 4.7 ethos. It's small enough and light enough to use with any scope.

I've owned the ZS61 and the now defunct TS65Q which has the field flattener built in. Can't speak about the TSED70 but the TS65Q does have a successor in the TSED70Q which might be worth investigating, although it is more expensive. But you get some of the cost back on the flattener not required. Optically both were excellent. Used visually, the ZS61 had slightly more contrast and sparkle, but field curvature was noticeable with longer top-notch eyepieces. But, to my eyes, no 60mm scope is impressive visually..they serve much better as astrographs. I'm not that fastidious about pixel peeping, as far as I'm concerned both were fine to the corners of a APS-C sensor. The ZS61 was the lighter of the two but a bit more clumsy to set up with the flattener, with the usual spacing accuracy issues. It fitted very well on a star adventurer mount with a Canon DSLR. There is no finder foot and the mounting look a bit weedy with a single foot compared to a pair of rings and a dovetail. Having said that I was never aware of any flexure, but I never used it with an autoguider. You can get red dot finders that clip on to a camera hotshoe. You have to reverse the mounting foot to get the scope+flattener+camera to balance. The TS65Q was the most intelligently designed scope I personally have ever owned from the astrophotography point of view. The focuser was rock-solid ( not that the ZS was in any way deficient), you could rotate the camera, there was a mounting foot for a finder. The TS65Q had a pair of FPL-53 elements in it and the image plane was indeed flat and well corrected on CA. The dewcap also has a locking screw so it won't drop down as it gets looser with age. The whole scope is built like a Panzer tank and weighs more than the ZS61, and I found it too heavy for the SA mount. Mine is on a MK1 Sphinx. The WO ZS71 5-element scope was around at the same time which put the TS65Q somewhat in the shade. There were early production problems with a pinched element (very easily fixed) but i expect TS lave learned the lesson by now. I sold the ZS61 but have kept the TS65Q which must say something.

John Thanks for writing up that post. I had assumed I'd missed the point of closest approach last night due to cloud and the weather here today has not been much better. But I read your comments and sure enough, there was a break in the clouds. Broke out the trusty GT81 and a 21 ethos....as you say. a very clear thin brilliant white crescent for Venus, and a pinkish tiny Mercury dot. Upped the mag with a 10mm ethos and the pair just fitted in the field. Widefield eyepieces are wonderful! Upping the mag to *100, Mercury like a tiny Mars with the dust storms. The phase was difficult to discern with turbulence; I had to wait a couple of minutes for a steady couple of seconds. All in all, a magic 10 minutes. With both planets so near the horizon, I've never before been so aware of atmospheric refraction/ dispersion. On previous nights I've tried lucky imaging but both planets have had red/ blue ends that won't mix. Thanks again, I probably would not have bothered had I not seen the post.

I like all the red giants. around the outside .you have caught those well.

What were the chances? Sadly all too high..